Characterisation and antifungal activity of silver nanoparticles biologically synthesised by Amaranthus retroflexus leaf extract

ABSTRACT

Following the emergence of resistant fungal pathogens, silver nanoparticles (AgNPs) biosynthesized by plants have been recognized as promising tools to combat parasitic fungi. This study evaluated the potency of Amaranthus retroflexus in producing AgNPs, followed by testing their antifungal effects. The AgNPs exhibited a maximum absorption at 430 nm through ultraviolet-visible spectroscopy, while the X-ray diffraction indicated that they were crystal in nature. Fourier transform infrared spectroscopy confirmed the conversion of Ag⁺ ions to AgNPs due to the reduction by capping material of plant extract. The transmission electron microscope analysis further revealed that the AgNPs were spherical ranging from 10 nm to 32 nm in size. The AgNPs at the concentrations of 50, 100, 200, and 400 μg/mL were applied to the growth of plant, mushroom, and human pathogenic fungi. The 50% minimum inhibitory concentrations (MIC₅₀) against Macrophomina phaseolina, Alternaria alternata and Fusarium oxysporum were observed to be 159.80 ± 14.49, 337.09 ± 19.72, and 328.05 ± 13.29 μg/mL, respectively. However, no considerable inhibition was observed regarding Trichoderma harzianum or Geotrichum candidum. These findings may suggest A. retroflexus as a green solution for biosynthesizing AgNPs with potent antifungal activities against plant pathogenic fungi.     

Microwave-assisted rapid synthesis of alumina nanoparticles using tea,coffee and triphala extracts

Alumina nanoparticles (AlNP) were synthesized from aluminium nitrate using extracts of tea, coffee and triphala—a well known herbal plant as well as a nontoxic and eco—friendly green material. The synthesis was carried out taking 1:4 ratio of metal salt and these extracts under microwave irradiations at 540 W, which gave better yield of nanoparticles. Water was taken as solvent medium. The formations of AlNP were initially monitored by the colour changes occurring in the reaction mixture during the incubation period. As synthesized nanoparticles were characterized by scanning electron microscope (SEM),
UV–Visible (UV–Vis) spectroscopy and Fourier transform infrared spectroscopy (FTIR). The AlNP were found to be spherical in shape in case of tea and coffee extracts with a size of 50–200 nm and to be oval shaped in case of triphala extract with an average size of 200–400 nm. The formation of AlNP with the microwave-assistance using these plant extracts has proved to be very faster than any other methods. In addition, excellent reproducibility of these nanoparticles, without the use of any additional capping agent or stabilizer will have great advantages in comparison with microbial synthesis, avoiding all the tedious and hygienic complications.     

Silver nanoparticles fabricated using medicinal plant extracts show enhanced antimicrobial and selective cytotoxic propensities

Nanoparticles fabricated using medicinal plant extract have great potential in the area of nanomedicine. High surface‐to‐volume ratio of nanoparticle enhances the local active biomolecules concentration, leading to many fold increase in the medicinal potentials. The silver nanoparticles (AgNPs) fabricated using indigenous medicinal plants of India, Azadirachta indica and Syzygium cumini, have shown a significant effect on the viability of prokaryotic and eukaryotic cells. Biofabrication of AgNP was confirmed using different spectroscopic and microscopic techniques. Extraction and purification of AgNP from non‐conjugated plant moieties are done using centrifugation and size exclusion chromatography. The cytotoxic propensity of AgNP formulations was screened against Gram‐positive (Bacillus subtilis), Gram‐negative (Escherichia coli) bacteria, cancerous (HT1080) and non‐cancerous (HEK293) cell lines. The nanoparticle formulations showed a relatively higher cytotoxic propensity against Gram‐positive bacteria and cancerous cell lines. In addition, the surface roughness and reactive oxygen species (ROS) measurements indicated that AgNP formulations mediate the cell activity predominantly by ROS‐mediated disruptive change in membrane morphology upon direct interaction with the membrane. Hence, the nanoparticle formulations show an enhanced selective cytotoxic propensity towards Gram‐positive bacteria and cancerous cell lines.Inspec keywords: nanofabrication, chromatography, nanoparticles, purification, toxicology, drugs, drug delivery systems, antibacterial activity, microorganisms, cancer, silver, surface roughness, nanomedicine, cellular biophysicsOther keywords: medicinal plant extracts, medicinal potentials, prokaryotic cells, eukaryotic cells, microscopic techniques, nonconjugated plant moieties, centrifugation, AgNP formulations, noncancerous cell lines, nanoparticle formulations, Gram‐positive bacteria, cancerous cell lines, surface roughness, cell activity, local active biomolecule concentration     

Rapid biologically one-step synthesis of stable bioactive silver nanoparticles using Osage orange (Maclura pomifera) leaf extract and their antimicrobial activities

Synthesis of nanoparticles by using natural products as reducing and stabilizing agents have been widely used in various fields especially medicine, primarily because of its lower cost, simplicity, and less toxic byproducts. In the present work, silver nanoparticles (Ag NPs) were rapidly synthesized from silver nitrate in a green one-step synthesis by the aqueous extracts of Osage orange (Maclura pomifera) leaf as a reducing and stabilizing agent simultaneously. The effects of pH, extract quantity, and silver salt concentration were investigated to determine the optimum conditions of green synthesis of Ag NPs. The synthesized Ag NPs were characterized by different techniques including UV–Visible (UV–Vis) absorption spectroscopy, X-ray diffraction (XRD), Fourier transform Infrared (FT-IR) Spectroscopy, and Transmission Electron Microscopy (TEM). The Ag NPs showed surface plasmon resonance centered at 415?nm. The XRD pattern and TEM analysis revealed spherical, stable, and uniform Ag NPs with the average particle size of about 12?nm. The FT-IR spectroscopy showed that mainly hydroxyl functional groups, as both the reducing and stabilizing agent are responsible for silver nanoparticles synthesis. The antimicrobial activity of the synthesized Ag NPs showed a significant microbicidal effect on all clinical isolates especially, Gram-negative bacteria and fungi. These results suggest that such stable and uniform Ag NPs can be synthesized rapidly and simply for clinical as well as pharmaceutical applications.     

Effect of biologically synthesised silver nanoparticles on Staphylococcus aureus biofilm quenching and prevention of biofilm formation

The development of green experimental processes for the synthesis of nanoparticles is a need in the field of nanotechnology. In the present study, the authors reported rapid synthesis of silver nanoparticles using fresh leaves extract of Cymbopogan citratus (lemongrass) with increased stability. The synthesised silver nanoparticles were found to be stable for several months. UV-visible spectrophotometric analysis was carried out to assess the synthesis of silver nanoparticles. The synthesised silver nanoparticles were further characterised by using nanoparticle tracking analyser (NTA), transmission electron microscope (TEM) and energy-dispersive x-ray spectra (EDX). The NTA results showed that the mean size was found to be 32?nm. Silver nanoparticles with controlled size and shape were observed under TEM micrograph. The EDX of the nanoparticles confirmed the presence of elemental silver. These silver nanoparticles showed enhanced quorum quenching activity against Staphylococcus aureus biofilm and prevention of biofilm formation which can be seen under inverted microscope (40X). In the near future, silver nanoparticles synthesised using green methods may be used in the treatment of infections caused by a highly antibiotic resistant biofilm.     

Synthesis of gold nanoparticles of variable morphologies using aqueous leaf extracts of Cocculus hirsutus

Spherical, triangular (prismatic) and square plate shaped gold nanoparticles have been synthesised from HAuCl₄?·?3H₂O solution using the aqueous leaf extract of Cocculus hirsutus. Nanoparticles are characterised using higher resolution transmission electron microscope, X-ray diffraction and UV–Vis absorption spectroscopic study. FT-IR analysis reveals that the gold nanostructures are mostly stabilised by the carbonyl and amide groups present in the active component of C. hirsutus leaf extract. Formation of gold nanostructures of variable morphologies has been explained due to slow reduction of gold ions by the mild reducing ascorbic acid present within the extract and this controlled reduction assists the preferential deposition of Au atom on different lesser-protected faces of initially grown gold nanostructure.     

Antimicrobial power of biosynthesized Ag nanoparticles using refined Ginkgo biloba leaf extracts

Silver nanoparticles (Ag NPs), relative to existing antibacterial agents, are more effective, less toxic and more economical, and have shown enormous potential for the nanomedicine application. In this work, we report a ‘green’ method for the rapid and efficient synthesis of Ag NPs using Ginkgo biloba extracts as reducing agent and capping agent. The properties of Ag NPs against fungi and bacteria were investigated. The results showed that the Ginkgo biloba extracts are crucial for the preparation of uniform and monodispersed Ag NPs. The prepared Ag NPs exhibited remarkable antibacterial activities. The minimum inhibitory concentrations of Ag NPs for Escherichia coli and Pseudomonas aeruginosa were 0.044 and 0.088 μg·mL⁻¹, respectively. Moreover, Ag NPs exhibited excellent bactericidal performance against MDR-Pseudomonas aeruginosa. It was found that the effect of the antibacterial activity of Ag NPs on Escherichia coli and Staphylococcus aureus was tightly related to the reactive oxygen species accumulation. This research provides guidelines for the efficient green synthesis of Ag NPs and its antibacterial applications.     

Characterisation of gold nanoparticles synthesised by leaf and seed extract of Syzygium cumini L.

Here, Syzygium cumini leaf extract (LE) and seed extract (SE) were explored for the synthesis of gold nanoparticles (GNP). LE and SE as well as their polar (water) fractions showed potential for GNP synthesis. Comparative synthesis kinetics and morphological characterisation studies revealed the synthesis of smaller sized GNP by LE than SE. Only polar (water) fractions showed potential for GNP synthesis, which are smaller in size compared to their respective extracts. SE contained more polyphenols and biochemical constituents than LE and therefore, showed higher synthesis rate and bigger sized GNP. Atomic force microscope and scanning electron microscope analysis indicated that both extracts and their fractions catalysed the synthesis of spherical GNP. The average size of GNP synthesised by LE, leaf water fraction (LWF), SE and seed water fraction (SWF) were 24, 23, 35 and 32?nm, respectively. Fourier transform infrared analysis identified the biomolecules involved in the synthesis and stability of GNP. This study documented the potential of S. cumini for the synthesis of GNP in addition to silver nanoparticles (SNP). However, nature and types of polyphenols involved in GNP synthesis seem to be different from that involved in SNP synthesis. This might be the possible reason for smaller sized GNP that SNP.     

A review of the biological synthesis of gold nanoparticles using fruit extracts: scientific potential and application

Gold nanoparticles (GNPs) are well-known nanomaterials that can be used for multiple biomedical applications. There are various methods for synthesis of GNPs using microorganisms and plants, particularly through the use of fruit extracts. Their use is due to the fact that fruit extracts are the natural concentrate of substances that possesses therapeutic properties. In this review, we aim to compare the recent studies concerning the methods for synthesis of GNPs from fruit extracts, the methods used to characterize the properties of GNPs and capping biomaterial and the potential applications of GNPs. The most frequently used methods to characterize GNPs and capping biomaterial are UV–visible spectroscopy, transmission or scanning electron microscopy, dynamic light scattering and Fourier transformation infrared spectroscopy techniques. Because of GNPs’ optoelectronic properties, biocompatibility, stability and oxidation resistance, they can be used in areas such as electronics, chemical and biological sensing, tumour imaging, drug delivery and phototherapy.     

Antibacterial and dye degradation potential of zero‐valent silver nanoparticles synthesised using the leaf extract of Spondias dulcis

The present study reports a simple and low cost synthesis of zero‐valent silver nanoparticles (ZVSNPs) from silver nitrate using the leaf extract of Spondias dulcis. The ZVSNPs showed a unique peak at 420 nm in UV–vis spectrum. The SEM image portrayed cuboidal shaped particles. The EDX spectrum designated the elemental silver peak at 3 keV. In XRD, a sharp peak at 32.47° denoted the existence of (1 0 1) lattice plane and the average crystallite size was calculated as 48.61 nm. The lattice parameter was determined as 0.39 nm. The FTIR spectra of the leaf extract and ZVSNPs showed shifts in the specific functional group bands which ascertained the involvement of phytoconstituents in the formation and capping of nanoparticles. The average hydrodynamic size was measured as 59.66 nm by DLS method. A low PDI, 0.187 witnessed the monodispersity. A negative zeta potential value of −15.7 mV indicated the negative surface charges of the nanoparticles. The bactericidal action of ZVSNPs was demonstrated against two pathogens S.typhimurium and E.coli during which a dosage dependent zone of inhibition results was observed. Additionally, the catalytic potential of ZVSNPs was examined for the degradation of methylene blue dye in which an accelerated degradation of the dye was observed.Inspec keywords: antibacterial activity, crystallites, electrokinetic effects, scanning electron microscopy, nanoparticles, particle size, ultraviolet spectra, X‐ray chemical analysis, microorganisms, light scattering, nanofabrication, materials preparation, X‐ray diffraction, visible spectra, silver, dyes, Fourier transform infrared spectraOther keywords: wavelength 420.0 nm, Ag, voltage ‐15.7 mV, size 59.66 nm, size 0.39 nm, size 48.61 nm, electron volt energy 3.0 keV, Fourier transform infrared spectra, methylene blue dye, bactericidal action, dynamic light scattering, lattice parameter, Escherichia coli, Salmonella typhimurium, Spondias dulcis, negative zeta potential, polydispersity index, crystallite size, leaf extract, X‐ray diffraction, energy dispersive X‐ray spectrum, cuboidal‐shaped particles, scanning electron microscopy image, ultraviolet–visible spectrum, silver nitrate, zero‐valent silver nanoparticles     

Preparation and bactericidal properties of silver nanoparticles in aqueous tea leaf extract

Ag nanoparticles 10 to 60 nm in size have been prepared by reducing silver ions in aqueous tea leaf extract. The properties of the nanoparticles have been studied by ultraviolet spectroscopy, atomic absorption, surface-enhanced Raman spectroscopy, and atomic force microscopy. According to the Raman spectroscopy results, the equilibrium of the redox reaction is displaced to an antioxidant form of flavonoids. The presence of silver nanoparticles enhances the antioxidant and bactericidal properties of tea.     

Bio-directed synthesis of gold nanoparticles using Ananas comosus aqueous leaf extract and their photocatalytic activity for LDPE degradation

A bio-directed synthesis of gold nanoparticles (Au NPs) was developed via the reduction of hydrogen tetrachloroaurate (III) (HAuCl₄·3H₂O) solution by the aqueous leaf extract of Ananas comosus. The polyphenol stabilized Au NPs were characterized by UV–visible, Fourier transform infrared (FTIR), powder X-ray diffraction (PXRD)/selected area electron diffraction (SAED), high resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectroscopy (EDX) analyses. The HRTEM images revealed that Au NPs were well dispersed with spherical structures. The size ranges from 7.39 to 32.09 nm with average particle size of 18.85 ± 6.74 nm. The peaks of XRD analysis at (2θ) 37.96°, 44.06°, 64.54°, 77.50° and 81.73° were respectively assigned to (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) planes of the face-centered cubic (fcc) lattice of gold. The photocatalytic potential of Au NPs was studied through the solid-phase degradation of low-density polyethylene (LDPE) film. The photoinduced degradation of LDPE@Au nanocomposite film was higher than that of the pure LDPE film. The weight loss of LDPE@Au (1.0 wt%) nanocomposite film steadily increased and reached 51.4 ± 4.8% in 240 h under solar light irradiation, compared to the photo-induced LDPE with only 8.6 ± 0.7%. However, LDPE film with 1.0% Au NPs gave a weight loss value of 4.72 ± 0.71 under the dark condition at the end of 240 h. Thus, LDPE film with 1.0% Au NPs showed a degradation efficiency of 90.8% under solar irradiation after 240 h. The sustainability of the nanoparticles was confirmed through reusability in the photocatalytic degradation reaction up to five consecutive cycles without substantial loss in its catalytic performance.     

Myxobacteria ‐mediated synthesis of silver nanoparticles and their impregnation in wrapping paper used for enhancing shelf life of apples

The authors report Myxobacteria virescens (M. virescens) mediated synthesis of silver nanoparticles (AgNPs) and its efficacy against Staphylococcus aureus (ATCC‐33591), Salmonella typhi (ATCC‐51812), Escherichia coli (E. coli) (ATCC‐14948), Klebsiella pneumoniae (MTCC‐4030) and Pseudomonas aeruginosa (MTCC‐4673). The organism exhibiting resistance to various antibiotics showed remarkable sensitivity, when used in combination of antibiotics and AgNPs. Antimicrobial property of AgNPs is playing a significant role in medicine and food storage. In this study, they have used M. virescens for the synthesis of AgNPs, which were characterised by using UV‐Vis spectrophotometer, nano‐particles tracking and analysis, zeta potential, Fourier transform infrared spectroscopy, X‐ray diffraction and transmission electron microscopy. Synthesised AgNPs were impregnated into paper by three different methods, i.e. glass rod method (without binder), glass rod method (with binder) and direct synthesis of AgNPs on paper. Nanoparticles synthesis on paper showed the significant antimicrobial activity against Staphylococcus aureus (ATCC‐33591), Salmonella typhi (ATCC‐51812), E. coli (ATCC‐14948), Klebsiella pneumoniae (MTCC‐4030) and Pseudomonas aeruginosa (MTCC‐4673). Paper impregnated with AgNPs was used for wrapping of fruits (apples) which increases their shelf life up to 15 days. This study demonstrates a new method for wrapping of fruits, which increases the shelf life of apples.Inspec keywords: microorganisms, biotechnology, nanoparticles, wrapping, food packaging, antibacterial activity, ultraviolet spectra, electrokinetic effects, Fourier transform infrared spectra, X‐ray diffraction, transmission electron microscopy, food productsOther keywords: silver nanoparticles, wrapping paper impregnation, apple shelf life enhancement, Myxobacteria virescens mediated synthesis, glass rod method, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared, zeta potential, nanoparticle analysis, nanoparticle tracking, UV‐Vis spectrophotometer, antimicrobial property, antibiotic resistance, MTCC‐4673, Pseudomonas aeruginosa, MTCC‐4030, Klebsiella pneumoniae, ATCC‐14948, E. coli, Escherichia coli, ATCC‐51812, Salmonella typhi, ATCC‐33591, Staphylococcus aureus, M. virescens mediated synthesis     

Optimised microwave-assisted biosynthesis of silver nanoparticles from Nothapodytes foetida leaf extracts and its anti-microbial activities

The present investigation reports the biogenesis of silver nanoparticles (Ag NPs) using extracts of a medicinal plant Nothapodytes foetida. Total phenolic content (TPC) and ferric reducing antioxidant power (FRAP) assay were carried out for the microwave-assisted extract (MAE) of N. foetida using methanol as solvent and the conditions for extraction were optimised by response surface methodology (RSM). The effects of operating variables such as extraction time, temperature and ratio of sample to solvent were studied using central composite design (CCD). A mathematical model with a high determination coefficient (R²) for TPC (0.991) and FRAP (0.995) was obtained. The optimal conditions of extraction for TPC were 48.6 ºC, 23.15 min and 2.04:30 (g/mL) and for FRAP 52.31ºC, 12.32 min and 1.67: 30 (g/mL). Under these conditions, the experimental yields of TPC and FRAP were 2.426 mg gallic acid equivalents (GAE)/g dry powder and 14.985mg of FeSO₄·7H₂O/g of dry powder, respectively. Ag NPs were characterised using UV–Vis spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The synthesised Ag NPs have also shown potent activity against the human pathogenic Staphylococcus aureus.     

Synthesis and characterisation of silver nanoparticles using leaf extract of Artemisia afra and their in vitro antimicrobial and antioxidant activities

In this study, the conversion of silver ions into ∼30.74 nm sized silver nanoparticles (AgNPs) was achieved in 30 min at a reaction temperature of 80–90°C in aqueous leaf extract of Artemisia afra. The synthesised AgNPs showed surface plasmon resonance in the range of 423–438 nm. Spherical and face‐centred cubic nanoparticles were confirmed by transmission electron microscope (TEM) and X‐ray diffraction (XRD) analysis, respectively. Fourier transform infra‐red (FTIR) results indicated that the obtained nanoparticles were stabilised and capped through the carbonyl and carboxylate ion groups possibly from flavonoids, terpenoids, phenolics and esters content of the extracts. In addition, the AgNPs were assessed for their biological potentials against some microbes and, also, their free radical scavenging ability was established. The AgNPs exhibited interesting antimicrobial and antioxidant properties better than the aqueous extract of A. afra. Inspec keywords: silver, transmission electron microscopy, ultraviolet spectra, visible spectra, surface plasmon resonance, antibacterial activity, X‐ray diffraction, microorganisms, nanoparticles, nanofabrication, Fourier transform infrared spectraOther keywords: silver nanoparticles, reaction temperature, surface plasmon resonance, face‐centred cubic nanoparticles, antioxidant properties, silver ion conversion, aqueous leaf extract, carboxylate ion group, antimicrobial properties, Artemisia afra, spherical nanoparticles, TEM, XRD, FTIR spectra, Ag, temperature 80 degC to 90 degC, time 30.0 min, free radical scavenging, esters, phenolics, terpenoids, flavonoids, carbonyl ion group     

Photocatalytic degradation of dye pollutants under solar,visible and UV lights using green synthesised CuS nanoparticles

A green method for the solvothermal synthesis of copper sulphide nanoparticles (CuS NPs) using xanthan gum as a capping agent was developed. The CuS NPs were characterised by scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction, Brunauer–Emment–Teller, zeta analysis, thermal gravimetric– differential thermal analysis, Fourier transform infrared and UV–visible absorption spectra. These characterisations together determine the composition, structural, thermal and optical properties. The UV–visible spectrum had a broad absorption in the visible range. The particle size of the products was observed by TEM in the range of 8–20 nm. The photocatalytic performance of the CuS NPs was evaluated for the degradation of organic dyes (methylene blue, rhodamine B, eosin Y and congo red) under irradiation of solar, visible and UV lights. The CuS NPs showed good photocatalytic activity. Kinetic analyses indicate that the photodegradation rates of dyes usually follow pseudo-first-order kinetics for degradation mechanisms.     

In-service creep of materials for steam lines of thermal power plants and extension of their life

An analysis of 200,000 h of laboratory creep data for chromium-nickel-molybdenum-niobium steel tested at service loads and temperatures demonstrated a multistage creep nature, a transient stage of long duration (up to 20,000–25,000 h), an extended accelerated creep stage as compared to the duration of the steady-state one, and the existence of an avalanche creep stage. The relationships and their alternating sequences common to laboratory tests and service of mateirals in the structural elements of thermal power plants show that the creep data can be used to predict the service life of these materials. Institute for Problems of Strength, National Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Problemy Prochnosti, No. 3, pp. 56–61, May–June, 1998.     

Biosynthesis of gold and silver nanoparticles using Emblica Officinalis fruit extract, their phase transfer and transmetallation in an organic solution

The design, synthesis and characterization of biologically synthesized nanomaterials have become an area of significant interest. In this paper, we report the extracellular synthesis of gold and silver nanoparticles using Emblica Officinalis (amla, Indian Gooseberry) fruit extract as the reducing agent to synthesize Ag and Au nanoparticles, their subsequent phase transfer to an organic solution and the transmetallation reaction of hydrophobized silver nanoparticles with hydrophobized chloroaurate ions. On treating aqueous silver sulfate and chloroauric acid solutions with Emblica Officinalis fruit extract, rapid reduction of the silver and chloroaurate ions is observed leading to the formation of highly stable silver and gold nanoparticles in solution. Transmission Electron Microscopy analysis of the silver and gold nanoparticles indicated that they ranged in size from 10 to 20 nm and 15 to 25 nm respectively. Ag and Au nanoparticles thus synthesized were then phase transferred into an organic solution using a cationic surfactant octadecylamine. Transmetallation reaction between hydrophobized silver nanoparticles and hydrophobized chloroaurate ions in chloroform resulted in the formation of gold nanoparticles.     

Synthesis of ZnO nanoparticles using Melia dubia leaf extract and its characterisation

The present work deals with the synthesis of zinc oxide (ZnO) nanoparticles (Nps) using the biocompounds extracted from Melia dubia leaves (MD L.) and zinc acetate as precursors. The choice of the precursors was based on the intention to use the synthesised ZnO Nps for the healthcare applications. In this line, the antimicrobial property of ethanolic extract of MD L., uncalcined ZnO Nps and calcined ZnO Nps has been assessed and compared. The prepared particles have been characterised by comparing their Fourier transform infrared spectrum, X‐ray diffraction (XRD) diffractogram and TEM images. The presence of ZnO has been confirmed using IR spectrum. The crystal structure and crystallite size have been found out using XRD diffractogram, and the obtained crystallite size was confirmed using TEM images. Finally, an attempt has been made to correlate the structure with the antimicrobial property of the material.Inspec keywords: zinc compounds, nanoparticles, nanofabrication, Fourier transform infrared spectra, X‐ray diffraction, transmission electron microscopy, crystal structure, antibacterial activity, nanobiotechnologyOther keywords: ZnO, antimicrobial property, crystallite size, crystal structure, TEM images, X‐ray diffraction, Fourier transform infrared spectrum, zinc acetate, biocompounds, Melia dubia leaf, zinc oxide nanoparticle synthesis     

Green synthesis of silver nanoparticles using Nervalia zeylanica leaf extract and evaluation of their antioxidant,catalytic, and antimicrobial potentials

ABSTRACT

Here we report a simple, one-pot, inexpensive, and eco-friendly method for the synthesis of silver nanoparticles. The leaf extract of a medicinal plant Nervalia zeylanica was used as reducing and stabilizing agent for the synthesis of nanoparticles by microwave-assisted strategy. The nanoparticles show characteristic surface plasmon peak at 468?nm in UV–vis absorption spectrum. The involvement of phytochemicals in the reduction and stabilization of nanoparticles was confirmed by FTIR analysis. Using X-ray diffraction analysis, the crystalline nature of the nanoparticles was demonstrated. Transmission electron microscopic analysis shows that the nanoparticles were in spherical shape with average particle size of 34.2?nm. The antioxidant studies were performed by the 1,1-diphenyl-2-picryl hydrazyl method. The nanoparticles show excellent scavenging activities than the leaf extract. The IC₅₀ values of silver nanoparticles and the leaf extract, respectively, were 15.20 and 92.83?µg?mL^?1. The catalytic activities of synthesized nanoparticles were examined by using them in the reduction of organic dyes. The nanoparticles show excellent catalytic activities and follow pseudo-first-order kinetics. The antimicrobial activities of nanoparticles were analyzed by an agar well diffusion method against six microbial strains and found that the nanoparticles were highly toxic against all the tested microbial strains.