To decipher the phytochemical agent and mechanism for Urginea indica mediated green synthesis of Ag nanoparticles and investigation of its antibacterial activity against Methicillin-resistant Staphylococcus aureus.

Globally, Methicillin-Resistant Staphylococcus aureus bacteraemia is one of the commonest bloodstream infections associated with clinical complications and high mortality. Thence, devising effective and targeted biogenic silver based strategies are in great demand. However, limited insights regarding the biosynthesis methodologies impedes the possible scale up and commercial potentials. We, hereby demonstrate the biosynthesis of Ag nanoparticles using the phytochemical agent extracted and purified from bulb extract of Urginea indica. The chemical structure of the phytochemical agent is investigated by various chromatographic and spectroscopic techniques and was found closely relatable to N-ethylacetamide. Ag nanoparticles synthesis by this agent was found to have a strong Surface Plasmon band at 402 nm. X-ray diffraction and transmission electron microscopy further validated the formation of Ag nanoparticles with face-centred cubic structure with a size range of 20-30 nm. The biogenic metal nanoparticles have shown potential antibacterial activity against S. aureus and MRSA (within a range of 10-50 µg/mL). The nanoparticles have also shown promising anti-biofim activity against the above mentioned strains. The nanoparticles were expected to induce ROS mediated bactericidal mechamism. Cell viability and in-vitro infection studies advocate noticeable biocompatibility and future clinical potential of the developed nanoparticles against Staphylococcus infections.

Management of tannery waste effluents towards the reclamation of clean water using an integrated membrane system: A state-of-the-art review.

Tanning and other leather processing methods utilize a large amount of freshwater, dyes, chemicals, and salts and produce toxic waste, raising questions regarding their environmental sensitivity and eco-friendly nature. Total suspended solids, total dissolved solids, chemical oxygen demand, and ions such as chromium, sulfate, and chloride turn tannery wastewater exceedingly toxic for any living species. Therefore, it is imperative to treat tannery effluent, and existing plants must be examined and upgraded to keep up with recent technological developments. Different conventional techniques to treat tannery wastewater have been reported based on their pollutant removal efficiencies, advantages, and disadvantages. Research on photo-assisted catalyst-enhanced deterioration has inferred that both homogeneous and heterogeneous catalysis can be established as green initiatives, the latter being more efficient at degrading organic pollutants. However, the scientific community experiences significant problems developing a feasible treatment technique owing to the long degradation times and low removal efficiency. Hence, there is a chance for an improved solution to the problem of treating tannery wastewater through the development of a hybrid technology that uses flocculation as the primary treatment, a unique integrated photo-catalyst in a precision-designed reactor as the secondary method, and finally, membrane-based tertiary treatment to recover the spent catalyst and reclaimable water. This review gives an understanding of the progressive advancement of a cutting-edge membrane-based system for the management of tanning industrial waste effluents towards the reclamation of clean water. Adaptable routes toward sludge disposal and the reviews on techno-economic assessments have been shown in detail, strengthening the scale-up confidence for implementing such innovative hybrid systems.

Effect of Tidal Cycle on Escherichia coli Variability in a Tropical Estuary.

A faecal indicator bacteria, Escherichia coli (E. coli), is widely used in monitoring health of estuaries, where tidal amplitude plays a critical role in its variability. Mahanadi estuary, formed at the mouth of a major tropical river Mahanadi, has large socio-economic importance. This anthropogenically stressed estuary remains understudied with respect to E. coli. Hence, this study addressed E. coli variability in Mahanadi estuary with novel sampling strategy that can be implemented at other tropical estuaries. The sampling strategy includes simultaneous measurements, at lesser-saline upper-estuary and higher-saline lower-estuary, over a tidal cycle. Although no significant variability of E. coli was observed between upper and lower-estuary, overall average count was higher during low tide and lower during high tide attributed to salinity fluctuations. Intermittent surpass of E. coli counts above recommended limits in Mahanadi estuary, indicated potential health risk, thus demands for frequent water quality monitoring and management strategies.

Sonophotocatalytic disinfection of Shigella species under visible light irradiation: Insights into its molecular mechanism, antibacterial resistance and biofilm formation.

Microbial contamination of water is one of the major sources of many diseases worldwide. Evolution of antibacterial resistance (ABR) alongside the caveats in most of the water treatment methods causes the severity of the current problem extremely vexing. This calls for an urgent need to develop new treatment methods aiming to reduce the microbial as well as ABR load in the environment. Herein, we successfully developed a visible light assisted sonophotocatalysis (SPC) using Fe/ZnO nanoparticles (NPs) for the disinfection of Shigella dysenteriae. A consortia containing S. dysenteriae and S. flexineri was also completely disinfected using SPC. Growth conditions of S. dysenteriae like growth phases and growth temperaturehad different outcomes on the overall efficacy of SPC. Compared with catalysts such as ZnO and TiO2, Fe/ZnO resulted in better disinfection. Multi-ROS production, mostly containing h+ and O2· radicals, due to the electron displacement in the catalyst and acoustic cavitation was identified as the factors behind bacterial lethality. The ROS produced was found to interfere with the metabolic activities of S. dysenteriae by causing membrane perturbation. We identified DNA damage inside the cells and the subsequent release of intracellular components. The compositional changes in the fatty acid makeup of the cells were altered as a result of SPC and few fatty acid markers indicating the stress posed by SPC were also identified. Loss of ABR in S. dysenteriae was also recorded post SPC treatment. Abatement in the biofilm forming ability of the injured bacterial cells was also recorded, proving the extremity of stress induced by SPC. Hence, the excellent efficacy of SPC in disinfecting bacteria is proposed for tertiary water treatment applications.

Biogenic Au@ZnO core-shell nanocomposites kill Staphylococcus aureus without provoking nuclear damage and cytotoxicity in mouse fibroblasts cells under hyperglycemic condition with enhanced wound healing proficiency.

The aim of the present study is focused on the synthesis of Au@ZnO core-shell nanocomposites, where zinc oxide is overlaid on biogenic gold nanoparticles obtained from Hibiscus Sabdariffa plant extract. Optical property of nanocomposites is investigated using UV-visible spectroscopy and crystal structure has been determined using X-ray crystallography (XRD) technique. The presence of functional groups on the surface of Au@ZnO core-shell nanocomposites has been observed by Fourier transforms infrared (FTIR) spectroscopy. Electron microscopy studies revealed the morphology of the above core-shell nanocomposites. The synthesized nanocomposite material has shown antimicrobial and anti-biofilm activity against Staphylococcus aureus and Methicillin Resistant Staphylococcus haemolyticus (MRSH). The microbes are notorious cross contaminant and are known to cause infection in open wounds. The possible antimicrobial mechanism of as synthesized nanomaterials has been investigated against Staphylococcus aureus and obtained data suggests that the antimicrobial activity could be due to release of reactive oxygen species (ROS). Present study has revealed that surface varnishing of biosynthesized gold nanoparticles through zinc oxide has improved its antibacterial proficiency against Staphylococcus aureus, whereas reducing its toxic effect towards mouse fibroblast cells under normal and hyperglycaemic condition. Further studies have been performed in mice model to understand the wound healing efficiency of Au@ZnO nanocomposites. The results obtained suggest the possible and effective use of as synthesized core shell nanocomposites in wound healing.

Antibacterial Efficacy of ZnO/Bentonite (Clay) Nanocomposites against Multidrug-Resistant Escherichia coli.

The emergence of multidrug-resistant (MDR) bacteria has spurred the exploration of therapeutic nanomaterials such as ZnO nanoparticles. However, the inherent nonspecific toxicity of ZnO has posed a significant obstacle to their clinical utilization. In this research, we propose a novel approach to improve the selectivity of the toxicity of ZnO nanoparticles by impregnating them onto a less toxic clay mineral, Bentonite, resulting in ZB nanocomposites (ZB NCs). We hypothesize that these ZB NCs not only reduce toxicity toward both normal and carcinogenic cell lines but also retain the antibacterial properties of pure ZnO nanoparticles. To test this hypothesis, we synthesized ZB NCs by using a precipitation technique and confirmed their structural characteristics through X-ray diffraction and Raman spectroscopy. Electron microscopy revealed composite particles in the size range of 20-50 nm. The BET surface area of ZB NCs, within a relative pressure (P/P0) range of 0.407-0.985, was estimated to be 31.182 m2/g. Notably, 50 mg/mL ZB NCs demonstrated biocompatibility with HCT 116 and HEK 293 cell lines, supported by flow cytometry and fluorescence microscopy analysis. In vitro experiments further confirmed a remarkable five-log reduction in the population of MDR Escherichia coli in the presence of 50 mg/mL of ZB NCs. Antibacterial activity of the nanocomposites was also validated in the HEK293 and HCT 116 cell lines. These findings substantiate our hypothesis and underscore the effectiveness of ZB NCs against MDR E. coli while minimizing nonspecific toxicity toward healthy cells.

Erratum: Antibacterial Efficacy of ZnO/Bentonite (Clay) Nanocomposites against Multidrug-Resistant Escherichia coli.

[This corrects the article DOI: 10.1021/acsomega.3c07950.].

Two-Phase Crude Oil-Water Flow Through Different Pipes: An Experimental Investigation Coupled with Computational Fluid Dynamics Approach.

The present study deals with two-phase non-Newtonian pseudoplastic crude oil and water flow inside horizontal pipes simulated by ANSYS. The study helps predict velocity and velocity profiles, as well as pressure drop during two-phase crude-oil-water flow, without complex calculations. Computational fluid dynamics (CFD) analysis will be very important in reducing the experimental cost and the effort of data acquisition. Three independent horizontal stainless steel pipes (SS-304) with inner diameters of 1 in., 1.5 in., and 2 in. were used to circulate crude oil with 5, 10, and 15% v/v water for simulation purposes. The entire length of the pipes, along with their surfaces, were insulated to reduce heat loss. A grid size of 221,365 was selected as the optimal grid. Two-phase flow phenomena, pressure drop calculations, shear stress on the walls, along with the rate of shear strain, and phase analysis were studied. Moreover, velocity changes from the wall to the center, causing a velocity gradient and shear strain rate, but at the center, no velocity variation (velocity gradient) was observed between the layers of the fluid. The precision of the simulation was investigated using three error parameters, such as mean square error, Nash-Sutcliffe efficiency, and RMSE-standard deviation of observation ratio. From the simulation, it was found that CFD analysis holds good agreement with experimental results. The uncertainty analysis demonstrated that our CFD model is helpful in predicting the rheological parameters very accurately. The study aids in identifying and predicting fluid flow phenomena inside horizontal straight pipes in a very effective way.

Optimizing methanol synthesis from CO2 using graphene-based heterogeneous photocatalyst under RSM and ANN-driven parametric optimization for achieving better suitability.

Assessment of the performance of linear and nonlinear regression-based methods for estimating in situ catalytic CO2 transformations employing TiO2/Cu coupled with hydrogen exfoliation graphene (HEG) has been investigated. The yield of methanol was thoroughly optimized and predicted using response surface methodology (RSM) and artificial neural network (ANN) model after rigorous experimentation and comparison. Amongst the different types of HEG loading from 10 to 40 wt%, the 30 wt% in the HEG-TiO2/Cu assisted photosynthetic catalyst was found to be successful in providing the highest conversion efficiency of methanol from CO2. The most influencing parameters, HEG dosing and inflow rate of CO2, were found to affect the conversion rate in the acidic reaction regime (at pH of 3). According to RSM and ANN, the optimum methanol yields were 36.3 mg g-1 of catalyst and 37.3 mg g-1 of catalyst, respectively. Through the comparison of performances using the least squared error analysis, the nonlinear regression-based ANN showed a better determination coefficient (overall R2 > 0.985) than the linear regression-based RSM model (overall R2 ∼ 0.97). Even though both models performed well, ANN, consisting of 9 neurons in the input and 1 hidden layer, could predict optimum results closer to RSM in terms of agreement with the experimental outcome.

Synthesis, characterization and application of BR@Ag nanocomposite material for high degree reduction of p-nitro phenol under a suitable condition.

One of the most essential chemical processes that is utilized in the manufacturing of a great deal of contemporary goods is called heterogeneously catalyzed reactions, and it is also one of the most fascinating. Metallic nanostructures are heterogeneous catalysts for range reactions due to their huge surface area, large assembly of active surface sites, and quantum confinement effects. Unprotected metal nanoparticles suffer from irreversible agglomeration, catalyst poisoning, and limited life cycle. To circumvent these technical disadvantages, catalysts are frequently spread on chemically inert materials like as mesoporous Al2O3, ZrO2, and different types of ceramic material. In this research, plentiful bauxite residue is used to create a low-cost alternative catalytic material. We have hydrogenated p-Nitrophenol to p-Aminophenol on bauxite residue (BR) supported silver nanocomposites (Ag NCs). The phase and crystal structure, bond structure and morphological analysis of the developed material will be done XRD, FTIR, and SEM-EDX respectively. The ideal conditions were 150 ppm of catalyst, 0.1 mM of p-NP, and 10 minutes overall up-to 99% conversion of p-NP to p-AP. A multi-variable predictive model created using Response Surface Methodology (RSM) and a data-based Artificial Neural Network (ANN) model were found to be the best ways to predict the maximum conversion efficiency. ANN models predicted efficiency more accurately than RSM models, and the strong agreement between model predictions and experimental data was indicated by their low relative error (RE0.10), high regression coefficient (R2>0.97), and Willmott-d index (dwill-index > 0.95) values.

Fabrication of ZnO/Gypsum/Gelatine nanocomposites films and their antibacterial mechanism against Staphylococcus aureus.

Staphylococcus aureus (S. aureus) has long been acknowledged as being one of the most harmful bacteria for human civilization. It is the main contributor to skin and soft tissue infections. The gram positive pathogen also contributes to bloodstream infections, pneumonia, or bone and joint infections. Hence, developing an efficient and targeted treatment for these illnesses is greatly desired. Recently, studies on nanocomposites (NCs) have significantly increased due to their potent antibacterial and antibiofilm properties. These NCs provide an intriguing way to control the growth of bacteria without causing the development of resistance strains that come from improper or excessive use of the conventional antibiotics. In this context, we have demonstrated the synthesis of a NC system by precipitation of ZnO nanoparticles (NPs) on Gypsum followed by encapsulation with Gelatine, in the present study. Fourier transform infrared (FTIR) spectroscopy was used to validate the presence of ZnO NPs and Gypsum. The film was characterized by X-ray diffraction (XRD) spectroscopy and scanning electron microscopy (SEM). The system exhibited promising antibiofilm action and was effective in combating S. aureus and MRSA in concentrations between 10 and 50 ug/ml. The bactericidal mechanism by release of reactive oxygen species (ROS) was anticipated to be induced by the NC system. Studies on cell survival and in-vitro infection support the film's notable biocompatibility and its potential for treating Staphylococcus infections in the future.

CuO/TiO2/ZnO NPs Anchored Hydrogen Exfoliated Graphene: To Comprehend the Role of Graphene in Catalytic Reduction of p-Nitrophenol.

The present study deals with sonochemically in situ synthesis of a novel functional catalyst using hydrogen exfoliated graphene (HEG) supported titanium dioxide (TiO2) and copper sulfate (CuSO4) doped with zinc oxide (ZnO) (abbreviated as Ti/Cu/Zn-HEG). The synthesis of the Ti/Cu/Zn-HEG nanocomposite (NCs) catalyst was confirmed through its characterizations by XRD, SEM-EDX, TEM, XPS, FTIR, and BET methods. It was assessed for catalytic conversion of a model aromatic compound para-nitrophenol (p-NP) in an aqueous solution. The p-NP is a nitroaromatic compound that has a toxic and mutagenic effect. Its removal from the water system is necessary to protect the environment and living being. The newly synthesized Ti/Cu/Zn-HEG NCs were applied for their higher stability and catalytic activity as a potential candidate for reducing p-NP in practice. The operating parameters, such as p-NP concentration, catalyst dosage, and operating time were optimized for 150 ppm, 400 ppm, and 10 min through response surface methodology (RSM) in Design-Expert software to obtain the maximum reduction p-NP up to 98.4% at its normal pH of 7.1 against the controls (using HEG, Ti/Cu-HEG, and Zn-HEG). Analysis of variance of the response suggested the regression equation to be significant for the process with a major impact on catalyst concentration and operating time. The model prediction data (from RSM) and experimental data were corroborated well as reflected through model's low relative error (RE < 0.10), high regression coefficient (R2 > 0.97), and Willmott d-index (dwill-index > 0.95) values.

A critical review on nanomaterial based therapeutics for diabetic wound healing.

Diabetes mellitus is a chronic endocrine disease that occurs mostly in the state of hyperglycemia (elevated blood glucose level). In the recent times, diabetes is listed under world's utmost critical health issues. Wound treatment procedures are complicated in diabetic individuals all over the world. Diabetic wound care not only involves high-cost, but also the primary cause of hospitalization, which can lead to amputation thereby reducing diabetic patient life expectancy. To lower the risk of amputation, wound healing requires the development of effective treatments. Traditional management systems for Diabetes are frequently chastised due to their high costs, difficulties in maintaining a sustainable supply chain and limited disposal alternatives. The worrisome rise in diabetes prevalence has sparked a surge of interest in the discovery of viable remedies to supplement existing treatments. Nanomaterials wound healing has a lot of potential for treating and preventing wound infections and it has recently gained popularity owing to its ability to transport drugs to the wound area in a regulated fashion, potentially overpowering the limits of traditional approaches. This research assessed several nanosystems, such as nanocarriers and nanotherapeutics, to explore how they can benefit in diabetic wound healing, with a focus on current obstacles and future prospects.

Biogenic Ag/CaO nanocomposites kill Staphylococcus aureus with reduced toxicity towards mammalian cells.

Rapid increase in the case of bacterial infections is considered as a major public health concern and hence exploration of alternative treatment procedures including development of nanomaterials based therapeutic strategies is receiving much attention. In this aspect, here we investigated the antibacterial efficacy of a simple and potential metal/metal oxide nanocomposite system. Biogenic synthetic protocol was designed for processing of Ag/CaO nanocomposites (NCs). Structural features and morphology of the synthesized nanomaterials were investigated by X-ray diffraction (XRD) and electron microscopy techniques respectively. Optical properties of the nanomaterials were analyzed by UV-vis spectrophotometer. Presence of water and possible impurity molecules on the materials surface was examined by Fourier-transform infrared spectroscopy (FTIR). Effective antibacterial activity of the NCs was observed (within a range of 25-150 µg/mL of NCs) against Staphylococcus aureus (S. aureus) and Methicillin-resistant Staphylococcus aureus (MRSA). The potential anti-biofilm effect of as synthesized NCs was tested against S. aureus. Experimental results suggest that the antibacterial action of the NCs could be due to the induction of reactive oxygen species (ROS). DNA degradation and change in the bacterial cell membrane has further indicated the complete disinfection of the target bacterial system. The cytotoxicity evaluation has confirmed that the formation of NCs has maintained the antibacterial efficacy of Ag NPs but reduced its toxicity towards mammalian cells.

Sunlight Assisted Photocatalytic Degradation of Ciprofloxacin in Water Using Fe Doped ZnO Nanoparticles for Potential Public Health Applications.

Antibiotic residues in the aquatic environment have the potential to induce resistance in environmental bacteria, which ultimately might get transferred to pathogens making treatment of diseases difficult and poses a serious threat to public health. If antibiotic residues in the environment could be eliminated or reduced, it could contribute to minimizing antibiotic resistance. Towards this objective, water containing ciprofloxacin was treated by sunlight-assisted photocatalysis using Fe- doped ZnO nanoparticles for assessing the degradation potential of this system. Parameters like pH, temperature, catalytic dosage were assessed for the optimum performance of the system. To evaluate degradation of ciprofloxacin, both spectrophotometric as well as microbiological (loss of antibiotic activity) methods were employed. 100 mg/L Fe-doped ZnO nanoparticle catalyst and sunlight intensity of 120,000⁻135,000 lux system gave optimum performance at pH 9 at 30 °C and 40 °C. Under these conditions spectrophotometric analysis showed complete degradation of ciprofloxacin (10 mg/L) at 210 min. Microbiological studies showed loss of antibacterial activity of the photocatalytically treated ciprofloxacin-containing water against Staphylococcus aureus (108 CFU) in 60 min and for Escherichia coli (108 CFU) in 75 min. The developed system, thus possess a potential for treatment of antibiotic contaminated waters for eliminating/reducing antibiotic residues from environment.

Doped ZnO nanoparticles impregnated on Kaolinite (Clay): A reusable nanocomposite for photocatalytic disinfection of multidrug resistant Enterobacter sp. under visible light.

Water contamination by multidrug resistant (MDR) enteric bacteria can be considered as the foremost cause of gastrointestinal infections and poses a threat to global public health. Therefore, there is an urgent need to pursue unorthodox techniques with potential of community scale applications for purging of water borne pathogenic bacteria. We communicate visible-light assisted photocatalytic disinfection (PCD) of an enteric MDR bacterium; Enterobacter sp. using Fe-doped ZnO nanoparticles impregnated on Kaolinite (Clay) (ZnO/K). ZnO/K was synthesized by co-precipitation technique and was found to be more effective than Fe-doped ZnO (ZnO) and Kaolinite for PCD process. Analysis from fluorescence microscopy and electron microscopy (FESEM) proposed complete bacterial cell death via PCD due to damage of bacterial cell membrane. Experimental evidences indicated that O2- could be acting as the most significant component in disinfection of MDR Enterobacter sp. in visible-light assisted PCD process in presence of ZnO/K. Considering the experimental data of Resazurin assay, it is proposed that reactive oxygen species (ROS) generated during PCD might have impeded the oxido-reductase enzyme system of the bacteria and hence trammeling its metabolic activity. Crystal structure and particle size of ZnO/K was found to be unaltered during the photocatalytic process indicating its potential for reusability. When ZnO/K was exposed to HCT-116 Human Colorectal Carcinoma cell lines, about 79% cell survivability was noticed. The synthesized material was successful in completely disinfecting the target microorganism in Zebra Fish model, without producing any adverse effects on the Fish itself, further reinforcing its biocompatibility factor. High effectiveness of PCD process using ZnO/K under visible light in disinfecting enteric MDR bacteria, might have promising outcome as an alternative water disinfection technology to prevent the spread of infectious and resistant bacteria without producing any adverse effect on non-specific flora and fauna.

Biosynthesis of magnesium oxide (MgO) nanoflakes by using leaf extract of Bauhinia purpurea and evaluation of its antibacterial property against Staphylococcus aureus.

Nanobiotechnology has become a newly evolving field of interest in biomedical applications due to its biocompatibility and non-toxic nature towards the environment. Metal and metal oxide nanoparticles have been widely used as an antibacterial agent due to the emergence of antibiotic resistant pathogens, which leads to the outbreak of infectious diseases. In the present paper, biogenic synthesis of magnesium oxide (MgO) nanoflakes is reported by using Bauhinia purpurea leaf extract through alkaline precipitation method along with its detailed characterization. The average size of synthesized nanoflakes was found to be around 11 nm. Electron microscopy was used to investigate the morphology of the MgO nanoflakes. Additionally, the presence of antioxidants, phenolics and flavonoids in B. purpurea leaf extract has been studied by using different assays, which suggested the efficacy of leaf extract as a potential reducing agent for MgO nanoflakes synthesis. Antibacterial activity of synthesized MgO nanoflakes was investigated against Staphylococcus aureus, a gram positive bacteria known to cause various infections in humans. Results suggested the high efficacy of MgO nanoflakes as a potential antibacterial agent against S. aureus at meager dose size (250 µg/ml) and possible mode of action was investigated through surface morphology analysis of bacterial cells by field emission scanning electron microscopy.

Disinfection of Multidrug Resistant Escherichia coli by Solar-Photocatalysis using Fe-doped ZnO Nanoparticles.

Spread of antibiotic resistant bacteria through water, is a threat to global public health. Here, we report Fe-doped ZnO nanoparticles (Fe/ZnO NPs) based solar-photocatalytic disinfection (PCD) of multidrug resistant Escherichia coli (MDR E. coli). Fe/ZnO NPs were synthesized by chemical precipitation technique, and when used as photocatalyst for disinfection, proved to be more effective (time for complete disinfection = 90 min) than ZnO (150 min) and TiO2 (180 min). Lipid peroxidation and potassium (K+) ion leakage studies indicated compromisation of bacterial cell membrane and electron microscopy and live-dead staining confirmed the detrimental effects on membrane integrity. Investigations indicated that H2O2 was the key species involved in solar-PCD of MDR E. coli by Fe/ZnO NPs. X-ray diffraction and atomic absorption spectroscopy studies showed that the Fe/ZnO NPs system remained stable during the photocatalytic process. The Fe/ZnO NPs based solar-PCD process proved successful in the disinfection of MDR E. coli in real water samples collected from river, pond and municipal tap. The Fe/ZnO NPs catalyst made from low cost materials and with high efficacy under solar light may have potential for real world applications, to help reduce the spread of resistant bacteria.

Disinfection of the Water Borne Pathogens Escherichia coli and Staphylococcus aureus by Solar Photocatalysis Using Sonochemically Synthesized Reusable Ag@ZnO Core-Shell Nanoparticles.

Water borne pathogens present a threat to human health and their disinfection from water poses a challenge, prompting the search for newer methods and newer materials. Disinfection of the Gram-negative bacterium Escherichia coli and the Gram-positive coccal bacterium Staphylococcus aureus in an aqueous matrix was achieved within 60 and 90 min, respectively, at 35 °C using solar-photocatalysis mediated by sonochemically synthesized Ag@ZnO core-shell nanoparticles. The efficiency of the process increased with the increase in temperature and at 55 °C the disinfection for the two bacteria could be achieved in 45 and 60 min, respectively. A new ultrasound-assisted chemical precipitation technique was used for the synthesis of Ag@ZnO core-shell nanoparticles. The characteristics of the synthesized material were established using physical techniques. The material remained stable even at 400 °C. Disinfection efficiency of the Ag@ZnO core-shell nanoparticles was confirmed in the case of real world samples of pond, river, municipal tap water and was found to be better than that of pure ZnO and TiO2 (Degussa P25). When the nanoparticle- based catalyst was recycled and reused for subsequent disinfection experiments, its efficiency did not change remarkably, even after three cycles. The sonochemically synthesized Ag@ZnO core-shell nanoparticles thus have a good potential for application in solar photocatalytic disinfection of water borne pathogens.

Understanding the Antifungal Mechanism of Ag@ZnO Core-shell Nanocomposites against Candida krusei.

In the present paper, facile synthesis of Ag@ZnO core-shell nanocomposites is reported where zinc oxide is coated on biogenic silver nanoparticles synthesized using Andrographis paniculata and Aloe vera leaf extract. Structural features of as synthesized nanocomposites are characterized by UV-visible spectroscopy, XRD, and FTIR. Morphology of the above core-shell nanocomposites is investigated by electron microscopy. As synthesized nanocomposite material has shown antimicrobial activity against Candida krusei, which is an opportunistic pathogen known to cause candidemia. The possible mode of activity of the above material has been studied by in-vitro molecular techniques. Our investigations have shown that surface coating of biogenic silver nanoparticles by zinc oxide has increased its antimicrobial efficiency against Candida krusei, while decreasing its toxicity towards A431 human epidermoid carcinoma cell lines.