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Heusser A, Dax A, McArdell CS, Udert KM. Comparing the adsorption of micropollutants on activated carbon from anaerobically stored, organics-depleted, and nitrified urine. Water Res 2024; 257:121615. [PMID: 38692253 DOI: 10.1016/j.watres.2024.121615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/27/2024] [Accepted: 04/14/2024] [Indexed: 05/03/2024]
Abstract
Separate collection and treatment of urine optimizes nutrient recovery and enhances micropollutant removal from municipal wastewater. One typical urine treatment train includes nutrient recovery in three biological processes: anaerobic storage, followed by aerobic organics degradation concurrently with nitrification. These are usually followed by activated carbon adsorption to remove micropollutants. However, removing micropollutants prior to nitrification would protect nitrifiers from potential inhibition by pharmaceuticals. In addition, combining simplified biological treatment with activated carbon adsorption could offer a cheap and robust process for removing micropollutants where nutrient recovery is not the first priority, as a partial loss of ammonia occurs without nitrification. In this study, we investigated whether activated carbon adsorption could also take place between the three biological treatment steps. We tested the effectiveness of micropollutant removal with activated carbon after each biological treatment step by conducting experiments with anaerobically stored urine, organics-depleted urine, and nitrified urine. The urine solutions were spiked with 19 pharmaceuticals: amisulpride, atenolol, atenolol acid, candesartan, carbamazepine, citalopram, clarithromycin, darunavir, diclofenac, emtricitabine, fexofenadine, hydrochlorothiazide, irbesartan, lidocaine, metoprolol, N4-acetylsulfamethoxazole, sulfamethoxazole, trimethoprim, venlafaxine, and two artificial sweeteners, acesulfame and sucralose. Batch experiments were conducted with powdered activated carbon (PAC) to determine how much activated carbon achieve which degree of micropollutant removal and how organics, pH, and speciation change from ammonium to nitrate influence adsorption. Micropollutant removal was also tested in granular activated carbon (GAC) columns, which is the preferred technology for micropollutant removal from urine. The carbon usage rates (CUR) per person were lower for all urine solutions than for municipal wastewater. The results showed that organics depletion would be needed when micropollutant removal was the sole aim of urine treatment, as the degradation of easily biodegradable organics prevented clogging of GAC columns. However, CUR did hardly improve with organics-depleted urine compared to stored urine. The lowest CUR was achieved with nitrified urine. This resulted from the additional organics removal during nitrification and not the lower pH or the partial conversion of ammonium to nitrate. In addition, we showed that the relative pharmaceutical removal in all solutions was independent of the initial pharmaceutical concentration unless the background organics matrix changed considerably. We conclude that removal of micropollutants in GAC columns from organics-depleted urine can be performed without clogging, but with the drawback of a higher carbon usage compared to removal from nitrified urine.
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Affiliation(s)
- Aurea Heusser
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; ETH Zürich, Institute of Environmental Engineering, 8093 Zürich, Switzerland
| | - Anne Dax
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Christa S McArdell
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Kai M Udert
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; ETH Zürich, Institute of Environmental Engineering, 8093 Zürich, Switzerland.
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Huang J, Gao F, Liu Q, Gong P, Li H, Jiang Y. Facilitation of Fenton-Like Reaction of Copper-Nitrogen-Doped Carbon-Based Nanocatalysts by Enhancing Hydroxyl Adsorption on Single-Atom Cu-N xC 4- x Sites. Small 2024; 20:e2309637. [PMID: 38010990 DOI: 10.1002/smll.202309637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Indexed: 11/29/2023]
Abstract
Copper-nitrogen-doped carbon-based nanocatalysts (Cu-NCs), containing atomically dispersed Cu-NxC4- x sites, are efficient in boosting the Fenton-like reaction. However, the mechanisms of the Fenton-like reaction, including the pH effect on the products and the effect of the coordination environment on catalytic activity, remain controversial, restricting the development of Cu-NCs. Cu-NCs are experimentally synthesized with Cu-N4 sites and prove that the Fenton-like reaction generates mainly hydroxyl radicals (·OH) in the acidic but ·OH and superoxide radicals (·O2 -) in the neutral. The density functional theory (DFT) calculations reveal that the catalytic activity of Cu-NCs in the Fenton-like reaction is associated with the adsorption strength of ·OH at the Cu site. Further investigation of the effect of the coordination environment of Cu-NCs indicates that the Cu-N2C2 site, which can enhance the ·OH adsorption strength, is an ideal catalyst site for the Fenton-like reaction. These results open the way to facilitating the catalytic activity of Cu-NCs in the Fenton-like reaction.
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Affiliation(s)
- Jian Huang
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan, 250061, China
| | - Fucheng Gao
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan, 250061, China
| | - Qingshui Liu
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan, 250061, China
| | - Pengyu Gong
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan, 250061, China
| | - Hui Li
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan, 250061, China
| | - Yanyan Jiang
- Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan, 250061, China
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Nguyen Xuan T, Nguyen Thi D, Tran Thuong Q, Nguyen Ngoc T, Dang Quoc K, Molnár Z, Mukhtar S, Szabó-Bárdos E, Horváth O. Effect of Copper-Modification of g-C 3N 4 on the Visible-Light-Driven Photocatalytic Oxidation of Nitrophenols. Molecules 2023; 28:7810. [PMID: 38067540 PMCID: PMC10708227 DOI: 10.3390/molecules28237810] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 11/22/2023] [Accepted: 11/23/2023] [Indexed: 04/07/2024] Open
Abstract
Graphitic carbon nitride (g-C3N4) has proved to be a promising heterogeneous photocatalyst in the visible range. It can be used, among others, for the oxidative conversion of environmentally harmful nitrophenols occurring in wastewater. However, its photocatalytic activity needs to be enhanced, which can be achieved by modification with various dopants. In our work, copper-modified g-C3N4 was prepared by ultrasonic impregnation of the pristine g-C3N4 synthesized from thiourea. The morphology, microstructure, and optical properties of the photocatalysts were characterized by XRD, FT-IR, DRS, SEM, XPS, and TEM. DRS analysis indicated a slight change in both the CB and the VB energies of Cu/g-C3N4 compared to those of g-C3N4. The efficiency of the photocatalysts prepared was tested by the degradation of nitrophenols. Copper modification caused a sevenfold increase in the rate of 4-nitrophenol degradation in the presence of H2O2 at pH = 3. This dramatic enhancement can be attributed to the synergistic effect of copper and H2O2 in this photocatalytic system. A minor Fenton reaction role was also detected. The reusability of the Cu/g-C3N4 catalyst was demonstrated through five cycles. Copper-modified g-C3N4 with H2O2 proved to be applicable for efficient visible-light-driven photocatalytic oxidative degradation of nitrophenols.
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Affiliation(s)
- Truong Nguyen Xuan
- School of Chemistry and Life Sciences, Hanoi University of Science and Technology, No.1 Dai Co Viet Street, Hai Ba Trung District, Hanoi 100000, Vietnam; (T.N.X.); (Q.T.T.); (T.N.N.)
| | - Dien Nguyen Thi
- Viettel Aerospace Institute, Viettel Group, Hoa Lac High-Tech Park, Thach That District, Hanoi 10000, Vietnam;
| | - Quang Tran Thuong
- School of Chemistry and Life Sciences, Hanoi University of Science and Technology, No.1 Dai Co Viet Street, Hai Ba Trung District, Hanoi 100000, Vietnam; (T.N.X.); (Q.T.T.); (T.N.N.)
| | - Tue Nguyen Ngoc
- School of Chemistry and Life Sciences, Hanoi University of Science and Technology, No.1 Dai Co Viet Street, Hai Ba Trung District, Hanoi 100000, Vietnam; (T.N.X.); (Q.T.T.); (T.N.N.)
| | - Khanh Dang Quoc
- School of Materials Science and Engineering, Hanoi University of Science and Technology, No.1 Dai Co Viet Street, Hai Ba Trung District, Hanoi 100000, Vietnam;
| | - Zsombor Molnár
- Environmental Mineralogy Research Group, Research Institute of Biomolecular and Chemical Engineering, University of Pannonia, P.O. Box 1158, H-8210 Veszprém, Hungary;
| | - Shoaib Mukhtar
- Research Group of Environmental and Inorganic Photochemistry, Center for Natural Sciences, Faculty of Engineering, University of Pannonia, P.O. Box 1158, H-8210 Veszprém, Hungary (E.S.-B.)
| | - Erzsébet Szabó-Bárdos
- Research Group of Environmental and Inorganic Photochemistry, Center for Natural Sciences, Faculty of Engineering, University of Pannonia, P.O. Box 1158, H-8210 Veszprém, Hungary (E.S.-B.)
| | - Ottó Horváth
- Research Group of Environmental and Inorganic Photochemistry, Center for Natural Sciences, Faculty of Engineering, University of Pannonia, P.O. Box 1158, H-8210 Veszprém, Hungary (E.S.-B.)
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4
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De Simone G, Monaca SD, Fattibene P, Bocedi A, Coletta M, Ascenzi P. Ferrous nitrosylated cytochrome c: The unusual strength of the proximal His18-Fe bond. J Inorg Biochem 2023; 247:112338. [PMID: 37549473 DOI: 10.1016/j.jinorgbio.2023.112338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/04/2023] [Accepted: 07/20/2023] [Indexed: 08/09/2023]
Abstract
NO binding to horse heart cytochrome c (hhcyt c) has been investigated as a function of pH by both optical absorption and EPR spectroscopies. Lowering pH from 3.5 to 1.5 induces: (i) a blue-shift of the maximum of the optical absorption spectrum in the Soret region from 415 to about 404 nm, and (ii) the appearance of a strong three hyperfine splitting in the gz region of the EPR spectrum. Both spectroscopic features indicate the cleavage of the proximal His18-Fe(II)-NO bond giving rise to the five-coordinated Fe(II)-NO species. By quantification of the relative weight for the six- and the five-coordinated component in the EPR spectra, the pKa value was determined. The apparent pKa of the proximal His Nε atom (1.8 ± 0.1) is unusually low for a ferrous nitrosylated form since in all investigated ferrous NO-bound heme-proteins the pKa value for the cleavage of the proximal His-Fe(II) bond ranges between 3.7 and 5.8. The pKa value of ferrous nitrosylated hhcyt c indicates that the strength of the proximal His18-Fe(II) bond (= 27.9 kJ/mol) is about 10-22 kJ/mol higher than that observed in all investigated heme-proteins. The strong coordination of the heme-Fe atom by His18 is extremely important to maintain the redox efficiency of cyt c and to keep apoptosis under control. This is a crucial point in tissues, such as retina, where apoptosis might trigger macular degenerative processes.
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Affiliation(s)
| | - Sara Della Monaca
- Servizio Grandi Strumentazioni and Core Facilities, Istituto Superiore di Sanità, 00185 Roma, Italy
| | - Paola Fattibene
- Servizio Grandi Strumentazioni and Core Facilities, Istituto Superiore di Sanità, 00185 Roma, Italy
| | - Alessio Bocedi
- Department of Chemical Sciences and Technologies, University of Roma "Tor Vergata", 00133 Roma, Italy
| | | | - Paolo Ascenzi
- Department of Sciences, Roma Tre University, 00146 Roma, Italy; Accademia Nazionale dei Lincei, 00165 Roma, Italy.
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Vrettos NN, Wang P, Wang Y, Roberts CJ, Xu J, Yao H, Zhu Z. Controlled release of MT-1207 using a novel gastroretentive bilayer system comprised of hydrophilic and hydrophobic polymers. Pharm Dev Technol 2023; 28:724-742. [PMID: 37493413 DOI: 10.1080/10837450.2023.2238822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 07/17/2023] [Indexed: 07/27/2023]
Abstract
In the present study, novel gastroretentive bilayer tablets were developed that are promising for the once-a-day oral delivery of the drug candidate MT-1207. The gastroretentive layer consisted of a combination of hydrophilic and hydrophobic polymers, namely polyethylene oxide and Kollidon® SR. A factorial experiment was conducted, and the results revealed a non-effervescent gastroretentive layer that, unlike most gastroretentive layers reported in the literature, was easy to prepare, and provided immediate tablet buoyancy (mean floating lag time of 1.5 s) that lasted over 24 h in fasted state simulated gastric fluid (FaSSGF) pH 1.6, irrespective of the drug layer, thereby allowing a 24-hour sustained release of MT-1207 from the drug layer of the tablets. Furthermore, during in vitro buoyancy testing of the optimised bilayer tablets in media of different pH values (1.0, 3.0, 6.0), the significant difference (one-way ANOVA, p < 0.001) between the respective total floating times indicated that stomach pH effects on tablet buoyancy are important to be considered during the development of non-effervescent gastroretentive formulations and the choice of dosing regimen. To the best of our knowledge, this has not been reported before, and it should probably be factored in when designing dosing regimens. Finally, a pharmacokinetic study in Beagle dogs indicated a successful in vivo 24-hour sustained release of MT-1207 from the optimised gastroretentive bilayer tablet formulations with the drug plasma concentration remaining above the estimated minimum effective concentration of 1 ng/mL at the 24-hour timepoint and also demonstrated the gastroretentive capabilities of the hydrophilic and hydrophobic polymer combination. The optimised formulations will be forwarded to clinical development.
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Affiliation(s)
| | - Peng Wang
- School of Pharmacy, China Pharmaceutical University, Nanjing, P.R. China
| | - Yuhan Wang
- School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | - Clive J Roberts
- School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | - Jinyi Xu
- School of Pharmacy, China Pharmaceutical University, Nanjing, P.R. China
| | - Hong Yao
- School of Pharmacy, China Pharmaceutical University, Nanjing, P.R. China
| | - Zheying Zhu
- School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
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Chubar N, Szlachta M, Gerda V. Extended X-ray Absorption Fine Structure Revealed the Mechanism of Arsenate Removal by the Fe/Mn Oxide-Based Composite under Conditions of Fully Saturated Sorption Sites. ACS Appl Mater Interfaces 2023; 15:44572-44588. [PMID: 37672648 DOI: 10.1021/acsami.3c10999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
Molecular mechanism of arsenate removal by a promising inorganic composite based on Fe/Mn oxides and MnCO3 was studied under the rarely investigated conditions of fully saturated sorption sites (characteristic of dynamic sorption, such as water treatment plants) at the pH of 4/6/7/8 using As K-edge extended X-ray absorption fine structure (EXAFS)/X-ray absorption near-edge structure (XANES), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). Comparison of arsenic speciation in the initial adsorbate solution (calculated by Visual MINTEQ) and after sorption (determined by As 3d XPS) allowed the interpretation of the initializing forces of the interfacial processes. Contribution of various solid phases of this composite anion exchanger to the removal of arsenate was disclosed by examining the Fe 2p3/2 and Mn 2p3/2 XPS spectra supported by FTIR. As K-edge EXAFS simulation not only proved the chemisorptive binding of aqueous As(V) anions to the Fe/Mn oxide-based adsorbent but also demonstrated the presence of a variety of sorption sites in this complex structured porous material, which became available step-wise upon an increasing pressure on the interface with high arsenate loading during the long-term sorption process. The type of inner-sphere complexation of As(V) on the saturated surface discovered by As K-edge EXAFS modeling was a function of pH. Analysis of EXAFS fitting data resulted in suggestion of a methodological idea on how the EXAFS-derived coordination numbers can be used to distinguish the localization of adsorbed ions (surface versus structure emptiness). This work also provides more insights into the superiority of composite adsorbents (compared to the materials based on individual compounds) in terms of their capability to adapt/change the molecular sorption mechanism in order to inactivate (remove) more toxic aqueous anions.
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Affiliation(s)
- Natalia Chubar
- Department of Earth Sciences, Utrecht University, Budapestlaan 4, Utrecht 3584 CD, Netherlands
| | - Małgorzata Szlachta
- Department of Earth Sciences, Utrecht University, Budapestlaan 4, Utrecht 3584 CD, Netherlands
- Faculty of Environmental Engineering, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, Wrocław 50-370, Poland
| | - Vasyl Gerda
- Department of Earth Sciences, Utrecht University, Budapestlaan 4, Utrecht 3584 CD, Netherlands
- Faculty of Chemistry, Taras Shevchenko National University of Kyiv, Lva Tolstogo Street 12, Kyiv 01601, Ukraine
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7
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Zeng Q, Liu Y, Sun J, Jin Y. Providing New Insights on the Molecular Properties and Thermal Stability of Ovotransferrin and Lactoferrin. Foods 2023; 12:foods12030532. [PMID: 36766060 PMCID: PMC9914018 DOI: 10.3390/foods12030532] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 01/21/2023] [Accepted: 01/23/2023] [Indexed: 01/27/2023] Open
Abstract
Ovotransferrin (OVT) is a multi-functional protein showing over 50% homology with Bovine lactoferrin (BLF) and human lactoferrin (HLF), which have the potential to be a substitute for lactoferrin (LF) due to the limited production of LF. To explore the substitutability of OVT, the molecular properties and thermal stability of OVT, BLF and HLF were characterized because these properties will affect the processing quality and biological activities of protein products when exposed to different processing conditions (e.g., temperature, pH, ion strength). The results showed that although obviously different isoelectric point (5.31, 9.12 and 8.75 for OVT, BLF and HLF, respectively), particle size distribution and hydrophobicity were found, they exhibited good dispersity because of high potential value. They showed an endothermic peak at 80.64 °C, 65.71 °C and 90.01 °C, respectively, and the denaturation temperature varied at different pH and ionic strength. OVT and BLF were more susceptible to heating at pH 5.0 as reflected by the decline of denaturation temperature (21.78 °C shift for OVT and 5.81 °C shift for BLF), while HLF could remain stable. Compared with BLF, OVT showed higher secondary structure stability at pH 7.0 and 9.0 with heating. For example, the α-helix content of OVT changed from 20.35% to 15.4% at pH 7.0 after heating, while that of BLF changed from 20.05% to 6.65%. The increase on fluorescence intensity and redshifts on the maximum wavelength after heating indicated the changes of tertiary structure of them. The turbidity measurements showed that the thermal aggregation degree of OVT was lower than BLF and HLF at pH 7.0 (30.98%, 59.53% and 35.66%, respectively) and pH 9.0 (4.83%, 12.80% and 39.87%, respectively). This work demonstrated the similar molecular properties and comparable thermal stability of OVT to BLF and HLF, which can offer a useful reference for the substitute of LF by OVT.
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Affiliation(s)
- Qi Zeng
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yaping Liu
- College of Food Science and Engineering, Northwest A&F University, Xianyang 712100, China
| | - Jing Sun
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
- Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Science, Wuhan 430072, China
| | - Yongguo Jin
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
- Correspondence:
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Azueta-Aguayo PH, Chuc-Gamboa MG, Aguilar-Pérez FJ, Aguilar-Ayala FJ, Rodas-Junco BA, Vargas-Coronado RF, Cauich-Rodríguez JV. Effects of Neutralization on the Physicochemical, Mechanical, and Biological Properties of Ammonium-Hydroxide-Crosslinked Chitosan Scaffolds. Int J Mol Sci 2022; 23. [PMID: 36499146 DOI: 10.3390/ijms232314822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/17/2022] [Accepted: 11/17/2022] [Indexed: 12/03/2022] Open
Abstract
It has been reported that chitosan scaffolds, due to their physicochemical properties, stimulate cell proliferation in different tissues of the human body. This study aimed to determine the physicochemical, mechanical, and biological properties of chitosan scaffolds crosslinked with ammonium hydroxide, with different pH values, to better understand cell behavior depending on the pH of the biomaterial. Scaffolds were either neutralized with sodium hydroxide solution, washed with distilled water until reaching a neutral pH, or kept at alkaline pH. Physicochemical characterization included scanning electron microscopy (SEM), elemental composition (EDX), Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, thermogravimetric analysis (TGA), and mechanical testing. In vitro cytotoxicity was assessed via dental-pulp stem cells' (DPSCs') biocompatibility. The results revealed that the neutralized scaffolds exhibited better cell proliferation and morphology. It was concluded that the chitosan scaffolds' high pH (due to residual ammonium hydroxide) decreases DPSCs' cell viability.
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AbuMousa RA, Khezami L, Ismail M, Ben Aissa MA, Modwi A, Bououdina M. Efficient Mesoporous MgO/g-C 3N 4 for Heavy Metal Uptake: Modeling Process and Adsorption Mechanism. Nanomaterials (Basel) 2022; 12:3945. [PMID: 36432231 PMCID: PMC9693060 DOI: 10.3390/nano12223945] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 10/30/2022] [Accepted: 11/04/2022] [Indexed: 06/16/2023]
Abstract
Removing toxic metal ions arising from contaminated wastewaters caused by industrial effluents with a cost-effective method tackles a serious concern worldwide. The adsorption process onto metal oxide and carbon-based materials offers one of the most efficient technologies adopted for metal ion removal. In this study, mesoporous MgO/g-C3N4 sorbent is fabricated by ultrasonication method for the uptake Pb (II) and Cd (II) heavy metal ions from an aqueous solution. The optimum conditions for maximum uptake: initial concentration of metal ions 250 mg g-1, pH = 5 and pH = 3 for Pb++ and Cd++, and a 60 mg dose of adsorbent. In less than 50 min, the equilibrium is reached with a good adsorption capacity of 114 and 90 mg g-1 corresponding to Pb++ and Cd++, respectively. Moreover, the adsorption isotherm models fit well with the Langmuir isotherm, while the kinetics model fitting study manifest a perfect fit with the pseudo-second order. The as fabricated mesoporous MgO/g-C3N4 sorbent exhibit excellent Pb++ and Cd++ ions uptake and can be utilized as a potential adsorbent in wastewater purification.
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Affiliation(s)
- Rasha A. AbuMousa
- Department of Mathematics and Sciences, College of Humanities and Sciences, Prince Sultan University, Riyadh 11586, Saudi Arabia
| | - Lotfi Khezami
- College of Science, Chemistry Department, Imam Mohammad Ibn Saud Islamic University (IMSIU), P.O. Box 5701, Riyadh 11432, Saudi Arabia
| | - Mukhtar Ismail
- Department of Chemistry, College of Science and Arts, Qassim University, Ar Rass 51921, Saudi Arabia
| | - Mohamed Ali Ben Aissa
- Department of Chemistry, College of Science and Arts, Qassim University, Ar Rass 51921, Saudi Arabia
| | - Abueliz Modwi
- Department of Chemistry, College of Science and Arts, Qassim University, Ar Rass 51921, Saudi Arabia
| | - Mohamed Bououdina
- Department of Mathematics and Sciences, College of Humanities and Sciences, Prince Sultan University, Riyadh 11586, Saudi Arabia
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Martínez-Mendoza LJ, Lebrero R, Muñoz R, García-Depraect O. Influence of key operational parameters on biohydrogen production from fruit and vegetable waste via lactate-driven dark fermentation. Bioresour Technol 2022; 364:128070. [PMID: 36202282 DOI: 10.1016/j.biortech.2022.128070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/28/2022] [Accepted: 09/30/2022] [Indexed: 06/16/2023]
Abstract
This study aims at investigating the influence of operational parameters on biohydrogen production from fruit-vegetable waste (FVW) via lactate-driven dark fermentation. Mesophilic batch fermentations were conducted at different pH (5.5, 6.0, 6.5, 7.0, and non-controlled), total solids (TS) contents (5, 7, and 9%) and initial cell biomass concentrations (18, 180, and 1800 mg VSS/L). Higher hydrogen yields and rates were attained with more neutral pH values and low TS concentrations, whereas higher biomass densities enabled higher production rates and avoided wide variations in hydrogen production. A marked lactate accumulation (still at neutral pH) in the fermentation broth was closely associated with hydrogen inhibition. In contrast, enhanced hydrogen productions matched with much lower lactate accumulations (even it was negligible in some fermentations) along with the acetate and butyrate co-production but not with carbohydrates removal. At pH 7, 5% TS, and 1800 mg VSS/L, 49.5 NmL-H2/g VSfed and 976.4 NmL-H2/L-h were attained.
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Affiliation(s)
- Leonardo J Martínez-Mendoza
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain
| | - Raquel Lebrero
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain
| | - Raúl Muñoz
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain
| | - Octavio García-Depraect
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain.
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11
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Boonamnaj P, Pandey R, Sompornpisut P. Effect of pH on stability of dimer structure of the main protease of coronavirus-2. Biophys Chem 2022; 287:106829. [PMID: 35635893 PMCID: PMC9119281 DOI: 10.1016/j.bpc.2022.106829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/04/2022] [Accepted: 05/14/2022] [Indexed: 02/09/2023]
Abstract
The viral main protease (Mpro) from a novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a key enzyme essential for viral replication and has become an attractive target for antiviral drug development. The Mpro forms a functional dimer and exhibits a pH-dependent enzyme activity and dimerization. Here, we report a molecular dynamics (MD) investigation to gain insights into the structural stability of the enzyme dimer at neutral and acidic pH. Our data shows larger changes in structure of the protein with the acidic pH than that with the neutral pH. Structural analysis of MD trajectories reveals a substantial increase in intersubunit separation, the loss of domain contacts, binding free energy and interaction energy of the dimer which implies the protein instability and tendency of dimer dissociation at acidic pH. The loss in the interaction energy is mainly driven by electrostatic interactions. We have identified the intersubunit hydrogen-bonding residues involved in the decreased dimer stability. These findings may be helpful for rational drug design and target evaluation against COVID-19.
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Affiliation(s)
- Panisak Boonamnaj
- The Center of Excellence in Computational Chemistry, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - R.B. Pandey
- School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA
| | - Pornthep Sompornpisut
- The Center of Excellence in Computational Chemistry, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand,Corresponding author
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12
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Ko B, Ahn J, Song SH. pH-Dependent Photophysical Properties of Metallic Phase MoSe 2 Quantum Dots. Materials (Basel) 2022; 15:ma15144945. [PMID: 35888412 PMCID: PMC9318461 DOI: 10.3390/ma15144945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 06/30/2022] [Accepted: 07/14/2022] [Indexed: 12/10/2022]
Abstract
Fluorescence properties of quantum dots (QDs) are critically affected by their redox states, which is important for practical applications. In this study, we investigated the optical properties of MoSe2-metallic phase quantum-dots (MoSe2-mQDs) depending on the pH variation, in which the MoSe2-mQDs were dispersed in water with two sizes (Φ~3 nm and 12 nm). The larger MoSe2-mQDs exhibited a large red-shift and broadening of photoluminescence (PL) peak with a constant UV absorption spectra as varying the pH, while the smaller ones showed a small red-shift and peak broadening, but discrete absorption bands in the acidic solution. The excitation wavelength-dependent photoluminescence shows that the PL properties of smaller MoSe2-mQDs are more sensitive to the pH change compared to those of larger ones. From the time-resolved PL spectroscopy, the excitons dominantly decaying with an energy of ~3 eV in pH 2 clearly show the shift of PL peak to the lower energy (~2.6 eV) as the pH increases to 7 and 11 in the smaller MoSe2-mQDs. On the other hand, in the larger MoSe2-mQDs, the exciton decay is less sensitive to the redox states compared to those of the smaller ones. This result shows that the pH variation is more critical to the change of photophysical properties than the size effect in MoSe2-mQDs.
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13
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Liu B, Gao Y, Pan J, Feng Q, Yue Q, Guo K, Gao B. Coagulation behavior of polyaluminum-titanium chloride composite coagulant with humic acid: A mechanism analysis. Water Res 2022; 220:118633. [PMID: 35613484 DOI: 10.1016/j.watres.2022.118633] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 05/07/2022] [Accepted: 05/16/2022] [Indexed: 06/15/2023]
Abstract
The hydrolysate species of metal-based coagulants and the binding sites of humic acid (HA) are highly dependent on the pH conditions. Exploring the binding sites and modes between coagulant hydrolysates and HA molecules is critical to understanding the coagulation mechanism. In this paper, the binding behavior between HA molecules and the hydrolysates of a polyaluminum-titanium chloride composite coagulant (PATC) was investigated under different pH conditions by semi-quantitative FTIR and XPS. It was found that oligomeric and mesopolymeric hydrolysates were the dominant species under acid conditions, which could complex with the hydroxyl and carboxyl groups of HA by forming COAl/Ti coordinate bonds. However, large amounts of H+ could compete with Al3+ and weaken the removal efficiency of HA. With the increase of pH, the hydrolysis process of the PATC and the deprotonation of HA were simultaneously underway. Under weakly acid conditions, the complexation of the aluminum hydrolysates with carboxyl groups was improved due to the gradually diminishing competition of H+ and the enhanced charge neutralization of the further polymerized hydrolysates. Consequently, the maximum UV254 removal by adding PATC was observed at pH 6. Under alkaline conditions, the sweeping effect of amorphous hydroxide dominated the HA removals, which was accompanied by the surface complexation of Al/Ti nuclear with carboxyl groups as well as the hydrogen bonds between hydroxyl and hydroxide. This study provides a new clue for the interaction mechanisms between the hydrolysates of composite coagulants and the dominant functional groups of HA at various pH conditions.
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Affiliation(s)
- Beibei Liu
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 26600, PR China
| | - Yue Gao
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 26600, PR China
| | - Jingwen Pan
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 26600, PR China
| | - Qiyun Feng
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 26600, PR China
| | - Qinyan Yue
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 26600, PR China
| | - Kangying Guo
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 26600, PR China.
| | - Baoyu Gao
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 26600, PR China.
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14
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Bae WB, Kim HJ, Jhee KH. Selective Homocysteine Assay with Cucurbit[7]uril by pH Regulation. J Microbiol Biotechnol 2022; 32:514-521. [PMID: 35131958 PMCID: PMC9628864 DOI: 10.4014/jmb.2201.01016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 01/21/2022] [Indexed: 12/15/2022]
Abstract
We report the effect of pH on the supramolecular complexation of two biothiols, viz., homocysteine (Hcy) and cysteine (Cys), with cucurbit[7]uril (CB[7]). Under basic pH conditions, Cys did not complex with CB[7], whereas Hcy efficiently complexed with CB[7], as confirmed by 1H NMR spectroscopy and Ellman's reagent (5,5'-dithio-bis(2-nitrobenzoic acid), DTNB) assay. 1H NMR and Raman spectroscopic studies revealed that, in the absence of CB[7], Hcy auto-oxidized slowly (~36 h) to homocystine (HSSH) under basic pH conditions. However, the rate of Hcy oxidation increased by up to 150 fold in the presence of CB[7], as suggested by the DTNB assay. Thus, supramolecular complexation under basic pH conditions led to the formation of a HSSH-CB[7] complex, and not Hcy-CB[7]. The results indicate that Hcy is rapidly oxidized to HSSH under the catalysis of CB[7], which acts as a reaction chamber, in basic pH conditions. Our studies suggest that Hcy concentration, a risk factor for cardiovascular disease, can be selectively and more easily quantified by supramolecular complexation with CB [7].
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Affiliation(s)
- Won-Bin Bae
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea
| | - Hee-Joon Kim
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea,
H.-J. Kim Phone: +82-54-478-7822 E-mail:
| | - Kwang-Hwan Jhee
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea,Corresponding authors K.-H. Jhee Phone: +82-54-478-7837 Fax: +82-54-478-7710 E-mail:
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15
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Ligorio C, Vijayaraghavan A, Hoyland JA, Saiani A. Acidic and basic self-assembling peptide and peptide-graphene oxide hydrogels: characterisation and effect on encapsulated nucleus pulposus cells. Acta Biomater 2022; 143:145-58. [PMID: 35196554 DOI: 10.1016/j.actbio.2022.02.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 02/11/2022] [Accepted: 02/16/2022] [Indexed: 12/28/2022]
Abstract
Extracellular pH can have a profound effect on cell metabolism, gene and protein expression. Nucleus pulposus (NP) cells, for example, under acidic conditions accelerate the production of degradative enzymes and pro-inflammatory cytokines, leading ultimately to intervertebral disc degeneration, a major cause of back pain. Self-assembling peptide hydrogels constitute a well-established class of biomaterials that could be exploited as pH-tunable platform to investigate cell behaviour under normal and non-physiological pH. In this paper we formulated acidic (pH = 4) and basic (pH = 9) hydrogels, from the same octapeptide FEFKFEFK (F8) (F = phenyalanine, E = glutamic acid, K = lysine), to test the effect of non-physiological pH on encapsulated NP cells. Similarly, graphene oxide-containing F8 hydrogels (GO-F8) were formulated as stiffer analogues. Acidic and basic hydrogels showed peculiar morphologies and rheological properties, with all systems able to buffer within 30 minutes of exposure to cell culture media. NP cells seeded in acidic F8 hydrogels showed a more catabolic phenotype compared to basic hydrogels, with increased gene expression of degradative enzymes (MMP-3, ADAMTS-4), neurotrophic factors (NGF and BDNF) and NF-κB p65 phosphorylation. Acidic GO-F8 hydrogels also induced a catabolic response, although milder than basic counterparts and with the highest gene expression of characteristic NP-matrix components, aggrecan and collagen II. In all systems, the cellular response had a peak within 3 days of encapsulation, thereafter decreasing over 7 days, suggesting a 'transitory' effect of hydrogel pH on encapsulated cells. This work gives an insight on the effect of pH (and pH buffering) on encapsulated NP cells and offers new designs of low and high pH peptide hydrogels for 3D cell culture studies. STATEMENT OF SIGNIFICANCE: We have recently shown the potential of graphene oxide - self-assembling peptide hybrid hydrogels for NP cell culture and regeneration. Alongside cell carrier, self-assembling peptide hydrogels actually provide a versatile pH-tunable platform for biological studies. In this work we decided to explore the effect of non-physiological pH (and pH buffering) on encapsulated NP cells. Our approach allows the formulation of both acidic and basic hydrogels, starting from the same peptide sequence. We showed that the initial pH of the scaffold does not affect significantly cell response to encapsulation, but the presence of GO results in lower inflammatory levels and higher NP matrix protein production. This platform could be exploited to study the effect of pH on different cell types whose behaviour can be pH-dependent.
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16
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Kang JM, Lê HG, Na BK, Yoo WG. pH-Dependent Structural Dynamics of Cathepsin D-Family Aspartic Peptidase of Clonorchis sinensis. Pathogens 2021; 10:1128. [PMID: 34578162 DOI: 10.3390/pathogens10091128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 08/27/2021] [Accepted: 08/29/2021] [Indexed: 12/03/2022] Open
Abstract
Cathepsin D (CatD; EC 3.4.23.5) family peptidases of parasitic organisms are regarded as potential drug targets as they play critical roles in the physiology and pathobiology of parasites. Previously, we characterized the biochemical features of cathepsin D isozyme 2 (CatD2) in the carcinogenic liver fluke Clonorchis sinensis (CsCatD2). In this study, we performed all-atomic molecular dynamics simulations by applying different systems for the ligand-free/bound forms under neutral and acidic conditions to investigate the pH-dependent structural alterations and associated functional changes in CsCatD2. CsCatD2 showed several distinctive characteristics as follows: (1) acidic pH caused major conformational transitions from open to closed state in this enzyme; (2) during 30–36-ns simulations, acidic pH contributed significantly to the formation of rigid β-sheets around the catalytic residue Asp219, higher occupancy (0% to 99%) of hydrogen bond than that of Asp33, and enhanced stabilization of the CsCatD2-inhibtor complex; (3) neutral pH-induced displacement of the N-terminal part to hinder the accessibility of the active site and open allosteric site of this enzyme; and (4) the flap dynamics metrics, including distance (d1), TriCα angles (θ1 and θ2), and dihedral angle (ϕ), account for the asymmetrical twisting motion of the active site of this enzyme. These findings provide an in-depth understanding of the pH-dependent structural dynamics of free and bound forms of CsCatD2 and basic information for the rational design of an inhibitor as a drug targeting parasitic CatD.
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17
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Pavanelli ALS, Máximo LNC, da Silva RS, Borissevitch IE. Effect of Serum Albumin on Porphyrin-Quantum Dot Complex Formation, Characteristics and Spectroscopic Analysis. Nanomaterials (Basel) 2021; 11:1674. [PMID: 34202308 DOI: 10.3390/nano11071674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 11/17/2022]
Abstract
The effect of bovine serum albumin (BSA) upon interaction between CdTe QD functionalized by 3-Mercaptopropionic Acid (CdTe-3-MPA QD) and two water soluble porphyrins: positively charged meso-tetra methyl pyridyl porphyrin (TMPyP) and negatively charged meso-tetrakis(p-sulfonato-phenyl) porphyrin (TPPS4), was studied in function of pH using the steady-state and time resolved optical absorption and fluorescence spectroscopies. It was shown that, depending on the charge state of the components, interaction with albumin could either prevent the formation of the QD…PPh complex, form a mixed QD…PPh…BSA complex or not affect PPh complexation with QD at all. The obtained results may be of interest for application in photomedicine.
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18
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Farh MEA, Abdellaoui N, Seo JA. pH Changes Have a Profound Effect on Gene Expression, Hydrolytic Enzyme Production, and Dimorphism in Saccharomycopsis fibuligera. Front Microbiol 2021; 12:672661. [PMID: 34248880 PMCID: PMC8265565 DOI: 10.3389/fmicb.2021.672661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 05/25/2021] [Indexed: 11/21/2022] Open
Abstract
Saccharomycopsis fibuligera is an amylolytic yeast that plays an important role within nuruk (a traditional Korean fermentation starter) used for the production of makgeolli (Korean rice wine), which is characterized by high acidity. However, the effect of pH change (neutral to acidic) on the yeast cell to hyphal transition and carbohydrate-hydrolyzing enzyme activities for S. fibuligera has not been investigated yet. In this study, S. fibuligera strains were cultured under the different pH conditions, and the effect on the enzyme production and gene expression were investigated. An acidic pH induced a hyphal transition from yeast cell of S. fibuligera KPH12 and the hybrid strain KJJ81. In addition, both strains showed a gradual decrease in the ability to degrade starch and cellulose as the pH went down. Furthermore, a transcriptome analysis demonstrated that the pH decline caused global expression changes in genes, which were classified into five clusters. Among the differentially expressed genes (DEGs) under acidic pH, the downregulated genes were involved in protein synthesis, carbon metabolism, and RIM101 and cAMP-PKA signaling transduction pathways for the yeast-hyphal transition. A decrease in pH induced a dimorphic lifestyle switch from yeast cell formation to hyphal growth in S. fibuligera and caused a decrease in carbohydrate hydrolyzing enzyme production, as well as marked changes in the expression of genes related to enzyme production and pH adaptation. This study will help to elucidate the mechanism of adaptation of S. fibuligera to acidification that occur during the fermentation process of makgeolli using nuruk.
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Affiliation(s)
| | - Najib Abdellaoui
- School of Systems Biomedical Science, Soongsil University, Seoul, South Korea
| | - Jeong-Ah Seo
- School of Systems Biomedical Science, Soongsil University, Seoul, South Korea
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19
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Abstract
FOLFOX is the most common chemotherapy combination prescribed in colorectal cancer. It is composed of calcium levofolinate, 5-fluorouracil and oxaliplatin which demonstrated synergistic outcome. Nowadays, the lack of all-in-one formulation is due to the chemical composition of the pharmaceutical products and the highly pH-dependent stability of each drug. Herein, we aimed to investigate the stability of a ternary mixture of 5-fluorouracil, oxaliplatin and calcium levofolinate, knowing that coadministering these drugs would improve their efficacy. The effect of three pHs (5.0, 6.0 and 7.5) and two drug concentrations (8/3/6 and 1/1/1 mg/ml for 5-fluorouracil, oxaliplatin and calcium levofolinate, respectively) were examined. A high-performance liquid chromatography method was developed to separate and quantify the three drugs in one run. At higher concentrations, the ternary mixture was unstable regardless of pH. By reducing concentration, drug stability and compatibility in the mixture was improved at pH 5.0 for up to 3 days at +5°C ± 3 °C. In addition, binary mixtures provided stable properties at defined pHs. 5-fluorouracil/oxaliplatin mixture was stable at pH 5.0 over 48 hours while 5-fluorouracil/calcium levofolinate mixture was stable at pHs 6.0 and 7.5 up to 7 days.
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Affiliation(s)
- Chantal Al Sabbagh
- Faculté de Pharmacie, Université de Paris, UTCBS (Unité de Technologies Chimiques et Biologiques pour la Santé), Paris, France
| | - Elena Agapova
- Faculté de Pharmacie, Université de Paris, UTCBS (Unité de Technologies Chimiques et Biologiques pour la Santé), Paris, France
| | - Vincent Boudy
- Faculté de Pharmacie, Université de Paris, UTCBS (Unité de Technologies Chimiques et Biologiques pour la Santé), Paris, France.,Pharmaceutical R&D Department, Agence Générale des Equipements et Produits de Santé (AGEPS), Paris, France
| | - Nathalie Mignet
- Faculté de Pharmacie, Université de Paris, UTCBS (Unité de Technologies Chimiques et Biologiques pour la Santé), Paris, France
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20
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Ghaffarinasab S, Motamedian E. Improving ethanol production by studying the effect of pH using a modified metabolic model and a systemic approach. Biotechnol Bioeng 2021; 118:2934-2946. [PMID: 33913513 DOI: 10.1002/bit.27800] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 03/19/2021] [Accepted: 04/21/2021] [Indexed: 11/06/2022]
Abstract
pH is an important factor affecting the growth and production of microorganisms; especially, its effect on ethanologenic microorganisms. It can change the ionization state of metabolites via the change in the charge of their functional groups that may lead to metabolic alteration. Here, we estimated the ionization state of metabolites and balanced the charge of reactions in genome-scale metabolic models of Saccharomyces cerevisiae, Escherichia coli, and Zymomonas mobilis at pH levels 5, 6, and 7. The robustness analysis was first implemented to anticipate the effect of proton exchange flux on growth rates for the constructed metabolic models at various pH. In accordance with previous experimental reports, the models predict that Z. mobilis is more sensitive to pH rather than S. cerevisiae and the yeast is more regulated by pH rather than E. coli. Then, a systemic approach was proposed to predict the pH effect on metabolic change and to find effective reactions on ethanol production in S. cerevisiae. The correlated reactions with ethanol production at predicted optimal pH in a range of proton exchange rates determined by robustness analysis were identified using the Pearson correlation coefficient. Then, fluxes of these reactions were applied to cluster the various pHs by principal component analysis and to identify the role of these reactions on metabolic differentiation because of pH change. Finally, 12 reactions were selected for up and downregulation to improve ethanol production. Enzyme regulators of the selected reactions were identified using the BRENDA database and 11 selected regulators were screened and optimized via Plackett-Burman and two-level full factorial designs, respectively. The proposed approach has enhanced yields of ethanol from 0.18 to 0.36 mol/mol carbon. Hence, not only a comprehensive approach for understanding the effect of pH on metabolism was proposed in this study, but also it successfully introduced key manipulations for ethanol overproduction.
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Affiliation(s)
- Sajjad Ghaffarinasab
- Department of Biotechnology, Faculty of Chemical Engineering, Tarbiat Modares University, Tehran, Iran
| | - Ehsan Motamedian
- Department of Biotechnology, Faculty of Chemical Engineering, Tarbiat Modares University, Tehran, Iran
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21
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Wang D, Yin Q, Zheng M, Xie Y, He W, Li Z, Hou S, Wang H. Fluorescent sensor based on triphenylamine for Zn 2+ with high selectivity and imaging in living cells. Spectrochim Acta A Mol Biomol Spectrosc 2021; 251:119480. [PMID: 33513549 DOI: 10.1016/j.saa.2021.119480] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/06/2021] [Accepted: 01/09/2021] [Indexed: 05/27/2023]
Abstract
It is of great importance to design a fluorescent sensor with high selectivity, sensitivity and large Stokes shift to zinc detection for environmental water sample and in vivo. Herein, A novel Zn2+ fluorescent sensor with larger Stokes shift (110 nm) 1-((5-(4-(diphenylamino)phenyl)pyridine-2-imino)methyl)naphthalene-2-ol (abbr. TPA-PN) was designed and synthesized. In DMF-H2O (V: V = 1: 1, pH = 7.0) solution, it could achieve high selectivity and sensitivity to Zn2+, there was a linear responsive range of 0-20 μM of concentration of Zn2+ ions for the sensor, the detection limit was as low as 19.134 nM and the binding constant was calculated to be 3.24 × 104 M-1. The species of TPA-PN and zinc were clarified at different pH. Besides, the interaction properties and fluorescence mechanism were demonstrated by the species theory, density functional theory (DFT) calculation, 1H NMR titration, FT-IR and MS. Most importantly, it provided a new real-time, on-site method and showed excellent potential in-vivo imaging ability.
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Affiliation(s)
- Dongyuan Wang
- Hunan Key Laboratory for The Design and Application of Actinide Complexes, University of South China, Hengyang, Hunan 421001, PR China
| | - Qiang Yin
- School of Chemistry and Chemical Engineering, University of South China, Hengyang, Hunan 421001, PR China
| | - Ming Zheng
- School of Chemistry and Chemical Engineering, University of South China, Hengyang, Hunan 421001, PR China
| | - Yongbo Xie
- School of Chemistry and Chemical Engineering, University of South China, Hengyang, Hunan 421001, PR China
| | - Wen He
- School of Chemistry and Chemical Engineering, University of South China, Hengyang, Hunan 421001, PR China
| | - Zheng Li
- School of Chemistry and Chemical Engineering, University of South China, Hengyang, Hunan 421001, PR China
| | - Sanying Hou
- School of Chemistry and Chemical Engineering, University of South China, Hengyang, Hunan 421001, PR China
| | - Hongqing Wang
- Hunan Key Laboratory for The Design and Application of Actinide Complexes, University of South China, Hengyang, Hunan 421001, PR China.
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22
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Mudie DM, Stewart AM, Rosales JA, Biswas N, Adam MS, Smith A, Craig CD, Morgen MM, Vodak DT. Amorphous Solid Dispersion Tablets Overcome Acalabrutinib pH Effect in Dogs. Pharmaceutics 2021; 13:pharmaceutics13040557. [PMID: 33921109 PMCID: PMC8071435 DOI: 10.3390/pharmaceutics13040557] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/13/2021] [Accepted: 04/13/2021] [Indexed: 12/12/2022] Open
Abstract
Calquence® (crystalline acalabrutinib), a commercially marketed tyrosine kinase inhibitor (TKI), exhibits significantly reduced oral exposure when taken with acid-reducing agents (ARAs) due to the low solubility of the weakly basic drug at elevated gastric pH. These drug-drug interactions (DDIs) negatively impact patient treatment and quality of life due to the strict dosing regimens required. In this study, reduced plasma drug exposure at high gastric pH was overcome using a spray-dried amorphous solid dispersion (ASD) comprising 50% acalabrutinib and 50% hydroxypropyl methylcellulose acetate succinate (HPMCAS, H grade) formulated as an immediate-release (IR) tablet. ASD tablets achieved similar area under the plasma drug concentration-time curve (AUC) at low and high gastric pH and outperformed Calquence capsules 2.4-fold at high gastric pH in beagle dogs. In vitro multicompartment dissolution testing conducted a priori to the in vivo study successfully predicted the improved formulation performance. In addition, ASD tablets were 60% smaller than Calquence capsules and demonstrated good laboratory-scale manufacturability, physical stability, and chemical stability. ASD dosage forms are attractive for improving patient compliance and the efficacy of acalabrutinib and other weakly basic drugs that have pH-dependent absorption.
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Affiliation(s)
- Deanna M. Mudie
- Global Research & Development, Lonza, Bend, OR 97703, USA; (A.M.S.); (J.A.R.); (N.B.); (M.S.A.); (A.S.); (C.D.C.); (M.M.M.); (D.T.V.)
- Correspondence:
| | - Aaron M. Stewart
- Global Research & Development, Lonza, Bend, OR 97703, USA; (A.M.S.); (J.A.R.); (N.B.); (M.S.A.); (A.S.); (C.D.C.); (M.M.M.); (D.T.V.)
| | - Jesus A. Rosales
- Global Research & Development, Lonza, Bend, OR 97703, USA; (A.M.S.); (J.A.R.); (N.B.); (M.S.A.); (A.S.); (C.D.C.); (M.M.M.); (D.T.V.)
- Pharmaceutics Department, University of Washington, Seattle, WA 98195, USA
| | - Nishant Biswas
- Global Research & Development, Lonza, Bend, OR 97703, USA; (A.M.S.); (J.A.R.); (N.B.); (M.S.A.); (A.S.); (C.D.C.); (M.M.M.); (D.T.V.)
| | - Molly S. Adam
- Global Research & Development, Lonza, Bend, OR 97703, USA; (A.M.S.); (J.A.R.); (N.B.); (M.S.A.); (A.S.); (C.D.C.); (M.M.M.); (D.T.V.)
| | - Adam Smith
- Global Research & Development, Lonza, Bend, OR 97703, USA; (A.M.S.); (J.A.R.); (N.B.); (M.S.A.); (A.S.); (C.D.C.); (M.M.M.); (D.T.V.)
| | - Christopher D. Craig
- Global Research & Development, Lonza, Bend, OR 97703, USA; (A.M.S.); (J.A.R.); (N.B.); (M.S.A.); (A.S.); (C.D.C.); (M.M.M.); (D.T.V.)
| | - Michael M. Morgen
- Global Research & Development, Lonza, Bend, OR 97703, USA; (A.M.S.); (J.A.R.); (N.B.); (M.S.A.); (A.S.); (C.D.C.); (M.M.M.); (D.T.V.)
| | - David T. Vodak
- Global Research & Development, Lonza, Bend, OR 97703, USA; (A.M.S.); (J.A.R.); (N.B.); (M.S.A.); (A.S.); (C.D.C.); (M.M.M.); (D.T.V.)
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Berton P, Tian H, Rogers RD. Phase Behavior of Aqueous Biphasic Systems with Choline Alkanoate Ionic Liquids and Phosphate Solutions: The Influence of pH. Molecules 2021; 26:1702. [PMID: 33803761 PMCID: PMC8003127 DOI: 10.3390/molecules26061702] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 03/11/2021] [Accepted: 03/15/2021] [Indexed: 01/26/2023] Open
Abstract
Aqueous biphasic systems (ABS) composed of the choline alkanoate ionic liquids (ILs) choline acetate [Cho][OAc], choline propanoate [Cho][Pro], choline butyrate [Cho][But], and choline hexanoate [Cho][Hex], mixed with K3PO4 solutions at pH 7.2 and 14.5, were prepared and their phase diagrams were compared. The ability to form ABS with alkaline K3PO4 solutions decreased in the order [Cho][OAc] ≈ [Cho][Pro] > [Cho][But] > [Cho][Hex], while with neutral K3PO4 solutions, [Cho][OAc] could not form an ABS, and the other three ILs performed similarly. All of the biphasic regions of the ABS decreased with the increase in pH. 1H-NMR data indicated anion exchange between phases in ABS at neutral pH. The ABS at neutral pH were evaluated to extract the triazine herbicides simazine, cyanazine, and atrazine, and the ABS formed by [Cho][Pro] and the pH 7.2 K3PO4 solution has shown extraction recoveries higher than 90%.
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Affiliation(s)
- Paula Berton
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, QC H3A 0B8, Canada;
- Chemical and Petroleum Engineering Department, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
| | - Hongzhe Tian
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, QC H3A 0B8, Canada;
- Plant Protection College, Shenyang Agricultural University, 120 Dongling Road, Shenyang 110161, China
| | - Robin D. Rogers
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, QC H3A 0B8, Canada;
- 525 Solutions Inc., P.O. Box 2206, Tuscaloosa, AL 35403, USA
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24
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Cao Q, Chen C, Li K, Sun T, Shen Z, Jia J. Arsenic(V) removal behavior of schwertmannite synthesized by KMnO 4 rapid oxidation with high adsorption capacity and Fe utilization. Chemosphere 2021; 264:128398. [PMID: 33007570 DOI: 10.1016/j.chemosphere.2020.128398] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 09/15/2020] [Accepted: 09/19/2020] [Indexed: 06/11/2023]
Abstract
Adsorption is a simple and efficient way for arsenic contamination purification in water, with a pressing challenge to find a cheap and efficient adsorbent. As a poorly crystalline Fe(III)-oxyhydroxy sulfate mineral, schwertmannite can be As(V) adsorbent because of its tunnel structure and low cost. However, the schwertmannite synthesized commonly by H2O2 rapid oxidation suffers from the low Fe utilization and limited As(V) adsorption capacity. In this research, the schwertmannite is synthesized by KMnO4. The results show that the Fe utilization can be improved from 40% to 56%, with the As(V) adsorption capacities double times better than those synthesized by H2O2 at pH 7 and 2. The As(V) adsorption mechanisms at different pHs and the reason for the improvement of As(V) adsorption capacity are thoroughly investigated. The FTIR and EDS images confirm that As(V) adsorption exchange with SO42- is the dominant mechanism at pH 7 and 2. At pH 11, the As(V) is mainly removed by surface complexation because the surface SO42- is exchanged by OH-. The intraparticle diffusion model fitting and XPS results further reveal that the tunnel structure built by Fe-SO4 in the KMnO4 oxidized schwertmannite is more stable, possibly resulting in the better As(V) adsorption performance.
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Affiliation(s)
- Qingwei Cao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai, 200240, PR China
| | - Chen Chen
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai, 200240, PR China
| | - Kan Li
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai, 200240, PR China.
| | - Tonghua Sun
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai, 200240, PR China
| | - Zhemin Shen
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai, 200240, PR China
| | - Jinping Jia
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai, 200240, PR China.
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25
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Quílez-Bermejo J, Strutyński K, Melle-Franco M, Morallón E, Cazorla-Amorós D. On the Origin of the Effect of pH in Oxygen Reduction Reaction for Nondoped and Edge-Type Quaternary N-Doped Metal-Free Carbon-Based Catalysts. ACS Appl Mater Interfaces 2020; 12:54815-54823. [PMID: 33237716 DOI: 10.1021/acsami.0c17249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Metal-free carbon-based catalysts have gained much attention during the last 15 years as an alternative toward the replacement of platinum-based catalysts for the oxygen reduction reaction (ORR). However, carbon-based catalysts only show promising catalytic activity in alkaline solution. Concurrently, the most optimized polymer electrolyte membrane fuel cells use proton exchange membranes. This means that the cathode electrode is surrounded by a protonic environment in which carbon materials show poor performance, with differences above 0.5 V in EONSET for nondoped carbon materials. Therefore, the search for highly active carbon-based catalysts is only possible if we first understand the origin of the poor electrocatalytic activity of this kind of catalysts in acidic conditions. We address this matter through a combined experimental and modeling study, which yields fundamental principles on the origin of the pH effects in ORR for carbon-based materials. This is relevant for the design of pH-independent metal-free carbon-based catalysts.
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Affiliation(s)
- Javier Quílez-Bermejo
- Departamento de Química Inorgánica and Instituto de Materiales, Universidad de Alicante, Ap. 99, Alicante 03080, Spain
| | - Karol Strutyński
- CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, Aveiro 3810-193, Portugal
| | - Manuel Melle-Franco
- CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, Aveiro 3810-193, Portugal
| | - Emilia Morallón
- Departamento de Química Física and Instituto de Materiales, Universidad de Alicante, Ap. 99, Alicante 03080, Spain
| | - Diego Cazorla-Amorós
- Departamento de Química Inorgánica and Instituto de Materiales, Universidad de Alicante, Ap. 99, Alicante 03080, Spain
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26
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Lu C, Kim TH, Bendix J, Abdelmoula M, Ruby C, Nielsen UG, Bruun Hansen HC. Stability of magnetic LDH composites used for phosphate recovery. J Colloid Interface Sci 2020; 580:660-8. [PMID: 32712472 DOI: 10.1016/j.jcis.2020.07.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 06/29/2020] [Accepted: 07/05/2020] [Indexed: 02/02/2023]
Abstract
Layered double hydroxides (LDH) and their magnetic composites have been intensively investigated as recyclable high-capacity phosphate sorbents but with little attention to their stability as function of pH and phosphate concentration. The stability of a Fe3O4@SiO2-Mg3Fe LDH P sorbent as function of pH (5-11) and orthophosphate (Pi) concentration (1-300 mg P/L) was investigated. The composite has high adsorption capacity (approx. 80 mg P/g) at pH 5 but with fast dissolution of the LDH component resulting in formation of ferrihydrite as evidenced by Mössbauer spectroscopy. At pH 7 more than 60% of the LDH dissolves within 60 min, while at alkaline pH, the LDH is more stable but with less than 40% adsorption capacity as compared to pH 5. The high Pi sorption at acid to neutral pH is attributed to Pi bonding to the residual ferrihydrite. Under alkaline conditions Pi is sorbed to LDH at low Pi concentration while magnesium phosphates form at higher Pi concentration evidenced by solid-state 31P MAS NMR, powder X-ray diffraction and chemical analyses. Sorption as function of pH and Pi concentration has been fitted by a Rational 2D function allowing for estimation of Pi sorption and precipitation. In conclusion, the instability of the LDH component limits its application in wastewater treatment from acid to alkaline pH. Future use of magnetic LDH composites requires substantial stabilisation of the LDH component.
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27
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Guerrieri A, Ciriello R, Bianco G, De Gennaro F, Frascaro S. Allosteric Enzyme-Based Biosensors-Kinetic Behaviours of Immobilised L-Lysine-α-Oxidase from Trichoderma viride: pH Influence and Allosteric Properties. Biosensors (Basel) 2020; 10:E145. [PMID: 33080859 PMCID: PMC7603024 DOI: 10.3390/bios10100145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/12/2020] [Accepted: 10/15/2020] [Indexed: 12/04/2022]
Abstract
The present study describes the kinetics of L-lysine-α-oxidase (LO) from Trichoderma viride immobilised by co-crosslinking onto the surface of a Pt electrode. The resulting amperometric biosensor was able to analyse L-lysine, thus permitting a simple but thorough study of the kinetics of the immobilised enzyme. The kinetic study evidenced that LO behaves in an allosteric fashion and that cooperativity is strongly pH-dependent. Not less important, experimental evidence shows that cooperativity is also dependent on substrate concentration at high pH and behaves as predicted by the Monod-Wyman-Changeux model for allosteric enzymes. According to this model, the existence of two different conformational states of the enzyme was postulated, which differ in Lys species landing on LO to form the enzyme-substrate complex. Considerations about the influence of the peculiar LO kinetics on biosensor operations and extracorporeal reactor devices will be discussed as well. Not less important, the present study also shows the effectiveness of using immobilised enzymes and amperometric biosensors not only for substrate analysis, but also as a convenient tool for enzyme kinetic studies.
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Affiliation(s)
- Antonio Guerrieri
- Dipartimento di Scienze, Università degli Studi della Basilicata, Viale dell’Ateneo Lucano 10, 85100 Potenza, Italy; (R.C.); (G.B.)
| | - Rosanna Ciriello
- Dipartimento di Scienze, Università degli Studi della Basilicata, Viale dell’Ateneo Lucano 10, 85100 Potenza, Italy; (R.C.); (G.B.)
| | - Giuliana Bianco
- Dipartimento di Scienze, Università degli Studi della Basilicata, Viale dell’Ateneo Lucano 10, 85100 Potenza, Italy; (R.C.); (G.B.)
| | | | - Silvio Frascaro
- RBM S.P.A.—Istituto di Ricerche Biomediche “A. Marxer”, Via Ribes 1, 10010 Colleretto Giacosa (To), Italy;
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28
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Evans KO, Skory C, Compton DL, Cormier R, Côté GL, Kim S, Appell M. Development and Physical Characterization of α-Glucan Nanoparticles. Molecules 2020; 25:E3807. [PMID: 32825708 PMCID: PMC7503850 DOI: 10.3390/molecules25173807] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 08/18/2020] [Accepted: 08/19/2020] [Indexed: 11/18/2022] Open
Abstract
α-Glucans that were enzymatically synthesized from sucrose using glucansucrase cloned from Leuconostoc mesenteroides NRRL B-1118 were found to have a glass transition temperature of approximately 80 °C. Using high-pressure homogenization (~70 MPa), the α-glucans were converted into nanoparticles of ~120 nm in diameter with a surface potential of ~-3 mV. Fluorescence measurements using 1,6-diphenyl-1,3,5-hexatriene (DPH) indicate that the α-glucan nanoparticles have a hydrophobic core that remains intact from 10 to 85 °C. α-Glucan nanoparticles were found to be stable for over 220 days and able to form at three pH levels. Accelerated exposure measurements demonstrated that the α-glucan nanoparticles can endure exposure to elevated temperatures up to 60 °C for 6 h intervals.
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Affiliation(s)
- Kervin O. Evans
- Renewable Product Technology Research Unit, National Center for Agricultural Utilization Research, USDA, 1815 N, University Street, Peoria, IL 61604, USA; (C.S.); (D.L.C.); (R.C.); (G.L.C.)
| | - Christopher Skory
- Renewable Product Technology Research Unit, National Center for Agricultural Utilization Research, USDA, 1815 N, University Street, Peoria, IL 61604, USA; (C.S.); (D.L.C.); (R.C.); (G.L.C.)
| | - David L. Compton
- Renewable Product Technology Research Unit, National Center for Agricultural Utilization Research, USDA, 1815 N, University Street, Peoria, IL 61604, USA; (C.S.); (D.L.C.); (R.C.); (G.L.C.)
| | - Ryan Cormier
- Renewable Product Technology Research Unit, National Center for Agricultural Utilization Research, USDA, 1815 N, University Street, Peoria, IL 61604, USA; (C.S.); (D.L.C.); (R.C.); (G.L.C.)
| | - Gregory L. Côté
- Renewable Product Technology Research Unit, National Center for Agricultural Utilization Research, USDA, 1815 N, University Street, Peoria, IL 61604, USA; (C.S.); (D.L.C.); (R.C.); (G.L.C.)
| | - Sanghoon Kim
- Plant Polymer Research Unit, National Center for Agricultural Utilization Research, USDA, 1815 N. University Street, Peoria, IL 61604, USA;
| | - Michael Appell
- Mycotoxin Prevention and Applied Microbiology Research Unit, National Center for Agricultural Utilization Research, USDA, 1815 N. University Street, Peoria, IL 61604, USA;
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29
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Corrêa Giron C, Laaksonen A, Barroso da Silva FL. On the interactions of the receptor-binding domain of SARS-CoV-1 and SARS-CoV-2 spike proteins with monoclonal antibodies and the receptor ACE2. Virus Res 2020; 285:198021. [PMID: 32416259 PMCID: PMC7228703 DOI: 10.1016/j.virusres.2020.198021] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/01/2020] [Accepted: 05/11/2020] [Indexed: 01/12/2023]
Abstract
A new betacoronavirus named SARS-CoV-2 has emerged as a new threat to global health and economy. A promising target for both diagnosis and therapeutics treatments of the new disease named COVID-19 is the coronavirus (CoV) spike (S) glycoprotein. By constant-pH Monte Carlo simulations and the PROCEEDpKa method, we have mapped the electrostatic epitopes for four monoclonal antibodies and the angiotensin-converting enzyme 2 (ACE2) on both SARS-CoV-1 and the new SARS-CoV-2 S receptor binding domain (RBD) proteins. We also calculated free energy of interactions and shown that the S RBD proteins from both SARS viruses binds to ACE2 with similar affinities. However, the affinity between the S RBD protein from the new SARS-CoV-2 and ACE2 is higher than for any studied antibody previously found complexed with SARS-CoV-1. Based on physical chemical analysis and free energies estimates, we can shed some light on the involved molecular recognition processes, their clinical aspects, the implications for drug developments, and suggest structural modifications on the CR3022 antibody that would improve its binding affinities for SARS-CoV-2 and contribute to address the ongoing international health crisis.
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MESH Headings
- Angiotensin-Converting Enzyme 2
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/metabolism
- Antibodies, Viral/immunology
- Antibodies, Viral/metabolism
- Betacoronavirus/chemistry
- Betacoronavirus/immunology
- Computer Simulation
- Epitope Mapping
- Humans
- Models, Molecular
- Monte Carlo Method
- Peptidyl-Dipeptidase A/chemistry
- Peptidyl-Dipeptidase A/metabolism
- Protein Binding
- Protein Conformation
- Protein Interaction Domains and Motifs
- Protein Interaction Mapping
- Receptors, Virus/chemistry
- Receptors, Virus/metabolism
- Severe acute respiratory syndrome-related coronavirus/chemistry
- Severe acute respiratory syndrome-related coronavirus/immunology
- SARS-CoV-2
- Spike Glycoprotein, Coronavirus/chemistry
- Spike Glycoprotein, Coronavirus/immunology
- Spike Glycoprotein, Coronavirus/metabolism
- Thermodynamics
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Affiliation(s)
- Carolina Corrêa Giron
- Universidade Federal do Triângulo Mineiro, Departamento de Saúde Coletiva, Rua Vigário Carlos, 38025-350 Uberaba, MG, Brazil; Universidade de São Paulo, Departamento de Ciências Biomoleculares, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Av. café, s/no - campus da USP, BR-14040-903 Ribeirão Preto SP, Brazil
| | - Aatto Laaksonen
- Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden; State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing, 210009, PR China; Centre of Advanced Research in Bionanoconjugates and Biopolymers, Petru Poni Institute of Macromolecular Chemistry, Aleea Grigore Ghica-Voda, 41A, 700487 Iasi, Romania; Department of Engineering Sciences and Mathematics, Division of Energy Science, Luleå University of Technology, SE-97187 Luleå, Sweden
| | - Fernando L Barroso da Silva
- Universidade de São Paulo, Departamento de Ciências Biomoleculares, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Av. café, s/no - campus da USP, BR-14040-903 Ribeirão Preto SP, Brazil; Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, United States.
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30
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López Zavala MÁ, Vega DA, Álvarez Vega JM, Castillo Jerez OF, Cantú Hernández RA. Electrochemical oxidation of acetaminophen and its transformation products in surface water: effect of pH and current density. Heliyon 2020; 6:e03394. [PMID: 32072068 PMCID: PMC7015988 DOI: 10.1016/j.heliyon.2020.e03394] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 10/08/2019] [Accepted: 02/06/2020] [Indexed: 11/25/2022] Open
Abstract
Several studies have been conducted worldwide to develop effective and affordable methods to degrade pharmaceuticals and their metabolites/intermediates/oxidation products found in surface water, wastewater and drinking water. In this work, acetaminophen and its transformation products were successfully degraded in surface water by electrochemical oxidation using stainless steel electrodes. The effect of pH and current density on the oxidation process was assessed and the oxidation kinetics and mechanisms involved were described. Additionally, the results were compared with those obtained in acetaminophen synthetic solutions. It was found that conducting the electrochemical oxidation at 16.3 mA/cm2 and pH 5, good performance of the process was achieved and not only acetaminophen, but also its transformation products were totally degraded in only 7.5 min; furthermore, small number of transformation products were generated. On the other hand, degradation rates of acetaminophen and its transformation products in surface water were much faster (more than 2.5 times) and the reaction times much shorter (more than 4.0 times) than in synthetic solutions at all current densities and pH values evaluated. At pH 3 and pH 5, greater soluble chlorine formation due to the higher HCl amount used to acidify the surface water solutions could enhance the degradation rates of acetaminophen and its transformation products. However, constituents of surface water (ions and solids) could also have an important role on the oxidation process because at pH 9 (non-acidified solutions) the degradation rates were also much greater and the reaction times were much shorter in surface water than in acetaminophen synthetic solutions.
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31
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Chen WY, Wu JH, Chu SC. Deciphering microbiomes in anaerobic reactors with superior trichloroethylene dechlorination performance at low pH conditions. Environ Pollut 2020; 257:113567. [PMID: 31733964 DOI: 10.1016/j.envpol.2019.113567] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 10/30/2019] [Accepted: 11/02/2019] [Indexed: 06/10/2023]
Abstract
Different pH conditions have been demonstrated to affect the activities of dechlorinating populations participating in the successive dechlorination of trichloroethylene to ethylene. However, the mechanism of the effect of pH conditions on the assembly of dechlorinating populations and their relations to the structure, function, and dynamics of the microbiome are unclear. In this study, we evaluated the effects of pH on microbiomes assembled in anaerobic trichloroethylene-dechlorinating reactors under neutral (pH 7.2), acidic (pH 6.2), and alkaline (pH 8.2) conditions. The results revealed that among the reactors, the acidic reactor had the highest efficiency for dechlorination without accumulation of dechlorinated metabolites, even at high loading rates. The results of high-throughput sequencing of the 16S rRNA gene indicated that the microbiomes in the 3 reactors underwent varied dynamic succession. The acidic reactor harbored a higher degree of complex microbes, dechlorinator diversity, and abundance of the Victoria subgroup of Dehalococcoides (1.2 ± 0.1 × 106 cell/mL), which were approximately 10-102-fold higher than those at neutral and alkaline conditions. The pH settings altered species-species connectivity and complexity of microbial interaction networks, with more commensal interactions in the dechlorinators of the acidic reactor. As predicted, abundances of several functional gene categories were in strong linearity with pH values, and the microbiome possessed significantly more abundant functions in the acidic reactor (P < 0.001), such as potentially stimulating hydrogen production, cobalamin synthesis, cobalt transport, transport and metabolism of amino acids and secondary metabolites, cell motility, and transcription. All results of microbiomic analyses consistently revealed the observed superior dechlorination process and suggested an association of the reductive dechlorination process with the pH-dependent microbiome. The results of this study provide a new insight into the trichloroethylene dechlorination with regards to pH, and they will be useful for improving bioremediation and management of trichloroethylene-contaminated sites.
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Affiliation(s)
- Wei-Yu Chen
- Department of Environmental Engineering, National Cheng Kung University, Taiwan
| | - Jer-Horng Wu
- Department of Environmental Engineering, National Cheng Kung University, Taiwan.
| | - Shun-Chieh Chu
- Environmental Forensic Department, Sustainable Environment Technology Division, Green Energy and Environment Research Labs (GEL), Industrial Technology Research Institute, Taiwan
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32
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Halasz A, Hawari J, Perreault NN. Photodegradation of bis(1H-tetrazol-5-yl)amine (H 2BTA), a high nitrogen content tetrazole-based energetic compound in water. Chemosphere 2020; 241:125008. [PMID: 31604194 DOI: 10.1016/j.chemosphere.2019.125008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 08/08/2019] [Accepted: 09/28/2019] [Indexed: 06/10/2023]
Abstract
Tetrazoles have wide industrial applications, notably in the pharmaceutical industry. Tetrazole derivatives such as bis(1H-tetrazol-5-yl)amine (H2BTA) have recently been considered by the defense industry as high nitrogen composite propellants. Photodegradation studies under solar simulating conditions showed that H2BTA was partially degraded in water, while it was completely degraded under UV light at 254 nm. When H2BTA (0.35 mM) was irradiated with simulated sunlight at pH 3.65, there was a 1-day lag phase before the chemical started to degrade, reaching 43.5% degradation after 7 d. However, when pH increased to 5.76, it degraded without lag phase, suggesting that an HBTA- anion was involved in the initial degradation of the chemical. 5-Aminotetrazole (5-AT) was identified as a final degradation product and N-(1H-tetrazol-5-yl)formamide(T(5 yl)FA) and 1H-tetrazol-5-ylcarbamic acid (T(5 yl)CA) as intermediate products. At λ = 254 nm, H2BTA disappeared rapidly, resulting in the loss of 94% after 65 min. 5-AT was detected together with several transient products including N-(1H-tetrazol-5-yl)carbamohydrazonic acid (T(5 yl)CHA) and T(5 yl)FA. Kinetic studies and products analysis revealed that H2BTA photodegraded via two initial routes. One route (a) marked by the initial loss of HN3 and another (b) marked by the initial loss of N2. Route a) was characteristics for irradiation with simulated sunlight; however, routes a) and b) proceeded simultaneously under UV light. 5-AT eventually degraded to presumably give N2 and/or HN3 under UV light. Understanding the photodegradation pathway of H2BTA under simulated sunlight can help in providing the basis for natural attenuation assessment of the chemical in contaminated aquatic environments.
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Affiliation(s)
- Annamaria Halasz
- National Research Council Canada, 6100 Royalmount Ave, Montreal, Quebec, H4P 2R2, Canada
| | - Jalal Hawari
- Department of Civil, Geological and Mining Engineering, Ecole Polytechnique de Montréal, Montreal, Quebec, H3C 3A7, Canada
| | - Nancy N Perreault
- National Research Council Canada, 6100 Royalmount Ave, Montreal, Quebec, H4P 2R2, Canada.
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33
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Kang JH, Yoon Y, Song J. Effects of pH on the simultaneous removal of hydrogen sulfide and ammonia in a combined absorption and electro-oxidation system. J Hazard Mater 2020; 382:121011. [PMID: 31446347 DOI: 10.1016/j.jhazmat.2019.121011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 07/11/2019] [Accepted: 08/12/2019] [Indexed: 06/10/2023]
Abstract
Biogas commonly contains both H2S and NH3, and these impurities need to be removed before use. In this study, a combined system consisting of an absorption column and an electro-oxidation reactor was developed to simultaneously treat H2S and NH3. In particular, the effect of the pH (6, 8, and 10) on the system performance was investigated. The mass transfer rate of H2S from the gas to liquid phases was sensitive to pH because of its relatively low solubility at low pHs, while more than 99% of the introduced NH3 was steadily absorbed. Therefore, a pH higher than 8 was favorable for the simultaneous removal of both gases. In the electro-oxidation reactor, H2S was primarily oxidized, while the NH3 oxidation started after H2S was completely eliminated. Furthermore, the oxidation rate and current efficiency of both H2S and NH3 increased with decreasing pH value. The results showed that a low pH was advantageous for the electro-oxidation. In conclusion, the mass transfer rate and oxidation kinetics should be balanced to increase the simultaneous removal of H2S and NH3. Therefore, among the tested pH values, the best performance in the combined system was achieved using a pH of 8.
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Affiliation(s)
- Jeong-Hee Kang
- Department of Civil & Environmental Engineering, Sejong University, Seoul, Republic of Korea; Department of Land, Water and Environment Research, Korea Institute of Civil Engineering and Building Technology, Gyeonggi-Do, Republic of Korea
| | - Yeojoon Yoon
- Department of Environmental Engineering, Yonsei University, Wonju, Republic of Korea
| | - JiHyeon Song
- Department of Civil & Environmental Engineering, Sejong University, Seoul, Republic of Korea.
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34
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Lorenzo D, García-Cervilla R, Romero A, Santos A. Partitioning of chlorinated organic compounds from dense non-aqueous phase liquids and contaminated soils from lindane production wastes to the aqueous phase. Chemosphere 2020; 239:124798. [PMID: 31527006 DOI: 10.1016/j.chemosphere.2019.124798] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 08/27/2019] [Accepted: 09/05/2019] [Indexed: 06/10/2023]
Abstract
Hexachlorocyclohexane (HCH) and mainly the γ-HCH isomer, namely lindane, were extensively produced and used as pesticides. Huge amounts of wastes, solids and liquids, were disposed of in the surroundings of the production sites. The liquid residuum was a complex mixture of chlorinated organic compounds, COCs, from chlorobenzene to heptachlorocyclohexane. This Dense Non-Aqueous Phase Liquid, DNAPL, migrated by density through the subsurface to greater depths, being trapped or adsorbed into the soil in this movement posing a significant risk to the groundwater. Knowledge of the partitioning in water of COCs in DNAPL is a key issue to determine its fate in the environment. However, there are no data in literature for the partitioning and/or solubility of many of the COCs in this DNAPL, such as pentachlorocyclohexene, hexachlorocyclohexene and heptachlorocyclohexane despite them constitute about 13-30% of the mole fraction of the DNAPLs. In this work, the partitioning to water of COCs in free and those adsorbed onto soil has been studied. In addition, measured and predicted aqueous concentrations of each COC in the DNAPL mixture have been compared. To do this, the solubility of a compound that is a solid crystal when pure at P = 298 K and P = 1 atm has been evaluated considering the approach of sub-cooled liquid state of solid organochlorines. Samples were obtained at Sabiñanigo landfills and soils used had several grain sizes. Transformation in alkaline media of COCs had a positive environmental impact.
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Affiliation(s)
- David Lorenzo
- Chemical and Materials Engineering Department. University Complutense of Madrid, Spain
| | - Raul García-Cervilla
- Chemical and Materials Engineering Department. University Complutense of Madrid, Spain
| | - Arturo Romero
- Chemical and Materials Engineering Department. University Complutense of Madrid, Spain
| | - Aurora Santos
- Chemical and Materials Engineering Department. University Complutense of Madrid, Spain.
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35
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Jusys Z, Behm RJ. The Effect of Anions and pH on the Activity and Selectivity of an Annealed Polycrystalline Au Film Electrode in the Oxygen Reduction Reaction-Revisited. Chemphyschem 2019; 20:3276-3288. [PMID: 31705610 PMCID: PMC6973112 DOI: 10.1002/cphc.201900960] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 10/31/2019] [Indexed: 01/06/2023]
Abstract
Aiming at a better understanding of correlations between the activity and selectivity of Au electrodes in the oxygen reduction reaction (ORR) under controlled transport conditions, we have investigated this reaction by combined electrochemical and in situ FTIR measurements, performed in a flow cell set‐up in an attenuated total reflection (ATR) configuration in acid and alkaline electrolytes. The formation of incomplete reduction products (hydrogen peroxyde/peroxyls) was detected by a collector electrode, the onset of OHad formation was probed by bulk CO oxidation. Using an electroless‐deposited, annealed Au film on a Si prism as working electrode and three different electrolytes for comparison (sulfuric acid, perchloric acid, sodium hydroxide solution), we could derive detailed information on the anion adsorption behavior, and could correlate this with the ORR characteristics. The data reveal pronounced effects of the anions and the pH on the ORR characteristics, indicated e. g., by a grossly different activity and selectivity for the 4‐electron pathway to water/hydroxyls, with the onset ranging from ca. 1.0 V in alkaline electrolyte to 0.6 V in sulfuric acid electrolyte, and the selectivity for the 4‐electron pathway ranging from 100 % (alkaline electrolyte, low overpotentials) to 40 % (acidic electrolytes, alkaline electrolyte at high overpotentials). In contrast, the effect of the ORR on the anion adsorption characteristics is small. Anion effects as well as correlations between anion adsorption and ORR are discussed.
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Affiliation(s)
- Zenonas Jusys
- Institute of Surface Chemistry and Catalysis, Ulm University, Albert-Einstein-Allee 47, 89081, Ulm, Germany
| | - R Jürgen Behm
- Institute of Surface Chemistry and Catalysis, Ulm University, Albert-Einstein-Allee 47, 89081, Ulm, Germany
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36
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Boudriche L, Safaei Z, Ramasamy D, Sillanpää M, Boudjemaa A. Sulfaquinoxaline oxidation by UV-C activated sodium persulfate: Degradation kinetics and toxicological evaluation. Water Environ Res 2019; 91:1412-1419. [PMID: 31054152 DOI: 10.1002/wer.1136] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 04/22/2019] [Accepted: 04/24/2019] [Indexed: 06/09/2023]
Abstract
This study evaluates the efficiency of sulfate radicals used in advanced oxidation process in water treatment. The targeted pollutant is an antibiotic, sulfaquinoxaline (SQ-Na) sodium, widely used in the veterinary field. The results show a degradation of SQ-Na until 90% after 300 min of irradiation at optimal sodium persulfate (SPS) concentration (200 mg/L). Degradation of the antibiotic obeys a pseudo-first-order kinetics when the concentration of sulfate radicals ranging from 0 to 240 mg/L. The decomposition of SQ-Na via the UV/SPS method is favored significantly under acidic conditions but becomes slow at neutral pH and almost inhibited under alkaline conditions. The contribution of the sulfate radicals alone and of both radicals hydroxyl and sulfate on the SQ-Na degradation is evaluated at 69% and 80%, respectively. Toxicity tests with Sinapis alba and Daphnia magna on treated samples, before and after irradiation, indicate the formation of new by-products more toxic during the treatment process. PRACTITIONER POINTS: SQ-Na was significantly degraded (90%) under UV/SPS system. SQ-Na decay exhibited a pseudo-first-order kinetics. SQ-Na was completely degraded via UV/SPS process under acidic conditions. The shoot growth appears to be more sensitive to oxidation by-products toxicity than root growth. Ineffectiveness in eliminating the ecotoxicity.
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Affiliation(s)
- Lilya Boudriche
- Centre de Recherche Scientifique et Technique en Analyses Physico-Chimiques, Tipaza, Algeria
| | - Zahra Safaei
- Laboratory of Green Chemistry, Lappeenranta University of Technology, Mikkeli, Finland
| | - Deepika Ramasamy
- Laboratory of Green Chemistry, Lappeenranta University of Technology, Mikkeli, Finland
| | - Mika Sillanpää
- Laboratory of Green Chemistry, Lappeenranta University of Technology, Mikkeli, Finland
| | - Amel Boudjemaa
- Centre de Recherche Scientifique et Technique en Analyses Physico-Chimiques, Tipaza, Algeria
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37
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Wanninayake US, Subedi B, Fitzpatrick PF. pH and deuterium isotope effects on the reaction of trimethylamine dehydrogenase with dimethylamine. Arch Biochem Biophys 2019; 676:108136. [PMID: 31604072 DOI: 10.1016/j.abb.2019.108136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 09/30/2019] [Accepted: 10/07/2019] [Indexed: 11/24/2022]
Abstract
The flavoprotein trimethylamine dehydrogenase is a member of a small class of flavoproteins that catalyze amine oxidation and transfer the electrons through an Fe/S center to an external oxidant. The mechanism of amine oxidation by this family of enzymes has not been established. Here, we describe the use of pH and kinetic isotope effects with the slow substrate dimethylamine to study the mechanism. The data are consistent with the neutral amine being the form of the substrate that binds productively at the pH optimum, since the pKa seen in the kcat/Kamine pH profile for a group that must be unprotonated matches the pKa of dimethylamine. The D(kcat/Kamine) value decreases to unity as the pH decreases. This suggests the presence of an alternative pathway at low pH, in which the protonated substrate binds and is then deprotonated by an active-site residue prior to oxidation. The kcat and Dkcat values both decrease to limiting values at low pH with similar pKa values. This is consistent with a step other than amine oxidation becoming rate-limiting for turnover.
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Affiliation(s)
- Udayanga S Wanninayake
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229, USA
| | - Bishnu Subedi
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229, USA
| | - Paul F Fitzpatrick
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229, USA.
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38
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Srivastava G, Darokar MP, Sharma A. Molecular investigation against the resistant mechanism of PncA mutated pyrazinamide resistance and insight into the role of pH environment for pyrazinamide activation. J Biomol Struct Dyn 2019; 38:3411-3431. [PMID: 31448694 DOI: 10.1080/07391102.2019.1659854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Pyrazinamide (PZA), a crucial component of anti-TB therapy, is a prodrug. PZA interacts with PncA protein to be converted into its functional form i.e. pyrazinoic acid (POA). It has unique feature to kill dormant tubercle bacilli of acidic environment. Although significance of pH environment in PZA activation has been investigated in several of previous studies, insight into the significant atomistic variations in the interaction pattern of PZA with PncA, at different pH environments, are still required to be explored. On the other hand, continuously emerging PncA mutants, associated with PZA resistance, have also become a serious threat for global TB control program. Therefore, the current study was designed to understand the role of pH environment in the PZA activation and to explore the PZA resistance mechanism in various PncA mutants. The study included various in silico experiments like molecular docking, MD simulation, binding free energy estimation, PCA and FEL. In our study, we have found pH-3 and pH-5 environment as a highly significant environment for PZA activation. It was found that protonation or deprotonation of PZA activation site (PAS) residues, majorly K48, D56, K96 and E107, resulted in rearrangement of the PAS according to the pH conditions. It has also been observed that positioning of PZA binding near to Fe2+ and residues of catalytic triad (i.e. D8, K96 and C138) also play a very crucial role in the activation of PZA. The overall insight from the current study may help to develop new therapeutics against PncA mutated PZA resistance.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Gaurava Srivastava
- Biotechnology Division, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - M P Darokar
- Biotechnology Division, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Ashok Sharma
- Biotechnology Division, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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39
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Cochran M. Would acetazolamide inhibit progression of atheromatous vascular calcification? Med Hypotheses 2019; 132:109354. [PMID: 31421415 DOI: 10.1016/j.mehy.2019.109354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 07/25/2019] [Accepted: 08/05/2019] [Indexed: 10/26/2022]
Abstract
Vascular calcification is a recognised source of morbidity among mid-age and elderly subjects. Its development follows classical mineralisation pathways, inhibited by acidosis. It is known that the final mechanism of tissue mineralization involves three processes, all of which are highly pH dependent. Calcium interacts with phosphate in its trivalent form, but this step is inhibited by pyrophosphate, itself a source of phosphate when hydrolysed by alkaline phosphatase. Separately, matrix vesicles create nucleation sites and may indirectly disrupt vascular smooth muscle cells. Metabolic acidosis acts at every point to delay mineralization. The diuretic acetazolamide creates a sustained mild acidosis with some phosphate loss and, though usually ineffective in the experimental model, has been used with success in certain clinical conditions. We suggest that acetazolamide, well studied and tolerated, might inhibit progression of vascular calcification in subjects at risk through its dual action of lowering tissue pH and local phosphate concentration.
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40
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Su Q, Domingo-Félez C, Zhang Z, Blum JM, Jensen MM, Smets BF. The effect of pH on N 2O production in intermittently-fed nitritation reactors. Water Res 2019; 156:223-231. [PMID: 30921538 DOI: 10.1016/j.watres.2019.03.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 02/28/2019] [Accepted: 03/12/2019] [Indexed: 06/09/2023]
Abstract
The effect of pH on nitrous oxide (N2O) production rates was quantified in an intermittently-fed lab-scale sequencing batch reactor performing high-rate nitritation. N2O and other nitrogen (N) species (e.g. ammonium (NH4+), nitrite, hydroxylamine and nitric oxide) were monitored to identify in-cycle dynamics and determine N conversion rates at controlled pH set-points (6.5, 7, 7.5, 8 and 8.5). Operational conditions and microbial compositions remained similar during long-term reactor-scale pH campaigns. The specific ammonium removal rates and nitrite accumulation rates varied little with varying pH levels (p > 0.05). The specific net N2O production rates and net N2O yield of NH4+ removed (ΔN2O/ΔNH4+) increased up to seven-fold from pH 6.5 to 8, and decreased slightly with further pH increase to 8.5 (p < 0.05). Best-fit model simulations predicted nitrifier denitrification as the dominant N2O production pathway (≥87% of total net N2O production) at all examined pH. Our study highlights the effect of pH on biologically mediated N2O emissions in nitrogen removal systems and its importance in the design of N2O mitigation strategies.
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Affiliation(s)
- Qingxian Su
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Carlos Domingo-Félez
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Zhen Zhang
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Jan-Michael Blum
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Marlene Mark Jensen
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
| | - Barth F Smets
- Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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41
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Sa B, Mukherjee S, Roy SK. Effect of polymer concentration and solution pH on viscosity affecting integrity of a polysaccharide coat of compression coated tablets. Int J Biol Macromol 2019; 125:922-30. [PMID: 30553857 DOI: 10.1016/j.ijbiomac.2018.12.101] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 11/26/2018] [Accepted: 12/11/2018] [Indexed: 11/23/2022]
Abstract
Tablets, compression coated with certain polysaccharides and intended for colon delivery, retain the integrity of the coat for an initial period of about 6 h (lag period) beyond which (post-lag period) the coat is degraded by colonic enzymes to induce drug release. This work was undertaken to investigate the factors which influence the integrity of the coat during the lag period. Core tablets containing two model drugs were compression coated with various amounts of carboxymethyl locust bean gum (CMLBG). In-vitro release of drugs, erosion of coat, and steady shear viscosity of CMLBG solutions having different concentrations and solution pH were determined. The viscosity of CMLBG that depended primarily on CMLBG concentration and partly on solution pH was responsible for erosion and integrity of the coat in the lag period. Evaluation of polymer viscosity could describe the integrity of coat of a polysaccharide coated tablet in the lag period.
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42
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Guo J, He Z, Wu S, Zeng M, Chen J. Binding of aromatic compounds with soy protein isolate in an aqueous model: Effect of pH. J Food Biochem 2019; 43:e12817. [PMID: 31608468 DOI: 10.1111/jfbc.12817] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 01/07/2019] [Accepted: 02/02/2019] [Indexed: 11/28/2022]
Abstract
Interactions of the flavoring compounds hexyl acetate (HxAc), heptyl acetate (HpAc), linalyl formate (LiFo), linalyl acetate (LiAc), geraniol, linalool, limonene, and myrcene with soy protein isolate (SPI) were estimated in pH 3.0, 6.0, and 9.0 aqueous solutions using headspace solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS). The binding capacity of HxAc, HpAc, LiFo, LiAc, geraniol, and linalool increased in the pH of the medium from 3 to 9. For limonene and myrcene, an unexpected increase in headspace concentration or a "salting-out" effect was observed. Between pH 3 and 9, better accessibility to the primary hydrophobic sites as a result of a modification to the protein's flexibility was observed. PRACTICAL APPLICATIONS: SPME method is a technology of dynamic adsorption for flavors. The lowest level of lead be practicably detected in food as low as the practiced concentration of flavors (0.01-0.1 mM) in our study. At low concentrations of flavors, it is close to the actual flavor's concentration of food. In the previous studies, the technology, such as equilibrium dialysis, headspace-gas phase which need higher concentration of flavors (>0.2 mM). The interaction between flavors and protein has a different binding law at high and low concentrations. As we produced the acid fruit soy protein milk beverage, the off-flavors present in the beverage were due to the change in the interaction between denature SPI and flavors. The present work is aimed at paving the way for further research to elucidate flavor imbalances in acid fruit soy protein milk beverage.
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Affiliation(s)
- Jun Guo
- State Key Laboratory of Food Science and Technology, JiangNan University, Wuxi, PR China.,Department of Chemistry and Material Engineering, Chizhou University, Chizhou, PR China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, PR China
| | - Zhiyong He
- State Key Laboratory of Food Science and Technology, JiangNan University, Wuxi, PR China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, PR China
| | - Shengfang Wu
- State Key Laboratory of Food Science and Technology, JiangNan University, Wuxi, PR China.,Department of Chemistry and Material Engineering, Chizhou University, Chizhou, PR China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, PR China
| | - Maomao Zeng
- State Key Laboratory of Food Science and Technology, JiangNan University, Wuxi, PR China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, PR China
| | - Jie Chen
- State Key Laboratory of Food Science and Technology, JiangNan University, Wuxi, PR China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, PR China
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43
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Reynoso E, Cacciari RD, Suchetti CA, Montejano HA, Biasutti MA. Influence of pH and micellar systems on the sensitized photo-oxidation of bovine serum albumin. LUMINESCENCE 2019; 34:324-333. [PMID: 30740864 DOI: 10.1002/bio.3610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 01/03/2019] [Accepted: 01/07/2019] [Indexed: 12/24/2022]
Abstract
Photosensitized oxidation of bovine serum albumin (BSA), by using perinaphtenone as a sensitizer, has been studied at pH 7.4 and 11. The selected sensitizer does not present ground-state complexation with BSA and ensures that the mechanism is mediated by O2 (1 △g ). Strong dependence between BSA-O2 (1 △g ) photo-oxidation and the pH of the medium has been found. The relative oxygen uptake rate (v- △ O2 ) and the total quenching rate constant (kt ) values are higher at pH 11 than pH 7.4. The enhancement in the alkaline condition is due to conformational changes in the protein and the reactivity of tyrosinate anion with O2 (1 △g ). Even when the tendency with the pH in the presence of sodium dodecyl sulfate (SDS) micelles is similar to that observed in homogeneous media, an increment on the kt value is detected. This effect may be attributable to the strong interaction of BSA-SDS, which leads to the protein unfolding and could leave more exposed photo-oxidizable amino acids. A protective effect against the O2 (1 △g )-mediated photo-oxidation was observed in reverse micelles (RMs) of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) by comparing the kt values obtained at W = 10 with respect to the one obtain in homogeneous media. The latter could be mainly explained by the modification in the solvent polarity. Also, another important observation was found, the internal pH inside RMs of AOT sensed through tyrosine absorption was independent of the one used for the formation of the water pool. Hence, the kt values observed at both pH, are quite similar.
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Affiliation(s)
- Eugenia Reynoso
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Córdoba, Argentina
| | - R Daniel Cacciari
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Córdoba, Argentina
| | - Carlos A Suchetti
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Córdoba, Argentina
| | - Hernán A Montejano
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Córdoba, Argentina
| | - M Alicia Biasutti
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Córdoba, Argentina
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Ahmad I, Mirza T, Anwar Z, Ejaz MA, Sheraz MA, Ahmed S. Multicomponent spectrofluorimetric method for the assay of formylmethylflavin and its hydrolytic products: Kinetic applications. Spectrochim Acta A Mol Biomol Spectrosc 2018; 205:540-550. [PMID: 30075434 DOI: 10.1016/j.saa.2018.07.066] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Revised: 07/18/2018] [Accepted: 07/23/2018] [Indexed: 06/08/2023]
Abstract
A multicomponent spectrofluorimetric method has been developed for the simultaneous assay of formylmethylflavin (FMF), an intermediate product in the photolysis of riboflavin (vitamin B2), and its side-chain hydrolytic products, lumichrome (LC) in acidic solution and LC and lumiflavin (LF) in the alkaline solution as well as its ring cleavage products, 1,2-dihydro-1-methyl-2-keto-3-quinoxaline carboxylic acid (KA) and 1,2,3,4-tetrahydro-1-methyl-2,3-dioxo-quinoxaline (DQ) in alkaline solution. The assay method also takes into account an oxidation product of FMF, i.e. carboxymethylflavin (CMF), in both acid and alkaline solutions. The method involves adjustment of the pH of hydrolysed solution to 2.0 to convert FMF to its protonated form, extraction of LC (acid solution) or LC and LF (alkaline solution) with chloroform and their simultaneous assay by fluorescence measurement at 478 and 530 nm, respectively. The aqueous phase is readjusted to pH 6.5, extracted with chloroform to remove undegraded FMF and used for the assay of CMF, KA and DQ at 530, 443 and 420 nm, respectively. The chloroform extract is used for the assay of FMF at 530 nm. The proposed method has been validated and applied to the study of the kinetics of a hydrolysis reaction of FMF at pH 11.0. The calibration curves for FMF and degradation products are linear in the range of 0.1-1.0 × 10-6 M. The limit of detection (LOD) and limit of quantification (LOQ) range from 2.54-5.75 × 10-8 M and 0.78-1.74 × 10-7 M, respectively, for these compounds. The mean recovery ranges from 99.3-102.1% with a RSD of 0.14-0.35%. Judging from the molar balance of FMF and the hydrolytic products, uniformity of analytical data during the reactions and linearity of kinetic plot, the method gives accurate results for the assay of FMF and all of its degradation products. It can be conveniently used for the assay of these compounds and for the kinetics and stability studies of FMF.
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Affiliation(s)
- Iqbal Ahmad
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, Karachi, Pakistan
| | - Tania Mirza
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, Karachi, Pakistan
| | - Zubair Anwar
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, Karachi, Pakistan.
| | - Muhammad Ahsan Ejaz
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, Karachi, Pakistan
| | - Muhammad Ali Sheraz
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, Karachi, Pakistan
| | - Sofia Ahmed
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, Karachi, Pakistan
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45
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Chen S, Belver C, Li H, Ren LY, Liu YD, Bedia J, Gao GL, Guan J. Effects of pH value and calcium hardness on the removal of 1,1,1-trichloroethane by immobilized nanoscale zero-valent iron on silica based supports. Chemosphere 2018; 211:102-111. [PMID: 30071421 DOI: 10.1016/j.chemosphere.2018.07.127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/19/2018] [Accepted: 07/22/2018] [Indexed: 06/08/2023]
Abstract
Immobilizing nanoscale zero-valent iron (NZVI) particles on silica-based supports is an effective way to overcome the NZVI aggregation. The pH value and calcium hardness can change the aggregation kinetics and alter the stability of the suspensions of NZVI-silica based materials, thus change the reactivity of these NZVI-silica based materials to remove chlorinated aliphatic hydrocarbons (CAHs). The removal of CAHs by these NZVI-silica based materials includes adsorption by silica based supports and degradation by NZVI particles. Using 1,1,1-TCA and mesoporous hydrated silica (mHS) as model chlorinated aliphatic hydrocarbon (CAH) and silica based support, the effects of pH value and Ca2+ concentration on both the adsorption and adsorption-degradation processes of CAHs by NZVI-silica based materials were studied. The structural and textural features, suspension stability, particle size distribution, and Zeta potential of the materials under various conditions were characterized by different techniques. Both decreasing initial pH value and increasing Ca2+ concentration can reduce the Zeta potential of mHS and lead to the aggregation of mHS particles, thus inhibiting the removal of 1,1,1-TCA via adsorption by mHS through decreasing the number of sites for adsorption. Low initial pH value can accelerate the corrosion of NZVI core and remove the passivation layer, thus promoting the removal of 1,1,1-TCA via adsorption-degradation by NZVI@mHS. Ca2+ can decrease the sites for adsorption and form precipitates which can block mesoporous channels, thus hinder the 1,1,1-TCA removal via adsorption-degradation by NZVI@mHS.
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Affiliation(s)
- Shuai Chen
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, PR China
| | - Carolina Belver
- Seccion de Ingenieria Quimica, Facultad de Ciencias, Universidad Autonoma de Madrid, Campus Cantoblanco, Madrid E, 28049, Spain
| | - Hui Li
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, PR China.
| | - Lu Yao Ren
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, PR China
| | - Yong Di Liu
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, PR China
| | - Jorge Bedia
- Seccion de Ingenieria Quimica, Facultad de Ciencias, Universidad Autonoma de Madrid, Campus Cantoblanco, Madrid E, 28049, Spain
| | - Gui Lan Gao
- School of Environmental and Materials Engineering, Shanghai Polytechnic University, Shanghai, 201209, PR China
| | - Jie Guan
- School of Environmental and Materials Engineering, Shanghai Polytechnic University, Shanghai, 201209, PR China
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Chen YT, Chen WR, Lin TF. Oxidation of cyanobacterial neurotoxin beta-N-methylamino-L-alanine (BMAA) with chlorine, permanganate, ozone, hydrogen peroxide and hydroxyl radical. Water Res 2018; 142:187-195. [PMID: 29879656 DOI: 10.1016/j.watres.2018.05.056] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Revised: 05/19/2018] [Accepted: 05/29/2018] [Indexed: 06/08/2023]
Abstract
Beta-N-methylamino-L-alanine (BMAA), a new cyanobacterial neurotoxin produced by more than 20 genera of cyanobacteria, has been associated with amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) or Alzheimer's disease. Although BMAA has been shown to be removed in drinking water treatment plants (DWTPs), studies regarding the reactions between BMAA and the commonly used oxidants in DWTPs are limited to chlorine under specific conditions. In this study, the reaction kinetics between BMAA and five oxidants commonly used in DWTPs, including chlorine, potassium permanganate, ozone, hydrogen peroxide and hydroxyl radical were investigated. The oxidation of BMAA by chlorine, ozone or OH radical followed the second order reaction rate law, and the reaction rate was in the order of OH radicals > ozone >> chlorine. The rate constants increased by 20 times from 2 × 103 M-1s-1 at pH 5.8 to 4.93 × 104 M-1s-1 at pH 7, and kept in a relatively stable level at pH 7-9.5; rate constants of OH radicals were 1.11 × 108 M-1s-1 at pH 6.5 and 5.51 × 109- 1.35 × 1010 M-1s-1 at pH > 6.5. For both permanganate and H2O2 only, the removal of BMAA was negligible. The pH dependency of chlorine and the OH radical may be attributed to the neutral form of BMAA with free lone pair electrons readily to be attacked by oxidants. However, for ozonation of BMAA, the rate constants were 1.88 × 106-3.72 × 1010 M-1s-1, with a linear dependency on pH, implying that the hydroxide concentration governs the reaction. In addition, the rate of BMAA degradation was found to be slower in natural water if compared with that in deionized water.
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Affiliation(s)
- Yi-Ting Chen
- Department of Environmental Engineering and Global Water Quality Research Center, National Cheng Kung University, Tainan City, 70101, Taiwan
| | - Wan-Ru Chen
- Department of Environmental Engineering and Global Water Quality Research Center, National Cheng Kung University, Tainan City, 70101, Taiwan
| | - Tsair-Fuh Lin
- Department of Environmental Engineering and Global Water Quality Research Center, National Cheng Kung University, Tainan City, 70101, Taiwan.
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47
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Mirza T, Anwar Z, Ejaz MA, Ahmed S, Sheraz MA, Ahmad I. Multicomponent spectrofluorimetric method for the assay of carboxymethylflavin and its hydrolytic products: kinetic applications. LUMINESCENCE 2018; 33:1314-1325. [PMID: 30259653 DOI: 10.1002/bio.3549] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 07/27/2018] [Accepted: 08/14/2018] [Indexed: 11/08/2022]
Abstract
The simultaneous assay of carboxymethylflavin (CMF), an intermediate in the photolysis of riboflavin, and its hydrolytic side-chain cleavage products, lumichrome (LC) (acid solution) and LC and lumiflavin (LF) as well as isoalloxazine ring cleavage products, 1,2-dihydro-1-methyl-2-keto-3-quinoxaline carboxylic acid (KA) and 1,2,3,4-tetrahydro-1-methyl-2,3-dioxo-quinoxaline (DQ) (alkaline solution) has been carried out by a multicomponent spectrofluorimetric method. The method is based on the adjustment of pH of the degraded solutions to 2.0 and extraction of LC and LF with chloroform. The chloroform extract is evaporated to dryness under reduced pressure, the residue dissolved in pH 6.5 citro-phosphate buffer and LC and LF determined at their fluorescence maxima at 478 and 530 nm, respectively. The pH of the aqueous phase is re-adjusted to 6.5 and the solution used for the determination of CMF, KA and DQ at the wavelengths of 530, 443 and 420 nm, respectively. The proposed method has been validated according to ICH guidelines. The calibration curves for CMF and its hydrolytic products are linear in the concentration range of 0.5-5.0 × 10-6 M. The mean recovery ranges from 99.0-102.0% with relative standard deviation (RSD) of 0.19-0.99%. The limit of detection (LOD) and the limit of quantification (LOQ) are in the range of 1.17-1.78 × 10-7 M and 3.55-5.40 × 10-7 M, respectively. The uniformity of molar balance of CMF and degradation products during hydrolytic reactions indicates the accuracy of the proposed method for the spectrofluorimetric assay of the compounds. It has been applied to study the kinetics of hydrolytic reactions of CMF.
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Affiliation(s)
- Tania Mirza
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, Karachi, Pakistan
| | - Zubair Anwar
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, Karachi, Pakistan
| | - Muhammad Ahsan Ejaz
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, Karachi, Pakistan
| | - Sofia Ahmed
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, Karachi, Pakistan
| | - Muhammad Ali Sheraz
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, Karachi, Pakistan
| | - Iqbal Ahmad
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, Karachi, Pakistan
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48
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Xie Y, Li X, Chen J, Deng Y, Lu W, Chen D. pH Effect and Chemical Mechanisms of Antioxidant Higenamine. Molecules 2018; 23:E2176. [PMID: 30158440 DOI: 10.3390/molecules23092176] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 08/22/2018] [Accepted: 08/25/2018] [Indexed: 02/07/2023] Open
Abstract
In this article, we determine the pH effect and chemical mechanism of antioxidant higenamine by using four spectrophotometric assays: (1) 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide radical (PTIO•)-scavenging assay (at pH 4.5, 6.0, and 7.4); (2) Fe3+-reducing power assay; (3) Cu2+-reducing power assay; and (4) 1,1-diphenyl-2-picryl-hydrazyl (DPPH•)-scavenging assay. The DPPH•-scavenging reaction product is further analyzed by ultra-performance liquid chromatography, coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) technology. In the four spectrophotometric assays, higenamine showed good dose-response curves; however, its IC50 values were always lower than those of Trolox. In UPLC-ESI-Q-TOF-MS/MS analysis, the higenamine reaction product with DPPH• displayed three chromatographic peaks (retention time = 0.969, 1.078, and 1.319 min). The first gave m/z 541.2324 and 542.2372 MS peaks; while the last two generated two similar MS peaks (m/z 663.1580 and 664.1885), and two MS/MS peaks (m/z 195.9997 and 225.9971). In the PTIO•-scavenging assays, higenamine greatly decreased its IC50 values with increasing pH. In conclusion, higenamine is a powerful antioxidant—it yields at least two types of final products (i.e., higenamine-radical adduct and higenamine-higenamine dimer). In aqueous media, higenamine may exert its antioxidant action via electron-transfer and proton-transfer pathways. However, its antioxidant action is markedly affected by pH. This is possibly because lower pH value weakens its proton-transfer pathway via ionization suppression by solution H+, and its electron-transfer pathway by withdrawing the inductive effect (-I) from protonated N-atom. These findings will aid the correct use of alkaloid antioxidants.
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49
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Shanbhag BK, Liu C, Haritos VS, He L. Understanding the Interplay between Self-Assembling Peptides and Solution Ions for Tunable Protein Nanoparticle Formation. ACS Nano 2018; 12:6956-6967. [PMID: 29928801 DOI: 10.1021/acsnano.8b02381] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Protein-based nanomaterials are gaining importance in biomedical and biosensor applications where tunability of the protein particle size is highly desirable. Rationally designed proteins and peptides offer control over molecular interactions between monomeric protein units to modulate their self-assembly and thus particle formation. Here, using an example enzyme-peptide system produced as a single construct by bacterial expression, we explore how solution conditions affect the formation and size of protein nanoparticles. We found two independent routes to particle formation, one facilitated by charge interactions between protein-peptide and peptide-peptide exemplified by pH change or the presence of NO3- or NH4+ and the second route via metal-ion coordination ( e.g., Mg2+) within peptides. We further demonstrate that the two independent factors of pH and Mg2+ ions can be combined to regulate nanoparticle size. Charge interactions between protein-peptide monomers play a key role in either promoting or suppressing protein assembly; the intermolecular contact points within protein-peptide monomers involved in nanoparticle formation were identified by chemical cross-linking mass spectrometry. Importantly, the protein nanoparticles retain their catalytic activities, suggesting that their native structures are unaffected. Once formed, protein nanoparticles remain stable over long periods of storage or with changed solution conditions. Nevertheless, formation of nanoparticles is also reversible-they can be disassembled by desalting the buffer to remove complexing agents ( e.g., Mg2+). This study defines the factors controlling formation of protein nanoparticles driven by self-assembly peptides and an understanding of complex ion-peptide interactions involved within, offering a convenient approach to tailor protein nanoparticles without changing amino acid sequence.
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Affiliation(s)
- Bhuvana K Shanbhag
- Department of Chemical Engineering , Monash University , Wellington Road , Clayton , VIC 3800 , Australia
| | - Chang Liu
- Department of Chemical Engineering , Monash University , Wellington Road , Clayton , VIC 3800 , Australia
| | - Victoria S Haritos
- Department of Chemical Engineering , Monash University , Wellington Road , Clayton , VIC 3800 , Australia
| | - Lizhong He
- Department of Chemical Engineering , Monash University , Wellington Road , Clayton , VIC 3800 , Australia
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Jagodzinski LS, O'Donoghue MT, Heffernan LB, van Pelt FNAM, O'Halloran J, Jansen MAK. Wood ash residue causes a mixture of growth promotion and toxicity in Lemna minor. Sci Total Environ 2018; 625:667-676. [PMID: 29306154 DOI: 10.1016/j.scitotenv.2017.12.233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 12/20/2017] [Accepted: 12/20/2017] [Indexed: 05/23/2023]
Abstract
The use of wood as a sustainable biofuel results in the generation of residual wood ash. The ash contains high amounts of plant macronutrients such as phosphorus, potassium, calcium as well as several micronutrients. To explore the potential use of wood ash as a fertiliser, the growth enhancing properties of Sitka spruce (Picea sitchensis Bong.) wood ash were contrasted with the potential toxic action, using common duckweed (Lemna minor L.) as a model test species. The growth of L. minor exposed to wood bottom and fly ash solids and corresponding leachates was assessed in ultra-oligotrophic and eutrophic media. Ash solids and leachates were also tested as neutralized preparations. Suspended ash solids promoted L. minor growth up to concentrations of 2.5-5g/L. Leachates promoted growth up to 10g ash equivalents per litre, but for bottom ash only. Beneficial effects of wood ash were most pronounced on ultra-oligotrophic medium. However, on such nutrient-deficient medium severe inhibition of L. minor biomass and frond growth was observed at relatively low concentrations of fly ash (EC50=14g/L). On standard, eutrophic medium, higher concentrations of fly ash (EC50=21g/L), or neutralized fly ash (EC50=37g/L) were required to impede growth. Bottom ash, or neutralized bottom ash retarded growth at concentrations of 51g/L and 74g/L (EC50), respectively, in eutrophic medium. It appears that phytotoxicity is due to the elemental composition of the ash, its alkaline character, and possible interactions between these two properties. Growth promotion was due to the substantial content of plant nutrients. This study underlines the importance of the receiving environment (nutrient status and pH) in determining the balance between toxicity and growth promotion, and shows that the margin between growth promoting and toxicity inducing concentrations can be enlarged through ash neutralization.
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Affiliation(s)
- Lucas S Jagodzinski
- University College Cork, School of Biological, Earth and Environmental Sciences, North Mall, Distillery Fields, Cork City, Ireland; Environmental Research Institute, Lee Road, Cork City, Ireland
| | - Marian T O'Donoghue
- University College Cork, School of Biological, Earth and Environmental Sciences, North Mall, Distillery Fields, Cork City, Ireland
| | - Liam B Heffernan
- University of Alberta, Department of Renewable Resources, 442 Earth Sciences Building, Edmonton, Canada
| | - Frank N A M van Pelt
- University College Cork, Department of Pharmacology and Therapeutics, Western Gateway Building, Western Road, Cork City, Ireland; Environmental Research Institute, Lee Road, Cork City, Ireland
| | - John O'Halloran
- University College Cork, School of Biological, Earth and Environmental Sciences, North Mall, Distillery Fields, Cork City, Ireland; Environmental Research Institute, Lee Road, Cork City, Ireland
| | - Marcel A K Jansen
- University College Cork, School of Biological, Earth and Environmental Sciences, North Mall, Distillery Fields, Cork City, Ireland; Environmental Research Institute, Lee Road, Cork City, Ireland.
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