Evaluation of antimicrobial activity of synthesised silver nanoparticles using Thymus kotschyanus aqueous extract

Development of a green chemistry process for the synthesis of silver nanoparticles (AgNPs) has become a focus of interest. Characteristics of AgNPs were determined using techniques, such as ultraviolet–visible spectroscopy (UV–vis), Fourier transform infrared (FTIR) analysis, scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy and X‐ray diffraction (XRD). The synthesised AgNPs using Thymus kotschyanus had the most growth inhibition against gram‐positive bacteria such as Staphylococcus aureus and Bacillus subtilise, while the growth inhibition of AgNPs at 1000–500 µg/ml occurred against Klebsiella pneumonia and at 1000–250 µg/ml of AgNPs was observed against E. coli. The UV–vis absorption spectra confirmed the formation of the AgNPs with the characteristic peak at 415 nm and SEM micrograph acknowledged spherical particles in a nanosize range. FTIR measured the possible biomolecules that are responsible for stabilisation of AgNPs. XRD analysis exhibited the crystalline nature of AgNPs and showed face‐centred cubic structure. The synthesised AgNPs revealed significant antibacterial activity against gram‐positive bacteria.Inspec keywords: visible spectra, microorganisms, ultraviolet spectra, biomedical materials, nanofabrication, nanoparticles, X‐ray diffraction, scanning electron microscopy, molecular biophysics, X‐ray chemical analysis, nanomedicine, silver, antibacterial activity, Fourier transform infrared spectraOther keywords: green chemistry process, ultraviolet–visible spectroscopy, gram‐positive bacteria, silver nanoparticles, Thymus kotschyanus aqueous extract, UV–vis spectroscopy, Fourier transform infrared spectroscopy, FTIR analysis, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, SEM micrograph, X‐ray diffraction, XRD, Staphylococcus aureus, Bacillus subtilise, Klebsiella pneumonia, E. coli, UV–vis absorption spectra, face‐centred cubic structure, antibacterial activity, antimicrobial activity, wavelength 415.0 nm, Ag     

Porcine skin gelatin–silver nanocomposites: synthesis,characterisation, cell cytotoxicity,and antibacterial properties

Silver nanoparticles (AgNPs) were synthesised with hydrothermal autoclaving technique by using AgNO₃ salt (silver precursor) at different concentrations (0.01, 0.1, 0.55, 1.1, 5.5, and 11 mM) and porcine skin (1% (w/v)) gelatin polymeric matrix (reducing and stabiliser agent). The reaction was performed in an autoclave at 103 kPa and 121°C and the hydrothermal autoclaving exposure time and AgNO₃ molar concentration were varied at a constant porcine skin gelatin concentration. The as‐prepared AgNPs were characterised by UV–visible spectroscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. The antibacterial properties of AgNPs were tested against gram‐positive and gram‐negative bacteria. Furthermore, 3‐(4,5‐dimethylthiazol‐2‐yl) 2,5‐diphenyltetrazolium bromide and 2,2‐diphenyl‐1‐picrylhydrazyl assays were used to test whether the synthesised AgNPs can be potentially applied in cancer therapy or used as an antioxidant. This approach is a promising simple route for synthesising AgNPs with a smaller average particle 10 nm diameter. Furthermore, AgNPs exhibited a good cytotoxicity activity, reducing the viability of the liver cancer cell line HepG2 with a moderate IC₅₀; they also showed a low‐to‐fair antioxidant activity. In addition, AgNPs had a remarkable preferential antibacterial activity against gram‐positive bacteria than gram‐negative bacteria. Therefore, these fabricated AgNPs can be used as an antibacterial agent in curative and preventive health care.Inspec keywords: gelatin, silver, nanoparticles, nanocomposites, nanobiotechnology, biomedical materials, antibacterial activity, microorganisms, Fourier transform infrared spectra, ultraviolet spectra, visible spectra, transmission electron microscopy, cancer, cellular biophysicsOther keywords: porcine skin gelatin–silver nanocomposites, cell cytotoxicity, antibacterial properties, silver nanoparticles, hydrothermal autoclaving technique, gelatin polymeric matrix, UV–visible spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, gram‐positive bacteria, gram‐negative bacteria, 3‐(4,5‐dimethylthiazol‐2‐yl) 2,5‐diphenyltetrazolium bromide assays, 2,2‐diphenyl‐1‐picrylhydrazyl assays, cancer therapy, antioxidant, liver cancer cell line HepG2, Ag     

Green‐route mediated synthesis of silver nanoparticles (AgNPs) from Syzygium cumini (L.) Skeels polyphenolic‐rich leaf extracts and investigation of their antimicrobial activity

Medicinal plants are widely utilised by the African population since they have no harmful side effects and low cost compared with different treatments. The field of nanotechnology is the most active part of research in modern material''s science. Though there are several chemicals as well as physical methods, however, green synthesis of nanomaterials is the most emerging method of synthesis. Conventionally, chemical reduction is the most often applied approach for the preparation of metallic nanoparticle''s however, in most of the synthesis protocols it cannot avoid the utilisation of toxic chemicals. Hence, the authors report an environmentally friendly, cost effective and green approach for synthesis of 1 mM AgNO₃ solution using the polyphenolic‐rich leaf extracts of Syzygium cumini (S. cumini) (L.) Skeels as a reducing and capping agent. The synthesised AgNPs are characterised by UV‐Vis spectroscopy and Fourier transform infrared (FTIR) spectroscopy. FTIR analysis revealed that the AgNPs were stable due to eugenols, terpenes, and other different aromatic compounds present in the extract. The green biosynthesised S. cumini AgNPs significantly inhibited the growth of human pathogenic both gram‐positive Staphylococcus aureus (1.40 mm) and gram‐negative bacteria Escherichia coli (2.75 mm) and Salmonella typhimurium (1.45 mm) showing promising antimicrobial activity.Inspec keywords: silver, nanoparticles, nanofabrication, nanomedicine, antibacterial activity, biomedical materials, visible spectra, ultraviolet spectra, Fourier transform infrared spectra, microorganismsOther keywords: green‐route mediated synthesis, silver nanoparticles, Syzygium cumini, Skeels polyphenolic‐rich leaf extracts, antimicrobial activity, medicinal plants, African population, nanotechnology, physical methods, nanomaterials, metallic nanoparticles, AgNO₃ solution, polyphenolic‐rich leaf extracts, capping agent, UV‐visible spectroscopy, Fourier transform infrared spectroscopy, FTIR, eugenols, terpenes, aromatic compounds, green biosynthesis, human pathogenic growth, gram‐positive Staphylococcus aureus, gram‐negative bacteria Escherichia coli, Salmonella typhimurium, antimicrobial activity, size 2.75 mm, size 1.45 mm, size 1.40 mm, Ag     

Greenly synthesised silver‐alginate nanocomposites for degrading dyes and bacteria

The environmentally friendly synthesis of silver nanoparticles (AgNPs) has been achieved employing silver nitrate and sodium alginate (SA) without using other chemicals except for sodium hydrate. In the synthesis process, SA functions as both reductive and stabilising agent. The as‐synthesised AgNPs size can be controlled just changing the reactive parameters such as the concentration of silver nitrate and SA, the solution pH, the reaction temperature and time. Formation of AgNPs was observed by the colour change in the reaction medium which was further established with UV–Vis spectroscopy. The characterisation of AgNPs infers that the as‐synthesised AgNPs with an average size of 8.2 nm were spherical in shape and a face cubic crystal structure. The AgNPs‐SA beads were easily prepared using AgNPs‐SA nanocomposites due to SA crosslinking with metal ions. The catalytic efficiency of the resulting AgNPs beads is evaluated for the reduction of dyes such as 4‐nitrophenol, methylene blue and reactive red in the presence of NaBH₄. Antibacterial efficacy of AgNPs was analysed against gram‐negative Escherichia Coli and gram‐positive Staphylococcus aureus by measuring the zones of inhibition on the solid growth medium. The as‐synthesised AgNPs have shown efficient inhibitory activity against the tested bacterial strains.Inspec keywords: nanocomposites, dyes, filled polymers, silver, nanoparticles, nanofabrication, pH, ultraviolet spectra, visible spectra, catalysis, dissociation, microorganisms, nanomedicine, reduction (chemical), antibacterial activityOther keywords: greenly synthesised silver‐alginate nanocomposites, dye degradation, environmentally friendly synthesis, sodium alginate, sodium hydrate, reductive agent, stabilising agent, reactive parameters, silver nitrate concentration, solution pH, reaction temperature, reaction time, colour change, reaction medium, UV‐visible spectroscopy, face cubic crystal structure, metal ions, catalytic efficiency, dye reduction, 4‐nitrophenol, methylene blue, reactive red, antibacterial efficacy, gram‐negative Escherichia Coli, gram‐positive Staphylococcus aureus, inhibition zones, solid growth medium, inhibitory activity, bacterial strains, Ag     

Fabrication and characterisation of silver nanoparticles using bract extract of Musa paradisiaca for its synergistic combating effect on phytopathogens,free radical scavenging activity,and catalytic efficiency

This work explores the rapid synthesis of silver nanoparticles (AgNPs) from Musa paradisiaca (M. paradisiaca) bract extract. The bio‐reduction of Ag⁺ ion was recorded using ultraviolet–visible spectroscopy by a surface plasmon resonance extinction peak with an absorbance at 420 nm. The phytoconstituents responsible for the reduction of AgNPs was probed using Fourier transform infrared spectroscopy. The X‐ray diffraction pattern confirmed the formation of crystalline AgNPs that were analogous to selected area electron diffraction patterns. Morphological studies showed that the obtained AgNPs were monodispersed with an average size of 15 nm. The biologically synthesised AgNPs showed higher obstruction against tested phytopathogens. The synthesised AgNPs exhibited higher inhibitory zone against fungal pathogen Alternaria alternata and bacterial pathogen Pseudomonas syringae. Free radical scavenging potential of AgNPs was investigated using 1,1‐diphenyl‐2‐picryl hydroxyl and 2,2‐azinobis (3‐ethylbenzothiazoline)‐6‐sulphonic acid assays which revealed that the synthesised AgNPs act as a potent radical scavenger. The catalytic efficiency of the synthesised AgNPs was investigated for azo dyes, methyl orange (MO), methylene blue (MB) and reduction of o‐nitrophenol to o‐aminophenol. The results portrayed that AgNPs act as an effective nanocatalyst to degrade MO to hydrazine derivatives, MB to leucomethylene blue, and o‐nitro phenol to o‐amino phenolInspec keywords: catalysis, dyes, electron diffraction, nanofabrication, silver, catalysts, surface plasmon resonance, reduction (chemical), free radicals, nanoparticles, transmission electron microscopy, nanobiotechnology, X‐ray diffraction, microorganisms, organic compounds, Fourier transform spectra, nanomedicine, visible spectra, antibacterial activity, infrared spectra, ultraviolet spectraOther keywords: silver nanoparticles, musa paradisiaca, synergistic combating effect, free radical scavenging activity, catalytic efficiency, M. paradisiaca, bio‐reduction, ultraviolet–visible spectroscopy, surface plasmon resonance extinction peak, Fourier transform infrared spectroscopy, X‐ray diffraction pattern, selected area electron diffraction patterns, radical scavenging potential, potent radical scavenger, size 420.0 nm, size 15.0 nm, Ag⁺      

Antimicrobial potential and in vitro cytotoxicity study of polyvinyl pyrollidone‐stabilised silver nanoparticles synthesised from Lysinibacillus boronitolerans

The main emphasis herein is on the eco‐friendly synthesis and assessment of the antimicrobial potential of silver nanoparticles (AgNPs) and a cytotoxicity study. Silver nanoparticles were synthesised by an extracellular method using bacterial supernatant. Biosynthesised silver nanoparticles were characterised by UV‐vis spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, dynamic light scattering, and zeta potential analysis. The synthesised silver nanoparticles exhibited a characteristic peak at 420 nm. TEM analysis depicted the spherical shape and approximately 20 nm size of nanoparticles. Silver nanoparticles carry a charge of −33.75 mV, which confirms their stability. Biogenic polyvinyl pyrrolidone‐coated AgNPs exhibited significant antimicrobial effects against all opportunistic pathogens (Gram‐positive and Gram‐negative bacteria, and fungi). Silver nanoparticles equally affect the growth of both Gram‐positive and Gram‐negative bacteria, with a maximum inhibition zone observed at 22 mm and a minimum at 13 mm against Pseudomonas aeruginosa and Fusarium graminearum, respectively. The minimum inhibitory concentration (MIC) of AgNPs against P. aeruginosa and Staphylococcus aureus was recorded at between 15 and 20 μg/ml. Synthesised nanoparticles exhibited a significant synergistic effect in combination with conventional antibiotics. Cytotoxicity estimates using C2C12 skeletal muscle cell line via 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) test and lactate dehydrogenase assay were directly related to the concentration of AgNPs and length of exposure. On the basis of the MTT test, the IC50 of AgNPs for the C2C12 cell line was approximately 5.45 μg/ml concentration after 4 h exposure.     

Biosynthesis of silver nanoparticles using Artemisia annua callus for inhibiting stem‐end bacteria in cut carnation flowers

A biological method for synthesising silver nanoparticles (AgNPs) was developed using the callus extracts from Artemisia annua L. under sunlight at 25,000 lx. The AgNPs were characterised using transmission electron microscopy, atomic force microscope, X‐ray diffraction and Fourier transform infrared spectroscopy. The AgNPs were mostly spherical with the size of 2.1 to 45.2 nm (average 10.9 nm). Pulse treatments of AgNPs at 125, 250 and 500 mg/l for 1 h extended vase life of cut carnation (Dianthus caryophyllus cv. Green Land) flowers. Four dominant bacteria strains Arthrobacter arilaitensis, Kocuria sp., Staphylococcus equorum and Microbacterium oxydans were isolated from the stem‐ends of cut D. caryophyllus flowers. AgNP pulse inhibited significantly bacterial growth in vase solution and cut stem ends during all of the vase period. The bacteria related blockage in the stem‐ends was significantly alleviated by AgNP pulse because of its higher antibacterial efficacy against the dominant bacteria. In addition, ethylene release of cut carnation flowers was inhibited in response to AgNP pulse. This is the first time that the biologically synthesised AgNPs could be applied as a promising preservative agent for cut carnation flowers.Inspec keywords: nanofabrication, silver, nanoparticles, microorganisms, transmission electron microscopy, atomic force microscopy, X‐ray diffraction, Fourier transform infrared spectraOther keywords: biosynthesis, silver nanoparticles, Artemisia annua callus, stem end bacteria, cut carnation flowers, biological method, transmission electron microscopy, atomic force microscope, X‐ray diffraction, Fourier transform infrared spectroscopy, Dianthus caryophyllus cv. Green Land, Arthrobacter arilaitensis, Kocuria sp, Staphylococcus equorum, Microbacterium oxydans, ethylene release, time 1 h, Ag     

Biosynthesis of Silver Nanoparticles by Streptomyces griseorubens isolated from Soil and Their Antioxidant Activity

Microbial mediated biological synthesis of metallic nanoparticles was carried out ecofriendly in the present study. Silver nanoparticles (AgNPs) were extracellularly biosynthesised from Streptomyces griseorubens AU2 and extensively characterised by ultraviolet–visible (UV–vis) and Fourier transform infrared spectroscopy, high‐resolution transmission electron microscopy, scanning electron microscopy and X‐ray diffraction analysis. Elemental analysis of nanoparticles was also carried out using energy dispersive X‐ray spectroscopy. The biosynthesised AgNPs showed the characteristic absorption spectra in UV–vis at 422 nm which confirmed the presence of metallic AgNPs. According to the further characterisation analysis, the biosynthesised AgNPs were found to be spherical and crystalline particles with 5–20 nm average size. Antioxidant properties of the biosynthesised AgNPs were determined by 2,2‐diphenyl‐1‐picrylhydrazyl free radical scavenging assay and was found to increase in a dose‐dependent matter. The identification of the strain was determined by molecular characterisation method using 16s rDNA sequencing. The present study is the first report on the microbial biosynthesis of AgNPs using S. griseorubens isolated from soil and provides that the active biological components found in the cell‐free culture supernatant of S. griseorubens AU2 enable the synthesis of AgNPs.Inspec keywords: silver, microorganisms, nanoparticles, nanofabrication, DNA, molecular biophysics, ultraviolet spectra, visible spectra, scanning electron microscopy, Fourier transform infrared spectra, transmission electron microscopy, X‐ray diffraction, X‐ray chemical analysis, absorption coefficients, cellular biophysicsOther keywords: silver nanoparticles, Streptomyces griseorubens AU2, soil, antioxidant activity, microbial mediated biological synthesis, ultraviolet‐visible spectroscopy, Fourier transform infrared spectroscopy, UV‐vis spectroscopy, high‐resolution transmission electron microscopy, scanning electron microscopy, X‐ray diffraction, elemental analysis, energy dispersive X‐ray spectroscopy, absorption spectra, spherical particles, crystalline particles, 2,2‐diphenyl‐1‐picrylhydrazyl free radical scavenging assay, strain identification, molecular characterisation method, rDNA sequencing, active biological components, cell‐free culture supernatant, wavelength 422 nm, size 5 nm to 20 nm, Ag     

Biofabrication of broad range antibacterial and antibiofilm silver nanoparticles

Silver nanoparticles (AgNPs) were biosynthesized via a green route using ten different plants extracts (GNP1‐ Caryota urens, GNP2‐Pongamia glabra, GNP3‐ Hamelia patens, GNP4‐Thevetia peruviana, GNP5‐Calendula officinalis, GNP6‐Tectona grandis, GNP7‐Ficus petiolaris, GNP8‐ Ficus busking, GNP9‐ Juniper communis, GNP10‐Bauhinia purpurea). AgNPs were tested against drug resistant microbes and their biofilms. These nanoparticles (NPs) were characterised using UV‐vis spectroscopy, transmission electron microscope, Fourier transform infrared spectroscopy, X‐ray diffraction and Image J software. Most of the AgNPs were distributed over a range of 1 of 60 nm size. The results indicated that AgNPs were antibacterial in nature without differentiating between resistant or susceptible strains. Moreover, the effect was more prominent on Gram negative bacteria then Gram positive bacteria and fungus. AgNPs inhibited various classes of microbes with different concentration. It was also evident from the results that the origin or nature of extract did not affect the activity of the NPs. Protein and carbohydrate leakage assays confirmed that the cells lysis is one of the main mechanisms for the killing of microbes by green AgNPs. This study suggests that the action of AgNPs on microbial cells resulted into cell lysis and DNA damage. Excellent microbial biofilm inhibition was also seen by these green AgNPs. AgNPs have proved their candidature as a potential antibacterial and antibiofilm agent against MDR microbes.Inspec keywords: silver, nanoparticles, antibacterial activity, nanofabrication, microorganisms, ultraviolet spectra, visible spectra, transmission electron microscopy, Fourier transform infrared spectra, X‐ray diffraction, proteins, DNA, nanomedicine, biomedical materials, cellular biophysicsOther keywords: biofabrication, broad range antibacterial nanoparticles, antibiofilm silver nanoparticles, plant extract contribution, drug resistant microbes, UV‐vis spectroscopy, transmission electron microscope, Fourier transform infrared spectroscopy, X‐ray diffraction, Image J software, resistant strains, susceptible strains, Gram positive bacteria, fungus, protein leakage assays, carbohydrate leakage assays, cell lysis, DNA damage, Ag     

Efficacy of mycosynthesised AgNPs from Earliella scabrosa as an in vitro antibacterial and wound healing agent

The silver nanoparticles (AgNPs) with their unique chemical and physical properties are proving as a new therapeutical agent. In the present study, the AgNPs synthesised from an aqueous extract of a macrofungus, Earliella scabrosa, were characterised by field emission scanning electron microscopy (FESEM), energy dispersive X‐ray analysis (EDX), high‐resolution transmission electron microscopy, X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and further evaluate for its in vitro antibacterial and wound healing efficacy. The mycosynthesised AgNPs exhibited the surface plasmon resonance peak at 410 nm with good stability over a period of a month. The FESEM and EDX analyses revealed the spherical‐shaped AgNPs of an average size of 20 nm and the presence of elemental Ag, respectively. The XRD pattern showed the crystalline nature of AgNPs. The FTIR spectra confirmed the conversion of Ag⁺ ions to AgNPs due to reduction by biomolecules of macrofungus extract. The mycosynthesised AgNPs showed effective antibacterial activity against two Gram‐positive bacteria, namely Bacillus subtilis and Staphylococcus aureus, and two Gram‐negative bacteria Escherichia coli and Pseudomonas aeruginosa. The pathogens were highly sensitive to AgNPs, whereas less sensitive to AgNO₃. The mycosynthesised AgNPs showed significant wound healing potential with 68.58% of wound closure.Inspec keywords: surface plasmon resonance, wounds, X‐ray diffraction, nanoparticles, molecular biophysics, nanomedicine, antibacterial activity, biomedical materials, reduction (chemical), silver, microorganisms, X‐ray chemical analysis, nanofabrication, transmission electron microscopy, particle size, field emission scanning electron microscopy, Fourier transform infrared spectraOther keywords: high‐resolution transmission electron microscopy, healing efficacy, mycosynthesised AgNPs, spherical‐shaped AgNPs, wound healing agent, in vitro antibacterial efficacy, Earliella scabrosa, silver nanoparticles, physical properties, chemical properties, therapeutical agent, aqueous extract, macrofungus, field emission scanning electron microscopy, FESEM, energy dispersive X‐ray analysis, EDX, X‐ray diffraction, XRD, Fourier transform infrared spectroscopy, FTIR spectroscopy, surface plasmon resonance peak, crystalline nature, biomolecules, Gram‐positive bacteria, Bacillus subtilis, Staphylococcus aureus, Gram‐negative bacteria, Escherichia coli, Pseudomonas aeruginosa, pathogens, wound closure, Ag     

Broad‐spectrum inhibitory effect of green synthesised silver nanoparticles from Withania somnifera (L.) on microbial growth,biofilm and respiration: a putative mechanistic approach

Multi‐drug resistance in pathogenic bacteria has created immense clinical problem globally. To address these, there is need to develop new therapeutic strategies to combat bacterial infections. Silver nanoparticles (AgNPs) might prove to be next generation nano‐antibiotics. However, improved efficacy and broad‐spectrum activity is still needed to be evaluated and understood. The authors have synthesised AgNPs from Withania somnifera (WS) by green process and characterised. The effect of WS‐AgNPs on growth kinetics, biofilm inhibition as well as eradication of preformed biofilms on both gram‐positive and gram‐negative pathogenic bacteria was evaluated. The authors have demonstrated the inhibitory effect on bacterial respiration and disruption of membrane permeability and integrity. It was found that WS‐AgNPs inhibited growth of pathogenic bacteria even at 16 µg/ml. At sub‐minimum inhibitory concentration concentration, there was approximately 50% inhibition in biofilm formation which was further validated by light and electron microscopy. WS‐AgNPs also eradicated the performed biofilms by varying levels at elevated concentration. The bacterial respiration was also significantly inhibited. Interaction of WS‐AgNPs with test pathogen caused the disruption of cell membrane leading to leakage of cellular content. The production of intracellular reactive oxygen species reveals that WS‐AgNPs exerted oxidative stress inside bacterial cell causing microbial growth inhibition and disrupting cellular functions.Inspec keywords: silver, nanoparticles, nanofabrication, nanomedicine, antibacterial activity, biomedical materials, cellular biophysics, microorganisms, biomembranes, electron microscopy, oxidation, biochemistry, permeabilityOther keywords: broad‐spectrum inhibitory effect, green synthesised silver nanoparticles, Withania somnifera (L.), microbial growth, putative mechanistic approach, multidrug resistance, therapeutic strategies, bacterial infections, next generation nanoantibiotics, broad‐spectrum activity, WS‐AgNPs, growth kinetics, biofilm inhibition, gram‐positive pathogenic bacteria, gram‐negative pathogenic bacteria, bacterial respiration, membrane permeability, membrane integrity, subminimum inhibitory concentration concentration, biofilm formation, light pathogenic bacteria, electron microscopy, cell membrane, cellular content leakage, intracellular reactive oxygen species, oxidative stress, microbial growth inhibition, Ag     

Antibacterial potential of silver nanoparticles biosynthesised using Canarium ovatum leaves extract

Silver nanoparticles (AgNPs) have been extensively used as antibacterial agents, owing to their ease of preparation. In the present study, leaves extract of Canarium ovatum have been employed for the biosynthesis of silver nanoparticles (CO‐AgNPs). CO‐AgNPs were synthesised under very mild, eco‐friendly manner where the plant extract acted both as reducing and capping agent. These AgNPs were synthesised by taking into account several parameters, that included, time of reaction, concentration of AgNO₃, amount of extract and temperature of reaction. The optimisation studies suggested efficient synthesis of CO‐AgNPs at 25°C when 1.5 mM AgNO₃ was reduced with 1:20 ratio of plant extract for 40 min. Size determination studies done on dynamic light scattering and scanning electron microscope suggested of spherical shape nanoparticles of size 119.7 ± 7 nm and 50–80 nm, respectively. Further, characterisations were done by Fourier transform infrared and energy‐dispersive X‐ray spectroscopy to evaluate the functional groups and the purity of CO‐AgNPs. The antibacterial efficacy of CO‐AgNPs was determined against the bacterial strain Pseudomonas aeruginosa. As evident from disc diffusion method studies, CO‐AgNPs remarkably inhibited the growth of the tested microorganism. This study suggested that C. ovatum extract efficiently synthesises CO‐AgNPs with significant antibacterial properties and can be good candidates for therapeutics.Inspec keywords: antibacterial activity, nanoparticles, silver, nanofabrication, particle size, light scattering, scanning electron microscopy, Fourier transform infrared spectra, X‐ray chemical analysis, microorganisms, biomedical materials, nanomedicineOther keywords: antibacterial potential, silver nanoparticles, biosynthesis, Canarium ovatum leave extract, plant extract, reducing agent, capping agent, antibacterial agents, reaction time, reaction temperature, dynamic light scattering, scanning electron microscopy, spherical shape nanoparticles, Fourier transform infrared spectroscopy, functional groups, bacterial strain Pseudomonas aeruginosa, disc diffusion method, microorganism, energy‐dispersive X‐ray spectroscopy, temperature 25 degC, time 40 min, Ag     

Green synthesis of silver nanoparticles using Mentha pulegium and investigation of their antibacterial,antifungal and anticancer activity

A simple and eco‐friendly method for efficient synthesis of stable colloidal silver nanoparticles (AgNPs) using Mentha pulegium extracts is described. A series of reactions was conducted using different types and concentrations of plant extract as well as metal ions to optimize the reaction conditions. AgNPs were characterized by using UV–vis spectroscopy, transmission electron microscopy, atomic force microscopy, dynamic light scattering, zetasizer, energy‐dispersive X‐ray spectroscopy (EDAX) and Fourier transform infrared spectroscopy (FTIR). At the optimized conditions, plate shaped AgNPs with zeta potential value of ‐15.7 and plasmon absorption maximum at 450 nm were obtained using high concentration of aqueous extract. Efficient adsorption of organic compounds on the nanoparticles was confirmed by FTIR and EDAX. The biogenic AgNPs displayed promising antibacterial activity on Escherichia coli, Staphylococcus aureus, and Streptococcus pyogenes. The highest antibacterial activity of 25 µg mL‐1 was obtained for all the strains using aqueous extract synthesized AgNPs. The aqueous extract synthesised AgNPs also showed considerable antifungal activity against fluconazole resistant Candida albicans. The cytotoxicity assay revealed considerable anticancer activity of AgNPs on HeLa and MCF‐7 cancer cells. Overall results indicated high potential of M. pulegium extract to synthesis high quality AgNPs for biomedical applications.Inspec keywords: silver, nanoparticles, nanofabrication, botany, antibacterial activity, biomedical materials, nanomedicine, ultraviolet spectra, visible spectra, transmission electron microscopy, atomic force microscopy, X‐ray chemical analysis, Fourier transform infrared spectra, electrokinetic effects, microorganisms, cellular biophysics, cancerOther keywords: antibacterial activity, antifungal activity, anticancer activity, stable colloidal silver nanoparticle, Mentha pulegium, plant extract, UV‐visible spectroscopy, transmission electron microscopy, atomic force microscopy, DLS, zetasizer, energy‐dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, methanolic extract, aqueous extract, plate‐shaped silver nanoparticle, zeta potential, plasmon absorption maximum, organic compounds adsorption, biogenic silver nanoparticle, Escherichia coli, Staphylococcus aureus, Streptococcus pyogenes, fluconazole‐resistant Candida albicans, MTT assay, HeLa cancer cell, MCF‐7 cancer cell, Ag     

Plant‐mediated green synthesis of silver nanoparticles using Trifolium resupinatum seed exudate and their antifungal efficacy on Neofusicoccum parvum and Rhizoctonia solani

In recent years, biosynthesis and the utilisation of silver nanoparticles (AgNPs) has become an interesting subject. In this study, the authors investigated the biosynthesis of AgNPs using Trifolium resupinatum (Persian clover) seed exudates. The characterisation of AgNPs were analysed using ultraviolet–visible spectroscopy, X‐ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infra‐red spectroscopy. Also, antifungal efficacy of biogenic AgNPs against two important plant‐pathogenic fungi (Rhizoctonia solani and Neofusicoccum Parvum) in vitro condition was evaluated. The XRD analysis showed that the AgNPs are crystalline in nature and have face‐centred cubic geometry. TEM images revealed the spherical shape of the AgNPs with an average size of 17 nm. The synthesised AgNPs were formed at room temperature and kept stable for 4 months. The maximum distributions of the synthesised AgNPs were seen to range in size from 5 to 10 nm. The highest inhibition effect was observed against R. solani at 40 ppm concentration of AgNPs (94.1%) followed by N. parvum (84%). The results showed that the antifungal activity of AgNPs was dependent on the amounts of AgNPs. In conclusion, the AgNPs obtained from T. resupinatum seed exudate exhibit good antifungal activity against the pathogenic fungi R. solani and N. Parvum.Inspec keywords: silver, nanoparticles, botany, ultraviolet spectra, visible spectra, X‐ray diffraction, transmission electron microscopy, Fourier transform infrared spectra, nanobiotechnology, biological techniquesOther keywords: plant‐mediated green synthesis, silver nanoparticles, Trifolium resupinatum seed exudate, antifungal efficacy, Neofusicoccum parvum, Rhizoctonia solani, biosynthesis, ultraviolet–visible spectroscopy, X‐ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, plant‐pathogenic fungi, XRD analysis, TEM images, antifungal activity, temperature 293 K to 298 K, Ag     

Biosynthesis of silver nanoparticles by Pseudomonas spp. isolated from effluent of an electroplating industry

The aim of this study was to isolate and screen bacteria from soil and effluent of electroplating industries for the synthesis of silver nanoparticles and characterize the potential isolate. Soil and effluent of electroplating industries from Mumbai were screened for bacteria capable of synthesizing silver nanoparticles. From two soils and eight effluent samples 20 bacterial isolates were obtained, of these, one was found to synthesize silver nanoparticles. Synthesis of silver nanoparticle by bacteria was confirmed by undertaking characterization studies of nanoparticles that involved spectroscopy and electron microscopic techniques. The potential bacteria was found to be Gram‐negative short rods with its biochemical test indicating Pseudomonas spp. Molecular characterization of the isolate by 16S r DNA sequencing was carried out which confirmed its relation to Pseudomonas hibiscicola ATCC 19867. Stable nanoparticles synthesized were 50 nm in size and variable shapes as seen in SEM micrographs. The XRD and FTIR confirmed the crystalline structure of nanoparticles and presence of biomolecules mainly proteins as agents for reduction and capping of nanoparticles. The study demonstrates synthesis of nanoparticles by bacteria from effluent of electroplating industry. This can be used for large scale synthesis of nanoparticles by cost effective and environmentally benign mode of synthesis.Inspec keywords: biotechnology, effluents, soil, biochemistry, scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, nanoparticles, electroplatingOther keywords: environmentally benign mode, large‐scale nanoparticles synthesis, proteins, biomolecules, Fourier transform infrared spectroscopy, X‐ray diffraction, SEM micrographs, pseudomonas hibiscicola ATCC 19867, 16S rDNA sequencing, molecular characterisation, biochemical test, gram‐negative short rods, potential bacteria, spectroscopy, electron microscopic techniques, soil, electroplating industries, effluent, pseudomonas spp, silver nanoparticles biosynthesis     

Phyto‐assisted synthesis of bio‐functionalised silver nanoparticles and their potential anti‐oxidant,anti‐microbial and wound healing activities

Bio‐ synthesis of silver nanoparticles (AgNPs) was made by using the aqueous leaf extract of Ardisia solanacea. Rapid formation of AgNPs was observed from silver nitrate upon treatment with the aqueous extract of A. solanacea leaf. The formation and stability of the AgNPs in the colloidal solution were monitored by UV–visible spectrophotometer. The mean particle diameter of AgNPs was calculated from the DLS with an average size ∼4 nm and ∼65 nm. ATR‐FTIR spectroscopy confirmed the presence of alcohols, aldehydes, flavonoids, phenols and nitro compounds in the leaf which act as the stabilizing agent. Antimicrobial activity of the synthesized AgNPs was performed using agar well diffusion and broth dilution method against the Gram‐positive and Gram‐negative bacteria. Further, robust anti‐oxidative potential was evaluated by DPPH assay. The highest antimicrobial activity of synthesized AgNPs was found against Pseudomonas aeruginosa (28.2 ± 0.52 mm) whereas moderate activity was found against Bacillus subtilis (16.1 ± 0.76), Candida kruseii (13.0 ± 1.0), and Trichophyton mentagrophytes (12.6 ± 1.52). Moreover, the potential wound healing activity was observed against the BJ‐5Ta normal fibroblast cell line. Current research revealed that A. solanacea was found to be a suitable source for the green synthesis of silver nanoparticles.Inspec keywords: antibacterial activity, nanoparticles, silver, nanomedicine, wounds, microorganisms, X‐ray diffraction, ultraviolet spectra, visible spectra, Fourier transform infrared spectra, transmission electron microscopyOther keywords: phyto‐assisted synthesis, biofunctionalised silver nanoparticles, antioxidant antimicrobial wound healing activities, silver nanoparticle biosynthesis, aqueous leaf extract, Ardisia solanacea, silver nitrate, UV–visible spectroscopy, dynamic light scattering, Fourier transform infra‐red spectroscopy, X‐ray diffraction, electron microscopy, attenuated total reflection Fourier transform infra‐red spectroscopy, dilution method, Gram‐positive bacteria, Gram‐negative bacteria, radical scavenging method, Pseudomonas aeruginosa, Trichophyton mentagrophytes, Bacillus subtilis, Candida kruseii, BJ‐5Ta normal fibroblast cell line, SEM, alcohols, aldehydes, flavonoids, phenols, nitro compounds, Ag     

Facile phyto‐mediated synthesis of silver nanoparticles using Chinese winter jujube (Ziziphus jujuba Mill. cv. Dongzao) extract and their antibacterial/catalytic properties

The aqueous extract of Chinese winter jujube (Ziziphus jujuba Mill. cv. Dongzao) was used as reducing and capping agents for the synthesis of silver nanoparticles (AgNPs) for the first time. The resulting AgNPs were characterised by UV/Visible (UV–Vis) spectroscopy, atomic force microscope, transmission electron microscopy, selected area electron diffraction, X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray and Fourier transform infrared spectroscopy (FTIR). The colloidal solution of AgNPs gave a maximum UV–Vis absorbance at 446 nm. The synthesised nanoparticles were almost in the spherical shapes with an average size of 11.5 ± 4. 8 nm. FTIR spectra were applied to identify the functional groups which were possibly responsible for the conversion of metal ions into nanoparticles. The results showed that the prepared AgNPs were coated with the biomolecules in the extract. The biosynthesised AgNPs showed a remarkable catalytic activity at room temperature, and they also showed good antibacterial properties against Escherichia coli and Staphylococcus aureus.Inspec keywords: silver, nanoparticles, nanofabrication, antibacterial activity, biomedical materials, nanobiotechnology, scanning electron microscopy, X‐ray diffraction, transmission electron microscopy, ultraviolet spectra, visible spectra, X‐ray chemical analysis, Fourier transform infrared spectra, catalysisOther keywords: wavelength 446 nm, temperature 293 K to 298 K, Ag, Escherichia coli, Staphylococcus aureus, biomolecules, catalytic activity, metal ions, colloidal solution, FTIR spectra, UV‐vis absorbance, TEM, SEM, XRD, Fourier transform infrared spectroscopy, energy‐dispersive X‐ray spectroscopy, scanning electron microscopy, X‐ray diffraction, selected area electron diffraction, transmission electron microscopy, atomic force microscopy, UV‐visible spectroscopy, catalytic properties, antibacterial properties, Chinese winter jujube extract, silver nanoparticles, facile phyto‐mediated synthesis     

Biogenic synthesis,optimisation and antibacterial efficacy of extracellular silver nanoparticles using novel fungal isolate Aspergillus fumigatus MA

To eliminate the elaborate processes employed in other non‐biological‐based protocols and low cost production of silver nanoparticles (AgNPs), this study reports biogenic synthesis of AgNPs using silver salt precursor with aqueous extract of Aspergillus fumigates MA. Influence of silver precursor concentrations, concentration ratio of fungal extract and silver nitrate, contact time, reaction temperature and pH are evaluated to find their effects on AgNPs synthesis. Ultraviolet–visible spectra gave surface plasmon resonance at 420 nm for AgNPs. Fourier transform infrared spectroscopy and X‐ray diffraction techniques further confirmed the synthesis and crystalline nature of AgNPs, respectively. Transmission electron microscopy observed spherical shapes of synthesised AgNPs within the range of 3–20 nm. The AgNPs showed potent antimicrobial efficacy against various bacterial strains. Thus, the results of the current study indicate that optimisation process plays a pivotal role in the AgNPs synthesis and biogenic synthesised AgNPs might be used against bacterial pathogens; however, it necessitates clinical studies to find out their potential as antibacterial agents.Inspec keywords: nanoparticles, microorganisms, cellular biophysics, silver, antibacterial activity, pH, surface plasmon resonance, ultraviolet spectra, visible spectra, X‐ray diffraction, Fourier transform infrared spectra, optimisation, nanomedicine, nanofabricationOther keywords: biogenic synthesis, optimisation, antibacterial efficacy, extracellular silver nanoparticles, fungal isolate Aspergillus fumigatus MA, nonbiological‐based protocols, silver salt precursor, fungal extract, silver nitrate, pH, ultraviolet‐visible spectra, surface plasmon resonance, Fourier transform infrared spectroscopy, X‐ray diffraction, crystalline nature, transmission electron microscopy, spherical shapes, potent antimicrobial efficacy, bacterial strains, optimisation process, bacterial pathogens, antibacterial agents, wavelength 420 nm, size 3 nm to 20 nm, Ag     

Synthesis and characterisation of neem leaf extract, 2, 3‐dehydrosalanol and quercetin dihydrate mediated silver nano particles for therapeutic applications

The utility of green silver nanoparticles (AgNPs) in veterinary medicine is steadily increasing as they have many therapeutic applications against pathogens and arthropods of livestock. In this study, green AgNPs using neem (N‐AgNPs), 2,3‐dehydrosalanol (2,3‐DHS‐AgNPs) and quercetin dihydrate (QDH‐AgNPs) were synthesised and characterised. Synthesised compounds were characterised by UV‐Vis spectroscopy and the peak absorbance was recorded at 370 nm for neem extract. For N‐AgNPs, 2,3‐DHS‐AgNPs and QDH‐AgNPs, the maximum absorbance peaks were at 430, 230 and 220 nm, respectively. The FTIR analysis confirmed the synthesis of green AgNPs. The XRD pattern of N‐AgNPs showed the peaks corresponding to whole spectra of 2 θ values ranging from 10–80. The relatively higher intensity of (111, 222) planes in face centred cubic crystalline structure supports the formation of synthesised AgNPs. In DLS analysis, the hydrodynamic diameter of neem leaf extract was found to be 259.8 nm, followed by 5.3, 6.7 and 261.8 nm for 2,3‐DHS‐AgNPs, N‐AgNPs and QDH‐AgNPs, respectively. Based on the transmission electron microscopy and scanning electron microscopy image analyses, confirmed the formation of N‐AgNPs, 2,3‐DHS‐AgNPs and QDH‐AgNPs. These eco‐friendly phyto‐AgNPs may be of use as an effective alternative to chemical control methods against the arthropods of livestock.Inspec keywords: nanoparticles, silver, nanomedicine, biomedical materials, nanofabrication, Fourier transform infrared spectra, ultraviolet spectra, visible spectra, X‐ray diffraction, light scattering, transmission electron microscopy, scanning electron microscopy, aggregation, veterinary medicineOther keywords: 2,3‐dehydrosalanol mediated silver nanoparticles, quercetin dihydrate mediated silver nanoparticles, therapeutic applications, green silver nanoparticles, veterinary medicine, Azadirachta indica, UV‐visible spectroscopy, Fourier transformed infrared analysis, X‐ray diffraction, (111) planes, (222) planes, face centred cubic crystalline structure, dynamic light scattering, hydrodynamic diameter, aqueous neem leaf extract, transmission electron microscopy, hexagonal shape, pencil head shape, cuboid shape, scanning electron microscopy, aggregation, arthropod infesting livestock, Ag, in‐vivo antiectoparasitic activity, in‐vitro antiectoparasitic activity     

Role of AgNPs in the enhancement of seed germination and its effect on plumule and radicle length of Pennisetum glaucum

The authors have investigated beneficial effects of 1 mM of silver nanoparticles (AgNPs) on agriculturally important plant Pennisetum glaucum (Bajara). The extracellular AgNPs were synthesised using Bacillus subtilis spizizenni and characterised using ultraviolet–visible absorption spectroscopy, Fourier transform infrared spectroscopy (FT‐IR) and transmission electron microscopy (TEM). Optical absorption spectrum showed characteristic peak of AgNPs at 423 nm. FT‐IR analysis of AgNPs showed peak at 3435 cm⁻¹, which indicates the presence of N–H group (primary, secondary amines and amides) on the surface of AgNPs. TEM studies indicate that synthesised AgNPs have average size of ∼2 nm. Energy dispersive X‐ray spectroscopy showed strong signal of Ag at 3 keV. Treatment of 1 mM AgNPs to the bajara seeds was found to be sufficient for excellent germination of seeds within 3 days. There was also significant increase in radicle and plumule length as compared with control bajara seeds according to statistical analysis by one‐way analysis of variance, followed by Tukey''s test. The percentage of AgNPs detected in root samples was 0.003% (by inductively coupled plasma atomic emission spectroscopy), which is negligible. There is still need to study the bioavailability and the type of interaction of AgNPs with plants, necessary for application in agriculture.Inspec keywords: transmission electron microscopy, ultraviolet spectra, scanning electron microscopy, nanofabrication, X‐ray diffraction, nanoparticles, visible spectra, silver, atomic emission spectroscopy, X‐ray chemical analysis, Fourier transform infrared spectra, statistical analysis, agricultureOther keywords: ultraviolet–visible absorption spectroscopy, transmission electron microscopy, Pennisetum glaucum, Bacillus subtilis spizizenni, energy dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, optical absorption spectrum, plumule length, radicle length, silver nanoparticles, Tukey''s test, inductively coupled plasma atomic emission spectroscopy, statistical analysis, Bajara seeds, scanning electron microscopy, X‐ray diffraction, analysis of variance, electron volt energy 3.0 keV, time 3.0 d, Ag