Construction of Ag/CdZnS QDs nanocomposite for enhanced visible light photoinactivation of Staphylococcus aureus.

With increasing use of antibiotics, the development of antibiotic-resistant pathogens poses a serious threat to human health and the environment. Photocatalytic inactivation of these harmful pathogens is one of the novel and non-antibiotic treatments. The study fabricated Ag NPs decorated CdZnS QDs via a facile and biological co-precipitation method using L. camara plant extract as a green alternative to treat the toxic chemicals. The fabricated Ag/CdZnS QDs (NCs) were prepared for the efficient treatment of antibiotic-resistant pathogens as they raise a major global concern. The fabricated NCs were characterized with various characterization techniques to verify its physicochemical properties. The fabricated NCs have shown excellent photo-sterilization performance of 97 % against S. aureus. The excellent activity was attributed to the decoration of Ag NPs on CdZnS QDs as it helped in shortening band gap, improved visible light absorption ability, increased active sites, and boosted photogenerated electron/hole pairs stability. Radical trapping experiment and ESR analysis indicated the involvement of •OH and h+ in the photoinactivation of bacteria. The photo sterilization reaction of NCs was carried out under different environmental conditions, including light and dark conditions and different pH conditions. The experiment was carried out in sewage-treated water in order to test the real-time application, and the fabricated NCs achieved excellent 95.9 % photo-inactivation of S. aureus cells in sewage treated water and the Chemical Oxygen Demand (COD) of the system was increased after photo inactivation treatment. The fabricated NCs have also shown excellent reusable efficiency of 95% after six runs and the photostability and anti-corrosive nature of NCs were confirmed. The study provides an insight for the employment of photocatalysis for the sterilization of pathogens in real time aquatic environment across the globe.

Self-propelled nanojets an interfacial Schottky junctions modulated oxygen vacancies enriched for enhanced photo-Fenton degradation of organic contaminant: Improving H2O2 generation, Fe3+/Fe2+ cycle and enhancing plant metabolism.

The study reports an innovative approach on sunlit driven heterostructure photocatalytic generation of H2O2 and removal of cefixime. In the present work, we have fabricated Mn/Mg doped CoFe2O4 modified CaCr2O4 decorated by Ag3PO4 quantum dots (Ag3PO4 QDs), a p-n-p nano heterojunction. The study promotes the photocatalytic production of H2O2 and self-Fenton photocatalytic degradation of cefixime. Egg white-assisted synthesis of Mn-doped CoFe2O4 causes the lattice oxygen defect, which enhances the photocatalytic activity. Lattice oxygen defect enable the adsorption of O2, which enable the conversion of •O2 in the valence band of CoFe2O4 for the endogenous production of H2O2. The higher in the surface area enhance the photocatalytic activity under visible light irradiation. Mn-CoFe2O4-CaCr2O4-Ag3PO4 QDs enables the complete photocatalytic degradation of cefixime (99.9%) and the complete removal was determined by total organic carbon (TOC) removal and it was around 99.4%. Meanwhile the photocatalytic degradation pathway of cefixime was determined by LC-MS/MS. Reusability of the nano heterojunction was determined by six cycle test, and the reusability of the nano heterojunction was 99.8%. Further, the toxicity of the nanomaterial was studied in maize plant and the results shows that the nanoheterojunction enhances the maize growth. The study systematically reveals the robust activity of nano heterojunction for sustainable water treatment.

Sunlight promoted self-fenton photodegradation and pathway of doxycycline: Interactive effects of nanomaterial on bean plant and its genotoxicity against Allium cepa.

Photocatalytic induction of electron/hole recombination, surface property and light response ability effectively enhance the photocatalytic activity of nanomaterial. In this work, the effective charge carrier separating Sn/Mn-ZnFe2O4-CdFe2O4-Ag3PO4 Quantum dots (M/SZFO-CFO-AP QDs) was fabricated for photocatalytic degradation of doxycycline (doxy) antibiotic. The result showed enhanced photocatalytic activity of doxy and the degradation efficiency of doxy was about 98.8% in short span of time. The calculated WH plot and urbach energy of prepared photocatalyst exhibited evidence for the prevalence of point defects and its contribution to efficient charge separation and transferability. The total organic carbon (TOC) removal was found to be 98.9%, which depicts the complete mineralization of doxy. The synergetic charge transfer of n-p-n heterojunction enables the effective removal of doxy under visible light irradiation. Further, the genotoxicity study was determined by interacting the SZFO-CFO-AP QDs with Allium Cepa. The results depict that SZFO-CFO-AP QDs show lower toxicity level and there were no trace of defective mitotic phases and micro nuclei. Further, the progression and development of bean plant was determined after treating with prepared nanomaterials and the result showed the enhanced growth in SZFO-CFO-AP QDs treated bean plant compared to the counterparts. Therefore, the prepared SZFO-CFO-AP QDs was can be used as an environmental friendly photocatalyst for effective treatment of antibiotic present in the water bodies.

Sunlit photocatalytic degradation of organic pollutant by NiCr2O4/Bi2S3/Cr2S3 tracheid skeleton nanocomposite: Mechanism, pathway, reactive sites, genotoxicity and byproduct toxicity evaluation.

In this study, 3D C2S3 (CS) and 2D Bi2S3 (BS) modified NiCr2O4 nanocomposite (NCO-BS-CS NCs) was prepared by sonochemical assisted co-precipitation method for the enhanced photocatalytic activity. Here, NCO-BS-CS NCs showed band gap energy of 2.23 eV and the PL intensity of NCO-BS-CS NCs was lower than NCO, BS, and CS NPs. Thus, the results indicate the fabricated NCO-BS-CS NCs enhance the charge segregation and lower in recombination rate. NCO-BS-CS NCs showed enhanced photodegradation of methyl orange (MO) (95%) and congo red (CR) (99.7%) respectively. The total organic compound (TOC) analysis shows the complete mineralization of about 91 and 98% for MO and CR respectively. Furthermore, the Fukui function was used for the prediction of reactive sites in the photodegradation pathway of MO and CR by NCs. ECOSAR program was done to determine the toxicity of the intermediate and the results conclude that the degraded product shows nontoxic to the environmental organism (fish, daphnia, and algae). Thus, the fabricated NCO-BS-CS NCs can be used for the remediation of toxic organic pollutants from the waste water by photocatalytic degradation.

Plasma-assisted in-situ preparation of L-cystine functionalized silver nanoparticle: An intelligent multicolor nano-sensing of cadmium and paracetamol from environmental sample.

L-cystine (L-cys) functionalized plasmonic silver nanomaterial (Ag NPs) was fabricated toward the selective and sensitive detection of paracetamol and cadmium. The prepared L-cys-Ag nanoparticles (NPs) were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD) and fourier transform infrared spectroscopy (FTIR) analyses. SEM imaging show that Ag NPs was decorated on the surface of L-cysteine 3D cubic nanosheet. L-cys-Ag NPs showed selective and sensitive detection towards paracetamol and cadmium. The interference study confirms that the presence of other metal ions didn't inhibit the detection of cadmium by L-cys-Ag NPs. The limit of detection of paracetamol and cadmium by L-cys-Ag NPs was calculated to be 1.2 and 2.82 nM respectively. In addition, the real sample detection of paracetamol on blood serum and urine, and cadmium on STP were performed and the recovery percentage was above 97%. Further, the real sample analysis was performed in tap and drinking water and the recovery percentage was more than 98%. The analytic logic gate on the multicolour detection of cadmium and paracetamol was performed for the semi-quantitative monitoring of paracetamol and cadmium by L-cys-Ag NPs. The developed L-cys-Ag NPs were found to be an effective tool for the monitoring of cadmium in environmental water bodies and paracetamol in blood and urine.

Photodegradation of 5-flurouracil, carvedilol, para-chlorophenol and methimazole with 3D MnWO4 nanoflower modified Ag2WO4 nanorods: A non-genotoxic nanomaterial for water treatment.

The present study focused on the photocatalytic degradation of 5-Flurouracil (FU), carvedilol (Car), para-chlorophenol (PCP) and methimazole (Met) under visible light irradiation by MnWO4/Ag2WO4 (MWO/AWO) nanohybrid. Here, MWO/AWO nanohybrid was characterized by XRD, TEM, EDS, XPS, ESR, EIS, BET and DRS. The band gap energy of the MWO/AWO nanohybrid was found to be 2.75 eV, which enables effective photocatalytic activity of nanohybrid under visible light. The photocatalytic degradation of various PhACs such as Fu, Car, PCP and Met was found to be 98.8, 100, 98 and 98.1% respectively. The degradation efficiency of the MWO/AWO nanohybrid on various PhACs was higher than the pure MWO and AWO nanoparticle. The effective formation of OH• and •O2 by MWO/AWO nanohybrid played an important role in degradation of PhACs and it was determined by radical scavenging experiment. Further, the intermediates formed during the photocatalytic process were analyzed by GC-MS/MS to elucidate the photodegradation pathway and the results reveal the complete mineralization of the PhACs. The toxicity of the degraded product was performed against on Bacillus subtilis and Escherichia coli where it shows that the nanohybrid possesses high relative growth inhibition than AWO and MWO nanoparticles. In addition, the genotoxicity of the nanohybrid against Allium cepa was performed and it exhibited lower toxicity. The synthesized nanohybrid proves to be an excellent photocatalyst with good stability, reusability, eco-friendly, and cost-effective material for implementation in practical applications.

Self-assembling of 3D layered flower architecture of BiOI modified MgCr2O4 nanosphere for wider spectrum visible-light photocatalytic degradation of rhodamine B and malachite green: Mechanism, pathway, reactive sites and toxicity prediction.

In this study, 3D BiOI nanoparticle (BOI NPs) modified MgCr2O4 nanoparticle (MCO NPs) was fabricated by simple sonochemical and coprecipitation method for the enhanced photocatalytic activity. The morphological structure of the MgCr2O4-BiOI nanocomposite (MCO-BOI NCs) was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (DRS), electron impedance spectroscopy (EIS) and photo luminescence (PL). The lower in the PL intensity and small arc in EIS for NCs shows the effective charge separation and lower in rate of recombination of charge carriers in NCs than the pure MCO and BOI NPs. The degradation efficiency of Rhodamine B (RhB) and malachite green (MG) by MCO-BOI NCs was found to be 99.5% and 98.2% receptivity. In addition, the photocatalytic degradation of RhB and MG was studied under various environmental parameters (different pH, varying the concentration of NCs and dyes) and response surface (RSM) plot was performed. The complete mineralization of RhB and MG by MCO-BOI NCs was determined by TOC. In addition, the photocatalytic degradation pathway was elucidated based on GC-MS results and Fukui function. In addition, the toxicity of intermediate formed during the degradation of RhB and MG was predicted by ECOSAR. The present work highlights the application of MCO-BOI NCs in environmental remediation for toxic pollutant removal.

Synthesis and application of CdS nanoparticles-decorated core-shell Ag@Ni nanohybrids for visible-light spectrophotometric assay of sulfide in aqueous sample.

Novel Ag@Ni nanosphere decorated with CdS NPs (Ag@Ni-CdS NCs) was synthesized by one step chemical synthesis method. The fabricated NCs were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), fourier transfer infra-red spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), zeta sizer and particle size analyzer. TEM and XRD confirmed the Ag in core and Ni in shell for the effective formation of Ag@Ni core shell nanosphere. EDAX and XPS spectra of NCs confirms the formation of Ag@Ni-CdS NCs. Zeta potential and particle size of the NCs was found to be 29.5 ± 1.5 mV and 24 ± 1 nm respectively. The complete loss in the peak intensity of Ag@Ni-CdS NCs (localized surface plasmon resonance (LSPR)) at ∼410 nm in presence of S2- ions was observed which indicates its selective detection towards S2- ions. The sulfide ion sensing by Ag@Ni-CdS NCs was due to the successive oxidation of Ag results in the formulation of Ag2+ ions in the system, which causes the diminishing of LSPR band of NCs. The limit of detection (LOD) of S2- ions by Ag@Ni-CdS NCs was calculated to be of 2.66 nM. The combination of CdS NPs with core-shell Ag@Ni nanosphere guides a promising strategy for S2- ions detection from environmental polluted samples.

A novel SPR based Fe@Ag core-shell nanosphere entrapped on starch matrix an optical probe for sensing of mercury(II) ion: A nanomolar detection, wide pH range and real water sample application.

Recent trends in nanotechnology paved a way for the development of detection systems for heavy metals, toxins and environmental pollutants. The present study focused on Hg2+ detection by a core shell Fe@Ag-starch nanosphere phenylalanine conjugate. The characterization of core shell Fe@Ag-starch nanosphere was performed by using TEM, zetasizer, particlesize analyzer, UV-visible absorption spectrophotometer, EDAX, FTIR and TGA. The NPs showed λmax at 408 nm. The effective diameter of synthesized nanosphere was 37 ± 2 nm and it possessed the surfaces charge of -36.12 ± 2.5 mV. The Fe@Ag-starch-phenylalanine conjugate reacted with Hg2+, the yellow colour of the nanosphere phenylalanine conjugate became colourless. The real water sample was collected and the amount of Hg2+ was calculated by using the prepared nanosphere. The detection of Hg2+ at different conditions including various saline concentrations, temperature and pH were also studied and the detection was found to be effective at 40 °C, pH 5 and 0.1% of saline concentration. The LOD of Hg2+ ions by Fe@Ag-starch nanosphere were calculated to be 1.84 nM. The influence of other metal ions present in the analyte did not show any interference on Hg2+ detection. In addition, the photocatalytic and antibacterial activities of Fe@Ag-starch nanosphere were also studied. The study confirmed that the core shell nanosphere can also be used for environmental cleanup and disinfection.

Preparation of Ag-cellulose nanocomposite for the selective detection and quantification of mercury at nanomolar level and the evaluation of its photocatalytic performance.

Mercury is a toxic heavy metal that reaches to the water bodies mainly by coal burning, mining and petrol refining. The study was focused to investigate the application of Ag-cellulose nanocomposite to detect and quantify mercury colorimetrically. The Ag-cellulose nanocomposite was characterized by X-ray diffraction, Transmission electron microscopy, Fourier transform infrared spectroscopy, UV-visible spectroscopy, particle size analyzer and zetasizer. The study identified that the presence of other metal ions did not interfere with the detection of Hg2+ ion by the probe. The prepared Ag-cellulose nanocomposite-phenylalanine conjugate incorporated paper strip showed an excellent result in Hg2+ detection. The Ag-cellulose nanocomposite was used to quantify the unknown concentration of mercury on real sample (environmental sample) and it was found to be highly accurate by confirming with atomic absorption spectrophotometric analysis. The Ag-cellulose nanocomposite showed effective detection at 45 °C, pH 9 and 0.1% of salinity. The Ag-cellulose nanocomposite showed efficient photocatalytic performance under visible light irradiation. The half-life period of MB by Ag-cellulose nanocomposite under visible light was determined to be 90 min. The study suggests the application of prepared probe in photocatalysis and the detection of Hg2+ from various environmental samples.

Colorimetric detection of mercury ions from environmental water sample by using 3-(Trimethoxysilyl)propyl methacrylate functionalized Ag NPs-tryptophan nanoconjugate.

Recent trend in the nanotechnology made an interest to make nano based system to detect the environmental pollutant including heavy metals, pesticides and antibiotics. Mercury is toxic heavy metals which causes hazardous effect to human and environmental organisms. They usually reach to the environment by mining, petrol refining and coal burning, which can change to its ionic forms according to the environmental condition. The present study was concentrated on the effective detection of Hg (II) ion from environmental sample colorimetrically by developing Ag NPs - tryptophan nanoconjugate functionalized with 3-(Trimethoxysilyl)propyl methacrylate (TMPM). The characterization of prepared particles was performed by UV-visible spectrophotometer, transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), particle size analyzer and zeta sizer. The size of prepared NPs was 9 ± 1.10 nm and it possess the surface charge of -37.41 ± 4 mV. Upon the interaction of Ag NPs - tryptophan nanoconjugate and Hg (II) ion, the colour of the conjugate disappeared. The effect of environmental factors (Temperature, pH and saline concentration) on Hg (II) ion detection was also investigated. The probe indicated that Ag NPs - tryptophan nanoconjugate functionalized with TMPM was found to be an efficient tool for mercury detection from various environmental water samples.

Rapid colorimetric detection of mercury using silver nanoparticles in the presence of methionine.

Development of potential sensors is inevitable for the detection of environmental pollutants including toxins, organic pollutants and heavy metal which cause hazardous effect to human and other living organisms. The present study is to develop silver nanoparticle (Ag NPs) based sensor for the accurate, sensitive and selective colorimetric detection of Hg2+ ions from aqueous samples at nano molar level. The nanoparticles were synthesized chemically and it was stabilized by polyvinylpyrrolidone (PVP). The prepared particles were characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), particle analysiser and Zetasizer. The UV-visible spectra of Ag NPs showed absorbance maximum at 392 nm. The average diameter of Ag NPs was determined to be 6 ±â€¯0.9 nm by using particle analyzer. The zeta sizer analysis showed that the PVP stabilized Ag NPs possessed a zeta potential of -35.56 ±â€¯3 mV. The Ag NPs-methionine conjugate showed the colour change from the brownish yellow colour to colourless when it was reacted with mercury. The Ag NPs conjugated methionine is sensitive to mercury and detects the mercury at nano molar level. The influence of other metal ion did not interfere with the detection and quantification of Hg2+. The detection of Hg2+ was also performed with paper strip and agarose gel method. The Ag NPs conjugate with methionine can applied for the detection of Hg2+ from various aqueous samples.