Facile one pot microbe-mediatedin situsynthesis and antibacterial activity of reduced graphene oxide-silver nanocomposite

The present research deals with the development of a novel bioinspiredin situfabrication of reduced graphene oxide (rGO)-silver nanoparticle (AgNPs) nanocomposite (rGO@AgNCs) using microbes namelyPseudomonas aeruginosa(PA) andStaphylococcus aureus(SA). The fabricated rGO@AgNCs were characterized using Ultraviolet-visible (UV-Vis) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), particle size analysis, polydispersity index (PDI), zeta potential analysis, energy dispersive x-ray analysis (EDAX), Raman spectroscopy, powder x-ray diffraction (PXRD), high-resolution transmission electron microscopy (HR-TEM) analysis, etc. Furthermore, the rGO@AgNCs-PA and rGO@AgNCs-SA interaction with serum protein, pH stability study, andin vitrodissolution of AgNPs were also performed. The research findings of the proposed study demonstrated the simultaneous reduction of graphene oxide (GO) and AgNPs and the formation of rGO@AgNCs in the presence of microbes. Thein vitrodissolution studies of rGO@AgNCs composites showed better AgNPs dissolution with controlled release and offered remarkable matrix integrity throughout the dissolution period. The size and stability of rGO@AgNCs-PA and rGO@AgNCs-SA had no significant changes at physiological pH 7.4. A minimal decrease in the zeta potential of rGO@AgNCs was observed, which may be due to the weak interaction of nanocomposites and albumin. The antibacterial application of the synthesized nanocomposite was evaluated against a pathogenic mastitis-forming bacterium. The obtained results suggested an admirable antibacterial activity of synthesized nanocomposites against the tested microbes. This knowledge will assist the scientific fraternity in designing novel antibacterial agents with enhanced antibacterial activity against various veterinary pathogens in near future.

Boosting Chemodynamic Therapy via a Synergy of Hypothermal Ablation and Oxidation Resistance Reduction

Chemodynamic therapy (CDT), deemed as a cutting-edge antineoplastic therapeutic tactics, efficaciously suppresses tumors via catalytically yielding hydroxyl radicals (^•OH) in tumor regions. Nevertheless, its biomedical applications are often restricted by the limited hydrogen peroxide (H₂O₂) level and upregulated antioxidant defense. Herein, a versatile nanoreactor is elaborately designed via integrating Cu_2-xS and MnO₂ for T₁-weighted magnetic resonance (MR) imaging-guided CDT, synergistically enhanced through hypothermal ablation and oxidation resistance reduction, thereby displaying splendid antitumor efficiency as well as suppression on pulmonary metastasis. The as-synthesized Cu_2-xS@MnO₂ nanoreactors afford acid-dependent Cu-based and glutathione (GSH)-activated Mn-based catalytic properties for bimodal CDT. Owing to excellent absorbance at the second near-infrared (NIR-II) window, the Cu_2-xS furnishes hypo-photo-thermal therapy (PTT) against tumor growth and ameliorates the catalytic performance for thermal-enhanced CDT. Additionally, MnO₂ significantly downregulates GSH and glutathione peroxidase 4, which synergistically boosts CDT via promoting oxidative stress, simultaneously generating Mn²⁺ for MR contrast improvement and activatable tumor imaging. Therefore, this study proffers a new attempt centered on the collaborative strategy integrating NIR-II hypothermal PTT and synergistically enhanced CDT for tumor eradication.

Design, synthesis and biological evaluation of N-oxide derivatives with potent in vivo antileishmanial activity

Leishmaniasis is a neglected disease that affects 12 million people living mainly in developing countries. Herein, 24 new N-oxide-containing compounds were synthesized followed by in vitro and in vivo evaluation of their antileishmanial activity. Compound 4f, a furoxan derivative, was particularly remarkable in this regard, with EC₅₀ value of 3.6 μM against L. infantum amastigote forms and CC₅₀ value superior to 500 μM against murine peritoneal macrophages. In vitro studies suggested that 4f may act by a dual effect, by releasing nitric oxide after biotransformation and by inhibiting cysteine protease CPB (IC₅₀: 4.5 μM). In vivo studies using an acute model of infection showed that compound 4f at 7.7 mg/Kg reduced ~90% of parasite burden in the liver and spleen of L. infantum-infected BALB/c mice. Altogether, these outcomes highlight furoxan 4f as a promising compound for further evaluation as an antileishmanial agent.

In vitro effects of CaO nanoparticles on Triticale callus exposed to short and long-term salt stress

Ca²⁺ NPs enhanced tolerance of Triticale callus under salt stress by improving biochemical activity and confocal laser scanning analysis, conferring salt tolerance on callus cells. CaO NPs (Ca²⁺) are significant components that act as transducers in many adaptive and developmental processes in plants. In this study, effect of Ca²⁺ NPs on the response and regulation of the protective system in Triticale callus under short and long-salt treatments was investigated. The activation of Ca²⁺ NPs was induced by salt stress in callus of Triticale cultivars. MDA, H₂O₂, POD, and protein activities were determined in callus tissues. Concerning MDA, H₂O₂, protein activities, it was found that the Ca²⁺ NPs treatment was significant, and it demonstrated a high correlation with the tolerance levels of cultivars. Tatlıcak cultivar was detected for better MDA activities in the short time with 1.5 ppm Ca²⁺ NPs concentration of 50 g and 100 g NaCl. Similarly, the same cultivar responded with better H₂O₂ activity at 1.5 ppm Ca²⁺ NPs 100 g NaCl in the short time. POD activities exhibited a decreasing trend in response to the increasing concentrations of Ca²⁺ NPs. The best result was observed at 1.5 ppm Ca²⁺ NPs 100 g NaCl in the short term. Based on the protein content, treatment of short-term cultured callus cells with 1.5 ppm Ca²⁺ NPs inhibited stress response and it significantly promoted Ca²⁺ NPs signals as compared to control callus. Confocal laser scanning analysis proved that the application of Ca²⁺ NPs could alleviate the adverse effects of salt stress by the inhibition of stress severity in callus cells. This study demonstrated, under in vitro conditions, that the application of Ca²⁺ NPs can significantly suppress the adverse effects of salt stress on Triticale callus; it was also verified that the concentration of Ca²⁺ NPs could be important parameter to be considered in adjusting the micronutrient content in the media for this plant.

Sonochemical synthesis of nickel-manganous oxide nanocrumbs decorated partially reduced graphene oxide for efficient electrochemical reduction of metronidazole

In the present work, we report on the synthesis of crump-like nickel manganous oxide nanoparticles decorated partially reduced graphene oxide (NiMnO@pr-GO) nanocomposite through high-intensity ultrasonic bath sonication (ultrasonic frequency = 37 kHz and power = 150 W). The NiMnO@pr-GO nanocomposite modified glassy carbon electrode (GCE) was then employed for the electrochemical reduction of detrimental metronidazole (MNZ). The crystalline phase and formation of the NiMnO@pr-GO nanocomposites were confirmed by X-ray diffraction and other spectroscopic techniques. The cyclic voltammetry results demonstrate that this NiMnO@pr-GO nanocomposite modified GCE has a lower reduction potential and higher catalytic activity towards MNZ than do NiMnO and GO modified GCEs. Under optimized conditions, the fabricated NiMnO@pr-GO electrode can detect metronidazole over a wide linear range with a lower limit of detection of 90 nM. The sensitivity of the sensor was 1.22 µA µM^-1cm^-2 and was found to have excellent selectivity and durability for the detection of MNZ.

Novel enantiopure isoxazolidine and C-alkyl imine oxide derivatives as potential hypoglycemic agents: Design, synthesis, dual inhibitors of α-amylase and α-glucosidase, ADMET and molecular docking study

In an effort to explore a new class of antidiabetic inhibitors, a new series of isoxazolidine and C-alkyl imine oxide derivatives scaffolds were designed, synthesized and fully characterized. The newly synthesized analogues were evaluated for their human pancreatic α-amylase (HPA) and human lysosomal acid-α-glucosidase (HLAG) inhibitory activities and have shown a higher potency than acarbose. The compounds 7b (23.1 ± 1.1 μM) and 7a (36.3 ± 1.6 μM) were identified as the potent HPA and HLAG inhibitors with inhibitory effect up to 9 and 21-fold higher than acarbose, respectively. Antihyperglycemic activity results were supported by molecular docking approach of the most potent compounds 7b and 7a showing stronger interactions with the active site of HPA and HLAG as well as by in silico absorption, distribution, metabolism, excretion and toxicity (ADMET) profile suggesting their satisfactory oral druglikeness without toxic effect. Therefore, it can be concluded that both 7b and 7a can be used as effective lead molecules for the development of HPA and HLAG inhibitors for the management of T2DM.

Nanocrystalline Antiferromagnetic High-κ Dielectric Sr2NiMO6 (M = Te, W) with Double Perovskite Structure Type

Double perovskites have been extensively studied in materials chemistry due to their excellent properties and novel features attributed to the coexistence of ferro/ferri/antiferro-magnetic ground state and semiconductor band gap within the same material. Double perovskites with Sr2NiMO6 (M = Te, W) structure type have been synthesized using simple, non-toxic and costless aqueous citrate sol-gel route. The reaction yielded phase-pure nanocrystalline powders of two compounds: Sr2NiWO6 (SNWO) and Sr2NiTeO6 (SNTO). According to the Rietveld refinement of powder X-ray diffraction data at room temperature, Sr2NiWO6 is tetragonal (I4/m) and Sr2NiTeO6 is monoclinic (C12/m1), with average crystallite sizes of 49 and 77 nm, respectively. Structural studies have been additionally performed by Raman spectroscopy revealing optical phonons typical for vibrations of Te6+/W6+O6 octahedra. Both SNTO and SNWO possess high values of dielectric constants (341 and 308, respectively) with low dielectric loss (0.06 for SNWO) at a frequency of 1 kHz. These values decrease exponentially with the increase of frequency to 1000 kHz, with the dielectric constant being around 260 for both compounds and dielectric loss being 0.01 for SNWO and 0.04 for SNTO. The Nyquist plot for both samples confirms the non-Debye type of relaxation behavior and the dominance of shorter-range movement of charge carriers. Magnetic studies of both compounds revealed antiferromagnetic behavior, with Néel temperature (TN) being 57 K for SNWO and 35 K for SNTO.

A sensitive "Switch-on" phosphorescent probe for ferrous iron quantification in drug and In vitro imaging of living cells

Iron plays an important role in various physiological processes. However, the detailed biological functions of iron have not been sufficiently explored because of a lack of effective methods to monitoring iron, especially the labile ferrous ion (Fe²⁺). In the current study, a novel turn-on phosphorescent probe for Fe²⁺ quantification and visualization has been proposed based on the hybrid nanocomposite of manganese dioxide and gemini iridium complex (MnO₂-GM-Ir). The surfactant-like GM-Ir with positive charges was beneficial to combine with the negatively charged manganese dioxide (MnO₂) nanosheets, and thus endowing the MnO₂-GM-Ir nanocomposite excellent dispersion ability in the water as well as efficiently avoiding the interference to the detection caused by the agglomeration of nanocomposite. Phosphorescence of GM-Ir was effectively quenched by MnO₂ nanosheets through fluorescence resonance energy transfer (FRET) and the inner filter effect (IFE), while the phosphorescence could be significantly recovered in the presence of Fe²⁺via a selective Fe²⁺-mediated reduction of MnO₂ nanosheets, indicating a highly-specific selectivity towards Fe²⁺ with a low detection limit (80 nM). The drug test assay and in vitro imaging studies further proved that the MnO₂-GM-Ir nanocomposite could be employed as a promising probe for the quantitative detection of exogenous Fe²⁺ in drug and in vitro imaging of living cells.

In vivo evaluation of interactions between biphasic calcium phosphate (BCP)-niobium pentoxide (Nb2O5) nanocomposite and tissues using a rat critical-size calvarial defect model

Natural or synthetic biomaterials are increasingly being used to support bone tissue repair or substitution. The combination of natural calcium phosphates with biocompatible alloys is an important route towards the development of new biomaterials with bioperformance and mechanical responses to mimic those of human bones. This article evaluated the structural, physical, mechanical and biological properties of a new mechanical improved nanocomposite elaborated by association of fish biphasic calcium phosphate (BCP) and niobium pentoxide (Nb₂O₅). The nanocomposite (Nb-BCP) and the pure BCP, used as a positive control, were obtained by powder metallurgy. The density, porosity and microhardness were measured. The structural analysis was determined by X-ray diffraction (XRD) and the biological properties were studied in histological sections of critical size calvaria defects in rats, 7, 15, 30, 45 and 60 days after implantation of disks of both materials. Morphological description was made after scanning electron microscopy (SEM) and optical microscopy analysis. After sintering, the Nb-BCP nanocomposite presented four crystalline phases: 34.36% calcium niobate (CaNb₂O₆), 21.68% phosphorus niobium oxide (PNb₉O₂₅), 42.55% β-tricalcium phosphate (Ca₃(PO₄)₂) and 1.31% of niobium pentoxide (Nb₂O₅) and exhibited increases of 17% in density, 66% in Vickers microhardness and 180% in compressive strength compared to pure BCP. In vivo study, showed biocompatibility, bioactivity and osteoconductivity similar to pure BCP. SEM showed the formation of globular accretions over the implanted nanocomposites, representing one of the stages of bone mineralization. In conclusion, the BCP and Nb₂O₅ formed a nanocomposite exhibiting characteristics that are desirable for a biomaterial, such as bioperformance, higher β-TCP percentage and improved physical and mechanical properties compared to pure BCP. These characteristics demonstrate the promise of this material for supporting bone regeneration.

Hot Carriers and Photothermal Effects of Monolayer MoOx for Promoting Sulfite Oxidase Mimetic Activity

Local surface plasmon resonance (LSPR)-enhanced catalysis has brought a substantial amount of opportunities across various disciplines such as photocatalysis, photodetection, and photothermal therapeutics. Plasmon-induced photothermal and hot carriers effects have also been utilized to activate the enzyme-like reactions. Compared with natural enzymes, the relatively low catalytic performance of nanozymes severely hampered the potential applications in the field of biomedicine. For these issues mentioned above, herein, we demonstrate a highly efficient sulfite oxidase (SuO_x) mimetic performance of plasmonic monolayer MoO_x (ML-MoO_x) upon LSPR excitation. We also established that the considerable photothermal effect and the injection of hot carriers induced by LSPR are responsible for promoting the SuO_x activity of ML-MoO_x. The high transient local temperature on the surface of ML-MoO_x generated by the photothermal effect facilitates to impact the reaction velocity and feed the SuO_x-like activity, while the generation of hot carriers which are suggested as predominant effects catalyzes the oxidation of sulfite to sulfate through significantly decreasing the activation energy for the SuO_x-like reaction. These investigations present a contribution to the basic understanding of plasmon-enhanced enzyme-like reaction and provided an insight into the optimization of the SuO_x mimetic performance of nanomaterials.

Synthesis of La-Sr-Mn-O and La-Sr-Ca-Mn-O Perovskites Through Solution Combustion Using Urea at Fuel Deficient Conditions

La_0.7 Sr_0.3 MnO₃ (LSMO) nanoparticles have been obtained via solution combustion synthesis (SCS) using urea and glycine as fuels. Also, La_0.7 Sr_0.27 Ca_0.03 MnO₃ (LSCMO) nanoparticles have been synthesized through solution combustion using urea as fuel. In this paper, the combustion process was carried out with a fuel to oxidant ratio giving fuel deficient conditions ( ). The thermal analysis (TGA) indicate that the organic residues from the urea-nitrates gel mixture are eliminated above 600 °C and the post-synthesis heat treatment yields the formation of the desired phase without impurities. The obtained phases were analyzed using X-ray diffraction. The infrared analysis confirms the purity of the samples obtained using urea. However, the sample obtained using glycine confirms the formation of SrCO₃. The morphology was analyzed using a FE-SEM microscope, and it was found that the particles present a spherical shape with a mean size of around 45 nm in the selected samples. The samples' energy dispersive X-ray spectra show that the desired elements (La, Sr, Ca, Mn and O) are present in the nanoparticles. The measured zero field cooled (ZFC) and field cooled (FC) magnetizations were recorded from 4.5 to 380 K at 105 A/m to obtain their blocking and Curie temperatures. Moreover, the hysteresis loops measured at room temperature confirm the superparamagnetic behavior of the elaborated samples. According to the results obtained, these nanoparticles have interesting properties that make them candidates to explore not only for their potential in biomedical applications but also in refrigeration and magnetic storage devices.

A Combined Mechanochemical and Calcination Route to Mixed Cobalt Oxides for the Selective Catalytic Reduction of Nitrophenols

Para-, or 4-nitrophenol, and related nitroaromatics are broadly used compounds in industrial processes and as a result are among the most common anthropogenic pollutants in aqueous industrial effluent; this requires development of practical remediation strategies. Their catalytic reduction to the less toxic and synthetically desirable aminophenols is one strategy. However, to date, the majority of work focuses on catalysts based on precisely tailored, and often noble metal-based nanoparticles. The cost of such systems hampers practical, larger scale application. We report a facile route to bulk cobalt oxide-based materials, via a combined mechanochemical and calcination approach. Vibratory ball milling of CoCl2(H2O)6 with KOH, and subsequent calcination afforded three cobalt oxide-based materials with different combinations of CoO(OH), Co(OH)2, and Co3O4 with different crystallite domains/sizes and surface areas; Co@100, Co@350 and Co@600 (Co@###; # = calcination temp). All three prove active for the catalytic reduction of 4-nitrophenol and related aminonitrophenols. In the case of 4-nitrophenol, Co@350 proved to be the most active catalyst, therein its retention of activity over prolonged exposure to air, moisture, and reducing environments, and applicability in flow processes is demonstrated.

Synthesis and Dissolution of Metal Oxides in Ionic liquids and Deep Eutectic Solvents

Ionic liquids (ILs) and deep eutectic solvents (DESs) have proven to be suitable solvents and reactants for low-temperature reactions. To date, several attempts were made to apply this promising class of materials to metal oxide chemistry, which, conventionally, is performed at high temperatures. This review gives an overview about the scientific approaches of the synthesis as well as the dissolution of metal oxides in ILs and DESs. A wide range of metal oxides along with numerous ILs and DESs are covered by this research. With ILs and DESs being involved, many metal oxide phases as well as different particle morphologies were obtained by means of relatively simple reactions paths. By the development of acidic task-specific ILs and DESs, even difficultly soluble metal oxides were dissolved and, hence, made accessible for downstream chemistry. Especially the role of ILs in these reactions is in the focus of discussion.

Aptamer/photosensitizer hybridized mesoporous MnO2 based tumor cell activated ROS regulator for precise photodynamic therapy of breast cancer

Herein, we report a turn-on strategy for selectively killing the tumor cell via combining the singlet-oxygen quenching MnO₂ and tumor cell-targeting aptamer. The photosensitizers were in the quenching state when loaded in the mesoporous MnO₂ (mMnO₂) nanoparticles and sealed by the aptamer on the particle surface. The aptamer can selectively recognize the specific membrane protein on the tumor cell and release the photosensitizers, activating the photosensitizer and killing the tumor cells. The specific binding-induced "off-on" switching of singlet oxygen generation reduced the damage to the nearby healthy cells to a large extent. The high loading ability for photosensitizer and the GSH consumption property of mMnO₂ endow the system with high local concentration of singlet-oxygen for killing the target tumor cell. The high selectivity and efficiency of the constructed singlet oxygen regulating system will pave a new way for utilizing PDT in cancer precise treatment.

Effect of reduced graphene oxide doping on photocatalytic reduction of Cr(VI) and photocatalytic oxidation of tetracycline by ZnAlTi layered double oxides under visible light

The existence of Cr(VI) and antibiotics in the environment can form the joint contaminant which can be hazardous to the ecosystem. To deal with this, we have explored a plausible method to remove the Cr(VI) and tetracycline (TC) from water by visible light photocatalysis. In this study, a series of reduced graphene oxide@ZnAlTi layered double oxides (rGO@LDO) composites with different doping ratio of rGO were successfully synthesized, which were applied in photocatalytic reduction of Cr(VI) and oxidation of TC. Graphene acts as an electron donor and it can enhance the adsorption of Cr(VI) and TC on the surface of the composites. It's found that the obtained ZnAlTi-LDO composites doped with rGO have higher photo-responsiveness in the visible region. The best-performing rGO@LDO composite (i.e., CGL3) exhibited enhanced visible light-driven photocatalytic Cr(VI) reduction, which was about five times higher than those of ZnAlTi-LDO (without adding hole catcher). The rGO@LDO also showed a satisfactory performance for photocatalytic oxidation of TC with the total organic carbon removal of 80%. However, the doping of rGO did not significantly enhance the removal of TC. The experiment of pH effects demonstrated that acidic pH was favorable to photocatalytic reduction of Cr(VI), while neutral pH was favorable to photocatalytic oxidation of TC. The band structure of ZnAlTi-LDO was first identified, and the E_VB and E_CB of ZnAlTi-LDO are -2.32 and 0.72 V (vs. RHE). This research provides a feasible method to remove Cr(VI) and tetracycline from water by employing ZnAlTi-LDO doped with rGO as photocatalyst.

Synthesis of modified amorphous manganese oxide using low-cost sugars and biochars: Material characterization and metal(loid) sorption properties

In this study, amorphous Mn oxides (AMOs) and their composites with biochar (BC) were synthesized using different sugars (glucose, sucrose, and molasses), and their sorption efficiency toward Zn(II), Cd(II), and As(V) was tested. Additionally, detailed characterization of synthesized materials using various solid-state analysis methods (e.g. XRD, FTIR-ATR, and/or SEM-EDX) was also performed. Despite glucose-based AMOs presented higher sorption efficiency for As(V), i.e., 0.73 mmol g^-1 (glucose) > 0.27 mmol g^-1 (sucrose and molasses), similar sorption efficiency toward Zn(II), i.e., 0.80 mmol g^-1 (glucose and molasses) > 0.66 (sucrose) and Cd(II) (0.71-0.74 mmol g^-1 (sucrose and molasses) > 0.36 mmol g^-1 (glucose), was observed for sucrose- and molasses-based AMOs under the given conditions. Next, the sorption efficiency of all AMO/BC composites was proportional to their AMO content. Finally, Mn(II) leaching from the structure of the new AMOs was negligible compared to that observed for the glucose-based AMOs, in this study as well as in other similar studies. Moreover, using molasses as reducing agent during AMO synthesis dramatically decreased the total cost of the final materials, which suggested that these new AMOs could represent interesting alternatives for standard remediation technologies. The AMOs synthesized using low-cost sugars could, therefore, be promising materials for real field applications, since the main disadvantages of using standard AMOs are mitigated. Nevertheless, the efficiency and stability of these composites under real-life conditions must be tested prior to their direct application for remediation technologies.

Ultrasonication-assisted synthesis of sphere-like strontium cerate nanoparticles (SrCeO3 NPs) for the selective electrochemical detection of calcium channel antagonists nifedipine

In this work, strontium cerate nanoparticles (SrCeO₃ NPs, SC NPs) were developed through facile synthetic techniques (Ultrasound-Assisted (UA) and Stirring-Assisted (SA) synthesis) and utilized as an electrocatalyst for the selective and sensitive electrochemical detection of calcium channel blocker nifedipine (NDF). The as-prepared UASC NPs and SASC NPs were characterized using XRD, Raman, TEM, EDS, mapping, XPS and BET analysis which exposed the formation of SC NPs in the form of spherical in shape and well crystalline in nature. BET studies reveal that UASC NPs have maximum surface area than that of SASC NPs. Further, the use of the as-developed UASC NPs and SASC NPs as an electrocatalyst for the detection of NDF. Interestingly, the UASC NPs modified screen printed carbon electrode (UASC NPs/SPCE) exhibited an excellent electrocatalytic activity in terms of lower reduction potential and enhanced reduction peak current when compared to SASC NPs and unmodified SPCE. Moreover, as-prepared UASC NPs/SPCE displayed wide linear response range (LR, 0.02-174 µM), lower detection limit (LOD, 5 nM) and good sensitivity (1.31 µA µM^-1 cm^-2) than that of SASC NPs (LR = 0.02-157 µM, LOD = 6.4 nM, sensitivity - 1.27 µA µM^-1cm^-2). Furthermore, UASC NPs/SPCE showed an excellent selectivity even in the existence of potentially co-interfering compounds such as similar functional group containing drugs, pollutants, biological substances and some common cations/anions. The developed sensor was successfully employed for the determination of NDF in real lake water, commercial NDF tablet and urine samples with acceptable recovery.

General, Practical and Selective Oxidation Protocol for CF₃S into CF₃S(O) Group

A simple and efficient protocol for the oxidation of trifluoromethyl, mono- and difluoromethyl sulfides to the corresponding sulfoxides without over-oxidation to sulfones, using TFPAA prepared in situ from trifluoroacetic acid and 15% H₂O₂ aqueous solution was developed. The methodology is suitable for a wide range of aromatic and aliphatic substrates in milligram and multigram scales.

Novel coating containing molybdenum oxide nanoparticles to reduce Staphylococcus aureus contamination on inanimate surfaces

We previously synthetized molybdenum oxide (MoO₃) nanoparticles (NP) and showed their antibacterial activity against a representative collection of the most relevant bacterial species responsible for hospital-acquired infections, including Staphylococcus aureus. The aim of the present study was to prepare and characterize a novel coating with these MoO₃ NP, confirm its mechanical stability, and investigate its biocidal effect to reduce S. aureus contamination on inanimate surfaces. In addition, the novel MoO₃ NP coating was compared to a silver (Ag) NP coating synthetized by the same procedure. The MoO₃ and Ag NP coatings were characterized in terms of their chemical structure by FT-IR, surface morphology by scanning electron microscopy, and mechanical properties by tensile and adhesion tests. The antimicrobial activity of the coatings was tested by following the loss of viability of S. aureus after 6h, 24h, 48h, and 72h exposure. MoO₃ and Ag coatings exhibited surfaces of comparable morphologies and both presented elastomeric properties (tensile strength of ~420 kPa, Young’s modulus of ~48 kPa, and maximum elongation of ~12%), and excellent (classification of 5B) adhesion to glass, steel and polystyrene surfaces. The two coatings exhibited a good antibacterial activity (R) against S. aureus over time (R_MoO3 = 0.2–0.81; R_Ag = 0.61–2.37), although the effect of the Ag NP coating was more pronounced, especially at 72h (R_MoO3 = 0.81 vs R_Ag = 2.37). Noteworthy, contrary to the Ag NP coating, the MoO₃ NP coating was colourless and transparent, avoiding undesired unaesthetic effects. The synthetized coating with NP of MoO₃, which has low toxicity to humans, capability of biodegradation, and rapid excretion, can be applied onto most standard materials and therefore is a promising tool to reduce S. aureus contamination on usual inanimate surfaces found in healthcare and community environments.

Recent advances in functionalized MnO2 nanosheets for biosensing and biomedicine applications

As one kind of redox active layered transition-metal dioxide nanomaterials, single-layer manganese dioxide (MnO₂) nanosheets have gained significant research attention in the fields of biosensing and biomedicine because of their large surface area, intense and broad optical absorption, strong oxidation ability, catalytic activity, and robust mechanical properties. This review provides a brief overview of the recent advances in the development of MnO₂ nanosheet-based biosensors, bioimaging as well as drug delivery for cancer therapy. The methodologies for the preparation of MnO₂ nanosheets are summarized, followed by an introduction of the nanostructure and properties of MnO₂ nanosheets. Special attention is paid to their applications in biosensing, bioimaging and cancer therapy. Future perspectives and the challenges of high-performance MnO₂ nanosheets are also discussed.

Removal of acetylsalicylate and methyl-theobromine from aqueous environment using nano-photocatalyst WO3-TiO2 @g-C3N4 composite

Highly efficient, visible light-driven and a novel ternary hybrid photocatalyst WO₃-TiO₂-g-C₃N₄ with robust stabilities and versatile properties has been synthesized through facile hydrothermal method. This study considers the photo-degradation of aspirin (acetylsalicylate) and caffeine (methyl-theobromine) via photocatalysts (WO₃, WO₃/TiO_2, and WO₃/TiO₂/g-C₃N₄ (WTCN) composite) under visible-light irradiation. The SEM and TEM images show the formation of WO₃ nanoparticles with orthorhombic structure and average particle size of 65 nm. The photocatalyst WTCN composite possesses higher-catalytic activity when compared to that of WO₃ and WO₃/TiO₂ for degradation of aspirin and caffeine. The incorporation of g-C₃N₄ in WO₃/TiO₂ composite exhibited significant influence on the photocatalytic performance for both pollutants. Excellent photocatalytic performance of WTCN composite was observed owing to hydroxyl radical (OH) and superoxide radical (O₂^-) as main active species. The enhanced photocatalytic activity of WTCN composite can be attributed to following three reasons: (1) extended visible-light absorption; (2) extended surface area; (3) efficient charge-separation due to synergistic effects between g- and WO₃/TiO₂ composite. The removal efficiency of aspirin and caffeine (Methyl theobromine) could be achieved as much as 98% and 97% for acetylsalicylate and methyl-theobromine using WTCN composite material, respectively. This study could provide new insights into the synthesis of novel WO₃-based materials for environmental and energy applications.

Synthesis of fibrous LaFeO3 perovskite oxide for adsorption of Rhodamine B

The LaFeO₃ perovskite oxide decorated active carbon fibers (LFO-ACFs) based on cotton fabric waste were successfully synthesized through sol-gel loading and thermal treatment. LaFeO₃ perovskite and cotton fabric waste were combined to an eco-friendly and cheap adsorbent, which could reuse the leftover materials of textile industry and realize their functional modification. The structural, morphology/microstructure and functional groups were investigated through X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Fourier Transform Infrared spectroscopy (FTIR), respectively. The XRD pattern suggested the cotton fabric matrix didn't influence the structure of LaFeO₃ perovskite oxide. In SEM studies, LFO-ACFs still maintained fibrous shape of the raw cotton fibers, and the EDX analysis showed that the main elements of the prepared LFO-ACFs were La, Fe, O and C. The synthesized LFO-ACF was employed for adsorption of cational dye of Rhodamine B (RhB), and the effects of adsorption parameters, i.e. pH, contact time, solution temperature and initial concentration of dye, on adsorption behavior were investigated. Results suggested the adsorption performance of LFO-ACF for RhB was nearly not affected by solution pH and its maximum adsorption capacity fitted by the Langmuir isothermal model could attain 182.6 mg/g at 293 K. The adsorption kinetics followed the pseudo-second-order equation and the regeneration of LFO-ACF could be well realized through an easy pyrolysis method.

Determination of 89Sr and 90Sr in fresh cow milk and raw urine using crystalline synthetic tunnel manganese oxides and layered metal sulfides

⁸⁹Sr and ⁹⁰Sr are both fission products of high radiotoxicity, which can be released in significant amounts in the event of a nuclear accident. Radiostrontium isotopes will follow calcium all along the food chain and, after ingestion, accumulate in the bones. Therefore, it is imperative to be able to determine ⁸⁹Sr and ⁹⁰Sr in raw milk samples in case of an accidental situation to evaluate the dose given by both radionuclides to the population. Several methods exist for conducting ⁸⁹Sr and ⁹⁰Sr determination. However, most of them use at least one chromatographic step to purify strontium. This, unfortunately, increases the analytical time before the results can be released to the authorities. In addition, they often use liquid scintillation counting to determine the ⁸⁹Sr and ⁹⁰Sr activities, a method which can handle only one sample at a time. Here we propose using synthetic tunnel manganese oxides such as cryptomelane and todorokite and layered metal sulfides to selectively extract strontium from fresh milk and raw urine in a batch sorption method. We found that the method is very quick and yields very pure sources of (radio)-strontium, which can be counted in a proportional counter. Data (counts per minute) from the counter were fitted to a mathematical expression enabling the simultaneous determination of ⁸⁹Sr and ⁹⁰Sr. Because a proportional counter often has several drawers, it is typically possible to measure up to 16 samples at a time. Since cryptomelane is a binding phase easily synthesized in a large quantity, we anticipate that this technique could be an interesting alternative to conventional solid phase extraction chromatography methods.

Microwave-Assisted Synthesis of Black Titanium Monoxide for Synergistic Tumor Phototherapy

Black titanium oxide has attracted tremendous interest in tumor phototherapy via converting light energy to heat and reactive oxygen species (ROS). Nevertheless, current synthesis methods suffer from inert gas shielding, high costs, complicated procedures, and expensive facilities, which are fairly impractical for treatment application. Herein, we propose a one-step strategy for fast facile synthesis of black TiO nanoparticles via a microwave-assisted hydrothermal synthesis approach with Ti power, hydrochloric acid, and hydrofluoric acid without the requirement of an reducing agent and high-temperature calcination. The prepared black TiO nanoparticles with an average size of 52 nm exhibit strong absorbance from ultraviolet (UV) to near-infrared light region, favoring a single agent and single light-induced synergistic phototherapy of tumors. The black TiO nanoparticles shows an excellent performance in phototherapy with a photothermal conversion efficiency up to 50% and a prominent ROS generation under 808 nm laser irradiation. The toxicity and therapeutic effect in vitro and in vivo are investigated, and the results elucidate that black TiO nanoparticles possess good biocompatibility and remarkable synergistic tumor therapeutic efficacy. The proposed microwave-assisted method opens up a novel way for the synthesis of titanium-based material in a simple and fast manner, promoting their applications in the biomedical field.

Facile synthesis of graphene oxide-silver nanocomposite for decontamination of water from multiple pollutants by adsorption, catalysis and antibacterial activity

Here in, we presented a facile one-step method for the synthesis of Graphene oxide-silver (GO-Ag) nanocomposite and its applications as a sorbent for the elimination of some toxic pollutants from aqueous medium, as an efficient catalyst in the individual as well as simultaneous reduction reactions of multiple compounds, and as an antibacterial agent for the destruction of some harmful microorganisms existent in wastewater. GO was prepared using a modified Hummers method and Ag nanoparticles were integrated on GO sheets by chemical reduction of Ag⁺ ions on the surfaces of GO sheets. The composition and morphology of the nanocomposite was extensively characterized with elemental dispersive X-ray analysis (EDX), Fourier transform infra-red (FT-IR) spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). The GO-Ag nanocomposite demonstrated remarkable adsorption capacities and recyclability for malachite green (MG) and ethyl violet (EV) dyes. Various experimental parameters affecting adsorptive behavior of nanocomposite like temperature, pH, time of contact between dye and adsorbent, and adsorbent dose were evaluated thoroughly. Experimental data was simulated with different adsorption isotherms and kinetic models to evaluate adsorption behavior of both dyes and results confirmed the adsorption of both the dyes to be followed by pseudo 2nd order kinetic model and Langmuir adsorption model. Moreover, adsorbent was regenerated in suitable media for both dyes without any loss in removal efficiency. The catalytic performance for the 2-nitroaniline (2-NA) reduction was investigated in detail. Most importantly, the prepared nanocomposite was found to have potential to adsorb multiple pollutants all together as well as to catalyze the simultaneous reduction of a mixture of dyes (MG, MO, and EV) and 2-NA. An additional advantage of the GO-Ag nanocomposite was its antibacterial activity acquired to the presence of Ag nanoparticles. Two bacterial strains (Gram-negative bacterium, E. coli and the Gram-positive bacterium, S. aureus) were used to test antibacterial activity of composite and the results confirmed the remarkable performance of the nanocomposite in destroying harmful pathogens.

Integration of Polymerization and Biomineralization as a Strategy to Facilely Synthesize Nanotheranostic Agents

Integration of biological macromolecules with inorganic materials via biomineralization has demonstrated great potential for development of nanotheranostic agents. To produce multifunctionality, integration of multiple components in the biomineralized theranostic agents is required; however, how to efficiently and reproducibly implement this is challenging. In this report, a universal biomineralization strategy is developed by incorporation of oxidization polymerization into albumin-templated biomineralization for facile synthesis of nanotheranostic agents. A series of biomineralized polymers and manganese dioxide hybrid nanoparticles (PMHNs) can be synthesized via the polymerization of various monomers, including dopamine (DA), epigallocatechin (EGC), pyrrole (PY), and diaminopyridine (DP), along with the reduction of KMnO₄ and formation of manganese dioxide nanoparticles in albumin templates. These biomineralized PMHNs demonstrate ultrahigh MRI (longitudinal relaxivity up to 38 mM^-1 s^-1) and ultrasonic (US) imaging contrasting capabilities and have excellent photothermal therapy efficacy with complete ablation of orthotopic tumors. Moreover, these biomineralized hybrid nanoparticles can be effectively excreted through the kidneys, avoiding potential systemic toxicity. Thus, integration of polymerization into biomineralization presents a strategy for the fabrication of hybrid nanomaterials, allowing the production of multifunctional and biocompatible nanotheranostic agents via a facile one-pot method.

Development of Fe/Nb-based solar photocatalysts for water treatment: impact of different synthesis routes on materials properties

Semiconductors based on Fe/Nb oxides can present both solar sensitivity and high catalytic activity. However, there is still a lack regarding the comparison between different routes to produce Fe/Nb-based solar photocatalysts and the evaluation of the impact of the synthesis operating conditions on the material properties. In this work, Fe/Nb₂O₅ ratio, type of precipitating agent, presence/absence of washing stage, and temperature of calcination were verified to be the most relevant parameters in the synthesis by the co-precipitation method. These factors led to remarkable differences in the properties and performance of the photocatalysts produced by each distinct synthesis route. Composition, iron species present in the materials, crystallinity characteristics, and pH of the catalysts were affected, leading to different photocatalytic activities under UV-Vis light. Due to their characteristics, the synthesized materials are potential photocatalysts for application in solar processes. Graphical abstract ᅟ.

Molybdenum Trioxide: Efficient Nanosorbent for Removal of Methylene Blue Dye from Aqueous Solutions

Nano Molybdenum trioxide (α-MoO₃) was synthesized in an easy and efficient approach. The removal of methylene blue (MB) in aqueous solutions was studied using this material. The effects of various experimental parameters, for example contact time, pH, temperature and initial MB concentration on removal capacity were explored. The removal of MB was significantly affected by pH and temperature and higher values resulted in increase of removal capacity of MB. The removal efficiency of Methylene blue was 100% at pH = 11 for initial dye concentrations lower than 150 ppm, with a maximum removal capacity of 152 mg/g of MB as gathered from Langmuir model. By comparing the kinetic models (pseudo first-order, pseudo second-order and intraparticle diffusion model) at various conditions, it has been found that the pseudo second-order kinetic model correlates with the experimental data well. The thermodynamic study indicated that the removal was endothermic, spontaneous and favorable. The thermal regeneration studies indicated that the removal efficiency (99%) was maintained after four cycles of use. Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM) confirmed the presence of the MB dye on the α-MoO₃ nanoparticles after adsorption and regeneration. The α-MoO₃ nanosorbent showed excellent removal efficiency before and after regeneration, suggesting that it can be used as a promising adsorbent for removing Methylene blue dye from wastewater.

Synthesis of Co3O4/graphene nanocomposite using paraffin wax for adsorption of methyl violet in water

This study discusses the use of Co3O4 impregnated graphene (CoOIG) as an efficient adsorbent for the removal of methyl violet (MV) dye from wastewater. CoOIG nanocomposites have been prepared by pyrolyzing paraffin wax with cobalt acetate. The synthesised nanocomposite was characterised by X-ray diffraction, field emission scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscope, Raman spectroscopy, and Brunauer-Emmett-Teller isotherm studies. The above studies indicate that the composites have cobalt oxide nanoparticles of size 51-58 nm embedded in the graphene nanoparticles. The adsorption studies were conducted with various parameters, pH, temperature and initial dye concentration, adsorbent dosage and contact time by the batch method. The adsorption of MV dye by the adsorbent CoOIG was about 90% initially at 15 min and 98% dye removal at pH 5. The data were fitted in Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich and Sips isotherm models. Various thermodynamic parameters like Gibbs free energy, enthalpy, and entropy of the on-going adsorption process have also been calculated.

Optimisation of green synthesis of MnO nanoparticles via utilising response surface methodology

This study concerns the optimisation of green synthesis of manganese oxide nanoparticles (MnO NPs) with Dittrichia graveolens (L.) extract via response surface methodology (RSM). Central composite design was used to evaluate the effect of pH, time, and the extract to the metal ratio on the synthesised nanoparticles (NPs). Nine runs were designed to investigate the effect of each parameter while NPs were synthesised under different conditions. Considering the p-values (p-value < 0.05), it is indicated that the extract to the metal ratio was the most effective parameter. The synthesised NPs were characterised using UV-vis. Synthesis of the NPs by polyphenolic compounds of green reducing agent and their stabilisation by curcumin was confirmed by Fourier transform infrared spectra and the surface morphology of the spherical MnO NPs was studied by field-emission scanning electron microscopy and transmission electron microscope techniques. The present researchers claimed the optimal condition as follows: time = 56.7 min, pH = 7.2, and the extract to the metal ratio = 87.9 v/v. MnO NPs at optimum condition were then employed for degradation of industrial dyes and they showed high dye degradation activity against Rhodamine B and light green dye. The average size of the synthesised MnO NPs at optimal condition was claimed to be nearly 38 nm.

Ammonia sensing by closely packed WO3 microspheres with oxygen vacancies

Ammonia (NH₃), is a precursor for the formation of atmospheric fine particulate matter (PM_2.5), and thus establishing efficient and cost-effective methods to detect ammonia emission is highly desired. Transition metal oxide semiconductors-based sensors for electrochemical gas sensing have been extensively explored. Among various types of semiconductors, tungsten oxide (WO₃) possesses an anisotropic layered crystalline structure and is recognized as a promising material for gas sensing. However, the performance of commercial WO₃ is unsatisfactory because of its high impedance and low charge transportation efficiency. Thus, the modification of commercial WO₃ is needed to make it an efficient ammonia sensor material. In this work, closely packed WO₃ microspheres with oxygen vacancies were synthesized successfully through a novel two-step hydrothermal route. Our WO₃ showed a good selectivity to ammonia sensing, and its response intensity was 2.6 times higher than that of commercial WO₃ because of its optimized conductivity. Moreover, the mechanism behind its robust ammonia sensing performance was elucidated. The effectiveness of the as-prepared WO₃ microspheres for ammonia sensing also suggests a new strategy for modifying transition metal oxide materials.

Reduced graphene oxide-ZnO nanocomposite based electrochemical sensor for sensitive and selective monitoring of 8-hydroxy-2'-deoxyguanosine

Developing reliable and feasible electrochemical sensors for the detection of 8-hydroxy-2'-deoxyguanosine (8-OHdG) is important because the urinary level of 8-OHdG is related to cancer disease. Moreover, the co-existed uric acid (UA) as an interference severe affects the sensitive detection of 8-OHdG. Herein, sensitive monitoring of 8-OHdG was conducted using a nanocomposite of reduced graphene oxide (rGO) and ZnO nanoparticles (ZnO@rGO) as the sensing material. This nanocomposite was prepared via in-situ reduction of GO with Zn powders. Compared with those obtained on the unmodified glassy carbon electrode (GCE) and GO modified GCE (GO/GCE) the oxidation signals of 8-OHdG are significantly enhanced on the ZnO@rGO nanocomposite coated GCE (ZnO@rGO/GCE). Moreover, uricase has been employed successfully to eliminate the interferences of UA. A large amount of UA did not affect the oxidation signals of trace level of 8-OHdG. The linear range for the detection of 8-OHdG using ZnO@rGO/GCE was from 5.0 to 5000.0 nM. The detection limit was 1.25 nM calculated from a three-signal-to-noise ratio. The developed monitoring system is sensitive and selective for the determination of 8-OHdG and thus useful in practical applications, such as for the monitoring of 8-OHdG in the clinic urine samples.

Feasibility of applying the LED-UV-induced TiO2/ZnO-supported H3PMo12O40 nanoparticles in photocatalytic degradation of aniline

In the present study, TiO₂/ZnO-supported phosphomolybdic acid nanoparticles are investigated by the impregnation method, followed by analyzing their photocatalytic activity under UV-LED light and degradation kinetics degrading aniline as an organic pollutant model. Nanoparticle characteristics and the remaining Keggin structure in the nanocomposites were confirmed by means of FESEM, FTIR, and XRD analyses. Heterogenization of phosphomolybdic acid on TiO₂ and ZnO nanoparticles resulted in the improved light absorption intensity and decreased band gap of nanocomposites. Photocatalytic degradation of aniline was also improved for composite nanoparticles and reached to 25.62, 43.48, and 38.25% for TiO₂/HPMo, ZnO/HPMo, and TiO₂/ZnO/HPMo, respectively. Overall, the results showed a good fit to the Langmuir-Hinshelwood kinetic model.

One-Step Synthesis of Nb2 O5 /C/Nb2 C (MXene) Composites and Their Use as Photocatalysts for Hydrogen Evolution

Hydrogen production through facile photocatalytic water splitting is regarded as a promising strategy to solve global energy problems. Transition-metal carbides (MXenes) have recently drawn attention as potential co-catalyst candidates for photocatalysts. Here, we report niobium pentoxide/carbon/niobium carbide (MXene) hybrid materials (Nb₂ O₅ /C/Nb₂ C) as photocatalysts for hydrogen evolution from water splitting. The Nb₂ O₅ /C/Nb₂ C composites were synthesized by one-step CO₂ oxidation of Nb₂ CT_x . Nb₂ O₅ grew homogeneously on Nb₂ C after mild oxidation, during which some amorphous carbon was also formed. With an optimized oxidation time of 1.0 h, Nb₂ O₅ /C/Nb₂ C showed the highest hydrogen generation rate (7.81 μmol h^-1  g_cat^-1 ), a value that was four times higher than that of pure Nb₂ O₅ . The enhanced performance of Nb₂ O₅ /C/Nb₂ C was attributed to intimate contact between Nb₂ O₅ and conductive Nb₂ C and the separation of photogenerated charge carriers at the Nb₂ O₅ /Nb₂ C interface; the results presented herein show that transition-metal carbide are promising co-catalysts for photocatalytic hydrogen production.

Programming Enzyme-Initiated Autonomous DNAzyme Nanodevices in Living Cells

Molecular nanodevices are computational assemblers that switch defined states upon external stimulation. However, interfacing artificial nanodevices with natural molecular machineries in living cells remains a great challenge. Here, we delineate a generic method for programming assembly of enzyme-initiated DNAzyme nanodevices (DzNanos). Two programs including split assembly of two partzymes and toehold exchange displacement assembly of one intact DNAzyme initiated by telomerase are computed. The intact one obtains higher assembly yield and catalytic performance ascribed to proper conformation folding and active misplaced assembly. By employing MnO₂ nanosheets as both DNA carriers and source of Mn²⁺ as DNAzyme cofactor, we find that this DzNano is well assembled via a series of conformational states in living cells and operates autonomously with sustained cleavage activity. Other enzymes can also induce corresponding DzNano assembly with defined programming modules. These DzNanos not only can monitor enzyme catalysis in situ but also will enable the implementation of cellular stages, behaviors, and pathways for basic science, diagnostic, and therapeutic applications as genetic circuits.

Injectable methylcellulose hydrogel containing silver oxide nanoparticles for burn wound healing

A thermo-sensitive methylcellulose (MC) hydrogel containing silver oxide nanoparticles (NPs) was prepared via one-pot synthesis in which a silver acetate precursor salt (CH₃COOAg) induces a salt-out effect in the MC solution. The silver oxide NPs were synthesized in situ from Ag⁺ ions during the MC hydrogelation, and the residual CH₃COO^- ions decreased the gelation temperature of the MC solution through the salt-out effect. The gelation behavior of the MC solution varied according to the CH₃COOAg content and was monitored. Also, the formation and structure of the silver oxide NPs in the MC hydrogel was confirmed. From the results, silver oxide NPs was successfully incorporated in MC hydrogels, simultaneously, acetate ion which was counter ion of Ag was affected gelation behavior of Ag. Finally, the antimicrobial activity and wound healing effect was examined using the shaking flask method and burn wound test, respectively. The MC hydrogel with silver oxide NPs showed excellent antimicrobial activity and burn wound healing. Therefore, this thermo-responsive MC hydrogel has great potential as an injectable hydrogel for wound regeneration.

Nanoscale wide-band semiconductors for photocatalytic remediation of aquatic pollution

Water pollution is a serious challenge to the public health. Among different forms of aquatic pollutants, chemical and biological agents create paramount threat to water quality when the safety standards are surpassed. There are many conventional remediatory strategies that are practiced such as resin-based exchanger and activated charcoal/carbon andreverse osmosis. Newer technologies using plants, microorganisms, genetic engineering, and enzyme-based approaches are also proposed for aquatic pollution management. However, the conventional technologies have shown impending inadequacies. On the other hand, new bio-based techniques have failed to exhibit reproducibility, wide specificity, and fidelity in field conditions. Hence, to solve these shortcomings, nanotechnology ushered a ray of hope by applying nanoscale zinc oxide (ZnO), titanium dioxide (TiO₂), and tungsten oxide (WO₃) particles for the remediation of water pollution. These nanophotocatalysts are active, cost-effective, quicker in action, and can be implemented at a larger scale. These nanoparticles are climate-independent, assist in complete mineralization of pollutants, and can act non-specifically against chemically and biologically based aquatic pollutants. Photocatalysis for environmental remediation depends on the availability of solar light. The mechanism of photocatalysis involves the formation of electron-hole pairs upon light irradiations at intensities higher than their band gap energies. In the present review, different methods of synthesis of nanoscale ZnO, TiO₂, and WO₃ as well as their structural characterizations have been discussed. Photodegradation of organic pollutants through mentioned nanoparticles has been reviewed with recent advancements. Enhancing the efficacy of photocatalysis through doping of TiO₂ and ZnO nanoparticles with non-metals, metals, and metal ions has also been documented in this report.

Interactions of two novel stabilizing amendments with sunflower plants grown in a contaminated soil

Several efficient stabilizing amendments have been recently proposed for the remediation of metal(loid)-contaminated soils. However, information on their interactions with plants, which is a crucial factor in soil environments, are still scarce. An amorphous manganese oxide (AMO) synthesized from organic compounds and nano zerovalent iron (nZVI) have been previously tested as promising stabilizing agents usable both for the stabilization of metals and As. Experiments with rhizoboxes were performed in order to evaluate their influence on the mobility of metal(loid)s in the bulk soil and rhizosphere of sunflower (Helianthus annuus L.) together with their impact on metal uptake and biomass yield. Generally, AMO proved more efficient than nZVI in all stages of experiment. Furthermore, the AMO effectively reduced water- and 0.01 M CaCl₂-extractable fractions of Cd, Pb and Zn. The decreased bioavailability of contaminating metal(loid)s resulted in significant increase of microbial activity in AMO-amended soil. Together with metal(loid) extractability, the AMO was also able to significantly reduce the uptake of metals and ameliorate plant growth, especially in the case of Zn, since this metal was taken up in excessive amounts from the control soil causing strong phytotoxicity and even death of young seedlings. On the other hand, AMO application lead to significant release of Mn that was readily taken up by plants. Resulting Mn concentrations in biomass exceeded toxicity thresholds while plants were showing emergent Mn phytotoxicity symptoms. We highlight the need of such complex studies involving plants and soil biota when evaluating the efficiency of stabilizing amendments in contaminated soils.

A new approach to 19-nor-A-ring phosphine oxide for the convergent synthesis of 19-nor-calcitriol

A new approach to 19-nor-A-ring phosphine oxide 5 together with a convergent synthesis of the vitamin D₃ analogue 1α,25-dihydroxy-19-norvitamin D₃ (3) have been developed. The 19-nor-A-ring is constructed from (S)-carvone. The triene system is assembled by a Wittig-Horner coupling.

Graphene oxide coated with porous iron oxide ribbons for 2, 4-Dichlorophenoxyacetic acid (2,4-D) removal

Graphene oxide (GO) was prepared from commercially available graphite powder. Porous iron oxide ribbons were grown on the surface of GO by solvothermal process. The prepared GO-Fe₃O₄ nanocomposites are characterized by FT-IR, XRD, VSM, SEM, TEM, Raman spectroscopy, surface functionality and zero point charge studies. The morphology of the iron oxide ribbons grown on GO is demonstrated with TEM at various magnifications. The presence of magnetite nanoparticles is evident from XRD peaks and the magnetization value is found to be 37.28emu/g. The ratio of intensity of D-peak to G-peak from Raman spectrum is 0.995. The synthesized Graphene oxide-Fe₃O₄ nanocomposites (GO-Fe₃O₄) were explored for its surface adsorptive properties by using a model organic compound, 2,4-Dichlorophenoxy acetic acid (2,4-D) from aqueous solution. Batch adsorption studies were performed and the equilibrium data are modelled with Langmuir, Freundlich and Temkin isotherms. The maximum monolayer capacity from Langmuir isotherm is 67.26mg/g. Kinetic studies were also carried out and the studied adsorption process followed pseudo second-order rate equation. Mechanism of the adsorption process is studied by fitting the data with intraparticle diffusion model and Boyd plot. The studied adsorption process is both by film diffusion and intraparticle diffusion.

Aminophosphine Oxides: A Platform for Diversified Functions

This review summarizes significant contributions reported on aminophosphine oxides (AmPOs), specifically those containing at least one amino group present as amino substituents on α- and β-carbons including direct P-N bond containing molecules. AmPOs have additional 'N' site(s), including highly basic 'P=O' groups, and these features make favor smooth and unexpected behavior. The most striking manifestations of flexibility of AmPOs are that they are exciting ligand systems for the coordination chemistry of actinides, and their involvement in catalytic organic reactions including enantioselective opening of meso-epoxides, addition of silyl enol ethers, allylation with allyltributylstannane, etc. The diverse properties of the AmPOs and their metal complexes demonstrate both the scope and complexity of these systems, depending on the basicity of phosphoryl group, and nature of the substituents on the pentavalent tetracoordinate phosphorus atom and metal. Two components key to understanding the challenges of actinide separations are detailed here, namely, previously described separation methods, and recent investigations into the fundamental coordination chemistry of actinides. Both are aimed at probing the critical features necessary for improved selectivity of separations. This review leads to the conclusion that, although many AmPOs have already been discovered and developed over the past century, many opportunities nevertheless exist for further developments towards new extraction processes and new catalytic materials by fine tuning the electronic and steric properties of substituents on the central phosphorus atom.

Synthesis of Photoactive Materials by Sonication: Application in Photocatalysis and Solar Cells

In recent years, a good number of methods have become available for the preparation of an important group of photoactive materials for applications in photocatalysis and solar cells. Nevertheless, the benefits derived from preparing those materials through unconventional approaches are very attractive from the green chemistry point of view. This critical review work is focused on sonication as one of these promising new synthetic procedures that allow control over size, morphology, nanostructure and tuning of catalytic properties. Ultrasound-based procedures offer a facile, versatile synthetic tool for the preparation of light-activated materials often inaccessible through conventional methods.

Stability of Fe,Al-bearing bridgmanite in the lower mantle and synthesis of pure Fe-bridgmanite

The physical and chemical properties of Earth's mantle, as well as its dynamics and evolution, heavily depend on the phase composition of the region. On the basis of experiments in laser-heated diamond anvil cells, we demonstrate that Fe,Al-bearing bridgmanite (magnesium silicate perovskite) is stable to pressures over 120 GPa and temperatures above 3000 K. Ferric iron stabilizes Fe-rich bridgmanite such that we were able to synthesize pure iron bridgmanite at pressures between ~45 and 110 GPa. The compressibility of ferric iron-bearing bridgmanite is significantly different from any known bridgmanite, which has direct implications for the interpretation of seismic tomography data.

Optically Monitoring Mineralization and Demineralization on Photoluminescent Bioactive Nanofibers

Bone regeneration and scaffold degradation do not usually follow the same rate, representing a daunting challenge in bone repair. Toward this end, we propose to use an external field such as light (in particular, a tissue-penetrating near-infrared light) to precisely monitor the degradation of the mineralized scaffold (demineralization) and the formation of apatite mineral (mineralization). Herein, CaTiO3:Yb(3+),Er(3+)@bioactive glass (CaTiO3:Yb(3+),Er(3+)@BG) nanofibers with upconversion (UC) photoluminescence (PL) were synthesized. Such nanofibers are biocompatible and can emit green and red light under 980 nm excitation. The UC PL intensity is quenched during the bone-like apatite formation on the surface of the nanofibers in simulated body fluid; more mineral formation on the nanofibers induces more rapid optical quenching of the UC PL. Furthermore, the quenched UC PL can recover back to its original magnitude when the apatite on the nanofibers is degraded. Our work suggests that it is possible to optically monitor the apatite mineralization and demineralization on the surface of nanofibers used in bone repair.

Effects of Fuel to Synthesis of CaTiO3 by Solution Combustion Synthesis for High-Level Nuclear Waste Ceramics

A solution combustion process for the synthesis of perovskite (CaTiO3) powders is described. Perovskite is one of the crystalline host matrics for the disposal of high-level radioactive wastes (HLW) because it immobilizes Sr and Lns elements by forming solid solutions. Solution combustion synthesis, which is a self-sustaining oxi-reduction reaction between nitrate and organic fuel, the exothermic reaction, and the heat evolved convert the precursors into their corresponding oxide products above 1100 degrees C in air. To investigate the effects of amino acid on the combustion reaction, various types of fuels were used; a glycine, amine and carboxylic ligand mixture. Sr, La and Gd-nitrate with equivalent amounts of up to 20% of CaTiO3 were mixed with Ca and Ti nitrate and amino acid. X-ray diffraction analysis, SEM and TEM were conducted to confirm the formed phases and morphologies. While powders with an uncontrolled shape are obtained through a general oxide-route process, Ca(Sr, Lns)TiO3 powders with micro-sized soft agglomerates consisting of nano-sized primary particles can be prepared using this method.

Oxadiazole-2-oxides may have other functional targets, in addition to SjTGR, through which they cause mortality in Schistosoma japonicum

BACKGROUND

Schistosomiasis is one of the world's major public health problems. Besides praziquantel (PZQ), there is currently no other effective treatment against schistosomiasis. The development of new antischistosomal agents to curb the emergence of PZQ resistance should be a high priority. Oxadiazole-2-oxides have been identified as potential antischistosomal reagents, with thioredoxin glutathione reductase (TGR) being one of their molecular targets.

METHODS

To develop novel treatment reagents against Schistosoma japonicum, 30 novel oxadiazole-2-oxides were synthesised and their antischistosomal activities on juvenile and adult S. japonicum were evaluated in vitro and in vivo. Their inhibitory activities against S. japonicum thioredoxin glutathione reductase (SjTGR) were also analysed.

RESULTS

Most of the oxadiazole-2-oxides showed good juvenile and adult S. japonica killing activities in vitro. However, the antischistosomal effects of these compounds were not positively correlated with either their inhibition of SjTGR, or with nitric oxide (NO) release. Compounds 4a, 4b, 7c, 13, 16 and 20 resulted in 87.7%, 83.1%, 87.1%, 84.6%, 90.8% and 69.5%, respectively, mortality in the adult worms, when used to treat infected mice at schistosomula stage. These mortality rates were similar to or higher than that of artemisinin. Furthermore, compounds 4a and 16 resulted in 66.7% and 69.4% reductions in the worm burdens, respectively, when infected mice were treated at the adult worm stage. These treatment effects were similar to PZQ. No differences in activity of the oxadiazole-2-oxides against female and male adult worms were observed. The toxicity of the oxadiazole-2-oxides on mammalian cells appeared to be similar to, or less than, that of PZQ.

CONCLUSIONS

The antischistosomal activity of the oxadiazole-2-oxides does not depend on NO production or the inhibition of SjTGR activity. There may be other functional targets of the oxadiazole-2-oxides in S. japonicum. Several of the novel oxadiazole-2-oxides synthesised in this study could be used to develop novel antischistosomal drugs and explore potential molecular targets.

Solvent-Assisted Preparation of High-Performance Mesoporous CH₃NH₃Pbl₃ Perovskite Solar Cells

Organometal trihalide perovskite based solar cells have attracted great attention worldwide since their power conversion efficiency (PCE) have risen to over 15% within only 3 years of development. Comparing with other types of perovskite solar cells, mesostructured perovskite solar cells based on CH₃NH₃Pbl₃ as light harvesting material have already demonstrated remarkable advance in performance and reproducibility. Here, we reported a mesoscopic TiO₂/CH₃NH₃Pbl₃ heterojunction solar cell with uniform perovskite thin film prepared via solvent-assisted solution processing method. The best performing device delivered photocurrent density of 20.11 mA cm⁻², open-circuit voltage of 1.02 V, and fill factor of 0.70, leading to a PCE of 14.41%. A small anomalous hysteresis in the J-V curves was observed, where the PCE at forward scan was measured to be 84% of the PCE at reverse scan. Based on a statistical analysis, the perovskite solar cells prepared by the reported method exhibited reproducible and high PCE, indicating its promising application in the fabrication of low-cost and high-efficiency perovskite solar cells.

Degradation of Amaranth azo dye in water by heterogeneous photo-Fenton process using FeWO4 catalyst prepared by microwave irradiation

FeWO4 particles were synthesized by a simple, rapid and facile microwave technique and their catalytic properties in heterogeneous photo-Fenton reaction were evaluated. This material was employed in the degradation of Amaranth azo dye. Individual and interactive effects of operational parameters such as pH, dye concentration and H2O2 dosage on the decolorization efficiency of Amaranth dye were evaluated by 2(3) central composite design. According to characterization techniques, a porous material and a well-crystallized phase of FeWO4 oxide were obtained. Regarding the photo-Fenton reaction assays, up to 97% color and 58% organic carbon removal were achieved in the best experimental conditions. In addition, the photo-Fenton process maintained treatment efficiency over five catalyst reuse cycles to indicate the durability of the FeWO4 catalyst. In summary, the results reveal that the synthesized FeWO4 material is a promising catalyst for wastewater treatment by heterogeneous photo-Fenton process.

Manganese oxides supported on gold nanoparticles: new findings and current controversies for the role of gold

We synthesized manganese oxides supported on gold nanoparticles (diameter <100 nm) by the reaction of KMnO4 with gold nanoparticles under hydrothermal conditions. In this green method Mn oxide is deposited on the gold nanoparticles. The compounds were characterized by scanning electron microscopy, energy-dispersive spectrometry, high-resolution transmission electron microscopy, X-ray diffraction, UV-Vis spectroscopy, Fourier transform infrared spectroscopy, and atomic absorption spectroscopy. In the next step, the water-oxidizing activities of these compounds in the presence of cerium(IV) ammonium nitrate as a non-oxo transfer oxidant were studied. The results show that these compounds are good catalysts toward water oxidation with a turnover frequency of 1.0 ± 0.1 (mmol O2/(mol Mn·s)). A comparison with other previously reported Mn oxides and important factors influencing the water-oxidizing activities of Mn oxides is also discussed.

Synthesis of double-clickable functionalised graphene oxide for biological applications

Azide- and alkyne-double functionalised graphene oxide (Click(2) GO) was synthesised and characterised with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA) and Raman spectroscopy. Fourteen-percentage increase in azide content was found, after pre-treatment of GO with meta-chloroperoxybenzoic acid (mCPBA), determined with elemental analysis. No effect on A549 cell viability was found, up to 100 μg mL(-1) and 72 h of incubation, determined with the modified lactate dehydrogenase (mLDH) assay. Two sequential copper(i) catalysed azide-alkyne cycloaddition (CuAAC) reactions were performed to conjugate the propargyl-modified blood-brain barrier targeting peptide Angiopep-2, and a bis-azide polyethylene glycol (MW = 3500), to the Click(2) GO. The final conjugate was characterised with ATR-FTIR and TGA.