Functionalized magnetic metal organic framework nanocomposites for high throughput automation extraction and sensitive detection of antipsychotic drugs in serum samples

Due to the complexity of biological sample matrix, the automated and high-throughput pretreatment technology is urgently needed for monitoring the antipsychotic drugs for mental patients. In this study, functionalized magnetic zirconium-based organic framework nanocomposites (Fe3O4@SiO2@Zr-MOFs) were successfully designed and synthesized by the layer-by-layer growth. Among them, Fe3O4@SiO2@UiO-67-COOH showed the best adsorption performance, and at the same time it exhibited excellent water dispersibility, high thermal stability, chemical stability and high hydrophobicity. Results of adsorption kinetics, isotherm and FT-IR showed that the adsorption process was dominated by chemical adsorption (hydrogen bond, electrostatic interaction, π-π interaction) and monolayer adsorption. Moreover, the smaller pore size improved the protein exclusion rate which reached 98.9-99.8%. Based on the above result, the synthesized magnetic nanoparticles were introduced to 96-well automatic extractor, antipsychotic drugs in 96 serum samples were automatically extracted within 9 min, which most greatly saved the time and labor costs and avoided artificial errors. By further integrating with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), antipsychotic drugs can be detected in the range of 0.2-3.0 ng mL-1 with a quantitative limit of 0.06-0.9 ng mL-1. The recoveries of antipsychotic drugs and their metabolites in serum ranged from 95.7% to 112.3% within 1.4-6.5% of RSD. These features indicate that the proposed method is promising for high throughput and sensitively monitoring of drugs and other hazardous substances.

1- and 2-Tetrazolylacetonitrile as Versatile Ligands for Laser Ignitable Energetic Coordination Compounds

1- and 2-Tetrazolylacetonitrile (1- and 2-TAN) have been synthesized by the reaction of chloroacetonitrile with 1H-Tetrazole under basic conditions. They further were reacted with sodium azide in the presence of zinc(II) chloride to form 5-((1H-tetrazol-1-yl)methyl)-1H-tetrazole (1-HTMT) and 5-((2H-tetrazol-2-yl)methyl)-1H-tetrazole (2-HTMT). The nitrogen-rich compounds have been applied as ligands for Energetic Coordination Compounds (ECCs) and show interesting coordinative behavior due to different bridging modes. The structural variability of the compounds has been proved by low-temperature X-ray analysis. The ECCs were analyzed for their sensitivities to provide information about the safety of handling and their capability to serve as primary explosives in detonator setups to replace the commonly used lead styphnate and azide. All colored ECCs were evaluated for their ignitability by a laser diode in translucent polycarbonate primer caps. In addition, the spin-crossover characteristics of [Fe(1-TAN)6](ClO4)2 were highlighted by the measurement of the temperature-dependent susceptibility curve.

Composite of a thiacalix[4]arene-copper(I) metal-organic framework and mesoporous carbon for efficient electrochemical detection of antibiotics

Abundant use of nitrofurantoin (NFT) and metronidazole (MTZ) antibiotics has led to excessive residues in the environments and humans, resulting in serious damage to the human body and ecosystem. Therefore, effective detection of NFT and MTZ is exceedingly necessary. In this regard, metal-organic frameworks (MOFs) are promising materials as electrochemical sensors. Herein, we synthesized a new two-dimensional thiacalix [4]arene-copper (I) MOF (Cu-TC4A-M). This MOF was mixed with mesoporous carbon (MC) to a give Cu-TC4A-M@MC composite. In addition, the sensors of Cu-TC4A-M@MC(2:1)/GCE and Cu-TC4A-M@MC(1:2)/GCE were achieved (GCE = glassy carbon electrode), and then were applied for effectively detecting NFT and MTZ, respectively. Markedly, the two sensors exhibited satisfactory linear detection range, anti-interference, reproducibility and stability. When they were utilized in the real samples, such as human serum, urine, tap water and lake water, satisfactory recoveries were attained. The relative standard deviations (RSDs) were in the range of 1.16 % ∼ 1.92 % for NFT and 0.95 % ∼ 2.33 % for MTZ. This work provided a new application prospect for the thiacalix [4]arene-based MOFs as promising candidate materials for NFT and MTZ detection.

Carboxymethyl potato starch hydrogels encapsulated cyclodextrin metal-organic frameworks for enantioselective loading of S-naproxen and its programmed release

A natural polysaccharide-based vehicle is facilely prepared for enantioselective loading of S-naproxen (S-NPX) and its programmed release. Cyclodextrin metal-organic frameworks (CD-MOF) are synthesized through the coordination of K+ with γ-cyclodextrin (γ-CD). Compared with R-NPX, the CD-MOF preferably combines with S-NPX, which can be confirmed by the thermodynamic calculations. The S-NPX loaded CD-MOF (CD-MOF-S-NPX) is grafted with disulfide bond (-S-S-) to improve its hydrophobicity, and the loaded S-NPX is further encapsulated in the chiral cavity of γ-CD by carboxymethyl potato starch (CPS) hydrogels. The intermolecular hydrogen bonding of the CPS hydrogels is prone to be destroyed in mildly basic media (∼pH 8.0), resulting in the swelling of the hydrogels; the -S-S- linkage in the vehicle can be cleaved in the presence of glutathione (GSH), leading to the collapse of the CD-MOF. Therefore, the programmed release of S-NPX can be achieved. Also in this work, the release kinetics is investigated, and the results indicate that the release of S-NPX is controlled by the Higuchi model.

Remarkable water-mediated proton conductivity of two porous zirconium(IV)/hafnium(IV) metal-organic frameworks bearing porphyrinlcarboxylate ligands

Obtaining crystalline materials with high structural stability as well as super proton conductivity is a challenging task in the field of energy and material chemistry. Therefore, two highly stable metal-organic frameworks (MOFs) with macro-ring structures and carboxylate groups, Zr-TCPP (1) and Hf-TCPP (2) assembled from low-toxicity as well as highly coordination-capable Zr(IV)/Hf(IV) cations and the multifunctional linkage, meso-tetra(4-carboxyphenyl)porphine (TCPP) have attracted our strong interest. Note that TCPP as a large-size rigid ligand with high symmetry and multiple coordination sites contributes to the formation of the two stable MOFs. Moreover, the pores with large sizes in the two MOFs favor the entry of more guest water molecules and thus result in high H2O-assisted proton conductivity. First, their distinguished structural stabilities covering water, thermal and chemical stabilities were verified by various determination approaches. Second, the dependence of the proton conductivity of the two MOFs on temperature and relative humidity (RH) is explored in depth. Impressively, MOFs 1 and 2 demonstrated the optimal proton conductivities of 4.5 × 10-4 and 0.78 × 10-3 S·cm-1 at 100 °C/98 % RH, respectively. Logically, based on the structural information, gas adsorption/desorption features, and activation energy values, their proton conduction mechanism was deduced and highlighted.

Bimetallic metal-organic framework-derived bamboo-like N-doped carbon nanotube-encapsulated Ni-doped MoC nanoparticles for water oxidation

Molybdenum carbide materials with unique electronic structures have received special attention as water-splitting catalysts, but their structural stability in the alkaline water electrolysis process is not satisfactory. This study reports an in situ pyrolysis method for preparing NiMo-based metal-organic framework (MOF)-derived chain-mail oxygen evolution reaction (OER) electrocatalysts and bamboo-like N-doped carbon nanotube (NCNT)-encapsulated Ni-doped MoC nanoparticles (NiMoC-NCNTs). The NCNTs can provide chain mail shells to protect the inner highly reactive Ni-doped MoC cores from electrochemical corrosion by the alkaline electrolyte and regulate their catalytic properties through charge redistribution. Benefiting from high N-doping with abundant pyridinic moieties and abundant active sites of the periodic bamboo-like nodes, the as-prepared NiMoC-NCNTs display an outstanding activity for the OER with an overpotential of 310 mV at 10 mA cm-2 and a superior long-term stability of 50 h. Density functional theory calculations reveal that the excellent electrocatalytic activity of NiMoC-NCNTs comes from the electron transfer from NiMoC nanoparticles to NCNTs, resulting in a decrease in the local work function at the carbon surface and optimized free efficiencies of OER intermediates on C sites. This work provides an effective approach to improve the structural stability of fragile catalysts by equipping them with carbon-based chain.

Metal-organic framework integrated hydrogel bioreactor for smart detection of metal ions

Bioreactors with environment responsiveness for smart detection has attracted widespread interest. Bioreactors that operate in liquid have excellent reaction speed and sensitivity, and those that operate at a solid interface have unique portability and stability. However, bioreactors that can simultaneously take advantage of both properties are still limited. Here, we developed a metal-organic framework (MOF) integrated hydrogel bioreactor that can accommodate both solid and liquid properties by using a hydrogel as a quasi-liquid medium. To enhance the stability and intelligence of the hydrogel bioreactor, we have opted for the utilization of europium metal-organic framework (Eu-MOF) as the optical output to withstand long-term storage challenges, and DNA as the highly programmable substance for intelligent target response. On this basis, smart detection of metal ions and biological micro-molecules have been achieved. Notably, this quasi-liquid hydrogel bioreactor has effectively tackled the intrinsic issues of inadequate dispersion stability of Eu-MOF in liquid systems and poor stability of DNA against environmental interference. Moreover, this MOF integrated hydrogel bioreactor has been applied to the construction of a portable hydrogel bioreactor, which enables platform-free and arrayed target detection via a smartphone, providing a new perspective for further promoting the application of quasi-liquid hydrogel bioreactors and intelligent nanobiological sensors.

Fluorescent Eu-MOF@nanocellulose-based nanopaper for rapid and sensitive detection of uranium (Ⅵ)

Radioactive uranium leaks into natural water bodies mainly in the form of uranyl ions (UO22+), posing ecological and human health risks. Fluorescent europium-based metal-organic frameworks (Eu-MOFs) have been demonstrated to be effective fluorescent sensors for UO22+, but the large size, powder state and poor dispersity limit their further application. In this work, fluorescent Eu-MOFs were in-situ grown on TEMPO-oxidized cellulose nanofibers (TOCNFs), which is the first time that spherical Eu-MOF crystals with sizes below 10 nm were prepared. Fluorescence spectral analysis revealed a nine-fold increase in the fluorescence intensity of TOCNF@Eu-MOF compared to Eu-MOF. The nanocomposites achieved rapid and sensitive fluorescence quenching to UO22+ through the "antenna effect" and unsaturated Lewis basic sites on the ligands binding with UO22+. Moreover, TOCNF@Eu-MOF demonstrated excellent selectivity and anti-interference for UO22+ detection. For the nanopaper-based sensor made from TOCNF@Eu-MOF, the Stern-Volmer quenching constant (KSV) was calculated as 8.21 × 104 M-1, and the lowest limit of detection (LOD) was 6.6 × 10-7 M, significantly lower than the 1.32 × 10-6 M of Eu-MOFs. In addition, the nanopaper exhibited good fluorescence stability and cyclic detection performance, enabling the rapid and convenient detection of UO22+ in the aqueous phase within 30 s by simple dipping.

Defective ferrocene-based metal-organic frameworks for efficient solar-powered water oxidation via the ligand competition and etching effect

Two-dimensional metal-organic frameworks are considered to be promising electrocatalytic materials due to their ultrathin lamellar structure, ultrahigh porosity and large surface area, but there are still many challenges such as the embedding of organic ligands leading to low density of active sites and poor conductivity. Herein, we synthesize two-dimensional ferrocene-based metal-organic frameworks nanosheet electrocatalysts via the one-step hydrothermal hydrogen peroxide etching method. The prepared FcNi-BDC-H2O2/NF exhibits excellent oxygen evolution reaction performance with a current density of 100 mA·cm-2 at only 258 mV and a small driving potential of 1.542 V (10 mA·cm-2) is required to achieve overall water splitting. Significantly, an overall water-cracked cell using a solar cell assembly achieves the solar hydrogen conversion efficiency of 19.5%. The introduction of high electronegativity ferrocene and the etching of H2O2 increase the Ni3+ content of FcNi-BDC-H2O2, and expose more unsaturated active sites, which improve the intrinsic activity of the catalysts and the mass transfer rate during the catalytic process. Moreover, the FcNi-BDC-H2O2/NF demonstrates significant urea oxidation reaction performance, achieving a potential of 1.35 V and producing 10 mA·cm-2. This study presents a viable approach to investigating highly efficient electrocatalysts for oxygen evolution reaction and urea oxidation reaction using MOF-based bifunctional catalysts.

Towards an E-nose: Metal-organic frameworks based quartz crystal microbalance array for fruit ripeness indexing

Ethylene is a hormone for fruit ripening control, and for the purpose of maintaining plant quality, ethylene monitoring is crucial. Due to the simple structure and limited functionality, the technical realization of ethylene detection by an artificial sensor remains a challenge. In this paper, we present a metal-organic frameworks (MOFs) array based electronic nose (e-nose) for rapid and accurate determination of ethylene. Six zirconium-based MOFs with systematically modified pore sizes and π-π binding sites have been prepared and fabricated into a sensor array using quartz crystal microbalance (QCM) technology. By virtue of the synergistic features of six MOF sensors, selectivity detection of ethylene has been achieved. The detection limit reaches to 0.27 ± 0.02 ppm, and high selectivity and stability (98.29 % ± 0.88 %) could also be confirmed. By submitting data to machine learning algorithm, an e-nose system could be established for discriminating ethylene from mixtures with a qualitative accuracy of 90.30 % and quantitative accuracy of 98.89 %. Practical evaluation suggests that the e-nose could index the fruit quality based on the accurate detection of ethylene released during fruit ripeness. This work demonstrates the promising potential of fabricating MOFs based e-nose systems for practical monitoring applications by selectively detecting challengeable target molecules.

Bioelectrocatalytic reduction by integrating pyrite assisted manganese cobalt-doped carbon nanofiber anode and bacteria for sustainable antimony catalytic removal

A novel manganese cobalt metal-organic framework based carbon nanofiber electrode (MnCo/CNF) was prepared and used as microbial fuel cell (MFC) anode. Pyrite was introduced into the anode chamber (MnCoPy_MFC). Synergistic function between pyrite and MnCo/CNF facilitated the pollutants removal and energy generation in MnCoPy_MFC. MnCoPy_MFC showed the highest chemical oxygen demand removal efficiency (82 ± 1%) and the highest coulombic efficiency (35 ± 1%). MnCoPy_MFC achieved both efficient electricity generation (maximum voltage: 658 mV; maximum power density: 3.2 W/m3) and total antimony (Sb) removal efficiency (99%). The application of MnCo/CNF significantly enhanced the biocatalytic efficiency of MnCoPy_MFC, attributed to its large surface area and abundant porous structure that provided ample attachment sites for electroactive microorganisms. This study revealed the synergistic interaction between pyrite and MnCo/CNF anode, which provided a new strategy for the application of composite anode MFC in heavy metal removal and energy recovery.

Visible light-driven oxidation of non-native substrate by laccase attached on Ru-based metal-organic frameworks

Light-induced electron transfer can broaden the substrate range of metalloenzyme. However, the efficiency of photo-enzyme coupling is limited by the poor combination of photosensitizer or photocatalyst with enzyme. Herein, we prepared the nano-photocatalyst MIL-125-NH2@Ru(bpy) by in site embedding ruthenium pyridine-diimine complex [Ru(bpy)3]2+ into metal organic frameworks MIL-125-NH2 and associated it with multicopper oxidase (MCO) laccase. Compared to [Ru(bpy)3]2+, the coupling efficiency of MIL-125-NH2@Ru(bpy)3 for enzymatic oxygen reduction increased by 35.7%. A series of characterizations confirmed that the amino group of laccase formed chemical bonds with the surface defects or hydrophobic groups of MIL-125-NH2@Ru(bpy)3. Consequently, the tight binding accelerated the quenching process and electron transfer between laccase and the immobilized ruthenium pyridine-diimine complex. This work would open an avenue for the synthesis of MOFs photocatalyst towards photo-enzyme coupling.

Flower-like Ni/Mn/MC microspheres derived from metal-organic frameworks for electrocatalytic degradation of ceftriaxone sodium

This study demonstrated the design and fabrication of flower-like Ni/Mn-MOFs materials, and three-dimensional ultrathin flower-like Ni/Mn/MC microspheres were fabricated by embedding metal or metal oxide nanoparticles into a porous carbon skeleton via high-temperature pyrolysis at 600 °C and used for the electrocatalytic degradation of ceftriaxone sodium. This unique ultrathin porous flower-like structure can expose more active sites, provide rapid ion/electron transfer, and improve electrocatalytic activity. Meanwhile, the excellent electrical conductivity of the carbon skeleton, as well as the rational composition and synergistic effect of the two components, can promote the generation of active radicals (•OH and •O2-) in the reaction system, which accelerates the electrochemical degradation process and improves the electrocatalytic degradation performance. The results showed that the Ni/Mn/MC-5:1 composite prepared when the molar ratio of Ni: Mn was 5:1 exhibited the best electrocatalytic degradation performance for the degradation of sodium ceftriaxone. The composites showed 98.2% degradation of ceftriaxone sodium in 120 min and maintained sound degradation after 20 cycles. Therefore, we concluded that this novel multicomponent composite has good electrocatalytic activity and stability for the degradation of antibiotic wastewater.

Research progress on antibacterial applications of metal-organic frameworks and their biomacromolecule composites

With the extensive use of antibiotics, resulting in increasingly serious problems of bacterial resistance, antimicrobial therapy has become a global concern. Metal-organic frameworks (MOFs) are low-density porous coordination materials composed of metal ions and organic ligands, which can form composite materials with biomacromolecules such as proteins and polysaccharides. In recent years, MOFs and their derivatives have been widely used in the antibacterial field as efficient antibacterial agents. This review offers a detailed summary of the antibacterial applications of MOFs and their composites, and the different synthesis methods and antibacterial mechanisms of MOFs and MOF-based composites are briefly introduced. Finally, the challenges and prospects of MOFs-based antibacterial materials in the rapidly developing medical field were briefly discussed. We hope this review will provide new strategies for the medical application of MOFs-based antibacterial materials.

Hydrogel-encapsulated medium chain lipid-modified zeolite imidazole framework-90 as a promising platform for oral delivery of proteins

The administration of protein therapeutics through oral means is seen as a convenient and painless experience for patients, making it a significant consideration in the field of drug delivery. Nevertheless, the challenging conditions within the gastrointestinal tract, along with the obstacles to absorption, impede the efficient transportation of proteins. Here, we successfully implemented post-synthetic modifications to attach medium-chain lipids (C10) onto the surface of zeolitic imidazole framework-90 (ZIF-90), then encapsulated the nanoparticles with sodium alginate, resulting in a potential platform for the oral administration of proteins. By means of biomimetic mineralization, ZIF-90 achieves a simple and efficient encapsulation of proteins of varying sizes, while shielding them against degradation by digestive enzymes. Sodium alginate hydrogel protects proteins against gastric acid and helps the cargo to rapidly penetrate the mucus layer. Through a mixed mechanism dominated by micropinocytosis, the C10-conjugated ZIF-90 (ZIF-90-C10) can be uptake by Caco-2 cells with a 200-400% increase and transported through the Golgi apparatus after escaping from lysosomes, exhibiting enhanced uptake in the overall gastrointestinal tract. Furthermore, ZIF-90-C10 retains its adenosine triphosphate-responsive release, which drastically lowers the likelihood of accumulation in vivo and allows targeted delivery for disease cells. Our work highlights mid-chain lipid conjugation as a potent approach to enhancing nanoparticle delivery efficiency and a potential strategy for oral delivery of biomacromolecules when combined with pH-responsive gels.

CO2 conversion in a dielectric barrier discharge plasma by argon dilution over MgO/HKUST-1 catalyst using response surface methodology

Metal-organic frameworks (MOFs) as carbon dioxide adsorption in combination with metal oxides have shown catalyst application in CO2 conversion. Herein, the MgO/HKUST-1 catalyst is synthesized to direct conversion of CO2 upon dilution by argon in a cylindrical dielectric barrier discharge (DBD) reactor. A water-cooling circulation adjusts the reactor temperature, and aluminum powder is used as a high-voltage electrode. The effect of the discharge power, feed flow rate, CO2 fraction, and their interaction in plasma and plasma catalyst method on CO2 conversion (R1), effective CO2 conversion (R2), and energy efficiency (R3) is evaluated by central composite design (CCD) based on response surface methodology. The Analysis of Variance (ANOVA) results demonstrate that the quadratic regression model describes CO2 conversion and effective CO2 conversion, and the reduced cubic model describes energy efficiency. The results indicate that the method (plasma, plasma catalyst) and discharge power on R1 and R2 have a considerable effect. Also, the method and CO2 fraction on R3 have the greatest impact, respectively. In the plasma and plasma catalyst method maximum CO2 conversion is 12.3% and 20.5% at a feed flow rate of 80 ml/min, CO2 fraction of 50%, and discharge power of 74 W.

Synthesis of ZIF-8/ZnFe2O4/GO-OSO3H nanocomposite as a superior and reusable heterogeneous catalyst for the preparation of pyrimidine derivatives and investigation of their antimicrobial activities

In this report, we synthesized some pyrimidine derivatives by multi-component reaction of urea, benzaldehydes, and 1,3-indandione in the presence of ZIF-8/ZnFe2O4/GO-OSO3H nanocomposite under reflux conditions. Initially, graphene oxide was prepared from graphite, and then it was sulfonated using ClOSO3H. Next, GO-OSO3H nanosheets were used to support ZIF-8/ZnFe2O4 nanostructure. The construction of the synthesized structure was established using different spectral techniques such as X-ray crystallography (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX/Mapping), Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), vibrating sample magnetometer (VSM), and Brunauer-Emmett-Teller (BET). The present method provides various benefits including the efficiency of outcomes, easy separation of the catalyst, and excellent yield of the products within short reaction times. Moreover, the antibacterial activities of pyrimidine derivatives were investigated via the agar-well diffusion method on gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria and the obtained results illustrated reasonable effects.

Adavosertib-encapsulated metal-organic frameworks for p53-mutated gallbladder cancer treatment via synthetic lethality

Adavosertib (ADA) is a WEE1 inhibitor that exhibits a synthetic lethal effect on p53-mutated gallbladder cancer (GBC). However, drug resistance due to DNA damage response compensation pathways and high toxicity limits further applications. Herein, estrone-targeted ADA-encapsulated metal-organic frameworks (ADA@MOF-EPL) for GBC synthetic lethal treatment by inducing conditional factors are developed. The high expression of estrogen receptors in GBC enables ADA@MOF-EPL to quickly enter and accumulate near the cell nucleus through estrone-mediated endocytosis and release ADA to inhibit WEE1 upon entering the acidic tumor microenvironment. Ultrasound irradiation induces ADA@MOF-EPL to generate reactive oxygen species (ROS), which leads to a further increase in DNA damage, resulting in a higher sensitivity of p53-mutated cancer cells to WEE1 inhibitor and promoting cell death via conditional synthetic lethality. The conditional factor induced by ADA@MOF-EPL further enhances the antitumor efficacy while significantly reducing systemic toxicity. Moreover, ADA@MOF-EPL demonstrates similar antitumor abilities in other p53-mutated solid tumors, revealing its potential as a broad-spectrum antitumor drug.

Co-immobilizing laccase-mediator system by in-situ synthesis of MOF in PVA hydrogels for enhanced laccase stability and dye decolorization efficiency

The laccase mediator system (LMS) with a broad substrate range has attracted much attention as an efficient approach for water remediation. However, the practical application of LMS is limited due to their high solubility, poor stability and low reusability. Herein, the bimetallic Cu/ZIFs encapsulated laccase was in-situ grown in poly(vinyl alcohol) (PVA) polymer matrix. The PVA-Lac@Cu/ZIFs hydrogel was formed via one freeze-thawing cycle, and its catalytic stability was significantly improved. The mediator was further co-immobilized on the hydrogel, and this hierarchically co-immobilized ABTS/PVA-Lac@Cu/ZIFs hydrogel could avoid the continuous oxidation reaction between laccase and redox mediators. The co-immobilized LMS biocatalyst was used to degrade malachite green (MG), and the degradation rate was up to 100 % within 4 h. More importantly, the LMS could be recycled synchronously from the dye solutions and reused to degrade MG multiple times. The degradation rate remained above 69.4 % after five cycles. Furthermore, the intermediate products were detected via liquid chromatography-mass spectrometry, and the potential degradation pathways were proposed. This study demonstrated the significant potential of utilizing the MOF nanocrystals and hydrogel as a carrier for co-immobilized LMS, and the effective reuse of both laccase and mediator was promising for laccase application in wastewater treatment.

Tuning microscopic structure of La-MOFs via ligand engineering effect towards enhancing phosphate adsorption

The selection of different organic ligands when synthesizing metal organic framework (MOFs) can change their effects on the adsorption performance. Here, four La-MOFs adsorbents (La-SA, La-FA, La-TA and La-OA) with different organic ligands and structures were synthesized by solvothermal method for phosphate adsorption, and the relationship between their adsorption properties and structures was established. Among four La-MOFs, their phosphate adsorption capacities and adsorption rates followed La-SA > La-FA > La-TA > La-OA. The results indicated that average pore diameter played a key role in phosphate adsorption and there was a positive correlation between average pore diameter and adsorption capacity (R2 = 0.86). Coexisting ion experiments showed that phosphate adsorptions on three La-MOFs (La-SA, La-FA and La-TA) were inhibited in the presence of CO32- and HCO3-. The inhibition of CO32- was the most pronounced and the results of redundancy analysis pointed out that it was mainly due to the change of pH value. In contrast, La-OA showed enhanced phosphate adsorption in the presence of CO32- and HCO3-, and the combination of pH experiments showed that phosphate adsorption by La-OA was increased under alkaline conditions. Further combined with FT-IR, XRD, high resolution energy spectra of XPS (La 3d, P 2p and O 1s) and XANES, the adsorption mechanisms were derived electrostatic attraction, chemical precipitation and inner sphere complexation, and the last two were identified as the main mechanisms. Moreover, it can be identified from XPS 2p that the phosphate adsorption on La-FA and La-OA were mainly in the LaPO4 state, while La-SA and La-TA mainly existed in the form of LaPO4·xH2O crystals and inner sphere complexes. From the perspective of material morphology, this work provides a thought for the rational design of MOFs with adjustable properties for phosphate adsorption.

Synthesis of novel Cu/Fe based benzene Dicarboxylate (BDC) metal organic frameworks and investigations into their optical and electrochemical properties

In the recent past Metal-organic frameworks (MOFs) based thin films have demonstrated superior performance in various technological applications such as optical and optoelectronic devices, electrochemical energy storage, catalysis, and sensing. Herein we report tuning the optical performance of stable complexes using Cu and Fe metal ions with carboxylate benzene dicarboxylic (BDC), leading toward the formation of novel MOF structures. The formation of Cu-BDC and Fe-BDC were confirmed by XRD and SEM studies. The thermal stability of two MOFs was investigated, indicating that, the Cu-BDC is more stable than Fe-BDC. Further, the optical properties were investigated in the wavelength range 325-1100 nm, and the Fe-BDC exhibited greater optical transmission properties than Cu-BDC by 33 %, as investigated by Wemple-DiDomenico and Tauc models. The dispersion parameters related to optical studies for Cu-BDC were better in comparison to Fe-BDC, which could be attributed to the increase in Cu valence electrons due to an increase in the number of cations. The electrochemical behavior in terms of CV measurements shows the presence of pseudo capacitance in both Fe-BDC and Cu-BDC MOFs. The improved CV performance of Cu-BDC MOF suggests that it could be used as a storage material. This work successfully demonstrates the tailoring of optical properties related to MOF thin films through the formation of stable complexes using BDC as a potential material for the fabrication of OLED's and Solar cells. The improved CV performance suggests that these MOF based materials could be used as anodes in fabrication of batteries or supercapacitors.

A critical review on metal-organic frameworks (MOFs) based nanomaterials for biomedical applications: Designing, recent trends, challenges, and prospects

Nanomaterials (NMs) have garnered significant attention in recent decades due to their versatile applications in a wide range of fields. Thanks to their tiny size, enhanced surface modifications, impressive volume-to-surface area ratio, magnetic properties, and customized optical dispersion. NMs experienced an incredible upsurge in biomedical applications including diagnostics, therapeutics, and drug delivery. This minireview will focus on notable examples of NMs that tackle important issues, demonstrating various aspects such as their design, synthesis, morphology, classification, and use in cutting-edge applications. Furthermore, we have classified and outlined the distinctive characteristics of the advanced NMs as nanoscale particles and hybrid NMs. Meanwhile, we emphasize the incredible potential of metal-organic frameworks (MOFs), a highly versatile group of NMs. These MOFs have gained recognition as promising candidates for a wide range of bio-applications, including bioimaging, biosensing, antiviral therapy, anticancer therapy, nanomedicines, theranostics, immunotherapy, photodynamic therapy, photothermal therapy, gene therapy, and drug delivery. Although advanced NMs have shown great potential in the biomedical field, their use in clinical applications is still limited by issues such as stability, cytotoxicity, biocompatibility, and health concerns. This review article provides a thorough analysis offering valuable insights for researchers investigating to explore new design, development, and expansion opportunities. Remarkably, we ponder the prospects of NMs and nanocomposites in conjunction with current technology.

Supramolecular host-guest interaction triggered dye extraction from metal-organic framework for dual-mode ATP sensing from serum

Adenosine triphosphate (ATP) universally exists in all living organisms and holds a paramount role as a fundamental energy molecule in daily life. The abnormal concentration of ATP is closely related to many diseases, making the highly efficient detection of ATP very urgent. In this study, a dual-mode sensing system was developed to detect ATP sensitively and selectively via both DPV and fluorescence (FL) techniques, based on the strong interaction of ATP and Zn (II) nodes of zeolitic imidazolate framework-90 (ZIF-90). The disassembly of ZIF-90 further induced the subsequent release of pre-loaded rhodamine B (RhB). Benefitting from the robust host-guest recognition of β-cyclodextrin (β-CD) towards RhB, an enzyme-free and highly specific DPV detection strategy was established with the linear detecting range of 10.0-1.0 × 108 pM and the limit of detection (LOD) as low as 0.13 pM. Meanwhile, the FL sensing mode based on RhB exhibits comparable sensing performance with the linearity range of 10.0-1.0 × 107 pM and the LOD of 0.29 pM. Furthermore, the enzyme-free ATP sensing system exhibit outstanding long-term storage stability. The two-mode sensing platform was successfully applied to detect the ATP in human serum samples with the yielded result highly agree with the results of commercial ELISA kits. This dual-mode sensing platform is inspiring and paves the road for developing high-performance biosensor, demonstrating enormous potential for vitro diagnosis and practice clinic.

Enhanced stability of anthocyanins by cyclodextrin-metal organic frameworks: Encapsulation mechanism and application as protecting agent for grape preservation

Anthocyanins are promising naturally occurring food preservatives for enhancing the quality of food products due to their excellent antioxidant properties. However, their low stability hinders their food packaging application. Here, we propose a facile strategy to achieve the improved stability of anthocyanins encapsulated in γ-cyclodextrin metal-organic frameworks (CD-MOFs) with an in-depth exploration of their structure-property relationships. The adsorbed anthocyanins in CD-MOFs are stabilized by multiple cooperative non-covalent interactions including hydrogen bonding and van der Waals (vdW) interactions as demonstrated by density functional theory (DFT) calculations and spectroscopy analysis. Particularly, by ion-exchange of acetate ions into the pores of CD-MOFs, the resulting CD-MOFs (CD-MOF_OAc) shows a higher anthocyanins adsorption rate with a maximum loading capacity of 83.7 % at 1 min. Besides, CD-MOF_OAc possesses the more effective protecting effect on anthocyanins with at least two-fold enhancement of stability in comparison of free anthocyanins under heating and light irradiation. The anthocyanins encapsulated CD-MOFs films for fruit freshness was validated by the Kyoho experiment. This novel encapsulation system provides a new possibility for the potential use of CD-MOFs as the encapsulating material for anthocyanins in fruit preservation.

Fabrication of Eu-MOFs rod-shaped nanospheres with dual emissions for ratiometric fluorescence detecting Hg2+ in water

The incorporation of novel nanostructure has been proven to significantly improve the performance of fluorescence-based sensors in terms of sensitivity, selectivity, and detection capability. Herein, a lanthanide metal-organic framework (BTC-Eu-BDC-NH2) with dual ligands of 2-aminobenzoic acid (BDC-NH2) and 1,3,5-benzene tricarboxylic acid (BTC) has been prepared for ratiometric fluorescent detection of Hg2+ through the rational one-step synthetic approach. Through adjusting the ratio of two ligands, this dual-ligands strategy not only provided two independent emissions at peaks of 435 nm and 615 nm to resist the influence of external conditions, but also introduced the visual detection with an obvious color change. Moreover, the specific rod-shaped nanospheres morphology substantially enlarged the surface area of BTC-Eu-BDC-NH2 to ensure good dispersion and rapid response during sensing. Upon the addition of Hg2+, the fluorescence at 435 nm of BTC-Eu-BDC-NH2 was obviously quenched because of the interaction between Hg2+ and -NH2 from the ligand, while the red fluorescence at 615 nm remains almost unchanged. As a result, the synthesized BTC-Eu-BDC-NH2 showed excellent performances for visual sensing detection of Hg2+ with a clear luminescent color conversion from blue to red, and the detecting range was 0-40 μM with a low detection limit of 67 nM. Finally, the developed sensor was applied to actual tap water, and a handy sensing kit was constructed by hydrogel with BTC-Eu-BDC-NH2, demonstrating its potential practical applications.

The effect of synthesis conditions on the in situ grown MIL-100(Fe)-chitosan beads: Interplay between structural properties and arsenic adsorption

Efficient sequestration of arsenic from drinking water is a global need. Herein we report eco-friendly porous hybrid adsorbent beads for removal of arsenic, through in situ synthesis of MIL-100(Fe) in the chitosan solvogel. To understand the structural vs. performance correlation, series of hybrid adsorbents were synthesized by modulating synthesis conditions like temperature, crystallization time, and concentration. Adsorbents were investigated using PXRD, FT-IR, SEM, and ICP-OES. Intriguing correlation between crystallinity and adsorption performance was observed as low and high crystalline MIL-100(Fe)-chitosan (ChitFe5 and ChitFe7, respectively) exhibited exceptional adsorption towards As5+ by removing it from water with 99% efficiency, whereas for As3+ species removal of about 85% was afforded. Adsorption isotherms indicated that increase in crystallinity (ChitFe5 -> ChitFe7), adsorption capacities of As5+ and As3+ increased from 23.2 to 64.5, and from 28.1 to 35.3 mg/g, respectively. Selectivity tests of the adsorbents towards As5+ and As3+ over competitive anions in the equimolar competitive systems having nitrates, sulfates, and carbonates demonstrated that the performance of the absorbents was fully maintained, relative to the control system. Through this study a highly selective and efficient adsorbent for arsenic species is designed and a clear insight into the structural tuning and its effect on adsorption performance is provided.

Sensitive SERS aptasensor for histamine detection based on Au/Ag nanorods and IRMOF-3@Au based flexible PDMS membrane

BACKGROUND

Histamine is a kind of biogenic amine with strong toxicity and potential carcinogenicity. Many traditional methods of detecting histamine have the disadvantages of cumbersome detection steps, expensive equipment, and high professional requirements for staff. In contrast, SERS has become the preferred method for quantitative analysis of histamine because of rich fingerprint information, rapidity and economy. However, most of SERS substrates still have technical problems, such as poor stability, low sample collection rate, and detection efficiency. Therefore, there is a great need for new strategies to develop high-performance SERS substrates based sensors.

RESULTS

In our study, a sensitive SERS aptasensor for the detection of histamine was synthesized. The assembly was formed between IRMOF-3@Au/PDMS (flexible SERS substrate) and AuNR-DTNB@Ag-HA apt (Raman signal probe with both the target capture ability) via π-π stacking interaction from HA aptamer and IRMOF-3. Consequently, the SERS signal of the assembly derived from DTNB reached highest due to the synergistic enhancement effect by AuNR@Ag and IRMOF-3@Au. Meanwhile, HA aptamer can specifically capture histamine, therefore histamine addition competitively bound to the probe, leading to a corresponding decrease in the DTNB signal value on the SERS substrate. The SERS intensity at 1331 cm-1 presented a good linear relationship towards the logarithmic value of histamine concentrations ranging from 0.0001 mg/L to 400 mg/L (R2 = 0.990) with the LOD of 3.6 × 10-5 mg/L. Furthermore, the application in wine samples demonstrated the accuracy and applicability of the developed sensor.

SIGNIFICANCE

This method effectively improves substrate stability, detection sensitivity and signal response immediacy to amplify the SERS sensor, thus satisfying the histamine detection requirements of various systems. According to this aptasensor design, our strategy can be extended to create other MOF-based SERS substrates for accurately detecting relative targets to ensure food safety.

In situ generation of hybrid alginate hydrogels for enhanced breast tumor ferrotherapy through multiplex magnifying redox imbalances

Ferroptosis has drawn great attention to tumor treatments over the past decade. However, how to specifically boost tumoral redox imbalance by simultaneously superimposing iron-mediated reactive oxygen species and undermining antioxidative pathways at the tumor site is still a significant challenge in ferroptosis-based tumor ferrotherapy. In this study, we designed an in situ generable hydrogel that contains paclitaxel/chlorin e6-loaded iron-based metal-organic framework (Fe-MOF) nanoparticles for enhanced breast tumor ferrotherapy by multiplex magnifying redox imbalance. The polysaccharide sodium alginate can crosslink with tumoral calcium ions to generate a hydrogel patch, which promotes the retention of Fe-MOF and therapeutic molecules. The Fe-MOF holds peroxidase/glutathione oxidase mimicking properties, resulting in OH generation via the Fenton reaction and glutathione consumption. Local ultrasound treatment facilitates the release of therapeutics and stimulates the generation of signet oxygen by activating the sonosensitizer chlorin e6. In the meanwhile, the low-dose paclitaxel reduces tumoral pH value by downregulating the glutaminolysis-related gene (SLC7A11) which in turn enhances the catalytic activity of Fe-MOF and inhibits antioxidative pathways, respectively. Both in vivo and in vitro experiments show that our designed hybrid hydrogels can induce significant ferrotherapeutic effects by augmenting the tumoral oxidative stresses.

Detection of acrylamide in food based on MIL-glucose oxidase cascade colorimetric aptasensor

BACKGROUND

Maillard reaction involves the polymerization, condensation, and other reactions between compounds containing free amino groups and reducing sugars or carbonyl compounds during heat processing. This process endows unique flavors and colors to food, while it can also produce numerous hazards. Acrylamide (AAm) is one of Maillard's hazards with neurotoxicity and carcinogenicity, these effects can trigger mutations and alternations in gene expression in human cells and accelerate organ aging. An accurate and reliable acrylamide detection method with high sensitivity and specificity for future regulatory activities is urgently needed.

RESULTS

Herein, we constructed a colorimetric aptasensor with the hybridization of MIL-glucose oxidase (MGzyme)-cDNA and magnetic nanoparticle-aptamer (MNP-Apt) to specifically detect AAm. The incorporation of MB-Apt and AAm released MGzyme-cDNA in the supernatant, took the supernatant out, with the addition of glucose and TMB, MGzyme would oxidize glucose, the resulting •OH facilitated the oxidation of colorless TMB to blue ox-TMB. The absorbance value at 652 nm, which indicates the characteristic absorption peak of ox-TMB, exhibited a proportion to the concentration of AAm. MGzyme avoided the addition of harmful intermediate H2O2 and created an acid microenvironment for the catalytic reaction. MNP-Apt possessed the advantages of high specificity and simplified separation. Under optimal conditions, this method displayed a linear range of 0.01-100 μM with the limit of detection of 1.53 nM. With the spiked analysis data cross-verified by ELISA kit, this aptasensor was proven to specifically detect AAm at low concentrations.

SIGNIFICANCE

This colorimetric aptasensor was the integration of aptamer and the enzyme-cascade system, which could broaden the applicable range of enzyme-cascade system, break the limits of specific detection of substrates, eliminate the need for harmful intermediates, improve the reaction efficiency, implement the specific detection, whilst enabling the accurate detection of AAm. Given these remarkable performances, this method has shown significant potential in the field of food safety inspection.

Porous carbon with the synergistic effect of cellulose fibers and MOFs as the anode for high-performance Li-ion batteries

The commercial graphene for Li ion batteries (LIBs) has high cost and low capacity. Therefore, it is necessary to develop a novel carbon anode. The cellulose nanowires (CNWs), which has advantages of low cost, high carbon content, is thought as a good carbon precursor. However, direct carbonization of CNWs leads to low surface area and less mesopores due to its easy aggregation. Herein, the metal-organic frameworks (MOFs) have been explored as templates to prepare porous carbon due to their 3D open pore structures. The porous carbon was developed with the coordination effect of CNWs and MOFs. The precursor of MOFs coordinates with the -OH and - COOH groups in the CNWs to provide stable structure. And the MOFs was grown in situ on CNWs to reduce aggregation and provide higher porosity. The results show that the porous carbon has high specific capacity and fast Li+/electronic conductivity. As anode for LIBs, it displays 698 mAh g-1 and the capacity retention is 85 % after 200 cycles. When using in the full-battery system, it exhibits energy density of 480 Wh kg-1, suggesting good application value. This work provides a low-cost method to synthesize porous carbon with fast Li+/electronic conductivity for high-performance LIBs.

Recombinant streptococcal protein G-modified metal-organic framework ZIF-8 for the highly selective purification of immunoglobulin G from human serum

A novel solid phase extractant His-rSPG@ZIF-8 was prepared by covalently coupling recombinant streptococcal protein G (His-rSPG) with ZIF-8. The His-rSPG@ZIF-8 composite was characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Due to the specific binding between the immunoglobulin binding region of His-rSPG and the Fc region of immunoglobulin G (IgG), the His-rSPG@ZIF-8 composite demonstrated exceptional selectivity in adsorbing IgG. In Britton-Robinson buffer (BR buffer) with a salt concentration of 500 mmol L-1 (0.04 mol L-1, pH 8.0), the His-rSPG@ZIF-8 composite exhibited a remarkable adsorption efficiency of 99.8 % for 0.05 mg of the composite on 200 μL of IgG solution (100 μg mL-1). The adsorption behavior of the His-rSPG@ZIF-8 composite aligns with the Langmuir adsorption model, and the theoretical maximum adsorption capacity is 1428.6 mg g-1. The adsorbed IgG molecules were successfully eluted using a SDS solution (0.5 %, m/m), resulting in a recovery rate of 91.2 %. Indeed, the His-rSPG@ZIF-8 composite was successfully utilized for the isolation and purification of IgG from human serum samples. The obtained IgG exhibited high purity, as confirmed by SDS-PAGE analysis. Additionally, LC-MS/MS analysis was employed to identify the human serum proteins following the adsorption and elution process using the His-rSPG@ZIF-8 composite material. The results revealed that the recovered solution contained an impressive content of immunoglobulin, accounting for 62.4 % of the total protein content. Furthermore, this process also led to the significant enrichment of low abundance proteins such as Serpin B4 and Cofilin-1. Consequently, the His-rSPG@ZIF-8 composite holds great promise for applications such as IgG purification and immunoassays. At the same time, it expands the application of metal-organic frameworks in the field of proteomics.

Microneedle-mediated nose-to-brain drug delivery for improved Alzheimer's disease treatment

Conventional transnasal brain-targeted drug delivery strategies are limited by nasal cilia clearance and the nasal mucosal barrier. To address this challenge, we designed dissolving microneedles combined with nanocarriers for enhanced nose-to-brain drug delivery. To facilitate transnasal administration, a toothbrush-like microneedle patch was fabricated with hyaluronic acid-formed microneedles and tannic acid-crosslinked gelatin as the base, which completely dissolved in the nasal mucosa within seconds leaving only the base, thereby releasing the loaded cyclodextrin-based metal-organic frameworks (CD-MOFs) without affecting the nasal cilia and nasal microbial communities. As nanocarriers for high loading of huperzine A, these potassium-structured CD-MOFs, reinforced with stigmasterol and functionalized with lactoferrin, possessed improved physical stability and excellent biocompatibility, enabling efficient brain-targeted drug delivery. This delivery system substantially attenuated H2O2- and scopolamine-induced neurocyte damage. The efficacy of huperzine A on scopolamine- and D-galactose & AlCl3-induced memory deficits in rats was significantly improved, as evidenced by inhibiting acetylcholinesterase activity, alleviating oxidative stress damage in the brain, and improving learning function, meanwhile activating extracellular regulated protein kinases-cyclic AMP responsive element binding protein-brain derived neurotrophic factor pathway. Moreover, postsynaptic density protein PSD-95, which interacts with two important therapeutic targets Tau and β-amyloid in Alzheimer's disease, was upregulated. This fruitful treatment was further shown to significantly ameliorate Tau hyperphosphorylation and decrease β-amyloid by ways including modulating beta-site amyloid precursor protein cleaving enzyme 1 and a disintegrin and metalloproteinase 10. Collectively, such a newly developed strategy breaks the impasse for efficient drug delivery to the brain, and the potential therapeutic role of huperzine A for Alzheimer's disease is further illustrated.

Enhanced carbon dioxide adsorption and carrier separation over amine functionalized zirconium metal organic framework/gold/indium oxide for boosting photocatalytic carbon dioxide reduction

Photocatalytic CO2 conversion is a prospective way to mitigate greenhouse effect. In2O3 is widely used in the resource conversion of CO2, but still exists a few drawbacks containing limited CO2 capture and activation, narrow light absorption range, low charge separation and utilization. To overcome these disadvantages, an NH2-UiO-66/Au/In2O3 composite photocatalyst is built, with Au nanoparticles and NH2-UiO-66 decorated on the surface of In2O3 nanorods. Significantly, the improved carrier separation ability is attributed to the Schottky junction at the Au/In2O3 interface and the heterostructure between In2O3 and NH2-UiO-66. And the widened light absorption is attributed to the plasmon effect caused by Au nanoparticles. Moreover, the increase of CO2 adsorption and activation is mainly due to the porosity of NH2-UiO-66, thereby greatly improving photocatalytic CO2RR efficiency of NH2-UiO-66/Au/In2O3 nanorods. The CO yield of NH2-UiO-66/Au/In2O3 is 8.56 μmol g-1 h-1, which is nearly 45 times that of In2O3. This work will present a novel idea to design high-efficient composite photocatalysts for CO2 reduction by multifunctional component synergistic enhancement.

An all-glass based micro gas chromatographic column for light hydrocarbon separation with HKUST-1 as stationary phase

BACKGROUND

The gas chromatography column is one of the key components of the gas chromatograph and typically be miniaturized using micro-electro-mechanical system (MEMS) technology. Due to the limited area of the Si wafer, the column length of micro gas chromatographic column (μGCC) is usually much smaller than that of commercial chromatographic columns. Therefore, it is always difficult to use μGCCs to separate small molecule gas components such as light hydrocarbons. More importantly, the heterogeneous microchannel surface formed by silicon glass bonding causes uneven stationary phase coating, further preventing the improvement of separation performance.

RESULTS

In this paper, a novel all-glass based μGCC with 2 m length for the separation of light hydrocarbons is proposed. The microchannels of the μGCC were directly prepared in the glass substrate by ultrafast laser assisted chemical etching (ULAE). The all-glass microchannels make the coating of the hydrophilic metal-organic frameworks (MOFs) stationary phase continuously because of the homogeneous material composition. Therefore, a widely used copper based hydrophilic MOFs HKUST-1 was used as stationary phase for coating and testing. The test results show that the μGCC which is an open tubular column can realize the baseline separation of light hydrocarbons at 100 °C. And the resolution of difficult separated compounds, methane and ethane, can reach 12.98, which is 201.86 % higher than the silica-based monolithic capillary column in the relevant research. The resolution of ethane and ethylene reaches 6.81 at 120 °C.

SIGNIFICANCE

The μGCC fabricated by ULAE method is composed of all-glass and has the uniform stationary phase coating because of the homogeneous microchannel surface which greatly improve the separation performance, resulting in a large resolution for methane and ethane. The all-glass μGCC has broad application prospects in light hydrocarbon separation.

A Recent Advancement in Food Quality Assessment: Using MOF-Based Sensors: Challenges and Future Aspects

Monitoring food safety is crucial and significantly impacts the ecosystem and human health. To adequately address food safety problems, a collaborative effort needed from government, industry, and consumers. Modern sensing technologies with outstanding performance are needed to meet the growing demands for quick and accurate food safety monitoring. Recently, emerging sensors for regulating food safety have been extensively explored. Along with the development in sensing technology, the metal-organic frameworks (MOF)-based sensors gained more attention due to their excellent sensing, catalytic, and adsorption properties. This review summarizes the current advancements and applications of MOFs-based sensors, including colorimetric, electrochemical, luminescent, surface-enhanced Raman scattering, and electrochemiluminescent sensors. and also focused on the applications of MOF-based sensors for the monitoring of toxins such as heavy metals, pesticide residues, mycotoxins, pathogens, and illegal food additives from food samples. Future trends, as well as current developments in MOF-based materials.

A core-shell AuNRs@BUT-16 nanocomposite for enhancement SERS detection and efficient removal of deoxynivalenol

INTRODUCTION

Deoxynivalenol (DON) is widely found in grains and poses a serious threat to human health, so there is an urgent need to develop methods for its simultaneous removal and detection. The novel metal organic framework (MOF) material BUT-16 has a high adsorption capacity (79.8%) for DON. Meanwhile, surface-enhanced Raman spectroscopy (SERS) has been widely used for rapid detection of analytes.

OBJECTIVES

The aim of this work is to prepare a material that can be used for enhancement SERS detection and efficient removal of DON.

METHODS

AuNRs@BUT-16 was prepared by in-situ solvothermal method and characterized using a series of characterization tools. AuNRs@BUT-16 was used as an adsorbent and SERS substrate for the removal and detection of DON, and some factors affecting the adsorption and SERS detection were investigated. The adsorption mechanism between DON and AuNRs@BUT-16 was investigated using molecular docking. The proposed SERS method was used to detect DON contamination in real samples.

RESULTS

The prepared core-shell AuNRs@BUT-16 showed a synergistic effect in improving DON adsorption and SERS response. 97.6 % of DON was removed by AuNRs@BUT-16 in aqueous solution, and 70 % in 80 % methanol. The pre-enrichment effect of BUT-16 could trap more DON molecules in the "hot spots" of AuNRs, thus the proposed SERS sensor based on AuNRs@BUT-16 substrate displayed outstanding SERS response and the limit of detection of DON was 3.87 × 10-3 μg/mL. Molecular docking revealed that hydrogen bond and π-alkyl interaction were the main reasons for high affinity between BUT-16 and DON, and Au-O bonds facilitated the adsorption of DON on AuNRs.

CONCLUSIONS

AuNRs@BUT-16 with superior enrichment and SERS detection capabilities has been used for simultaneous removal and SERS detection of DON, and it also has great potential to realize sensitive and selective detection and removal of DON in multiple disciplines.

Encapsulation of sulfur in MoS2-modified metal-organic framework-derived N, O-codoped carbon host for sodium-sulfur batteries

Room-temperature sodium-sulfur batteries (RT Na-S) are promising energy storage systems with high energy densities and low costs. Nevertheless, drawbacks, including the limited cycle life and sluggish redox kinetics of sodium polysulfides, hinder their implementation. Herein, a heterostructure of MoS2 nanosheets coated on a metal-organic framework (MOF)-derived N, O-codoped flower-like carbon matrix (NOC) was designed as a sulfur host for advanced RT Na-S batteries. The NOC@MoS2 hierarchical host provided a sufficient space to guarantee a high sulfur loading and confinement for the volume expansion of sulfur during the charge/discharge process. According to first-principle calculations, the NOC@MoS2 composite exhibited metallic conductivity because electronic states crossed the Fermi level, which indicates that the introduction of NOC significantly improved the electronic conductivity of MoS2. Furthermore, electron transfer from MoS2 to the O-doped carbon sites was observed owing to the strong electronegativity of O, which can effectively increase the Lewis acidity of MoS2 and weaken the sodium-sulfur bonds in sodium polysulfides after adsorption on the cathode, leading to reductions in the Na2S dissociation energy barrier and Gibbs free energy for the rate-limiting step of the sulfur reduction process. Therefore, with the synthetic effects of MoS2 and N, O-codoped carbon, the obtained cathode exhibited a superior electrochemical performance.

NiFe MOF modified BiVO4 photoanode with strong π-π conjugation enhances built-in electric field for boasting photoelectrochemical water oxidation

The photoelectrochemical (PEC) performance ofBiVO4 is limited by sluggish kinetics and poor stability. In this work, a novel high-performance BiVO4/NiFe MOF(BPDC) photoanode is constructed by loading NiFe MOF with biphenyl-4,4'-dicarboxylic acid (BPDC) as an organic ligand on BiVO4 by a simple one-step hydrothermal method. The XPS, OCP, UPS, and KPFM show that the enhanced π-π conjugation effect causes more electrons transfer from the BiVO4 to the MOFs and affects the magnitude of the work function, leading to a strong built-in electric field to drive carrier separation and migration. Therefore, the BiVO4/NiFe MOF(BPDC) has a strong hole extraction and carrier separation capability to enhance photoelectrochemical water oxidation and improve photostability. The BiVO4/NiFe MOF(BPDC) photoanode has an enhanced photocurrent density of 4.16 mA cm-2 at 1.23 VRHE, which is 4.33 times higher than that of the pure BiVO4 (0.96 mA cm-2) photoanode with a negative shift of 376 mV in the onset potential plot, exhibiting excellent photostability of 7 h at 1.23 VRHE. This work demonstrates that the composite photoanodes constructed by BiVO4 and the MOFs with strong π-π conjugation are promising, which provides an effective strategy for the preparation of efficient and stable photoanodes.

Adsorption of tetracycline from aqueous solution by ZIF-8: Isotherms, kinetics and thermodynamics

In this study, ZIF-8 nanoparticles were synthesized using a simple method at room temperature. The ZIF-8 nanoparticles were then characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET (Brunauer-Emmett-Teller) specific surface area, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and zeta potential. Subsequent batch adsorption experiments evaluated the adsorption performance of ZIF-8 on tetracycline, examining key pa-rameters like reaction time, pH, temperature, and adsorbent dosage. The results revealed a removal rate for TC of up to 90.59%. The adsorption data aligned with the Sips model, showcasing a maximum adsorption capacity of 359.61 mg/g at 303K. Further, the adsorption kinetics adhered to the pseudo-second-order kinetic model with an equilibrium adsorption capacity of 90 mg/g at 303K. The considerable specific surface area of ZIF-8, standing at 1674.169 m2/g, likely enhances the adsorption efficacy. Analysis using XRD and FTIR confirmed the adsorption of TC on the ma-terial's surface. Overall, the predominant driving forces behind the adsorption process were identified as electrostatic interactions and π-π stacking interactions.

Triple signal-enhanced electrochemiluminescence strategy using iron-based metal-organic frameworks modified with Ru(II) complexes for carcino-embryonic antigen detection

The development of a highly efficient electrochemiluminescence (ECL) emitter represents an effective strategy for enhancing the sensitivity and repeatability of ECL immunosensors. In this study, a sandwich-type ECL immunosensor with triple enhancement was developed to detect carcino-embryonic antigen (CEA). This sensor is based on a porous structure of iron-based metal-organic framework (NH2-MIL-88(Fe)), encapsulating the luminescent tris(2,2'-bipyridine)ruthenium (II) (Ru (bpy)32+), Au@MoS2 with a 3D nanoflower structure as an enhanced substrate. In this system, the MOFs framework encapsulated luminophore was realized to solve its water solubility to reach stable luminescence, as well as the triple enhancement effect based on the principle of amino catalysis, Mo4+/Mo6+ active site conversion, and gold nanoparticles (Au NPs) promotion, which significantly enhanced the detection sensitivity. Furthermore, the ECL immunosensor demonstrated successful application in the highly sensitive and selective detection of CEA, achieving a detection limit of 38.9 fg mL-1. The sensor demonstrates remarkable sensitivity, specificity, stability, repeatability, and practicality in the analysis of human serum samples. This investigation presents a highly effective approach for the ultrasensitive detection of trace proteins.

Boosting hydrogen production of a MOF-based multicomponent photocatalyst with clean interface via facile one-pot electrosynthesis

Hydrogen production from photocatalysis via the usage of multicomponent photocatalysts represents a promising pathway for carbon peaking and carbon neutrality, owing to their structural advantages in dealing with the three crucial processes in photocatalysis, namely, light harvesting, charge transfer, and surface redox reactions. We demonstrate the fabrication of a MOF-based multicomponent photocatalyst, denoted as semiconductor/MOF/cocatalyst, by a one-pot electrochemical synthetic route. The as-fabricated multicomponent photocatalyst has a clean interface among the components, leading to close connections that contribute to high-quality heterojunction and facilitate photogenerated charge transfer and separation, thereby the efficient hydrogen evolution. The hydrogen production rate of the resultant ZrO2 /Zr-MOF/Pt is 1327 μmol ⋅ g-1  ⋅ h-1 , which is much higher than that of ZrO2 /Zr-MOF (15 μmol ⋅ g-1  ⋅ h-1 ) and pure Zr-MOF (10.1 μmol ⋅ g-1  ⋅ h-1 ), as well as the photodeposited-Pt products ZrO2 /Zr-MOF/PtPD (287 μmol ⋅ g-1  ⋅ h-1 ) and Zr-MOF/PtPD (192 μmol ⋅ g-1  ⋅ h-1 ) obtained by the step-wise synthetic approach. The work gives a good inspiration for the rational design and construction of MOF-based multicomponent photocatalysts through the one-pot electrosynthesis.

Zeolite imidazolate framework-8 in bone regeneration: A systematic review

Zeolite imidazolate framework-8 (ZIF-8) is a biomaterial that has been increasingly studied in recent years. It has several applications such as bone regeneration, promotion of angiogenesis, drug loading, and antibacterial activity, and exerts multiple effects to deal with various problems in the process of bone regeneration. This systematic review aims to provide an overview of the applications and effectiveness of ZIF-8 in bone regeneration. A search of papers published in the PubMed, Web of Science, Embase, and Cochrane Library databases revealed 532 relevant studies. Title, abstract, and full-text screening resulted in 39 papers being included in the review, including 39 in vitro and 22 animal studies. Appropriate concentrations of nano ZIF-8 can promote cell proliferation and osteogenic differentiation by releasing Zn2+ and entering the cell, whereas high doses of ZIF-8 are cytotoxic and inhibit osteogenic differentiation. In addition, five studies confirmed that ZIF-8 exhibits good vasogenic activity. In all in vivo experiments, nano ZIF-8 promoted bone formation. These results indicate that, at appropriate concentrations, materials containing ZIF-8 promote bone regeneration more than materials without ZIF-8, and with characteristics such as promoting angiogenesis, drug loading, and antibacterial activity, it is expected to show promising applications in the field of bone regeneration. STATEMENT OF SIGNIFICANCE: This manuscript reviewed the use of ZIF-8 in bone regeneration, clarified the biocompatibility and effectiveness in promoting bone regeneration of ZIF-8 materials, and discussed the possible mechanisms and factors affecting its promotion of bone regeneration. Overall, this study provides a better understanding of the latest advances in the field of bone regeneration of ZIF-8, serves as a design guide, and contributes to the design of future experimental studies.

Magnetic nanocomposite through coating mannose-functionalized metal-organic framework with biopolymeric pectin hydrogel beads: A potential targeted anticancer oral delivery system

This study designed magnetic nanocomposite hydrogel beads for a potential targeted anticancer oral delivery system. To end this, nanohybrids of Fe3O4/MIL-88(Fe) (FM) were synthesized through in-situ method by the treatment of terephthalic acid (TPA) and (Fe(NO3)3·9H2O) in the presence of Fe3O4 nanoparticles. They were then modified with mannose sugar as an anticancer receptor to achieve a targeted drug delivery system. After loading methotrexate (MTX), they were coated with pH-sensitive pectin hydrogel beads in the presence of a calcium chloride crosslinker for possible transferring the nanohybrids to the intestine through the acidic environment of the digestive system. The results of different analysis techniques showed that the materials were properly synthesized, coated, and loaded. The designed magnetic nanocomposite hydrogel beads showed pH-sensitive swelling and drug release rate, protecting MTX from the acidic environment of the stomach. MTT test revealed a good cytotoxicity toward colon cancer HT29 cell lines. Remarkably, the functionalization of MTX-loaded FM nanohybrids with mannose (MTX-MFM) enhanced their anticancer properties up to about 20 %. The results recommended that the prepared novel magnetic nanocomposite hydrogel beads have a good potential to be used as a targeted anticancer oral delivery system.

Ligand-engineered Ru-doped cobalt oxides derived from metal-organic frameworks for large-current-density water splitting

The influence of the preorganized structure and chemical composition of metal-organic frameworks (MOFs) on the morphology, surface properties, and catalytic activity of the MOFs-derived metal oxides is yet to be revealed. In this work, two types of Co-MOFs with different coordination configurations are synthesized for the preparation of the structure-engineered ruthenium (Ru)-doped cobalt oxides. The effect of the preorganized coordination structure of the MOFs on the morphology and surface properties is investigated. Interestingly, the oxalate-based MOFs derived Ru-doped cobalt oxide (OX-Co3O4-Ru) exhibits much better surface wettability and more oxygen vacancies than the zeolitic imidazolate framework-67 derived Ru-doped cobalt oxide. As expected, the OX-Co3O4-Ru owns excellent catalytic properties towards both hydrogen evolution reaction and oxygen evolution reaction with an overpotential of 49 and 286 mV, respectively at a current density of 100 mA cm-2 in 1.0 M KOH. Importantly, the bifunctional OX-Co3O4-Ru catalyst offers an extremely high current density of 500 mA cm-2 at a cell voltage of 1.71 V for overall water splitting and as well demonstrates robust working stability.

Triethylenediamine cobalt complex encapsulated in a metal-organic framework cage to prepare a cobalt single-atom catalyst with a high Co-N4 density for an efficient oxygen reduction reaction

Transition metal single atom catalysts (TM SACs) are the most promising oxygen reduction reaction (ORR) catalysts for proton exchange membrane fuel cells (PEMFCs) and metal-air batteries. However, the low density of M-Nx active sites seriously hinders further improvement of the ORR electrocatalytic activity. Here, a strategy for encapsulating nitrogen-rich guest molecules (triethylenediamine cobalt complex, [Co(en)3]3+) was proposed to construct a high-performance cobalt single-atom catalyst (Co-encapsulated SAC/NC). With this strategy, the guest molecules are encapsulated into metal-organic framework (MOF) cages as an additional cobalt source to boost cobalt loading, while abundant nitrogen from guest molecules contributes to the formation of Co-N4 active sites. Remarkably, the resulting Co-encapsulated SAC/NC has a high cobalt loading amount of 4.03 wt%, and spherical aberration-corrected transmission electron microscopy (AC-TEM) has confirmed that most cobalt exists in a single-atom state. As a result, the Co-encapsulated SAC/NC exhibits excellent ORR catalytic performance with a half-wave potential of 0.88 V. Furthermore, Zn-air batteries employing Co-encapsulated SAC/NC as air cathode show high peak power density and excellent cycling stability. Density functional theory (DFT) calculations reveal that adjacent active sites have different rate-determining steps and lower reaction energy barriers than a single active site.

Synthesis and evaluation of gene delivery vectors based on PEI-modified metal-organic framework (MOF) nanoparticles

Objectives

Zirconium-based metal-organic frameworks (MOFs) nanostructures, due to their capability of easy surface modification, are considered interesting structures for delivery. In the present study, the surfaces of UIO-66 and NH2-UIO-66 MOFs were modified by polyethyleneimine (PEI) 10000 Da, and their efficiency for plasmid delivery was evaluated.

Materials and Methods

Two different approaches, were employed to prepare surface-modified nanoparticles. The physicochemical characteristics of the resulting nanoparticles, as well as their transfection efficiency and cytotoxicity, were investigated on the A549 cell line.

Results

The sizes of DNA/nanocarriers for PEI-modified UIO-66 (PEI-UIO-66) were between 212-291 nm and 267-321 nm for PEI 6-bromohexanoic acid linked UIO-66 (PEI-HEX-UIO-66). The zeta potential of all was positive with the ranges of +16 to +20 mV and +23 to +26 mV for PEI-UIO-66 and PEI-HEX-UIO-66, respectively. Cellular assay results showed that the PEI linking method had a higher rate of gene transfection efficiency with minimal cytotoxicity than the wet impregnation method. The difference between transfection of modified nanoparticles compared to the PEI 10 kDa was not significant but the PEI-HEX-UIO-66 showed less cytotoxicity.

Conclusion

The present study suggested that the post-synthetic modification of MOFs with PEI 10000 Da through EDC/NHS+6-bromohexanoic acid reaction can be considered as an effective approach for modifying MOFs' structure in order to obtain nanoparticles with better biological function in the gene delivery process.

Fabrication of Oriented Polycrystalline MOF Superstructures

The field of metal-organic frameworks (MOFs) has progressed beyond the design and exploration of powdery and single-crystalline materials. A current challenge is the fabrication of organized superstructures that can harness the directional properties of the individual constituent MOF crystals. To date, the progress in the fabrication methods of polycrystalline MOF superstructures has led to close-packed structures with defined crystalline orientation. By controlling the crystalline orientation, the MOF pore channels of the constituent crystals can be aligned along specific directions: these systems possess anisotropic properties including enhanced diffusion along specific directions, preferential orientation of guest species, and protection of functional guests. In this perspective, we discuss the current status of MOF research in the fabrication of oriented polycrystalline superstructures focusing on the specific crystalline directions of orientation. Three methods are examined in detail: the assembly from colloidal MOF solutions, the use of external fields for the alignment of MOF particles, and the heteroepitaxial ceramic-to-MOF growth. This perspective aims at promoting the progress of this field of research and inspiring the development of new protocols for the preparation of MOF systems with oriented pore channels, to enable advanced MOF-based devices with anisotropic properties.

Functionalization strategies of metal-organic frameworks for biomedical applications and treatment of emerging pollutants: A review

One of the representative coordination polymers, metal-organic frameworks (MOFs) material, is of hotspot interest in the multi field thanks to their unique structural characteristics and properties. As a novel hierarchical structural class, MOFs show diverse topologies, intrinsic behaviors, flexibility, etc. However, bare MOFs have less desirable biofunction, high humid sensitivity and instability in water, restraining their efficiencies in biomedical and environmental applications. Thus, a structural modification is required to address such drawbacks. Herein, we pinpoint new strategies in the synthesis and functionalization of MOFs to meet demanding requirements in in vitro tests, i.e., antibacterial face masks against corona virus infection and in wound healing and nanocarriers for drug delivery in anticancer. Regarding the treatment of wastewater containing emerging pollutants such as POPs, PFAS, and PPCPs, functionalized MOFs showed excellent performance with high efficiency and selectivity. Challenges in toxicity, vast database of clinical trials for biomedical tests and production cost can be still presented. MOFs-based composites can be, however, a bright candidate for reasonable replacement of traditional nanomaterials in biomedical and wastewater treatment applications.

Recent advances in surface tailoring of thin film forward osmosis membranes: A review

The recent advancements in fabricating forward osmosis (FO) membranes have shown promising results in desalination and water treatment. Different methods have been applied to improve FO performance, such as using mixed or new draw solutions, enhancing the recovery of draw solutions, membrane modification, and developing FO-hybrid systems. However, reliable methods to address the current issues, including reverse salt flux, fouling, and antibacterial activities, are still in progress. In recent decades, surface modification has been applied to different membrane processes, including FO membranes. Introducing nanochannels, bioparticles, new monomers, and hydrophilic-based materials to the surface layer of FO membranes has significantly impacted their performance and efficiency and resulted in better control over fouling and concentration polarization (CP) in these membranes. This review critically investigates the recent developments in FO membrane processes and fabrication techniques for FO surface-layer modification. In addition, this study focuses on the latest materials and structures used for the surface modification of FO membranes. Finally, the current challenges, gaps, and suggestions for future studies in this field have been discussed in detail.

Application of a manganese dioxide/amine-functionalized metal-organic framework nanocomposite as a bifunctional adsorbent-catalyst for the room-temperature removal of gaseous aromatic hydrocarbons

A high surface area (883 m2·g-1) nanocomposite composed of an amine-functionalized metal-organic framework (NH2-UiO-66 (U6N)) and manganese dioxide (MnO2@U6N) was prepared as bifunctional adsorbent-catalyst for the purification of multiple aromatic volatile organic compounds (VOCs) such as benzene (B), toluene (T), m-xylene (X), and styrene (S), i.e., BTXS. The performance of MnO2@U6N was assessed for BTXS removal both as single- and multi-component systems at room temperature (RT (20 °C)) under dark conditions. MnO2@U6N exhibited superior catalytic-adsorption activity for the RT removal of BTXS. The removal performance of MnO2@U6N against BTXS was then assessed across varying levels of flow rate, VOC concentration, adsorbent/catalyst mass, and relative humidity. To better understand the catalytic-adsorption activity, two types of non-linear kinetic models (pseudo-first-order and pseudo-second-order) were utilized to simulate the experimentally obtained data. In-situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) analysis was also conducted to interpret the removal mechanism of BTXS. Their adsorption capacity (mg·g-1) values are estimated to increase in the order of B (21.1) < T (66.0) < X (79.1) < S (129.7). It is suggested that the adsorbed aromatic VOC molecules on the surface of MnO2@U6N should react with active oxygen species (lattice and adsorbed oxygen) to yield the environmentally benigh end products (i.e., carbon dioxide and water) along with various intermediates (e.g., alkoxides, aldehydes, phenolates, carboxylates, and anhydrides). Accordingly, the VOC removal potential of MnO2@U6N has been validated through the synergistic combination between adsorption (primary process) and catalysis (subordinate process) at RT.