Spherical Shaped Silver Nanoparticles Research Articles

Development of ecofriendly and sustainable bioplastics from cassava starch: Tailoring the properties using nanoparticles

In an era marked by growing environmental concerns and the need for sustainable living, the development of environmentally friendly and biodegradable products has become paramount. This work proposes the preparation of eco-friendly and sustainable value-added products like carry bags and garbage bags from cassava starch. A cassava starch: plasticizer ratio of 1:0.05 has been optimized to prepare bioplastics with good mechanical properties. We have used nearly spherical shaped silver nanoparticles ranging between a particle size of 9–15 nm and spherical zinc oxide nanoparticles ranging between 12 and 38 nm prepared by green methods which were characterized using XRD, SEM and TEM. Using the optimum cassava starch:plasticizer ratio, two sets of bioplastics were prepared-one containing varying amounts of silver nanoparticles and the other with varying amounts of zinc oxide nanoparticles. For both types of bioplastics, 1% nanoparticle addition gave maximum tensile strength of 4.8037 N/mm2 for zinc oxide incorporated bioplastics and 4.3320 N/mm2 for silver incorporated bioplastics. The addition of nanoparticles did not much change the thermal stability of bioplastics. Soil, air and water degradation studies were done for 31 days. The rate of soil degradation increased on nanoparticle addition. The durability of the bioplastics was confirmed during air degradation studies. The nanoparticle incorporated samples showed lesser degradation in air and water. Thus, addition of nanoparticles customizes the properties of bioplastics, making them suitable substitutes for traditional plastics in a wide range of uses.

Biocontrol of chocolate spot disease of broad bean (Vicia faba L.) caused by Botrytis fabae using biosynthesized reduced graphene oxide/silver nanocomposite

This study was demonstrated to investigate the effects of reduced graphene oxide/silver nanocomposite (rGO/AgNC) on controlling the chocolate spot disease of broad bean (Vicia faba L.) caused by Botrytis fabae. rGO/AgNC was green synthesized using the cell-free supernatant of Escherichia coli D8 in the presence of sunlight and room temperature. rGO/AgNC revealed a broad UV–vis absorption peak at 433 nm. Transmission electron microscopy (TEM) images of rGO/AgNC confirmed the presence of spherical-shaped silver nanoparticles (AgNPs) with an average size of 7–26 nm. Zeta analysis of rGO/AgNC displayed their positive charge (+18.9 mV) and the good dispersion of AgNPs on the surface of rGO. rGO/AgNC had good antifungal activity against B. fabae in a dose-dependent pattern. In vivo, rGO/AgNC-treatment study on faba bean plants showed the biocidal action of rGO/AgNC (150 μg/ml) against B. fabae and completely prevented the pathogen infection. In addition, there was an increase in total phenolic content, peroxidase, and polyphenol oxidase activity, and protein content of rGO/AgNC-treated plants. Plants treated with rGO/AgNC displayed a typical cell morphology in their ultrastructure, including cell membranes and chloroplasts with ellipsoidal shapes and large starch grains. These are all encouraging findings for the use of the biosynthesized rGO/AgNC as a safe and efficient antifungal agent against B. fabae.

Hibiscus cannabinus seeds assisted spherical silver nanoparticles and its antibacterial and photocatalytic applications

Green nanomaterial manufacture limits hazardous substances and encourages noxious-free environments. The fields of photocatalysis and antibacterial resistance are more promising because of their chemical reductants and sterile environments. Here, we used Hibiscus Cannabinus seed as a bio source and developed a simple, environmentally friendly approach for the biosynthesis of AgNPs. Researchers and scientists have recently shown a strong interest in the green synthesis of silver nanoparticles due to their ease, eco-friendliness, non-toxicity, low cost, and ability to function as an antibacterial agent. Research goals include producing environmentally friendly, bacteriocidal, and photocatalytic dye removal products that can be applied to biomedical and water reuse applications. In this paper, we have reported spherical-shaped silver nanoparticles synthesized from Hibiscus cannabinus seeds and their characterization by X-ray Diffraction method, UV-Visible Spectroscopy, and Transmission Electron Micrograph. The surface functionalization of prepared silver particles by phenolic compounds in Hibiscus cannabinus seeds enhances antibacterial activity. Both Staphylococcus aureus and Escherichia coli are inhibited by the prepared silver nanoparticles. By preparing silver nanoparticles at a significantly higher extract concentration, we were able to obtain effective and increased bactericidal activity. The photocatalytic degradation of congo red by prepared silver particles was studied under 150 min of UV light irradiation. The produced silver nanoparticles' structural, optical, morphological, compositional, and bactericidal activity are all shown to be dependent on the concentration of Hibiscus cannabinus seeds extract that is attached to the silver surface.

In Vitro Antibacterial Activity of Green Synthesized Silver Nanoparticles Using Azadirachta indica Aqueous Leaf Extract against MDR Pathogens.

Rice is the most important staple food crop feeding more than 50% of the world's population. Rice blast is the most devastating fungal disease, caused by Magnaporthe oryzae (M. oryzae) which is widespread in rice growing fields causing a significant reduction in the yield. The present study was initiated to evaluate the effect of green synthesized silver nanoparticles (AgNPs) on the biochemical constituents of rice plants infected with blast. AgNPs were synthesized by using Azadirachta indica leaf extract and their characterization was performed using UV-visible spectroscopy, particle size analyser (PSA), scanning electron microscope (SEM), and X-ray diffraction (XRD) which confirmed the presence of crystalline, spherical shaped silver nanoparticles with an average size of 58.9 nm. After 45 days of sowing, artificial inoculation of rice blast disease was performed. After the onset of disease symptoms, the plants were treated with AgNPs with different concentrations. Application of nanoparticles elevated the activity of antioxidative enzymes such as superoxide dismutase, catalase, peroxidase, glutathione reductase, and phenylalanine ammonia-lyase compared to control plants, and total phenol and reducing sugars were also elevated. The outcome of this study showed that an increase in all biochemical constituents was recorded for A. indica silver nanoparticles-treated plants. The highest values were recorded in 30 ppm and 50 ppm AgNPs-treated plants, which showed the highest resistance towards the pathogen. Green synthesized AgNPs can be used in future for disease control in susceptible varieties of rice. The synthesized AgNPs using A. indica leaf extract have shown promising antibacterial activity when tested against 14 multidrug-resistant (MDR) bacteria comprising Gram-negative bacteria Escherichia coli (n = 6) and Klebsiella pneumoniae (n = 7) with a good zone of inhibition diameter, tested with the disc diffusion method. Based on these findings, it appears that A. indica AgNPs have promise as an antibacterial agent effective against MDR pathogens.

MICROWAVE-ASSISTED GREEN SYNTHESIS OF SILVER NANOPARTICLES USING EXTRACT OF SPONDIAS PINNATA BARK

Formation of silver nanoparticles with irradiation of microwaves using biological agents such as plant extracts is one of the eco-friendly green synthesis approaches which is economical in comparison with the physical and chemical methods. This study is focused at preparation of silver nanoparticles silver using Spondias pinnata bark extract by microwave irradiation and its comparison with aging method. Formation of silver nanoparticles was identified by observing the surface plasmon resonance absorption band peak at ~432 nm by UV-visible spectrophotometer. Optimization of the synthesis procedure was carried out using different amount of extract, concentration of substrate and microwave irradiation time and morphological features were characterised. A solution containing 8ml plant extract and 8 mM silver nitrate exposed to 90 sec microwave irradiation time was identified as optimised condition for the production of spherical shaped silver nanoparticles with a size of 34.52 nm which indicates that faster formation of silver nanoparticles compared to the aging method. Present research shows the importance of optimization of bio reduction conditions and the amount of reactants required for regulation of the morphology of silver nanoparticles as well as to obtain homogenous solution which is the main problem encountered in plant- mediated production of silver nanoparticles.

Antifungal activity of silver/silicon dioxide nanocomposite on the response of faba bean plants (Vicia faba L.) infected by Botrytis cinerea

Silicon (Si) and its nanomaterials could help plants cope with different negative effects of abiotic and/or biotic stresses. In this study, the antifungal role of silver/silicon dioxide nanocomposite (Ag/SiO2NC) biosynthesized using a free-cell supernatant of Escherichia coli D8 was investigated for controlling the growth parameters and yield of faba bean (Vicia faba L.) infected by Botrytis cinerea. This nanocomposite was characterized using UV–Vis spectroscopy, Fourier transform-infrared (FTIR), transmission electron microscopy (TEM), zeta analysis, and X-ray diffraction pattern (XRD). Positively charged Ag/SiO2NC (+ 31.0 mV) with spherical-shaped silver nanoparticles (AgNPs) showed strong in vitro antifungal activity with minimal inhibition concentration (MIC) value equal to 40 ppm. In vivo experiments revealed the good resistance of Ag/SiO2NC-treated plants against the B. cinerea infection due to the increase of total phenolic content, peroxidase, and polyphenol oxidase activity. The ultrastructure of Ag/SiO2NC-treated plants showed normal morphology of cells including cell membranes and ellipsoidal-shaped chloroplasts with big starch grains. The concentration of silver content in Ag/SiO2NC-treated plants was similar to the untreated control plant indicating the low realizability of AgNPs. All of these results are promising outcomes for the application of the biosynthesized Ag/SiO2NC as a safe and effective antifungal agent against B. cinerea.Graphical

Green synthesis and standardization of Biologically Synthesized Silver Nanoparticles

The biological silver nanoparticle was synthesized extracellularly by using Musa balbisiana. The leaf extract has been used as reducing agent in the process of nanoparticles synthesis. In 50 ml leaf extract volume of AgNO3 stock solution was added to make finally the concentration as 1 mM of AgNO3 and allowed to shake in an incubator for several hours in the dark. The changed color was considered as the primary indication of nanoparticles formation. It was indicated that stable and 20-40nm roughly spherical shaped silver nanoparticles was formed. To standardize the nanoparticles biosynthesis different physical parameters like substrate concentration (0-8 mM), pH of range 5 to 12, temperature range of 5 to 500°C, incubation time range of 0 to 120 hrs and salinity of 0.1-1.0% were investigated. It was reported that 4mM AgNO3 conc, pH of 9, temperature 300°C, incubation time 72h and 0.2% salinity were found to be optimum for the synthesis and stability of the silver nanoparticles.

Silver nanoparticles-essential oils combined treatments to enhance the antibacterial and antifungal properties against foodborne pathogens and spoilage microorganisms

Plant-derived essential oils (EOs) and commercial silver nanoparticles (AgNPs) were tested to evaluate their antibacterial and antifungal efficiency against two pathogenic bacteria (Escherichia coli O157:H7 and Salmonella Typhimurium) and three spoilage fungi (Aspergillus niger, Penicillium chrysogenum, and Mucor circinelloides). A broth microdilution assay was used to determine the minimal inhibitory concentration (MIC) of EOs and AgNPs. In the MIC assay, the cinnamon EO, Mediterranean formulation, citrus EO and spherical-shaped silver nanoparticles (AgNPs) (AGC 1, AGC 0.5, AGPP and AGPPH) showed moderate to high antibacterial and antifungal properties, with MIC ranging from 7.8 to 62.5 ppm for AgNPs and 312.5–1250 ppm for EOs against the tested bacteria and fungi. The possible interaction between the EOs and the AgNPs was determined using a checkerboard method by evaluating fractional inhibitory concentration (FIC) values. The combination of two or more EOs and AgNPs (Active combination 1: AGPPH+cinnamon EO, Active combination 2: AGC 0.5+Mediterranean formulation+citrus EO, Active combination 3: AGPP+cinnamon EO+Asian formulation+lavang EO) showed synergistic effects (FIC <1.0) against all tested bacteria and fungi. A modified Gompertz model was used to evaluate growth parameters including maximum colony diameter (A), maximum growth rate (Vm), and lag phase (λ), under the three active combinations suggested by the checkerboard method using a vapor assay. The three active combinations 1, 2 and 3 reduced the growth rate and maximum colony diameter of E. coli, S. Typhimurium, A. niger, P. chrysogenum, and M. circinelloides, and extended their lag phase from 1 to 5 days. In in situ tests with inoculated rice, the three active combinations showed a significant reduction of all tested bacteria and fungi at 27 °C for 28 days.

Growth inhibition of tropical fungi by silver nanoparticles incorporated polyurethane coating

Polyurethanes (PUs) have been widely used in the coating industry due to their high flexibility and good UV resistance. Extensive formulations of PU coatings have been reported previously in the literature. Scientists nowadays improvise products whereby nanomaterial additives such as silver nanoparticles are incorporated to obtain antibacterial and antifungal properties. In this study, spherical shaped silver nanoparticles with an average size of 46 nm were added into polyol (polypropylene glycol) which was cross-linked with toluene isocyanate to obtain PU nanocomposite coating films. Characterizations of the coating film were carried out using Fourier transform infrared (FTIR) spectroscopy to observe the urethane linkage that was formed during the cross-linking and Field Emission Scanning Electron Microscope with Energy Dispersive X-Ray (FESEM-EDX) Spectroscopy analysis to determine size, shape and distribution of the nanoparticles. The antifungal activity of the nanocomposite coating was studied against Cladosporium cladosporiodes, Penicillium oxalicum and Aspergillus aculaetus. The results showed that the AgNPs-incorporated PU coating film has the ability to inhibit the tropical fungi growth.

“MYCO SYNTHESIS OF SILVER NANOPARTICLES USING GLIOCLADIUM ROSEUM (CLONOSTACHYS ROSEA (LINK) SCHROERS, SAMUELS) AND ITS ANTIMICROBIAL EFFICACY AGAINST SELECTED PATHOGENS”

Objective: Antimicrobial efficacy of silver nanoparticles from Gliocladium roseum, culture filtrate (C. F.) and mycelial mat extract (M. E.) against selected pathogens.&#x0D; Methods: Culture filtrate (C. F.) and Mycelial mat extract (M. E.) of Gliocladium roseum were subjected to 10 Mm silver nitrate solution for the synthesis of silver nanoparticles. Formed silver nanoparticles were evaluated via UV-vis spectroscopy and the structural elucidation was done by FT-IR and TEM. Antimicrobial efficacy was tested against bacterial (Salmonella typhi and Klebsiella pneumonia) and fungal (Cladosporium cladosporioides and Alternaria alternata) pathogens. Different nanoparticle concentrations-50, 100, 150 and 200 µl were checked via disc diffusion method.&#x0D; Results: Gliocladium roseum (C. F. and M. E.) on interaction with silver nitrate solution effectively reduced metallic silver exhibiting a colour change from yellow to dark brown within 24 h due to the formation of silver nanoparticles. The UV-vis spectrum of C. F. and M. E. showed maximum absorption peaks at 350-400 nm and 400-450 nm respectively and FT-IR and TEM showed strong N-H bonding and spherical shaped silver nanoparticles with the size of 11-19 nm (C. F.) and 25-38 nm (M. E.). Antimicrobial analysis resulted in efficient inhibitory activity against Salmonella typhi, Klebsiella pneumonia and also showed moderate inhibitory activity against Alternaria alternata and Cladosporium cladopsorioides.&#x0D; Conclusion: The synthesis of silver nanoparticles from fungus Gliocladium roseum is simple, cheap, safe and eco-friendly thus emphasising on large scale scientific application.

Novel method for biosynthesis of silver nanoparticles using melanin and its application on wool to impart antimicrobial activity

A novel method for biosynthesis of silver nanoparticles using a polyphenolic pigment (melanin) has been proposed to impart antimicrobial properties to wool fabric. A diphenolic catechol has been combined with potato juice to produce melanin, which is used as a simultaneous reducing and dispersing agent for the synthesis of silver nanoparticles. The process variables used for the synthesis of melanin have been optimized to produce melanin with maximum reduction potential. The synthesized silver nanoparticles are then characterized and quantified. The optimum conditions used for the synthesis of melanin are found to be 0.1% catechol, 25% potato juice, 6.5 pH, 95˚C temperature and 45 min treatment time. Spherical shaped silver nanoparticles with average sizes of 35 nm and 50 nm are obtained and then applied on wool fabrics by exhaustion method to observe antimicrobial effect. It is observed that the treated wool has excellent antimicrobial activity against both the Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria.

Green Synthesis of Spherical Shaped Silver Nanoparticles Using &lt;i&gt;Allium cepa&lt;/i&gt; Leaves Extract and its Photocatalytic Activity

Spherical silver nanoparticles (AgNPs) (5–15 nm) were synthesized by a simple electrochemical method at room temperature using Allium Cepa (AC) leaves extract. AC leaves extract that acts as a reducing and stabilizing agent is capable of producing AgNPs without any agglomeration. The phytochemical properties of the leaves extract including total phenolic content, total flavonoid content, and its active species were studied. The crystallinity, morphology, and functional characteristics of the AgNPs were analyzed using an X–ray diffractometer, a transmission electron microscope, and a Fourier–transform infrared spectrometer, respectively. The characterization results verified the contribution of phenolic acids and flavonoids in reduction of Ag+ to metallic AgNPs and also in stabilization of the AgNPs. The catalytic activity of the AgNPs was tested towards the photodegradation of 2, 4–dichlorophenoxyacetic acid (2,4–D) herbicide, in which showing a remarkable degradation performance of 80%. The results provide strong evidence to support the potential use of AC leaves extract to act as green reducing and stabilizing agents as well as a green electrolyte to synthesize well–scattered spherical shaped AgNPs.

Mosquito Larvicidal and Catalytic Activity of Spherical-Shaped Silver Nanoparticles as Nano-Catalysts

Mosquito Larvicidal and Catalytic Activity of Spherical-Shaped Silver Nanoparticles as Nano-Catalysts

Biogenic fabrication and characterization of silver nanoparticles using aqueous-ethanolic extract of lichen (Usnea longissima) and their antimicrobial activity

BackgroundBiogenic fabrication of silver nanoparticles from naturally occurring biomaterials provides an alternative, eco-friendly and cost-effective means of obtaining nanoparticles. It is a favourite pursuit of all scientists and has gained popularity because it prevents the environment from pollution. Our main objective to take up this project is to fabricate silver nanoparticles from lichen, Usnea longissima and explore their properties. In the present study, we report a benign method of biosynthesis of silver nanoparticles from aqueous-ethanolic extract of Usnea longissima and their characterization by ultraviolet–visible (UV-vis), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses. Silver nanoparticles thus obtained were tested for antimicrobial activity against gram positive bacteria and gram negative bacteria.ResultsFormation of silver nanoparticles was confirmed by the appearance of an absorption band at 400 nm in the UV-vis spectrum of the colloidal solution containing both the nanoparticles and U. longissima extract. Poly(ethylene glycol) coated silver nanoparticles showed additional absorption peaks at 424 and 450 nm. FTIR spectrum showed the involvement of amines, usnic acids, phenols, aldehydes and ketones in the reduction of silver ions to silver nanoparticles. Morphological studies showed three types of nanoparticles with an abundance of spherical shaped silver nanoparticles of 9.40–11.23 nm. Their average hydrodynamic diameter is 437.1 nm. Results of in vitro antibacterial activity of silver nanoparticles against Staphylococcus aureus, Streptococcus mutans, Streptococcus pyrogenes, Streptococcus viridans, Corynebacterium xerosis, Corynebacterium diphtheriae (gram positive bacteria) and Escherichia coli, Klebsiella pneuomoniae and Pseudomonas aeruginosa (gram negative bacteria) showed that it was effective against tested bacterial strains. However, S. mutans, C. diphtheriae and P. aeruginosa were resistant to silver nanoparticles.ConclusionLichens are rarely exploited for the fabrication of silver nanoparticles. In the present work the lichen acts as reducing as well as capping agent. They can therefore, be used to synthesize metal nanoparticles and their size may be controlled by monitoring the concentration of extract and metal ions. Since they are antibacterial they may be used for the treatment of bacterial infections in man and animal. They can also be used in purification of water, in soaps and medicine. Their sustained release may be achieved by coating them with a suitable polymer. Silver nanoparticles fabricated from edible U. longissima are free from toxic chemicals and therefore they can be safely used in medicine and medical devices. These silver nanoparticles were stable for weeks therefore they can be stored for longer duration of time without decomposition.

Kinetics and growth mechanism of the photoinduced synthesis of silver nanoparticles stabilized with lysozyme.

A fast and single-step procedure is reported for the preparation of stable solutions of spherical-shaped silver nanoparticles (AgNPs) coated with lysozyme (LZ). The preparation of the AgNP@LZ nanocomposites was based on the reduction of Ag+ with ketyl radicals photo-generated by the UVA-photolysis of the benzoin I-2959. Both reaction precursors bind to LZ, modifying its superficial charge and conformational structure. The photo-induced kinetics of formation of the AgNPs as a function of the LZ concentration was monitored in-situ by UV-vis absorption spectroscopy. The multivariate curve resolution-alternating least square (MCR-ALS) method was used for the deconvolution of the kinetic curves for each transient species formed before the growth of the final AgNPs colloids. The Kolmogorov-Johnson-Mehl-Avrami (KJMA) model to describe the formation of the AgNPs was used, and the respective first-order rate constants for the growth of the AgNPs as a function of the lysozyme concentration were calculated and the role of the protein capping in the growth kinetics was evaluated. Despite the protein being partially oxidized by the photo-generated radicals, it was strongly adsorbed onto the silver surface forming a tight coating shell around the AgNPs of approximately 30-60 protein molecules. As a result of the partial denaturation and crowded packing, its intrinsic lytic activity was strongly reduced.

Biosynthesis of silver nanoparticles by Enterobacter sp. and their antifungal activity against the phytopathogenic fungus Fusarium oxysporum f. sp. lycopersici

This study was concerned with the isolation of bacterial strains from different water sources. Among these strains; Enterobacter sp. exhibited extracellularly biosynthesized silver nanoparticles with good monodispersity. Enterobacter sp. has produced extremely stable nanoparticles within 72 hrs at 35°C in dark conditions. These nanoparticles are characterized by UV–vis spectrophotometer, transmission electron microscopy, Zeta potential analyzer, and size distribution by volume. Enterobacter sp. synthesized 9.45-17.15 nm sized spherical shaped silver nanoparticles. The presence and binding of stabilized proteins with nanoparticles were confirmed by the zeta size distribution by volume. Our study demonstrates that silver nanoparticles are potent inhibitors of the plant pathogenic fungus, Fusarium oxysporum f. sp. lycopersici.

Green Synthesis and Characterization of Silver Nanoparticles Using Vitex negundo (Karu Nochchi) Leaf Extract and its Antibacterial Activity

The present paper focuses on the synthesis of silver nanoparticles using with different leaf extract concentrations of Vitex negundo. The biosynthesized nanoparticles were characterized by UV-vis absorption spectrophotometry, fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray, atomic force microscopy, transmission electron microscopy, photoluminescence and zeta potential techniques. The formation of silver nanoparticles was confirmed by the surface plasmon resonance absorption peak at 423 nm in UV-vis absorption spectra of the synthesized silver nanoparticles. The fourier transform infrared spectroscopy indicates flavonoids as a potential reduced agents. Field emission scanning electron microscopy shows the synthesized silver nanoparticles are in spherical shape. Energy dispersive X-ray spectroscopy shows the strong peak belongs to silver, and it confirms the formation of Ag NPs. X-ray diffraction spectra of synthesized silver nanoparticles exhibit they are in face centered cubic crystalline structure. The photoluminescence spectra of synthesized silver nanoparticles show their emission peak at 489-481 nm and the emission intensity is proportional to the different concentrations of leaf extract. The spherical shaped silver nanoparticles are observed by atomic force microscopy technique. The zeta potential value is observed at -13.5 mV, which shows the synthesized silver nanoparticles are incipient instability. The antimicrobial activity of the synthesized nanoparticles is studied using the disc diffusion method, which indicates that both Gram positive and Gram negative microorganisms have been affected by the silver nanoparticles. The observed antibacterial activity could be find important applications in medicine, biology and industry.

One-pot synthesis of poly vinyl alcohol (PVA) supported silver nanoparticles and its efficiency in catalytic reduction of methylene blue

Stable silver nanoparticles were synthesized using polyvinyl alcohol (PVA) as reducing and capping agent. The method of steric stabilization was adopted for the incorporation of silver nanoparticles in the polymer matrix. The successful incorporation of silver nanoparticles in a PVA matrix was confirmed by UV–Visible spectroscopy, transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectroscopy. The synthesized silver nanoparticles were characterized by a peak at 426 nm in the UV–Vis spectrum. TEM studies showed the formation of spherical shaped silver nanoparticles of 10–13 nm, following the reduction by UV irradiation. Catalytic properties were studied by means of UV-Visible spectroscopic analysis. The synthesized silver nanoparticles exhibited good catalytic properties in the reduction of methylene blue.

Biosynthesis of PVA encapsulated silver nanoparticles

Green synthesis of metal nanoparticles is an important technique in the methods of eco-friendly nanoparticle production. The synthesis of silver nanoparticles was accomplished using Ocimum sanctum leaf extract at room temperature. These particles were then encapsulated with polyvinyl alcohol (PVA) polymer matrix. The presence of silver was confirmed by different characterization techniques such as UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and X-Ray Diffraction (XRD). Scanning electron microscopic (SEM) images of the synthesized powder shows spherical shaped silver nanoparticles embedded in sponge-like polymer matrix. The energy dispersive X-ray analysis confirms the presence of elemental silver along with iron signal. Energy dispersive signal corresponding to elemental iron has been attributed to O. sanctum plant. The silver nanoparticles in PVA matrix thus obtained shows high antibacterial activity against gram positive Staphylococcus aureus (S. aureus) and gram negative Escherichia coli (E. coli) water borne bacteria. The inhibition zone against S. aureus and E. coli were also calculated.

Biosynthesis and characterization of silver nanoparticles (AgNPs) using marine bacteria against certain human pathogens

The present work investigates the synthesis of silver nanoparticles (AgNPs) by biological method using marine bacteria. The minimum inhibitory concentration (MIC) test was performed to find the inhibitory concentration of AgNO3 against marine bacterial isolate. After MIC study, the biogenic AgNPs was prepared through marine bacterial isolate and characterized by using UV-visible spectroscopy, Scanning Electron Microscopy (SEM), X Ray Diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). From the UV-visible spectroscopy, the absorption peak was found at 420 nm. In SEM image, it is confirmed that the sample contains spherical shaped silver nanoparticles and most of the particles were below 100 nm in size. In XRD analysis, it was confirmed that the silver nanoparticles are crystalline in nature, which was confirmed by the FTIR peak at 518 cm-1 corresponding to the Ag vibration present in crystalline structure. The antimicrobial activity of silver nanoparticles was determined by disk diffusion method, and found that silver nanoparticles have significant antibacterial activity against most of the pathogens.