Tansy fruit mediated greener synthesis of silver and gold nanoparticles

In this paper we have reported the green synthesis of silver (AgNPs) and gold (AuNPs) nanoparticles by reduction of silver nitrate and chloroauric acid solutions, respectively, using fruit extract of Tanacetum vulgare; commonly found plant in Finland. The process for the synthesis of AgNPs and AuNPs is rapid, novel and ecofriendly. Formation of the AgNPs and AuNPs were confirmed by surface plasmon spectra using UV–Vis spectrophotometer and absorbance peaks at 452 and 546 nm. Different tansy fruit extract concentration (TFE), silver and gold ion concentration, temperature and contact times were experimented in the synthesis of AgNPs and AuNPs. The properties of prepared nanoparticles were characterized by TEM, XRD, EDX and FTIR. Finally zeta potential values at various pH were analyzed along with corresponding SPR spectra.     

The synthesis of chitosan-based silver nanoparticles and their antibacterial activity

Chitosan-based silver nanoparticles were synthesized by reducing silver nitrate salts with nontoxic and biodegradable chitosan. The silver nanoparticles thus obtained showed highly potent antibacterial activity toward both Gram-positive and Gram-negative bacteria, comparable with the highly active precursor silver salts. Silver-impregnated chitosan films were formed from the starting materials composed of silver nitrate and chitosan via thermal treatment. Compared with pure chitosan films, chitosan films with silver showed both fast and long-lasting antibacterial effectiveness against Escherichia coli. The silver antibacterial materials prepared in our present system are promising candidates for a wide range of biomedical and general applications.     

Green synthesis of silver nanoparticles using Ocimum canum and their anti-bacterial activity

Green synthesis of nanoparticles is an important area in the field of nanotechnology, which has cost effective and environment friendly benefit over physical and chemical methods. The present study aims at preparation of silver nanoparticles through green route using leaves of Ocimum canum Sims, a widely distributed medicinal herb. The synthesized silver nanoparticles were characterized by SEM and XRD. The spherical and rod like morphological shapes were proven by SEM techniques. Crystallographic structure was confirmed by XRD and average particle size of synthesized silver nanoparticles was calculated which was found to be of 15.72 nm. The antibacterial activity of these prepared silver nanoparticles against pathogenic bacterium Escherichia coli (E. coli) has shown the highest ZOI of 2.45 cm at 30 ppm.     

Eco-friendly synthesis of silver nanoparticles by Bacillus subtilis and their antibacterial activity

Bacillus subtilis was used for biogenic of silver nanoparticles. Characterization of the prepared silver nanoparticles was done by UV–Vis spectroscopy, Transmission Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FT-IR). The particle size of the prepared nanoparticles ranges from 3 to 20 nm with spherical or roughly spherical forms. The antimicrobial efficacy of the produced nanoparticles was investigated against five strains of multidrug resistant microorganisms including: Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Klebsiella. pneumoniae, Escherichia coli and Candida albicans tested as yeast. During this study, the minimum inhibitory concentrations (MICs) and the minimum lethal concentrations (MLCs) of synthesized silver nanoparticles were detected using selected strains of the genus Bacillus by a broth dilution method. The rate of MIC of the prepared silver nano-particles versus the investigated clinical isolates exhibit a massive anti-microbial efficacy; (230 µgml⁻¹) for MRSA; 180 for Staphylococcus epidermidis, 200 for Escherichia coli and 100 µgml⁻¹ for Candida albicans. On the other hand, the lowest anti-microbial efficacy (300 µgml⁻¹) was appeared for Klebsiella pneumonia. The obtained results demonstrated the effectiveness of the biogenic nanoparticles and the possibility of using them as a new method in combating infectious diseases.     

Pine cone-mediated green synthesis of silver nanoparticles and their antibacterial activity against agricultural pathogens

The medicinal and physicochemical properties of nanoscale materials are strong functions of the particle size and the materials used in their synthesis. The nanoparticle shape also contributes significantly to their medicinal properties. Several shapes ranging from oval, spherical, rods, to teardrop structures may be obtained by chemical methods. Triangular and hexagonal nanoparticles have been synthesized by using a pine cone extract (PCE). Here, we report the discovery that PCE, when reacted with silver nitrate ions, yields a high percentage of thin, flat, single-crystalline nanohexagonal and nanotriangular silver nanoparticles. The nanohexagonal and nanotriangular nanoparticles appear to grow by a process involving rapid reduction with assembly at room temperature at a high pH. The nanoparticles were characterized by UV–Vis absorption spectroscopy, SEM-EDS, TEM, FTIR, and X-ray diffraction analyses. The anisotropy of the nanoparticle shape results in large near-infrared absorption by the particles. Highly anisotropic particles are applicable in various fields, including agriculture and medicine. The obtained silver nanoparticles (Ag NPs) had significant antibacterial action on both Gram classes of bacteria associated with agriculture. Because the Ag NPs are encapsulated with functional group-rich PCE, they can be easily integrated in various applications.     

Entomofaunal survey and larvicidal activity of greener silver nanoparticles: A perspective for novel eco-friendly mosquito control

The entomofaunal survey and its toxicity of Blumea mollis (Asteraceae) leaf aqueous extract-mediated (Bm-LAE) silver nanoparticles (AgNPs) were assessed against selected human vector mosquitoes (HVMs). A total of 1800 individuals of 29 species belongs to 7 genera were identified. Month-wise and Genus-wise abundance of HVMs larval diversity were calculated and one-way ANOVA statistically analyzed the average physico-chemical characteristics. The relationship between physicochemical characteristics and HVMs larvae in KWS was interpreted. The total larval density and container index were 23530.18 and 1961.85 examined against 10 different containers. Various spectroscopic and microscopic investigation characterized Bm-AgNPs. The Bm- AgNPs tested against HVMs larvae, the predominant LC₅₀/LC₉₀ values of 18.17/39.56, 23.45/42.49 and 21.82/40.43 μg/mL were observed on An. subpictus Cx. vishnui and Ae. vittatus, respectively. The findings of this investigation, improperly maintained drainages, containers and unused things in study sites, are engaged to HVMs development. This will be essential for designing and implementing HVMs control. The larval toxic potentiality of Bm- AgNPs had a prompt, inexpensive and compelling synthesis of multi-disperse action against HVMs.     

Biosynthesis of silver nanoparticles using Malva parviflora and their antifungal activity

Cheeseweed mallow (Malva parviflora L.) was used to biosynthesize silver nanoparticles. The biosynthesized silver nanoparticles were classified by UV–vis Spectroscopy and Fourier-Transform Infrared Spectroscopy (FT-IR). The shape and size distribution were visualized by Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FE-SEM), and Zeta potential analysis. The chemical composition of M. parviflora leaf extract was identified by Gas Chromatography and Mass Spectroscopy (GC/MS). Finally, in vitro antifungal assay was done to assess the potential of biosynthesized silver nanoparticles and crude leaf extract of M. parviflora for inhibiting the mycelial growth of phytopathogenic fungi. The UV–vis analysis manifests the formation of silver nanoparticles. FTIR analysis established that chemicals of the leaf extract stabilized the biosynthesized silver nanoparticles by binding with the free silver ions. The TEM, FE-SEM and zeta potential analyzer confirmed that the biosynthesized silver nanoparticles were mostly spherical with an average diameter of 50.6 nm. The biosynthesized silver nanoparticles and leaf extract of M. parviflora effectively mitigate the mycelial growth of Helminthosporium rostratum, Fusarium solani, Fusarium oxysporum, and Alternaria alternata. The maximum reduction in mycelial growth by biosynthesized nanoparticles was observed against H. rostratum (88.6%). Whereas, the leaf extract of M. parviflora was most effective against F. solani (65.3%). Thus, the biosynthesis of nanoparticle assisted by M. parviflora is a feasible and eco-friendly method for the synthesis of silver nanoparticles. Further the silver nanoparticles and leaf extract of M. parviflora could be explored for the development of the fungicide.     

Green synthesis,characterization and biological activity of Solanum trilobatum-mediated silver nanoparticles

Biologically inspired synthesis of nanoparticles was found to be more attractive in metal nanoparticle synthesis. The present study reported an in-situ biogenic synthesis of silver nanoparticles (AgNPs) using Solanum trilobatum aqueous leaf extract. On this basis, the aqueous leaf extract of S. trilobatum acted as a reducing agent and stabilizing agent to synthesize highly stable AgNPs at ambient temperature. Eventually, the synthesized and stabilized AgNPs surface plasmon resonance was near 430 nm through a UV–visible (UV–vis) spectrophotometer. Here, the stability of the silver colloids monitored through zeta potential and mean particle size was evaluated through diffraction light scattering (DLF). Further, the average particle size was found to be 27.6 nm and spherical, confirmed with transmission electron microscopy (TEM). Also, colloidal AgNPs and aqueous extract are found to be rich sources of antioxidants and exhibit higher free radical scavenging ability. Thus, efficient inhibition with COX1 and COX2 enzymes and the protective effect with human red blood cell (HRBC) membrane stability showed significant results. These features are promising, suggesting the possibility of the AgNPs to be useful to disease-modifying for treating inflammatory disorders and associated complications.     

Green synthesis of silver and gold nanoparticles using Zingiber officinale root extract and antibacterial activity of silver nanoparticles against food pathogens

In the present study, we synthesized silver and gold nanoparticles with a particle size of 10–20 nm, using Zingiber officinale root extract as a reducing and capping agent. Chloroauric acid (HAuCl₄) and silver nitrate (AgNO₃) were mixed with Z. officinale root extract for the production of silver (AgNPs) and gold nanoparticles (AuNPs). The surface plasmon absorbance spectra of AgNPs and AuNPs were observed at 436–531 nm, respectively. Optimum nanoparticle production was achieved at pH 8 and 9, 1 mM metal ion, a reaction temperature 50 °C and reaction time of 150–180 min for AgNPs and AuNPs, respectively. An energy-dispersive X-ray spectroscopy (SEM–EDS) study provides proof for the purity of AgNPs and AuNPs. Transmission electron microscopy images show the diameter of well-dispersed AgNPs (10–20 nm) and AuNPs (5–20 nm). The nanocrystalline phase of Ag and Au with FCC crystal structures have been confirmed by X-ray diffraction analysis. Fourier transform infrared spectroscopy analysis shows the respective peaks for the potential biomolecules in the ginger rhizome extract, which are responsible for the reduction in metal ions and synthesized AgNPs and AuNPs. In addition, the synthesized AgNPs showed a moderate antibacterial activity against bacterial food pathogens.     

Development and evaluation of different strategies for the clean synthesis of silver nanoparticles using Yarrowia lipolytica and their antibacterial activity

An environment-friendly, cheap method, biogenic synthesis of silver nanoparticles (AgNPs) is interesting as compared to physical and chemical synthesis methods. The aim of the present study was to utilize the inherent capability of Yarrowia lipolytica as a novel biocatalyst for green production of AgNPs using different strategies, including growing cells, resting cells, and cell-free extracts (CFE) under optimized reaction conditions. The produced AgNPs were evaluated with UV–vis spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, and Fourier transform infrared spectrometry. In the growing cells strategy, Y. lipolytica produced spherical AgNPs under the optimized conditions, 2.5 mM of silver ions, 7.5 g/l of yeast biomass, a temperature of 30 °C, a pH of 6, and a shaking rate of 50 rpm after 48 h. The sizes and monodispersity of the AgNPs in the resting cells strategy were better than those in the other two. However, the AgNPs were produced faster in the CFE strategy. The antibacterial activity and minimal inhibitory concentration of the AgNPs against certain Gram-positive and Gram-negative bacteria were determined by the agar well diffusion and broth microdilution methods. The AgNPs had a considerable antibacterial effect compared to chloramphenicol as a broad-spectrum antibiotic.     

Biosynthesis of silver nanoparticles using Penicillium verrucosum and analysis of their antifungal activity

The present study describes the biosynthesis of silver nanoparticles, using the fungus Penicillium verrucosum. The silver nanoparticles were synthesised by reacting silver nitrate (AgNO₃) with the cell free filtrates of the fungal culture, and were then characterized by UV–visible spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive, and X-ray diffraction analysis to further evaluate their successful biosynthesis, optical and morphological features (size and shape), and crystallinity. The bioactivity of the synthesized nanoparticles against two phytopathogenic fungi i.e: Fusarium chlamydosporum and Aspergillus flavus was evaluated using nanomaterial seeding media. These biogenic silver nanoparticles were polydisperse in nature, with a size of 10–12 nm. With regard to the antifungal activity, 150 ppm of the nanoparticles suppressed the growth of F. chlamydosporum and A. flavus by about 50%. To the best of our knowledge, this is the first report on the use of P. verrucosum to synthesise silver nanoparticles. The present study demonstrates a novel, simple, and eco-friendly process for the generation of biofunctionally useful biogenic nanoparticles.     

Biosynthesis of silver nanoparticles by natural precursor from clove and their antimicrobial activity

Silver nanoparticles (AgNPs) have attracted the attention of researchers because of their unique properties and applications in various fields, such as medicine, catalysis, textile engineering, and pollution treatment. The green synthesis of AgNPs has many advantages, such as less time requirement, highly stable AgNPs, better control over crystal growth, morphology, ease for scale up, and economic viability. Syzygium aromaticum (clove) was used for the extracellular biosynthesis of AgNPs. Eugenols are the active biomolecules present in clove, responsible for the bioreduction of AgNO₃ (Ag⁺) leading to the formation and capping of AgNPs (Ag⁰). One molecule of eugenol releases two electrons and these two electrons will be taken by 2 Ag⁺ ions and these will get reduced to 2 Ag⁰. The synthesis of AgNPs was confirmed by the appearance of brown colour. The synthesized AgNPs were characterised by various techniques, such as UV-VIS spectroscopy, transmission electron microscopy, X-ray diffraction and Fourier transformed infrared spectroscopy. The synthesised AgNPs have λ _max of 440 nm. It was evaluated that the AgNPs were biphasic in nature (cubic + hexagonal) with an average size of 50.0 nm. The synthesized AgNPs showed significant antimicrobial activity against Bacillus cereus NCDC 240 as they are nano-sized and have high surface area to volume ratio. AgNPs inhibit the growth of bacteria by various ways, such as by disrupting the cell membrane of bacteria, uncoupling the oxidative phosphorylation, inhibiting the DNA replication, forming free radicals and affecting the cellular signalling of bacteria leading to cell death.     

Mycosynthesis and characterization of silver nanoparticles and their activity against some human pathogenic bacteria

The aim of this study was to biosynthesis silver nanoparticles from the fungus Nigrospora sphaerica isolated from soil samples and to examine their activity against five human pathogenic strains of bacteria viz. Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi and Staphylococcus aureus using disc diffusion method. The synergistic effect of silver nanoparticles in combination with commonly used antibiotic Gentamycin against the selected bacteria was also examined. The synthesized silver nanoparticles from free-cell filtrate were characterized by using UV–Vis spectrophotometer analysis, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). UV–Vis spectrophotometer analysis showed a peak at 420 nm indicating the synthesis of silver nanoparticles, FTIR analysis verified the detection of protein capping of silver nanoparticles while SEM micrographs revealed that the silver nanoparticles are dispersed and aggregated and mostly having spherical shape within the size range between 20 and 70 nm. The synthesized silver nanoparticles exhibited a varied growth inhibition activity (15–26 mm diam inhibition zones) against the tested pathogenic bacteria. A remarkable increase of bacterial growth inhibition (26–34 mm diam) was detected when a combination of silver nanoparticles and Gentamycin was used. A significant increase in fold area of antibacterial activity was observed when AgNPs in combination with Gentamycin was applied. The synthesized silver nanoparticles produced by the fungus N. sphaerica is a promising to be used as safe drug in medical therapy due to their broad spectrum against pathogenic bacteria.     

Synthesis of silver nanoparticles by endosymbiont Pseudomonas fluorescens CA 417 and their bactericidal activity

The present study emphasizes on biogenic synthesis of silver nanoparticles and their bactericidal activity against human and phytopathogens. Nanoparticle synthesis was performed using endosymbiont Pseudomonas fluorescens CA 417 inhabiting Coffea arabica L. Synthesized nanoparticles were characterized using hyphenated spectroscopic techniques such as UV–vis spectroscopy which revealed maximum absorption 425 nm. Fourier transform infrared spectroscopy (FTIR) analysis revealed the possible functional groups mediating and stabilizing silver nanoparticles with predominant peaks occurring at 3346 corresponding to hydroxyl group, 1635 corresponding carbonyl group and 680 to aromatic group. X-ray diffraction (XRD) analysis revealed the Bragg’s diffraction pattern with distinct peaks at 38° 44°, 64° and 78° revealing the face-centered cubic (fcc) metallic crystal corresponding to the (111), (200), (220) and (311) facets of the crystal planes at 2θ angle. The energy dispersive X-ray spectroscopy (EDS) analysis revealed presence of high intense absorption peak at 3 keV is a typical characteristic of nano-crystalline silver which confirmed the presence of elemental silver. TEM analysis revealed the size of the nanoparticles to be in the range 5–50 nm with polydisperse nature of synthesized nanoparticles bearing myriad shapes. The particle size determined by Dynamic light scattering (DLS) method revealed average size to be 20.66 nm. The synthesized silver nanoparticles exhibited significant antibacterial activity against panel of test pathogens. The results showed Klebsiella pneumoniae (MTCC 7407) and Xanthomonas campestris to be more sensitive among the test human pathogen and phyto-pathogen respectively. The study also reports synergistic effect of silver nanoparticles in combination with kanamycin which displayed increased fold activity up to 58.3% against Klebsiella pneumoniae (MTCC 7407). The results of the present investigation are promising enough and attribute towards growing scientific knowledge on development of new antimicrobial agents to combat drug resistant microorganisms. The study provides insight on emerging role of endophytes towards reduction of metal salts to synthesize nanoparticles.     

Phyconanotechnology: synthesis of silver nanoparticles using brown marine algae Cystophora moniliformis and their characterisation

Biosynthesis of metallic nanoparticles is a relatively new developing area of nanotechnology which has economic and environmentally friendly advantages over conventional chemical and physical methods of synthesis. In this paper, we report for the first time, on the synthesis of silver nanoparticles (AgNPs) using the Australasian brown marine algae Cystophora moniliformis. An extract of this alga was used as a reducing and stabilising agent. Temperature-dependent variation of the size of the AgNPs was observed. Agglomeration of the nanoparticles was observed at high temperatures. The average size of the AgNPs formed at temperatures?<?65°C was 75 nm, whereas they were >2 μm at higher temperatures. The X-ray diffraction (XRD) pattern revealed face-centered cubic structure of the formed Ag nanoparticles.     

Morphology and antibacterial activity of carbohydrate-stabilized silver nanoparticles

Silver nanoparticles were prepared by a simple hydrothermal route and chemical reduction using carbohydrates (sucrose, soluble and waxy corn starch) as reducing as well as stabilizing agents. The crystallite size of these nanoparticles was evaluated from X-ray diffraction (XRD) and transmission electron microscopy (TEM) and was found to be 25 nm. The effect of carbohydrates on the morphology of the silver nanocomposites was studied using scanning EM (SEM). The nanocomposites exhibited interesting inhibitory as well as bactericidal activity against both Gram positive and Gram negative bacteria. Incorporation of silver also increased the thermal stability of the carbohydrates.     

Instant green synthesis of silver nanoparticles using Terminalia chebula fruit extract and evaluation of their catalytic activity on reduction of methylene blue

A novel green approach for the synthesis and stabilization of silver nanoparticles (AgNPs) using water extract of Terminalia chebula (T. chebula) fruit under ambient conditions is reported in this article. The instant formation of AgNPs was analyzed by visual observation and UV–visible spectrophotometer. Further the effect of pH on the formation of AgNPs was also studied. The synthesized AgNPs were characterized by FT-IR, XRD, HR-TEM with EDS and DLS with zeta potential. Appearance of brownish yellow color confirmed the formation of AgNPs. In the neutral pH, the stability of AgNPs was found to be high. The stability of AgNPs is due to the high negative values of zeta potential and capping of phytoconstituents present in the T. chebula fruit extract which is evident from zeta potential and FT-IR studies. The XRD and EDS pattern of synthesized AgNPs showed their crystalline structure, with face centered cubic geometry oriented in (1 1 1) plane. HR-TEM and DLS studies revealed that the diameter of stable AgNPs was approximately 25 nm. Moreover the catalytic activity of synthesized AgNPs in the reduction of methylene blue was studied by UV–visible spectrophotometer. The synthesized AgNPs are observed to have a good catalytic activity on the reduction of methylene blue by T. chebula which is confirmed by the decrease in absorbance maximum values of methylene blue with respect to time using UV–visible spectrophotometer and is attributed to the electron relay effect.