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Therapeutic management of mastitis faces significant challenges due to multidrug resistance. In the present study, multi-drug-resistant (MDR) Staphylococcus spp , Klebsiella pneumoniae, and Escherichia coli were isolated from bovine clinical mastitis cases and the phenotypic and genotypic multidrug resistance profiling was carried out. Silver nanoparticles (AgNPs) were biosynthesized using Ocimum sanctum leaf extracts and characterized via UV Vis absorption, Fourier Transform Infrared Spectroscopy, X-ray diffraction studies, Energy dispersive spectroscopy and Electron Microscopy. The determined minimum inhibitory concentration and minimum bactericidal concentration of the AgNPs against the recovered MDR isolates were 62.5 μg/ml and 125 μg/ml respectively. At a concentration of 50 μg/ml, the AgNPs demonstrated biofilm inhibitory activities of 80.35 % for MDR E. coli , 71.29 % for S. aureus and 60.18 % for MDR K. pneumoniae. Post-treatment observations revealed notable differences in biofilm formation across bacterial isolates. Furthermore, AgNP treatment led to significant downregulation of expression of the efflux pump genes acrB , acrE , acrF , and emrB in Gram-negative isolates and norB in Staphylococci isolates. This research underscores the potential for the development of an eco-friendly antimicrobial alternative in the form of green synthesized silver nanoparticles to combat drug resistance offering potential antibiofilm and efflux pump inhibitory activities. [Display omitted] • Multidrug resistant (MDR) Staphylococci, Klebsiella pneumoniae and Escherichia coli were isolated from clinical mastitis cases. • The phenotypic and genotypic multidrug resistance profiling was carried out. • Synthesized silver nanoparticles using Ocimum sanctum leaf extract as a reducing and capping agent. • Characterized the AgNPs using UV–vis spectroscopy, FTIR, XRD, SEM -EDAX and TEM. • They exhibited antimicrobial, antibiofilm and efflux pump inhibitory activity in multidrug resistant bacterial isolates. • Green synthesized silver nanoparticles are suitable candidates for combating multidrug resistant bacterial organisms. [ABSTRACT FROM AUTHOR]

The global rise of antibiotic resistance poses a substantial risk to mankind, underscoring the necessity for alternative antimicrobial options. Developing novel drugs has become challenging in matching the pace at which microbial resistance is evolving. Recently, nanotechnology, coupled with natural compounds, has emerged as a promising solution to combat multidrug-resistant bacteria. In the present study, silver nanoparticles were green-synthesized using aqueous extract of Phoenix dactylifera (variety Ajwa) fruits and characterized by UV–vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) coupled with Energy dispersive X-ray analysis (EDX), Transmission electron microscopy (TEM) and Thermogravimetric-differential thermal analysis (TGA-DTA). The in-vitro synergy of green synthesized P. dactylifera silver nanoparticle (PD-AgNPs) with selected antibiotics and bioactive extract of Punica granatum, i.e., ethyl acetate fraction (PGEF), was investigated using checkerboard assays. The most effective synergistic combination was evaluated against the QS-regulated virulence factors production and biofilm of Pseudomonas aeruginosa PAO1 by spectroscopic assays and electron microscopy. In-vivo anti-infective efficacy was examined in Caenorhabditis elegans N2 worms. PD-AgNPs were characterized as spherical in shape with an average diameter of 28.9 nm. FTIR analysis revealed the presence of functional groups responsible for the decrease and stabilization of PD-AgNPs. The signals produced by TGA-DTA analysis indicated the generation of thermally stable and pure crystallite AgNPs. Key phytocompounds detected in bioactive fractions include gulonic acid, dihydrocaffeic acid 3-O-glucuronide, and various fatty acids. The MIC of PD-AgNPs and PGEF ranged from 32 to 128 μg/mL and 250–500 μg/mL, respectively, against test bacterial strains. In-vitro , PD-AgNPs showed additive interaction with selected antibiotics (FICI 0.625–0.75) and synergy with PGEF (FICI 0.25–0.375). This combination inhibited virulence factors by up to 75 % and biofilm formation by 84.87 % in P. aeruginosa PAO1. Infected C. elegans worms with P. aeruginosa PAO1 had a 92.55 % survival rate when treated with PD-AgNPs and PGEF. The combination also reduced the reactive oxygen species (ROS) level in C. elegans N2 compared to the untreated control. Overall, these findings highlight that biosynthesized PD-AgNPs and bioactive P. granatum extract may be used as a potential therapeutic formulation against MDR bacteria. • Silver nanoparticles from aqueous extract of P. dactylifera (PD-AgNPs) were well-dispersed and spherical, with an average diameter of 28.9 nm. • PD-AgNPs and bioactive extract of P. granatum (PGEF) showed synergy in vitro with FICI of 0.25–0.375. • Synergistic formulation inhibited QS-regulated virulence factors in P. aeruginosa PAO1 more than 75 %.. • The anti-infective efficacy of synergistic formulations against P. aeruginosa PAO1-infected C. elegans N2 worms highlights in vivo therapeutic potential.. [ABSTRACT FROM AUTHOR]

[Display omitted] • Size-dependent activity of DMO hydrogenation over Ag catalysts. • A volcano-shape trend between hydrogenation activity and the Ag particle size. • Step-likes active sites are identified as the dominant active sites. • Electronic properties dominate the performances of <5.3 nm sized Ag catalysts. Ag catalysts are promising for the selective hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG), where the size of Ag nanoparticles strongly dominates their catalytic performances. Fundamental understandings on the size dependence, especially at the level of active sites, are still lacking but of great importance for the rational design of Ag-based catalysts for this reaction. Herein, a series of catalysts consisting of Ag nanoparticles sized from 2.9 to 8.8 nm anchored on amine-derivatized mesoporous silica nanospheres (Ag/AS) were synthesized and employed to understand the size-dependent DMO hydrogenation to MG. A volcano-shape trend between the hydrogenation activity and the increasing Ag particle size is observed for the differently sized Ag/AS catalysts, indicating a remarkable size dependence. The origin of the size dependence is further understood based on the cuboctahedron model of Ag nanoparticle, and the step-likes active sites are identified as the dominant ones. Results combining with the X-ray photoelectron spectroscopy, in situ Fourier transform infrared spectroscopy and temperature programmed desorption studies, indicate that the hydrogenation of DMO to MG on Ag/AS catalysts is mainly dominated by the number of active sites when the Ag particle size ≥ 5.3 nm, but by the electronic properties when the Ag particle size < 5.3 nm. The balance between the number of active sites and electronic structure gives rise to a maximal reaction rate in term of apparent TOF on the Ag/AS catalyst with Ag particle size of 5.3 nm. These understandings may guide the design of highly efficient Ag catalysts for the coal-based MG production. [ABSTRACT FROM AUTHOR]

Abstract Biosynthesis silver nanoparticles (AgNPs) have received a lot of attention as a cytotoxic and antimicrobial activity against pathogenic bacteria. This study was carried out to evaluate the potential ability of red marine algae Corallina elongata and Gelidium amansii to biosynthesis AgNPs capping with Sodium Dodecyl Sulfate (SDS) and to determine its antibacterial efficacy. Characterization of capping AgNPs were determined by Ultra violet-Visible spectroscopy, Transmission electron microscope (TEM), Scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), Energy dispersive X-ray spectroscopy (EDX), Zeta potential and sizer. The results indicated that there is no variation change between capping AgNPs synthesis by two red algae in plasmon resonance peak and also both stable along 3 weeks. The capping nanoparticles size were range from 8 to 25 nm in the case of G. amansii and 12–20 nm C. elongata. The results were obtained from Fourier transforms infrared spectroscopy (FTIR) indicated that same metals are present in both algae except Vanadium (V) was present with G. amansii. Capping AgNPs biosynthesis by C. elongata had more toxicity to Chlorella vulgaris than that of synthesized by G. amansii. Capping AgNPs by SDS have been shown to enhance antibacterial activity against Micrococcus leutus , Kocuria varians and Escherichia coli ATCC 8739 compared to non-capping AgNPs. The antibacterial activity and toxicity of AgNPs is affected by concentrations of capping agent and the biomaterial (red algae) that used for synthesis. Highlights • Biosynthesis of AgNPs using Corallina elongata and Gelidium amansii and capping by SDS possess different characterization, cytotoxic activity against Chlorella vulgaris and also differ effects against pathogenic bacteria. • Biosynthesis AgNPs and capping by SDS had more efficiency against pathogenic bacteria. • The best concentrations of SDS in case of AgNPs synthesis by C. elongate was 6 mM whereas G. amansii was 9 mM. [ABSTRACT FROM AUTHOR]

Abstract In this communication, we present the green synthesis of silver nanoparticles (AgNPs) using medicinally important Nardostachys jatamansi rhizome extract in the presence of sunlight. UV–vis spectroscopy, Fourier Transform Infrared spectroscopy (FTIR), Transmission electron microscope (TEM) and Energy dispersive X-ray analysis (EDX) were employed to characterize the synthesized AgNPs. UV–visible spectroscopic studies confirmed the presence of biosynthesized AgNPs. Transmission Electron Microscopic studies revealed the structure of spherical AgNPs in the diameter range of 10–15 nm. Energy dispersive X-ray analysis and elemental mapping clearly confirmed the presence of silver in AgNPs samples. Interestingly, biomolecules functionalised AgNPs exhibited a remarkable antioxidant, anti-inflammatory, and anti-biofilm activities and hence biosynthesized AgNPs from N. jatamansi can be used as a promising biomaterial for biomedical applications. Highlights • Green synthesis of AgNPs using Nardostachys jatamansi rhizome extract. • Biogenic AgNPs was found to be spherical in the size range of 10–15 nm. • AgNPs exhibited significant anti-biofilm effect against classical colonizers. [ABSTRACT FROM AUTHOR]

The bio-based nanoparticles synthesis and assessment of their potential biomedical applications related research is rapidly emerging. The ability of an aqueous ethanolic bark extract of Mangifera indica to synthesize silver nanoparticles (AgNPs) as well as its antibacterial, anti-inflammatory, and anticancer activities were investigated in this study. Interestingly, the bark extract effectively synthesized the AgNPs, including an absorbance peak at 412 nm and sizes ranging from 56 to 89 nm. The Fourier Transform Infrared spectroscopy (FTIR) analysis confirmed that the presence of most essential functional groups belongs to the most bioactive compounds. Synthesized AgNPs showed fine antibacterial activity against the Urinary Tract Infection (UTI) causing bacterial pathogens such as Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Proteus mirabilis, and Staphylococcus saprophyticus at 50 μg mL−1 concentrations. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of AgNPs against these pathogens were found as 12.5 ± 0.8 & 13 ± 0.6, 13.6 ± 0.5 & 14 ± 0.7, 11.5 ± 0.3 & 11.5 ± 0.4, 13 ± 0.8 & 13 ± 0.7, and 11.8 ± 0.4 & 12 ± 0.8 μg mL−1 respectively. Interestingly, this AgNPs also possesses outstanding anti-inflammatory and anticancer activities as studied against the egg albumin denaturation (85%) inhibition and MCF 7 (Michigan Cancer Foundation-7: breast cancer cells) cell line (cytotoxicity: 80.1%) at 50 μg mL−1 concentration. Similarly at 50 μg mL−1 concentration showed 75% of DPPH radical scavenging potential. These activities were dose dependent, and the findings suggest that the M. indica bark aqueous ethanolic extract synthesized AgNPs can be used as antibacterial, anti-inflammatory, and anticancer agents after in-vivo testing. • Mangifera indica bark aqueous ethanolic extract effectively synthesize the AgNPs. • Synthesized AgNPs were spherical in shape with size ranged from 56 to 89 nm. • AgNPs had considerable antibacterial activity against UTI causing bacterial pathogens. • Bark extract synthesized AgNPs also possesses fine anti-inflammatory activity. • AgNPs have remarkable anticancer activity (cytotoxicity) against MCF 7 cell line. [ABSTRACT FROM AUTHOR]

Acinetobacter baumanii , a gram-negative, non-motile, encapsulated coccobacillus which causes infections worldwide. The objective of this study was to find a fungal strain that could be utilized to biosynthesize antibacterial silver nanoparticles (AgNPs) against Acinetobacter baumanii . The present investigation explains rapid and extracellular biosynthesis of silver nanoparticles by the algicolous endophytic fungus, Penicillium polonicum , isolated from the marine green alga Chetomorpha antennina . The obtained silver nanoparticles were characterized by UV-Vis spectroscopy, Raman spectroscopy, Fourier transformation infrared (FTIR), and Transmission electron microscopy (TEM). The SNPs showed a characteristic UV- visible peak at 430 nm with an average size of 10–15 nm. As evident from the FTIR and Raman spectra, possibly the protein components of fungal extract have caused the reduction of silver nitrate. Parametric optimization, including the concentration of AgNO 3 , ratio of cell filtrate and AgNO 3 , fungal biomass, reaction time, pH, and presence of light, was done for rapid AgNPs production. The antibacterial efficacy of AgNPs against multi-drug-resistant, biofilm-forming Acinetobacter baumanii , was evaluated by well diffusion assay. The Minimum inhibitory concentration (MIC) of AgNP was 15.62 μgml −1 and the minimum bactericidal concentration (MBC) was 31.24 μgml −1 . Killing kinetic assay revealed complete killing of the bacterial cells within 6 h. Log reduction and percent survival of bacterial cells were analyzed from killing kinetic study. Bactericidal nature of synthesized nanoparticles was confirmed by fluorescent microscopical analysis. The effect of AgNPs on the ultrastructure of bacterial pathogen was evaluated by Transmission electron microscopy. [ABSTRACT FROM AUTHOR]

In this work, N -alkylated poly (4-vinylpyridine) (NPVP), a cationic polymer, was firstly applied for the surface modification of Fe 3 O 4 nanoparticles. Then the modified Fe 3 O 4 nanoparticles (Fe 3 O 4 @NPVP NPs) combined with graphene oxide (GO) through simple electrostatic binding. Subsequently, deposited Ag nanoparticles (Ag NPs) procedure was carried out to form the multiple antibacterial nanocomposites (GO-Fe 3 O 4 @NPVP-Ag). The synthesized nanostructures were well characterized by Transmission Electron Microscope (TEM), X-ray powder diffraction (XRD), Fourier-transform infrared (FT-IR) and Raman spectroscopy. The zeta potential measurement showed that the novel antibacterial nanocomposites exhibited a capacity of reversing its surface charge from negative (physiological pH) to positive (acidic condition). Furthermore, the incorporation of magnetic Fe 3 O 4 NPs into the nanosystems facilitates the cyclic utilization of GO-Fe 3 O 4 @NPVP-Ag by magnetic separation. The antibacterial properties of GO-Fe 3 O 4 @NPVP-Ag nanocomposites were evaluated with Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus . Moreover, the cytotoxicity of GO-Fe 3 O 4 @NPVP-Ag nanocomposites was studied using NIH-3T3 cells. The results showed that the GO-Fe 3 O 4 @NPVP-Ag nanocomposites exhibited excellent antibacterial properties and low cytotoxicity, thus confirming its application as a promising rapid bactericide in various antibacterial fields. [ABSTRACT FROM AUTHOR]

Our study aiming for the diminution of arsenic concentration in arsenic contaminated aqua environment by using novel adsorbents based on bio-fabricated silver nanoparticles on a fungal cell surface. Bioreduction of silver ion was done in a non-enzymatic manner in presence of the biomass of fungus Aspergillus foetidus MTCC8876. Aspergillus spp. cells were harvested following the bioreduction and made into carbon by carbonization that led to pore formation (pore width of 2.35 nm) on the cell surface. The average size of silver nanoparticles in the sample of SACF (silver nanoparticles adhered to mesoporous carbonized fungal cell) was 35 nm. Whereas mesoporous carbonized control fungal (CCF) cell was devoid of any particles on its surface. For structural characterizations of this adsorbent as well as to emerge its changes as a validation of arsenic adsorption, different biophysical methods such as FTIR, XRD, SEM, FESEM, TEM, BET surface area analysis and SERS analysis were followed. Batch mode experiments were performed to investigate the influence of As (V) concentrations, reaction time, pH of the solution and also the temperature of experiments on the efficiency of As (V) removal by adsorbents SACF & CCF. This arsenic-adsorbent interaction was proved to be endothermic in nature as well as the negative ΔG value indicated the spontaneity. SACF showed exceptional efficiency for the removal (>93%) of arsenic rather than CCF from an aqueous environment within a very short time of 3.5 h due to its porosity and the presence of the silver nanocrystals. [ABSTRACT FROM AUTHOR]

We demonstrated one-step synthesis of silver nanoparticles (AgNPs) from Cassia fistula fruit extract and their antibacterial activity against E. coli and K. pneumoniae. Biogenic AgNPs were characterized by scanning electron microscopy, X-Ray diffraction and fourier transform infrared spectroscopy. Results confirmed spherical shaped AgNPs with an average crystallite size of ∼69 nm. Dose-dependent (0, 10, 20, 40 and 80 μg mL −1 ) growth kinetic studies showed 100% potency against E. coli (20 μg mL −1 ) and K. pneumoniae (80 μg mL −1 ) after 1 and 5 h, respectively. Surface morphology analysis revealed formation of groove/pits in the lysed cell membrane that eventually led to bacterial death. [ABSTRACT FROM AUTHOR]

The present study was focused on the preparation of gold, silver, and gold-silver-alloy nanoparticles using Rhodomyrtus tomentosa acetone extract (RAE). The synthesized nanoparticles showed the surface plasmon resonance absorption peak corresponding to gold and silver nanoparticle. However, Au-Ag-Alloy nanoparticles showed the single peak between the peaks of AuNPs and AgNPs. TEM observation ascertained the shape and size of nanoparticles. FTIR results indicated the involvement of RAE for the synthesis and capping of nanoparticles. Study on antibacterial activity demonstrated the enhanced activity of RAE capped on silver and Au-Ag-Alloy nanoparticles against Escherichia coli. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) supported palladium cobalt bimetallic nanoparticles (PdCo@AC NPs) were obtained by green synthesis method using Cinnamomum verum (C. Verum) extract. The obtained NPs were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Crystallography (XRD), Transmission Electron Microscope (TEM) and Ultraviolet Visible (UV-VIS) spectroscopy, and the functional groups and morphology of the nanoparticle were elucidated. The resulting particle size was found to be 2.467 nm. NPs were evaluated using Cyclic Voltammetry (CV), Scan Rate (SR), and Differential Pulse Voltammetry (DPV) techniques for potential dopamine sensors application. According to the obtained DPV results, Limit of Detection (LOD) and Limit of Quantitation (LOQ) values are found to be 5.68 pM and 17.21 pM, respectively. It was also observed that AC supported PdCo nanoparticles obtained from C. verum extract sensed dopamine quite well. Besides, to examine the antibacterial properties of NPs, antibacterial analyzes were performed with Escherichia coli (E. Coli) and Staphylococcus aureus (S. Aureus). It was observed that it showed good antibacterial properties against gram positive (S. aureus) and gram negative (E. coli) bacteria. The study gave important results in terms of the synthesis of bimetallic NPs using the green synthesis method and their usability in different areas. With this study, it was observed that a good antibacterial dopamine sensor were obtained with the successful biogenic synthesis of AC supported PdCo bimetallic NPs. [ABSTRACT FROM AUTHOR]

A novel polypropylene glycol/silver nanoparticles (PPG/AgNPs) composite was prepared in-situ using natural honey as the reducing and capping agent. Characterization of the composite was done by UV–Vis spectroscopy, FTIR, TEM, XRD, and EDS. The TEM results reveal that the nanoparticles are spherical in shape. XRD and EDS results confirm the presence of elemental silver in the polymer matrix. The influence of the prepared composite on the corrosion inhibition of mild steel in 0.5 M H 2 SO 4 solution was studied by weight loss, electrochemical, SEM, EDS, and water contact angle measurements. Results show that PPG/AgNPs is effective inhibitor for mild steel in 0.5 M H 2 SO 4 solution and adsorbs onto the metal surface via chemisorption mechanism. Maximum inhibition efficiency of 94% is afforded by the highest studied concentration of PPG/AgNPs at 333 K from weight loss measurements. Potentiodynamic polarization results reveal that the composite acts as a mixed-type corrosion inhibitor. Adsorption of PPG/AgNPs composite onto the mild steel surface follows Temkin adsorption isotherm. The SEM, EDS, and water contact angle images confirm the formation of PPG/AgNPs protective film on the mild steel surface. [ABSTRACT FROM AUTHOR]

In this work, silver nanoparticles have been synthesized by wet chemical technique, green synthesis and microbial methods. Silver nitrate (10 −3 M) was used with aqueous extract to produce silver nanoparticles. From the results it was observed that the yield of nanoparticles was high in green synthesis. The size of the silver nanoparticles was determined from Scanning Electron Microscope analysis (SEM). Fourier Transform Infrared spectroscopy (FTIR) was carried out to determine the presence of biomolecules in them. Its cytotoxic effect was studied in cancerous cell line and normal cell line. MTT assay was done to test its optimal concentration and efficacy which gives valuable information for the use of silver nanoparticles for future cancer therapy. [ABSTRACT FROM AUTHOR]

In this work, the efficiency of the ubiquitous fungus Penicillium sp. 8L2 to remove Ag(I) ions from synthetic solutions and its potential to synthesize silver nanoparticles (AgNPs) was evaluated. Using a Rotatable Central Composite Design pH and biomass concentration were optimized. Maximum biosorption capacity 51.53 mg/g, by Langmuir model, comparing favourably with other reports. The fungal biomass was characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and analyzed before and after the biosorption process by different techniques: X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Ultra-High Resolution Transmission Electron Microscopy and Energy Dispersive X-ray (HR-TEM-EDX) and Ultraviolet–Visible Spectrophotometry (UV–vis). The results showed that the fungus applied several mechanisms to remove Ag(I) ions from the solution and that some of them induced the synthesis of AgNPs. This fact could be verified in the synthesis tests from the cell extract in which aqueous suspensions with high concentrations of AgNPs were obtained. These nanoparticles had diameters between 2 and 9 nm and therefore a high potential for their use as biocidal agents. The results indicated that the synthesis of nanoparticles could be an added value to the heavy metal biosorption process. • The ubiquitous fungus Penicillium sp. 8L2 is effective biosorbent for Ag(I). • Both the fungus and its cell extract are capable of synthesizing AgNPs as added value. • Nanoparticles are easily recovered and have very small sizes (<10 nm). • The recovered nanoparticles can be applied in other biotechnological areas. • FT-IR, UV–vis, XRD, TEM and FESEM-EDX techniques were used. [ABSTRACT FROM AUTHOR]

Despite the development potential in the field of nanotechnology, there is a concern about possible effects of nanoparticles on the environment and human health. In this study, silver nanoparticles (AgNPs) were synthesized by ‘green’ and ‘chemical’ methods. In the wet-chemistry method, sodium borohydrate, sodium citrate and silver nitrate were used as raw materials. Leaf extract of Nigella sativa was used as reducing as well as capping agent to reduce silver nitrate in the green synthesis method. In addition, toxic responses of both synthesized AgNPs were monitored on bone-building stem cells of mice as well as seed germination and seedling growth of six different plants (Lolium, wheat, bean and common vetch, lettuce and canola). In both synthesis methods, the colorless reaction mixtures turned brown and UV–visible spectra confirmed the presence of silver nanoparticles. Scanning electron microscope (SEM) observations revealed the predominance of silver nanosized crystallites and fourier transform infra-red spectroscopy (FTIR) indicated the role of different functional groups in the synthetic process. MTT assay showed cell viability of bone-building stem cells of mice was further in the green AgNPs synthesized using black cumin extract than chemical AgNPs. IC50 (inhibitory concentrations) values for seed germination, root and shoot length for 6 plants in green AgNPs exposures were higher than the chemical AgNPs. These results suggest that cytotoxicity and phytotoxicity of the green synthesized AgNPs were significantly less than wet-chemistry synthesized ones. This study indicated an economical, simple and efficient ecofriendly technique using leaves of N. sativa for synthesis of AgNPs and confirmed that green AgNPs are safer than chemically-synthesized AgNPs. [ABSTRACT FROM AUTHOR]

During this study, we report the green synthesis of silver nanoparticles (Ag NPs) using Euphorbia helioscopia Linn leaf extract for the synthesis of propargylamines. Also, the structural and optical properties are studied. The synthesized nanoparticles are characterized by TEM, XRD, FT-IR and UV–visible techniques. UV–visible studies show an absorption band at 440 nm due to surface plasmon resonance (SPR) of the silver nanoparticles. Furthermore, the catalyst exhibits high catalytic activity, superior cycling stability and excellent substrate applicability. [ABSTRACT FROM AUTHOR]

In the present investigation, we described the green synthesis of silver nanoparticles using plant leaf extract of Hemidesmus indicus . The synthesized silver nanoparticles were characterized by UV–visible spectroscopy, fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). TEM images proved that the synthesized silver nanoparticles were spherical in shape with an average particle size of 25.24 nm. To evaluate antibacterial efficacy, bacteria was isolated from poultry gut and subjected to 16S rRNA characterization and confirmed as Shigella sonnei . The in vitro antibacterial efficacy of synthesized silver nanoparticles was studied by agar bioassay, well diffusion and confocal laser scanning microscopy (CLSM) assay. The H. indicus mediated synthesis of silver nanoparticles shows rapid synthesis and higher inhibitory activity (34 ± 0.2 mm) against isolated bacteria S. sonnei at 40 μg/ml. [ABSTRACT FROM AUTHOR]

In this paper, we report different coordinations of citrates on gold (AuNP) and silver (AgNP) nanoparticles, as determined using Fourier transform infrared spectroscopy (FTIR) and molecular orbital (MO) calculations. AuNPs and AgNPs are found to have completely different interactions with the carboxylate anchoring groups, as indicated by their unique asymmetric stretching vibrations in the FTIR spectra. The ν as (COO − ) of citrate exhibits a high-frequency shift resulting from the formation of a unidentate coordination on AuNPs, whereas this vibration exhibits a low-frequency shift as a result of ionic bond formation on AgNPs, as predicted from the MO calculations of the corresponding metal complex salts. The enhancement in the IR signals when their vibration direction was perpendicular to the nanoparticle surface revealed the influence of localized surface plasmons excited on the metal nanoparticles. [ABSTRACT FROM AUTHOR]

Selective and sensitive optical sensor based on surface plasmon resonance for detection of various heavy metals in water using polyvinylpyrolidone modified silver nanoparticles was explained in this present study. The prepared nanoparticles were characterized by UV–visible spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FTIR) and Transmission electron microscopy (TEM). UV–visible spectra show the surface plasmon resonance (SPR) peak at 409 nm corresponding to silver nanoparticles. Crystalline nature of the nanoparticles was evident from TEM images and XRD analysis. TEM images showed average size of 10 nm for prepared silver nanoparticles. FTIR analysis provides the presence of various functional groups responsible for the reduction and stability of the prepared silver nanoparticles. SERS gives the molecular orientation of the adsorbed pyridine molecules via its nitrogen lone pair of electrons on the surface of silver. Prepared polyvinylpyrolidone modified silver nanoparticles (AgNPs) are demonstrated to detect the concentration of heavy metal contaminant Fe3+ ions in water based on linear change in surface plasmon resonance absorption strength. In addition, AgNPs showed promising activity towards E.coli. These observed optical properties suggest the possible utilization of prepared nanoparticles in the application of water purification. • Polyvinylpyrolidone modified silver nanoparticles was prepared. • The pyridine orientation on silver nanoparticles is stand-on configuration. • PVP to inhibiting the growth of E.coli exist in water. • Sensitive optical sensor based on surface plasmon resonance for detection of Fe3+ in water. [ABSTRACT FROM AUTHOR]

This study was aimed on the eco-friendly synthesis of silver nanoparticles (AgNPs), reduced graphene oxide (rGO) and AgNPs decorated rGO (rGO/AgNPs) nanocomposite and appraisal of their bioactivities and toxicity. As-prepared nanomaterials were established through high resolution X-ray diffraction (HR-XRD), high resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV–Vis. spectroscopy and Fourier transform infrared spectroscopy (FT-IR). In this study, leaves extract, graphene oxide (GO) and rGO did not show antibacterial and anticancer activities; no significant embryo toxicity was recorded. On the other hand, AgNPs displayed good antibacterial and anticancer activities; however, higher toxic effects were observed even at the lowest test concentration (0.7 μg/ml). In case of rGO/AgNPs nanocomposite, significant antibacterial activity together with low cytotoxicity was noticed. Interestingly, the embryo toxicity of AgNPs was significantly reduced by rGO, implying the biocompatible nature of as-synthesized nanocomposite. Taken together, these results clearly suggest that rGO/AgNPs nano hybrid composite could be developed as the promising biomaterial for future biomedical applications. [Display omitted] • In this study, AgNPs, rGO and rGO/AgNPs composites were prepared. • AgNPs showed good antibacterial and anticancer activities. • However, higher toxicity was observed even at 0.7 μg/ml of AgNPs. • rGO/AgNPs displayed good antibacterial activity with low cytotoxicity. • Interestingly, the toxic effects of AgNPs were significantly reduced by rGO. [ABSTRACT FROM AUTHOR]

In the present work, a green synthetic method for the preparation of extremely stable silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using Sargassum ilicifolium has been demonstrated. Thus produced nanoparticles were characterized by UV–Visible (UV–Vis) spectroscopy, Fourier Transform InfraRed spectroscopy (FT-IR), Energy Dispersive X-ray spectroscopy (EDX), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS) and Zeta potential analyses. The average size of Ag and Au NPs was 27.9 and 9.36 nm respectively from TEM, which was further substantiated by XRD data. Zeta potential values of −42.2 mV and −28.3 mV for Ag and Au NPs respectively suggested that the nanoparticles were negatively charged and highly stable. AgNPs showed desirable bactericidal activity towards Enterobacter species, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Proteus species. The photocatalytic behaviour of AgNPs was studied to degrade malachite green (MG) and methylene blue (MB) in aqueous medium. In MG, 82.9% degradation was achieved in 180 min of light exposure and the pseudo first order rate constant was 7.2 × 10−3 min−1. In MB, almost 100% of the dye was degraded in the same period and the pseudo first order rate constant calculated was 7.5 × 10−3 min−1. The bio-derived AgNPs are hence promising materials for treating effluent from dyeing industries and water purification. [Display omitted] • Rapid green synthesis of Ag and Au NPs using Sargassum ilicifolium in sunlight. • AgNPs have bactericidal effect and photocatalytic activity to degrade cationic dyes. • Methylene blue (100%) and malachite green (82.9%) are degraded in 3 h in sunlight. • AgNPs are promising materials for treating effluent from dyeing industries. [ABSTRACT FROM AUTHOR]

In this present research, we succeeded in synthesizing nanostructured silver particles (NS-AgPs) using bio active agent present in the leaf extracts of Cleome gynandra (CG) under green synthesis. While adding silver nitrate (AgNO 3) solution in green extracts of CG leaf containing bio compound, the mixture turns from yellow to reddish brown, as a consequence of existence of nanostructured silver particles (NS-AgPs) and later UV instrument is used to obtain the Ultraviolet visible spectroscopy (UV–vis) spectra to confirm existing nanostructured silver particles (NS-AgPs) in aqueous solutions (synthesized sample). To confirm existing functional groups in NS-AgPs, the fourier transform infrared spectroscopy (FTIR) study is carried throughout this research. The scanning and tunneling of wave like nature of electrons passing through powdered NS-AgPs sample gives Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) images respectively, which are carried out to find out the 2-dimensional size and shape distribution of NS-AgPs. Further dynamic light scattering (DLS) and zeta potential studies are used to confirm the size and good stability of NS-AgPs respectively. It is evident that NS-AgPs exhibits a strong toxic activity against microorganism and to confirm this mechanism the antibacterial (against Escherichia coli and Staphylococcus aureus) study is carried out. • Biological technique is cost-efficient, capable of processing AgNPs at 60 °C. • synthesized AgNPs were spherical in size and the size ranging from 18 to 35 nm. • The feasible biomolecules which are liable for the minimization of Ag + ions. • Alkyl halides bond reported that the indicates association of alkanes. • AgNPs reported that proteins could bind to silver nanoparticles which are compatible. [ABSTRACT FROM AUTHOR]

In the present study, Allium cepa leaf extract was utilized to reduce the silver nitrate into the nanoscale range of silver ions (Ag NPs). The biosynthesized Ag NPs were extensively characterized by X-ray diffraction analysis (XRD), Dynamic light scattering analysis (DLS), UV–Visible spectroscopy (UV–vis), Transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). The antioxidant activity of synthesized Ag NPs was verified by DPPH assay. From the results obtained from XRD and DLS studies, the size of Ag NPs was determined to be around 54.3 nm. The measured zeta potential value of −19.1 mV confirms the excellent stability of biosynthesized Ag NPs. TEM analyses reveal that the biosynthesized Ag NPs have a spherical structure of 13 nm in size. The presence of various functional groups was confirmed through FTIR studies and EDAX verifies the weight percentage of silver content in biosynthesized nanoparticles to be 30.33%. In the present study, anti-cancer activity was carried out by using breast cancer cell line MCF-7. Further, silver nanoparticles exhibited antimicrobial effectiveness against gram-positive Bacillus cereus and gram-negative Escherichia coli. The MTT assay also showed better cytotoxic activity against the MCF- 7 cell line. • antibacterial & antiproliferative activity on breast cancer cell line MCF-7. • The antioxidant activity of synthesized Ag NPs was confirmed by DPPH assay. • XRD & DLS analysis reveals that the size of AgNPs was found to be around 54.3 nm. • The value of zeta potential at −19.1 mV which confirms the great stability of Ag NPs. • EDAX verifies the weight percentage of Ag content in biosynthesized NPs to be 30.33%. [ABSTRACT FROM AUTHOR]

Green technology for the synthesis of nanoparticles has gained momentum due to its cost-effectiveness and eco-friendly nature. In this research study, silver nanoparticles (AgNps) were synthesized using an eco-friendly biological method involving the use of marine algae, Halimeda gracilis. The surface properties of the synthesized silver nanoparticles were studied using UV–visible spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy methods. During the synthesis of nano particles, the parameters namely temperature (30 °C to 90 °C), pH (6–10), silver nitrate (AgNO 3) concentration (1–3 mg/ml) and quantity of algal extract (1–3 ml) were optimized to improve the production of AgNPs. The application of the synthesized silver nanoparticles for the adsorptive removal of copper from aqueous and industrial wastewater was investigated. Intra-particle diffusion mechanism was identified to be controlling step in metal removal. Regeneration of sorbent was carried out using 2.0 M HCl and the reusability was verified for 6 cycles. A removal efficiency of copper (64.8%) from electroplating wastewater demonstrated the industrial application potential of the synthesized silver nanoparticles. • Green synthesize of silver nano particles (AgNPs) was carried out using Halimeda gracilis. • SEM, FTIR, TGA and UV Spectra were employed to characterize the synthesized AgNPs. • A maximum production of 2.72 g of AgNPs/100 ml of Halimeda gracilis was attained. • Isotherm, kinetics, desorption and regeneration studies were performed. • Equilibrium copper uptake capacity of AgNps was 46.30 mg/g. [ABSTRACT FROM AUTHOR]

Silver nanoparticles doped with FCNT-TiO 2 heterogeneous catalyst was prepared via one-step chemical reduction process and their efficacy was tested for hydrogen production under solar simulator. Crystallinity, purity, optical properties, and morphologies of the catalysts were examined by X-Ray diffraction, Raman spectroscopy, UV–Visible diffuse reflectance spectra, and Transmission Electron Microscopy. The chemical states and interface interactions were studied by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The optimized catalyst showed 19.2 mmol g−1 h−1 of hydrogen production, which is 28.5 and 7 times higher than the pristine TiO 2 nanoparticles and FCNT-TiO 2 nanocomposite, respectively. The optimized catalyst showed stability up to 50 h under the solar simulator irradiation. The natural solar light irradiated catalyst showed ~2.2 times higher hydrogen production rate than the solar simulator irradiation. A plausible reaction mechanism of Ag NPs/FCNT-TiO 2 photocatalyst was elucidated by investigating the beneficial co-catalytic role of Ag NPs and FCNTs for enhanced hydrogen production. [Display omitted] • Ag doped FCNT-TiO 2 ternary heterojunction prepared by chemical reduction process. • Ag doped FCNT-TiO 2 catalyst was showed a visible absorption. • The optimized catalyst showed 19.2 mmol g−1 h−1 of H 2 production under solar simulator. • Natural solar light irradiated catalyst showed ~2.2 times higher H 2 production rate than the solar simulator. [ABSTRACT FROM AUTHOR]

Fungi represent an interesting candidate for the synthesis of nanoparticles. The biosynthesis of silver nanoparticles (AgNPs) has many industrial and biomedical indications. We aimed in this work to biologically synthesize silver nanoparticles using Aspergillus niger and to evaluate its effect against the newly identified Allovahlkampfia spelaea that causes resistant human keratitis. Aspergillus niger (soil isolate) was treated with silver nitrate to produce silver nanoparticles. AgNPs were characterized by Ultraviolet–Visible Spectroscopy, Transmission Electron Microscopy, and Fourier Transform Infrared Spectroscopy. The effect of the synthesized nanoparticles against Allovahlkampfia spelaea growth, encystation, excystation, and toxicity in host cells was evaluated. AgNPs exhibited significant inhibition of Allovahlkampfia spelaea viability and growth of both trophozoites and cysts, with a reduction of amoebic cytotoxic activity in host cells. AgNPs may give a promising future to the treatment of Allovahlkampfia spelaea infections in humans. Image 1 • Allovahlkampfia spelaea is a newly identified human parasite causing resistant keratitis. • Silver nanoparticles were biologically synthesized using Aspergillus niger; to investigate their antiparasitic effect against Allovahlkampfia spelaea. • They exhibited a significant inhibition of A. spelaea growth and viability of both trophozoites and cysts. • AgNPs could be a promising future in the treatment of human keratitis caused by this organism. [ABSTRACT FROM AUTHOR]

The illegal disposal of waste from textile industries having recalcitrant pollutants is a worldwide problem with more severity in developing nations. We used an ecofriendly method to synthesize silver nanoparticles (AgNPs) from a locally-isolated bacterial strain Bacillus marisflavi TEZ7 and employed them as photocatalysts to degrade not only synthetic azo dyes but also actual textile effluents followed by phytotoxicity evaluation and identification of degradation molecules. The strain TEZ7 was taxonomically identified through the 16S rRNA gene sequence analysis. Biogenic AgNPs were characterized for stabilizing molecules, crystal structure, size, shape and elemental composition by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The photocatalytic degradation efficiency of biogenic AgNPs for three azo dyes such as Direct Blue-1, Methyl Red, and Reactive Black-5 ranged between 54.14 and 96.92% after 5 h of sunlight exposure at a concentration of 100 mg/L. Moreover, the actual wastewater treatment analysis revealed that the 100 mg/L dose of AgNPs significantly decreased the concentration of various physico-chemical parameters of textile effluents such as pH, EC, chlorides, sulphates, hardness, BOD, COD, TSS and TDS. Furthermore, six intermediate molecules of methyl red degradation were identified by LC-MS and it was established by a pot study that these degradation molecules have no phytotoxic effects on rice plants. It was concluded that the AgNPs can be used as an efficient and low-cost strategy for the degradation of azo dyes containing textile wastewaters. Image 1 • Bioinspired green synthesis of silver nanoparticles (AgNPs) from a bacterium. • Characterization of AgNPs through standard material characterization techniques. • Photocatalytic degradation of synthetic dyes and actual wastewaters by AgNPs. • No phytotoxicity shown by the degraded azo dye products to rice plants. • Identification of the new intermediate products of degradation by the LCMS analysis. [ABSTRACT FROM AUTHOR]