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     

Biosynthesis and characterisation of nano‐silica as potential system for carrying streptomycin at nano‐scale drug delivery

A growing trend within nanomedicine has been the fabrication of self‐delivering supramolecular nanomedicines containing a high and fixed drug content ensuring eco‐friendly conditions. This study reports on green synthesis of silica nanoparticles (Si‐NPs) using Azadirachta indica leaves extract as an effective chelating agent. X‐ray diffraction analysis and Fourier transform‐infra‐red spectroscopic examination were studied. Scanning electron microscopy analysis revealed that the average size of particles formed via plant extract as reducing agent without any surfactant is in the range of 100–170 nm while addition of cetyltrimethyl ammonium bromide were more uniform with 200 nm in size. Streptomycin as model drug was successfully loaded to green synthesised Si‐NPs, sustain release of the drug from this conjugate unit were examined. Prolong release pattern of the adsorbed drug ensure that Si‐NPs have great potential in nano‐drug delivery keeping the environment preferably biocompatible, future cytotoxic studies in this connection is helpful in achieving safe mode for nano‐drug delivery.Inspec keywords: silicon compounds, nanofabrication, nanomedicine, drug delivery systems, nanoparticles, X‐ray diffraction, Fourier transform infrared spectra, scanning electron microscopyOther keywords: nanosilica, streptomycin, nanoscale drug delivery, nanomedicine, silica nanoparticles, Azadirachta indica leaves extract, X‐ray diffraction analysis, Fourier transform‐infrared spectroscopy, scanning electron microscopy, cetyltrimethyl ammonium bromide, SiO₂      

Rapid synthesis of Bi 2 O 3 nano‐needles via ‘green route’ and evaluation of its anti‐fungal activity

Here, the authors report a rapid, simple, and eco‐friendly process for synthesis of Bi₂ O₃ nano‐needles. Dioscorea alata tuber extract was used as both reducing and capping agent for the first time. These nanoparticles were characterised by X‐ray diffraction, field emission scanning electron microscope, and Fourier transform infrared (FTIR) spectrometry, the nano‐structured Bi₂ O₃ needles have an average diameter of 158 nm with the lengths in the range of 1–3 μm. CLSI M27‐A2 standard was followed for evaluation of anti‐fungal activity. Bi₂ O₃ nano‐needles show remarkable activity against Candida albicans. It exhibits four time greater activity than bulk Bi₂ O₃ powder and two time greater activity than itraconazole, which makes it a potent anti‐fungal drug.Inspec keywords: bismuth compounds, nanoparticles, X‐ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectra, drugs, nanomedicine, biomedical materials, nanofabricationOther keywords: nanoneedles, antifungal activity, nanoparticles, X‐ray diffraction, field emission scanning electron microscope, Fourier transform infrared spectrometry, CLSI M27‐A2 standard, Candida albicans, itraconazole, antifungal drug, Bi₂ O₃      

Green synthesis of nanosilver‐decorated graphene oxide sheets

A green facile method has been successfully used for the synthesis of graphene oxide sheets decorated with silver nanoparticles (rGO/AgNPs), employing graphite oxide as a precursor of graphene oxide (GO), AgNO₃ as a precursor of Ag nanoparticles (AgNPs), and geranium (Pelargonium graveolens) extract as reducing agent. Synthesis was accomplished using the weight ratios 1:1 and 1:3 GO/Ag, respectively. The synthesised nanocomposites were characterised by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X‐ray diffraction, UV‐visible spectroscopy, Raman spectroscopy, energy dispersive X‐ray spectroscopy and thermogravimetric analysis. The results show a more uniform and homogeneous distribution of AgNPs on the surface of the GO sheets with the weight ratio 1:1 in comparison with the ratio 1:3. This eco‐friendly method provides a rGO/AgNPs nanocomposite with promising applications, such as surface enhanced Raman scattering, catalysis, biomedical material and antibacterial agent.Inspec keywords: silver, nanoparticles, graphene, nanocomposites, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X‐ray diffraction, ultraviolet spectra, visible spectra, X‐ray chemical analysis, surface enhanced Raman scattering, catalysis, nanofabricationOther keywords: antibacterial agent, biomedical material, catalysis, surface enhanced Raman scattering, rGO‐AgNP nanocomposite, eco‐friendly method, homogeneous distribution, thermogravimetric analysis, energy dispersive X‐ray spectroscopy, Raman spectroscopy, UV‐visible spectroscopy, X‐ray diffraction, atomic force microscopy, transmission electron microscopy, scanning electron microscopy, nanocomposites, reducing agent, geranium, graphene oxide sheets, graphite oxide, silver nanoparticles, green facile method     

Biosynthesis of γ ‐Fe2 O3 @CuO core–shell nanoclusters using aqueous extract of Sesbania grandiflora Linn fresh leaves,its characterisation,and antimicrobial activity studies against Staphylococcus aureus strains

The present study reports an eco‐friendly and rapid method for the synthesis of core–shell nanoclusters using the modified reverse micelle method. It is a green synthetic method which uses Sesbania grandiflora Linn extract which acts as a reducing and capping agent. It is observed that this method is very fast and convenient and the nanoclusters are formed with 5–10 min of the reaction time without using harsh conditions. The core–shell nanoclusters so prepared were characterised using UV–Vis spectroscopy, scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy. Further, their effective antibacterial activity towards the gram‐positive bacteria Staphylococcus aureus was found to be due to their smaller particle size.Inspec keywords: iron compounds, copper compounds, nanoparticles, particle size, nanofabrication, nanomedicine, biomedical materials, core‐shell nanostructures, antibacterial activity, ultraviolet spectra, visible spectra, microorganisms, reduction (chemical), scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, X‐ray photoelectron spectraOther keywords: biosynthesis, γ‐Fe₂ O₃ ‐CuO core‐shell nanoclusters, aqueous extract, Sesbania grandiflora Linn fresh leaves, antimicrobial activity, Staphylococcus aureus strains, eco‐friendly method, modified reverse micelle method, green synthetic method, reducing agent, capping agent, UV‐visible spectroscopy, scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, antibacterial activity, gram‐positive bacteria Staphylococcus aureus, particle size, time 5 min to 10 min, Fe₂ O₃ ‐CuO     

Enhancement of secondary metabolites in Bacopa monnieri (L.) Pennell plants treated with copper‐based nanoparticles in vivo

The study aims to document the effect of starch‐stabilised copper‐based nanoparticles (CuNPs) on the biosynthesis of pharmaceutically valuable secondary metabolites, especially saponins, of the reputed nootropic herb Bacopa monnieri (L.) Pennell. CuNPs were synthesised chemically by the reduction of cupric sulphate pentahydrate with ascorbic acid using starch as the capping agent. They were characterised by UV–visible spectrophotometry, Fourier‐transform infra‐red spectroscopy, X‐ray diffraction, high‐resolution transmission electron microscopy and zeta potential. The nanoparticles consisted of cuprous oxide and metallic copper, were approximately spherical, polydispersed with diameter <20 nm. Hydroponically grown B. monnieri plants were treated in vivo with the CuNPs between the concentrations of 0–100 mg l⁻¹. Spectrophotometric estimation of the total contents of saponins, alkaloids, phenolics, flavonoids and DPPH radical scavenging capacity from the methanolic extracts of the whole plants showed a hormetic increase in the content of secondary metabolites in a concentration‐dependent manner from 5 mg l⁻¹ until it declined at toxic metabolic concentration. This was accompanied by an increase in ROS markers hydrogen peroxide and malondialdehyde as well as a hormetic effect on activities of phenylalanine ammonia lyase and antioxidant enzymes catalase, ascorbate peroxidase and superoxide dismutase. CuNPs at sub‐toxic concentrations were found to enhance secondary metabolism and antioxidant capacity in Bacopa monnieri through ROS‐mediated defence response.Inspec keywords: organic compounds, pharmaceuticals, copper compounds, visible spectra, nanofabrication, hydrogen compounds, transmission electron microscopy, reduction (chemical), ultraviolet spectra, electrokinetic effects, X‐ray diffraction, nanoparticles, toxicology, copper, enzymes, Fourier transform infrared spectra, health and safety, agricultural productsOther keywords: starch‐stabilised copper‐based nanoparticles, secondary metabolites, cupric sulphate pentahydrate, capping agent, UV–visible spectrophotometry, X‐ray diffraction, high‐resolution transmission electron microscopy, DPPH radical scavenging capacity, toxic metabolic concentration, antioxidant capacity, saponin content, chemical reduction, ascorbic acid, Fourier transform infrared spectroscopy, zeta potential, hydroponical growth, methanolic extracts, alkaloid content, flavonoid content, malondialdehyde, phenylalanine ammonia lyase, antioxidant enzymes catalase, ascorbate peroxidase, superoxide dismutase, sub‐toxic concentration, spectrophotometric estimation, phenolic content, Pennell plants, Bacopa monnieri L, in vivo treatment, ROS‐mediated defence response, Cu, Cu₂ O, H₂ O₂ , CuSO₄ H₂ O     

Effects of spraying nano‐materials on the absorption of metal(loid)s in cucumber

This report investigates the spraying of nano‐silica and fullerene on cucumber leaves to expose their ability to reduce the toxicity and uptake of metal(loid)s. Cucumber seedlings were randomly divided into six treatment groups: 10 mg/L nano‐SiO₂, 20 mg/L nano‐SiO₂, 10 mg/L Fullerene, 20 mg/L Fullerene, 5 mg/L Fullerene + 5 mg/L nano‐SiO₂, and 10 mg/L Fullerene + 10 mg/L nano‐SiO₂. Nano‐silica‐treated plants exhibited evidence of the potential mitigation of metal(loid)s poisoning. Specifically, results showed that 20 mg/L of nano‐silica promoted Cd uptake by plants; comparatively, 10 mg/L of nano‐silica did not significantly increase the silicon content in plants. Both low‐concentration combined treatment and low‐concentration fullerene groups inhibited metal(loid)s uptake by plants. Scanning electron microscopy (SEM) was then used to observe the surface morphology of cucumber leaves. Significant differences were observed on disease resistance in plants across the different nano‐material conditions. Collectively, these findings suggest that both nano‐silica materials and fullerene have the potential to control metal(loid)s toxicity in plants.Inspec keywords: soil pollution, cadmium, silicon compounds, surface morphology, fullerenes, toxicology, fertilisers, scanning electron microscopy, crops, spraying, nanoparticles, sorption, plant diseases, agricultural safetyOther keywords: cucumber leaves, nanosilica materials, fullerene, spraying process, metalloids absorption, toxicity, scanning electron microscopy, surface morphology, disease resistance, soil pollution, SiO₂ , Cd     

Bio‐inspired synthesis of sulphur nanoparticles using leaf extract of four medicinal plants with special reference to their antibacterial activity

We report new, eco‐friendly and green method for the synthesis of sulphur nanoparticles using sodium polysulphide in the presence of leaf extracts of four different medicinal plants, which can be used for treatment of bacterial infections. Sodium polysulphide and acidic solution (H₂ SO₄) in the presence of plant leaf extract developed the yellowish precipitate in solution, which indicated the formation of sulphur nanoparticles. UV–Vis spectrophotometer analysis of reaction mixture showed absorbance spectra in the range of 292–296 nm, which is supposed to be specific for sulphur nanoparticles. Zeta potential study of sulphur nanoparticles synthesized from Catharanthus roseus showed more stability when compared with other medicinal plants. Sulphur nanoparticles synthesized from C. roseus were further characterized by XRD analysis, FTIR analysis, and TEM analysis. The biogenic sulphur nanoparticles were spherical, polydispersed with particle size of 70–80 nm. Evaluation of antibacterial study revealed that synthesized sulphur nanoparticles exhibited better bactericidal efficacy against common pathogenic bacteria Escherichia coli and Staphylococcus aureus with minimum inhibitory concentration of 200 μg/ml with significant activity used in combination with antibiotic. It can be concluded that the synthesized sulphur nanoparticles can be used as antibacterial agents after thorough experimental trials in animals.Inspec keywords: antibacterial activity, biomedical materials, nanoparticles, nanofabrication, sodium compounds, sulphur, ultraviolet spectra, visible spectra, Fourier transform infrared spectra, electrokinetic effects, transmission electron microscopy, X‐ray diffraction, microorganismsOther keywords: bio‐inspired synthesis, sulphur nanoparticles, leaf extract, medicinal plants, antibacterial activity, eco‐friendly, green synthesis, sodium polysulphide, bacterial infections, biological synthesis, UV–visible analysis, nanoparticle tracking analysis, zeta potential analysis, Fourier transform infrared spectroscopy, X‐ray diffraction analysis, transmission electron microscopy analysis, acidic solution, UV–Vis spectrophotometer analysis, pathogenic bacteria, Escherichia coli, Staphylococcus aureus, size 70 nm to 80 nm, wavelength 292 nm to 296 nm, S     

Biosynthesis of the CuO nanoparticles using Euphorbia Chamaesyce leaf extract and investigation of their catalytic activity for the reduction of 4‐nitrophenol

Through this study an eco‐friendly, simple, efficient, cheap and biocompatible approach to the biosynthesis and stabilisation of CuO nanoparticles (NPs) using the Euphorbia Chamaesyce leaf extract is presented. The CuO NPs were monitored and characterised by field emission scanning electron microscopy, energy dispersive X‐ray spectroscopy, Fourier transformed infrared spectroscopy, transmission electron microscope and UV‐visible spectroscopy. The biosynthesised CuO NPs showed good catalytic activity for the reduction of 4‐nitrophenol (4‐NP) in water during 180 s and reused 4 times without considerable loss of activity.Inspec keywords: copper compounds, nanoparticles, nanofabrication, catalysis, reduction (chemical), field emission electron microscopy, X‐ray chemical analysis, Fourier transform infrared spectra, transmission electron microscopy, ultraviolet spectra, visible spectraOther keywords: biosynthesis, CuO nanoparticles, Euphorbia Chamaesyce leaf extract, catalytic activity, 4‐nitrophenol reduction, nanoparticle stabilisation, field emission scanning electron microscopy, energy dispersive X‐ray spectroscopy, Fourier transformed infrared spectroscopy, transmission electron microscope, UV‐visible spectroscopy, CuO     

Sunlight induced biosynthesis of silver nanoparticle from the bark extract of Amentotaxus assamica D.K. Ferguson and its antibacterial activity against Escherichia coli and Staphylococcus aureus

Green synthesis of nanoparticles has gained importance due to its eco‐friendly, low toxicity and cost effective nature. This study deals with the biosynthesis of silver nanoparticles (AgNPs) from the bark extract of Amentotaxus assamica. The AgNPs have been synthesised by reducing the silver ions into stable AgNPs using the bark extract of Amentotaxus assamica under the influence of sunlight irradiation. The characterisation of the biosynthesised AgNPs was carried out by UV–vis spectroscopy, X‐ray diffraction analysis (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and energy dispersive X‐ray analysis. The UV–vis spectrum showed a broad peak at 472 nm. Also, the XRD confirmed the crystalline structure of the AgNPs. Moreover, the SEM analysis revealed that the biosynthesised AgNPs were spherical in shape. Also, dynamic light scattering techniques were used to evaluate the size distribution profile of the biosynthesised AgNPs. Furthermore, the biosynthesised AgNPs showed a prominent inhibitory effect against both Escherichia coli (MTCC 111) and Staphylococcus aureus (MTCC 97). Thus the biosynthesis of AgNPs from the bark extract of Amentotaxus assamica is found to eco‐friendly way of producing AgNPs compared to chemical method.Inspec keywords: X‐ray chemical analysis, microorganisms, transmission electron microscopy, nanoparticles, toxicology, scanning electron microscopy, ultraviolet spectra, particle size, Fourier transform spectra, X‐ray diffraction, antibacterial activity, visible spectra, infrared spectra, nanomedicine, silverOther keywords: stable AgNP, biosynthesised AgNP, SEM analysis, sunlight irradiation, silver ions, silver nanoparticle, amentotaxus assamica, biosynthesis, escherichia coli     

Green synthesis of gold nanoparticles using Citrus maxima peel extract and their catalytic/antibacterial activities

The peel of Citrus maxima (C. maxima) is the primary byproducts during the process of fruit or juice in food industries, and it was always considered as biomass waste for further treatments. In this study, the authors reported a simple and eco‐friendly method to synthesise gold nanoparticles (AuNPs) using C. maxima peel extract as reducing and capping agents. The synthesised AuNPs were characterised by UV–visible spectrum, X‐ray diffraction (XRD), transmission electron microscope (TEM) and Fourier‐transform infrared spectroscopy (FTIR). The UV–visible spectrum of the AuNPs colloid showed a characteristic peak at 540 nm. The peaks of XRD analysis at (2θ) 38.30°, 44.28°, 64.62°, 77.57° and 81.75° were assigned to (111), (200), (220), (311) and (222) planes of the face‐centered cubic (fcc) lattice of gold. The TEM images showed that AuNPs were nearly spherical in shape with the size of 8–25 nm. The FTIR spectrum revealed that some bioactive compounds capped the surface of synthesised AuNPs. The biosynthesised AuNPs performed strong catalytic activity in degradation of 4‐nitrophenol to 4‐aminophenol and good antibacterial activity against both gram negative (Escherichia coli) and gram positive (Staphylococcus aureus) bacterium. The synthesis procedure was proved simple, cost effective and environment friendly.Inspec keywords: gold, nanoparticles, nanofabrication, X‐ray diffraction, ultraviolet spectra, visible spectra, transmission electron microscopy, Fourier transform infrared spectra, crystal structure, catalysis, antibacterial activity, nanobiotechnologyOther keywords: gold nanoparticles, Citrus maxima peel extract, UV–visible spectrum, X‐ray diffraction, transmission electron microscope, Fourier‐transform infrared spectroscopy, XRD analysis, faced centre cubic lattice, TEM images, catalytic activity, 4‐nitrophenol, 4‐aminophenol, antibacterial activity, gram negative bacterium, gram positive bacterium, Au     

Role of Ribes khorassanicum in the biosynthesis of AgNPs and their antibacterial properties

Silver nanoparticles (AgNPs) have been biosynthesised through the extracts of Ribes khorassanicum fruits, which served as the reducing agents and capping agents. Biosynthesised AgNPs have been found to be ultraviolet–visible (UV–vis) absorption spectra since they have displayed one surface plasmon resonance peak at 438 nm, attesting the formation of spherical NPs. These particles have been characterised by UV–vis, field‐emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy analysis. The formation of AgNPs at 1.0 mM concentration of AgNO₃ has resulted in NPs that contained mean diameters in a range of 20–40 nm. The green‐synthesised AgNPs have demonstrated high antibacterial effect against pathogenic bacteria (i.e. Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa). Biosynthesising metal NPs through plant extracts can serve as the facile and eco‐friendly alternative for chemical and/or physical methods that are utilised for large‐scale nanometal fabrication in various medical and industrial applications.Inspec keywords: X‐ray diffraction, X‐ray chemical analysis, nanofabrication, surface plasmon resonance, nanoparticles, antibacterial activity, microorganisms, scanning electron microscopy, silver, nanomedicine, visible spectra, ultraviolet spectra, transmission electron microscopy, Fourier transform infrared spectra, field emission scanning electron microscopy, biomedical materialsOther keywords: antibacterial properties, silver nanoparticles, reducing agents, capping agents, surface plasmon resonance peak, spherical NPs, field‐emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, transmission electron microscopy analysis, plant extracts, ultraviolet‐visible absorption spectra, Fourier transform infrared spectroscopy, antibacterial effect, Ribes khorassanicum fruits, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, surface plasmon resonance, AgNO₃ , Ag     

Screening the UV‐blocking and antimicrobial properties of herbal nanoparticles prepared from Aloe vera leaves for textile applications

Nanomaterials play a vital role in textile industries due to their unique properties and applications. There is an increase in the use of nanoscale phyto products in textiles to control the bacterial infection in fabrics. Here, natural herbal nanoparticles of different sizes were prepared from shade‐dried Aloe vera plant leaves using ball milling technique without any additives. The amorphous herbal A. vera nanoparticles possess an average particle size of 40 ± 2 nm and UV‐absorption maximum at 269 nm. A. vera nanopowders–chitosan nanocomposites were prepared and coated on cotton fabrics using pad‐dry cure method. The evaluation of antibacterial activity against Escherichia coli (22.05 ± 0.06 mm) and Staphylococcus aureus (27.17 ± 0.02 mm), UV‐protection properties (UV‐protection factor = 57.2 ± 0.1), and superhydrophobic nature (155 ± 3°) of the prepared herbal nanoparticles and their composites were analysed by disc diffusion, UV–visible spectral analysis, and contact angle analysis. Understanding the functional properties of herbal nanoparticles, coated particles on fabrics highlights their potential applications in protective clothing with better antimicrobial properties, hydrophobicity, and UV‐protection properties. This study of using A. vera herbal nanoparticles in textiles significantly enhances the fabric performance to develop protective textile fabrics in defence and biomedical fields.Inspec keywords: nanoparticles, particle size, nanofabrication, nanomedicine, antibacterial activity, biomedical materials, hydrophobicity, ultraviolet spectra, visible spectra, radiation protection, textile fibres, cotton fabrics, ball milling, X‐ray diffraction, light scattering, scanning electron microscopy, X‐ray fluorescence analysis, fluorescence, amorphous state, nanocomposites, filled polymers, protective coatings, curing, microorganisms, biodiffusion, contact angle, surface morphology, protective clothingOther keywords: UV‐blocking, antimicrobial properties, disc diffusion, UV‐visible spectral analysis, contact angle analysis, morphological characteristics, protective clothing, protective textile fabrics, biomedical fields, superhydrophobic nature, UV‐protection factor, UV‐protection properties, Staphylococcus aureus, Escherichia coli, pad‐dry cure method, cotton fabrics, A. vera nanopowders‐chitosan nanocomposites, UV‐absorption maximum, average particle size, amorphous herbal A. vera nanoparticles, X‐ray fluorescence spectrometry, scanning electron microscopy, dynamic light scattering, UV‐visible spectrophotometry, X‐ray diffraction, ball milling, shade‐dried Aloe vera plant leaves, natural herbal nanoparticle size, bacterial infection, nanoscale phyto products, textile industries, nanomaterials, textile applications     

Role of catalytic protein and stabilising agents in the transformation of Ag ions to nanoparticles by Pseudomonas aeruginosa

Biological routes of synthesising metal nanoparticles (NPs) using microbes have been gaining much attention due to their low toxicity and eco‐friendly nature. Pseudomonas aeruginosa JP2 isolated from metal contaminated soil was evaluated towards extracellular synthesis of silver NPs (AgNPs). Cell‐free extract (24 h) of the bacterial isolate was reacted with AgNO₃ for 24 h in order to fabricate AgNPs. Preliminary observations were recorded in terms of colour change of the reaction mixture from yellow to greyish black. UV‐visible spectroscopy of the reaction mixture has shown a progressive increase in optical densities that correspond to peaks near 430 nm, depicting reduction of ionic silver (Ag⁺) to atomic silver (Ag⁰) thereby synthesising NPs. X‐ray diffraction spectra exhibited the 2θ values to be 38.4577° confirming the crystalline and spherical nature of NPs [9.6 − 26.7 (Ave. = 17.2 nm)]. Transmission electron microscopy finally confirmed the size of the particles varying from 5 to 60 nm. Moreover, rhamnolipids and proteins were identified as stabilising molecules for the AgNPs through Fourier transform‐infrared spectroscopy. Characterisation of bacterial crude and purified protein fractions confirmed the involvement of nitrate reductase (molecular weight 66 kDa and specific activity = 3.8 U/mg) in the Synthesis of AgNPs.Inspec keywords: microorganisms, silver, nanoparticles, enzymes, molecular biophysics, ultraviolet spectra, visible spectra, X‐ray diffraction, transmission electron microscopy, Fourier transform infrared spectra, catalysis, biochemistry, nanobiotechnologyOther keywords: catalytic protein, stabilising agents, Pseudomonas aeruginosa, metal nanoparticles, UV–visible spectroscopy, optical densities, ionic silver, atomic silver, X‐ray diffraction spectra, transmission electron microscopy, nitrate reductase, rhamnolipids, Fourier transform‐infrared spectroscopy, Ag     

Biogenic fabrication of CuNPs,Cu bioconjugates and in vitro assessment of antimicrobial and antioxidant activity

In the present study, the authors synthesised copper nanoparticles (CuNPs) by using extract of Zingiber officinale (ginger) and later the NPs were bioconjugated with nisin, which shows antimicrobial activity against food spoilage microorganisms. CuNPs and its bioconjugate were characterised by ultraviolet–vis spectroscopy, NP tracking analysis, Zetasizer, transmission electron microscopy analysis, X‐ray diffraction and Fourier transform infra‐red (FTIR) spectroscopy. Zeta potential of CuNPs and its bioconjugate were found to be very stable. They evaluated in vitro efficacy of CuNPs and its bioconjugate against selected food spoilage bacteria: namely, Staphylococcus aureus, Pseudomonas fluorescens, Listeria monocytogenes and fungi including Fusarium moniliforme and Aspergillus niger. Antimicrobial activity of CuNPs was found to be maximum against F. moniliforme (18 mm) and the least activity was noted against L. monocytogenes (13 mm). Antioxidant activity of CuNPs and ginger extract was performed by various methods such as total antioxidant capacity reducing power assay, 1‐1‐diphenyl‐2‐picryl‐hydrazyl free radical scavenging assay and hydrogen peroxide assay. Antioxidant activity of CuNPs was higher as compared with ginger extract. Hence, CuNPs and its bioconjugate can be used against food spoilage microorganisms.Inspec keywords: antibacterial activity, biomedical materials, copper, nanoparticles, nanofabrication, nanomedicine, microorganisms, ultraviolet spectra, visible spectra, electrokinetic effects, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectra, free radical reactions, food technologyOther keywords: biogenic fabrication, Cu bioconjugates, in vitro assessment, antimicrobial activity, antioxidant activity, copper nanoparticles, Zingiber officinale, ultraviolet‐visible spectroscopy, NP tracking analysis, Zetasizer, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, FTIR, zeta‐potential, food spoilage bacteria, Staphylococcus aureus, Pseudomonas fluorescens, Listeria monocytogenes, fungi, Fusarium moniliforme, Aspergillus niger, F. moniliforme, L. monocytogenes, ginger extract, total antioxidant capacity, power assay, 1‐1‐diphenyl‐2‐picryl‐hydrazyl free radical scavenging assay, hydrogen peroxide assay, food spoilage microorganisms, Cu     

Green synthesis,characterisation and biological evaluation of AgNPs using Agave americana,Mentha spicata and Mangifera indica aqueous leaves extract

The current study was performed to synthesize stable, eco‐friendly and bio‐compatible silver nano‐particles (AgNPs) of Agave americana, Mentha spicata and Mangifera indica leaves and to screen them for biological activities. The ultraviolet‐visible spectroscopic analysis revealed that λ‐max for AgNPs range from 350–500 nm. All AgNPs possessed polycrystalline structure as notified as intense graphical peaks in complete spectrum of 20 values ranging from 10–80° in X‐ray diffraction measurements and supported by scanning electron microscopy data. The size of the nano‐particles was confirmed by transmission electron microscopy (30–150 nm). Mass loss at variable temperatures was evaluated by simultaneous thermogravimetric and differential thermal analysis revealed reduction in mass and activity of compounds was notified by temperature increase from 200 to 800 °C, thus concluding it as thermally sensitive compounds. A. americana AgNPs showed significant (96%) activity against Methicillin resistant Staphylococcus aureus, Escherichia coli (95%) and Fusarium oxysporum (89%). Good antioxidant activity was shown by M. spicata AgNPs at 300 µl (79%). M. indica AgNPs showed significant phytotoxic activity (88%) at highest concentration. No haemagglutination reaction was observed for the test samples. The above results revealed that AgNPs synthesized from selected plant species possesses significant antimicrobial and phytotoxic effect.Inspec keywords: silver, nanoparticles, nanofabrication, X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, differential thermal analysis, microorganisms, antibacterial activity, nanomedicine, particle size, toxicologyOther keywords: green synthesis, biological evaluation, Agave americana aqueous leave extract, Mentha spicata aqueous leave extract, Mangifera indica aqueous leave extract, stable ecofriendly biocompatible silver nanoparticles, ultraviolet‐visible spectroscopy, polycrystalline structure, X‐ray diffraction, scanning electron microscopy, nanoparticle size, transmission electron microscopy, thermogravimetric analysis, differential thermal analysis, mass loss, thermally sensitive compounds, Methicillin resistant Staphylococcus aureus, Escherichia coli, Fusarium oxysporum, antioxidant activity, phytotoxic activity, plant species, antimicrobial effect, temperature 200 degC to 800 degC, Ag     

Biogenic gold nanoparticles for reduction of 4‐nitrophenol to 4‐aminophenol: an eco‐friendly bioremediation

The present study investigated the synthesis of gold nanoparticles (AuNPs) using mangrove plant extract from Avicennia marina as bioreductant for eco‐friendly bioremediation of 4‐nitrophenol (4‐NP). The AuNPs synthesised were confirmed by UV spectrum, transmission electron microscopy (TEM), X‐ray diffraction, Fourier transmission infrared spectroscopy (FTIR), dynamic light scattering (DLS), and zeta potential. The AuNPs were found to be spherical in shape with size ranging from 4 to 13 nm, as evident by TEM and DLS. Further, the AuNPs were encapsulated with sodium alginate in the form of gold nano beads and used as heterogeneous catalyst and degrading agent to reduce 4‐NP. This reduction in 4‐NP into 4‐aminophenol was confirmed by UV and FTIR. The aqueous solution of 4‐NP peaked its absorbance at 320 nm, and shifted to 400 nm, with an intense yellow colour, appeared due to formation of 4‐nitrophenolate ion. After the addition of AuNps, the 4‐NP solution became colourless and peaked at 400 nm and reduced to 290 nm corresponding to the formation of 4‐aminophenol. Hence, the present work suggested the AuNPs as the potent, eco‐friendly bionanocomposite catalyst for bioremediation of 4‐NP.Inspec keywords: gold, nanoparticles, nanobiotechnology, nanofabrication, ultraviolet spectra, transmission electron microscopy, X‐ray diffraction, Fourier transform spectra, infrared spectra, electrokinetic effects, catalysts, nanocomposites, biochemistryOther keywords: biogenic gold nanoparticles, 4‐nitrophenol, 4‐aminophenol, eco‐friendly bioremediation, mangrove plant extract, Avicennia marina, bioreductant, UV spectrum, transmission electron microscopy, TEM, X‐ray diffraction, Fourier transmission infrared spectroscopy, FTIR, dynamic light scattering, DLS, zeta potential, degrading agent, 4‐nitrophenolate, bionanocomposite catalyst, size 4 nm to 13 nm, wavelength 400 nm, wavelength 290 nm, Au     

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     

Gundelia tournefortii L.: a natural source for the green synthesis of silver nanoparticles

The present study focused on the synthesis of spherical silver nanoparticles (Ag NPs) using Gundelia tournefortii L. aerial part extract. The plant extract could reduce silver ions into Ag NPs. To identify the compounds responsible for the reduction of silver ions, functional groups present in plant extract were investigated by Fourier transform infrared spectroscopy. Techniques used to characterise synthesised nanoparticles included field emission scanning electron microscopy, X‐ray diffraction and transmission electron microscopy. UV‐visible spectrophotometer showed the absorbance peak in the range of 400–450 nm. The Ag NPs showed antibacterial activities against both gram positive (Staphylococcus aureus and Bacillus Cereus) and gram negative (Salmonella typhimurium and Escherichia coli) microorganisms. The results confirmed that this protocol was simple, rapid, eco‐friendly, low‐priced and non‐toxic; therefore, it could be used as an alternative to conventional physical/chemical methods. Only 5 min were required for the conversion of silver ions into Ag NPs at room temperature, without the involvement of any hazardous chemical.Inspec keywords: nanoparticles, silver, nanofabrication, microorganisms, Fourier transform infrared spectra, transmission electron microscopy, ultraviolet spectra, visible spectraOther keywords: Ag, temperature 293 K to 298 K, chemical method, physical method, Salmonella typhimurium, Escherichia coli, gram negative microorganisms, Bacillus Cereus, Staphylococcus aureus, gram positive microorganisms, antibacterial activities, absorbance peak, UV‐visible spectrophotometer, transmission electron microscopy, X‐ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, functional groups, plant extract, Gundelia tournefortii L. aerial part extract, spherical silver nanoparticle synthesis, silver nanoparticle green synthesis, natural source     

Green synthesis and characterisation of CuNPs: insights into their potential bioactivity

The current investigation involves the green synthesis of copper nanoparticles (CuNPs) from an aqueous plant extract of Moringa oleifera Lam by two methods: (I) time‐based approach and (II) heat treatment of aqueous solution. Prepared CuNPs were characterised via Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy and transmission EM. The study also reveals the potential bioactivity of the prepared CuNPs. In vitro anti‐microbial efficiency of CuNPs was estimated against bacterial and fungal strains by the agar well diffusion method. Anti‐oxidant capacity of CuNPs was determined using ferric reducing ability of plasma (FRAP), lipid peroxidation (LPO) and peroxidase assays, while the antiplatelet potential was determined by measuring two haemostatic parameters (PT & APTT assay). The minimum inhibitory concentration was observed at 60 µg/ml against Streptomyces griseus and Aspergillus niger when NPs were prepared by method II. CuNPs prepared by the method I showed higher FRAP and LPO activities, while increased POX activity was found in CuNPs prepared by method II. CuNPs prepared using method I also showed better anti‐oxidant and antiplatelet potential. It was observed that M. oleifera ‐derived CuNPs exhibits strong anti‐microbial, anti‐oxidant and APTT potential. This indicates potential utilization of green synthesized NPs for various industrial and therapeutic strategies.Inspec keywords: nanofabrication, nanoparticles, copper, biomedical materials, nanomedicine, heat treatment, Fourier transform infrared spectra, X‐ray diffraction, scanning electron microscopy, antibacterial activity, microorganisms, cellular biophysics, enzymes, biochemistry, molecular biophysicsOther keywords: green synthesis, copper nanoparticles, aqueous plant, Moringa oleifera Lam, time‐based approach, heat treatment, aqueous solution, Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, transmission EM, potential bioactivity, in vitro antimicrobial efficiency, fungal strains, bacterial strains, agar well diffusion method, ferric reducing ability of plasma, lipid peroxidation, peroxidase assays, haemostatic parameters, Streptomyces griseus, Aspergillus niger, APTT activity, therapeutic strategies, industrial strategies, Cu