Biogenic AgNPs Research Articles

Green Biosynthesis of Silver Nanoparticles Using Eriobotrya japonica (Thunb.) Leaf Extract for Reductive Catalysis.

This article reports on silver nanoparticles (AgNPs) that were green-synthesized by using Eriobotrya japonica (Thunb.) leaf extract and their use for the catalytic degradation of reactive dyes. The properties of biogenic AgNPs were characterized using UV-vis absorption spectroscopy, field emission scanning electron microscope (FESEM), X-ray powder diffraction (XRD), transmission electron microscope (TEM), Fourier transforming infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED) analysis. The UV-vis spectroscopy and X-ray analyses confirmed the formation of AgNPs and showed the strong absorbance around 467 nm with surface plasmon resonance (SPR). The mean diameter of biogenic AgNPs at room (20 °C), moderate (50 °C), and high temperatures (80 °C) were 9.26 ± 2.72, 13.09 ± 3.66, and 17.28 ± 5.78 nm, respectively. The reaction temperature had significant impacts on the sizes of synthesized AgNPs. The higher the synthesis temperature, the larger size and the lower catalysis activity for reductive decomposition of reactive dyes via NaBH4. The results supported a bio-green approach for developing AgNPs with a small size and stable degradation activity of reactive dyes over 92% in 30 min by using Eriobotrya japonica (Thunb.) leaf extract at pH 7, 20 °C, and 1:10 ratio of silver nitrate added to the leaf extract.

Emerging Theranostic Biogenic Silver Nanomaterials for Breast Cancer: A Systematic Review

Breast cancer remains the second common cause of cancer death in United State women in 2018. Consequently, it is of growing need to explore new strategies to treat cancer at various stages of breast cancer. This review discussing the efficacy of biogenic silver nanoparticles (AgNPs) against breast cancer and/or normal cells and its mechanisms of AgNPs toxicity. The research articles were systematically collected through databases including Cochrane, Web of Science, PubMed, Scopus, Science Direct, ProQuest, Google Scholar, and Embase. Significantly, most of the studies were carried out on MCF-7 cancer cell line. Furthermore, the general approach was phyto-fabrication of AgNPs. Specifically, a hefty 71.27% of studies employed plants to bio-fabricate AgNPs. Additionally, fungi with 14.89% of the studies were the second predominant resources conducted for synthesis of AgNPs. Majority of studies bio-fabricated spherical AgNPs with an average diameter of less than 100 nm. Interestingly, the general approach suggested significant toxic effects of biogenic AgNPs with inhibitory concentration of 50% in breast cancer cell lines, while less toxicity was reported in normal cell lines. Regarding the recent advantages in cancer nanomedicine, it is expected that biogenic AgNPs may emerge as potential breast cancer therapeutic agents alone or in combination with FDA-approved anti-cancer drugs in the near future.

Photocatalytic and antibacterial potential of silver nanoparticles derived from pineapple waste: process optimization and modeling kinetics for dye removal

Green chemistry offers several benefits over other synthesis routes of nanoparticles due to their eco-friendly attributes during their formulation as well as application stages. In the present study, an aqueous extract of Ananas comosus (Pineapple) peel waste was successfully exploited for the synthesis of ultra small (average size 14–20 nm) silver nanoparticles (AgNPs) without adding any reducing or stabilizing agents. Two major factors, i.e., concentration ratio between silver ion precursor versus peel extract and synthesis pH were found to be influential for achieving monodispersed and stable AgNPs. Biogenic AgNPs adorned with natural moieties demonstrated good photocatalytic activity against methylene blue (MB) dye under sunlight illumination for various conditions. The process variable, e.g., solution pH, initial MB concentration and contact time were optimized using response surface methodology (RSM) based on three levels Box-Behnken design. A maximum MB removal of 98.04% was achieved at optimized values of 9.96 pH, 40 ppm initial dye concentration and 173 min of contact time. The kinetics of MB removal was best fitted to its first order kinetic model (R2 = 0.996) in concurrence with intraparticle diffusion-mediated adsorption. AgNPs were also found to be effective to kill pathogenic bacterial strains, Pseudomonas aeruginosa and Bacillus subtilis as characterized from zone of inhibition (ZoI) and viability tests. Undergoing photochemical reactions, the generation of reactive oxygen species (ROS) was elucidated as the major mechanism of AgNPs’ toxicity modulating membrane permeability. This strategy is not only economically viable and environmentally benign, synthesized AgNPs were capable to remove methylene blue dye almost completely under ambient conditions through solar energy.

Green tea extract mediated biogenic synthesis of silver nanoparticles: Characterization, cytotoxicity evaluation and antibacterial activity

Silver nanoparticles (AgNPs) are widely used in biomedical fields because of their potent antimicrobial activity. Biogenic synthesis of nanoparticles has gained considerable attention due to its simplicity, low cost and absence of organic solvents. This work describes the one-pot one-minute biogenic synthesis of AgNPs with a commercial green tea extract (Camellia sinensis). The tea polyphenols acted as reducing and stabilizing agents for the nanoparticles. The surface of the biogenic AgNPs was further coated with polyethylene glycol (PEG) to enhance their dispersion and biocompatibility. The obtained nanoparticles were extensively characterized by ultraviolet-visible spectroscopy (UV–vis), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), electronic and atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), dynamic light scattering and inductively coupled plasma mass spectrometry (ICP-MS). The results demonstrated the formation of spherical nanoparticles of pure Ag° coated with tea polyphenols, at the nanoscale and with moderate polydispersity. The nanoparticles did not exhibit significant toxicity to human keratinocyte (HaCaT) cells. The antimicrobial efficacy of the biogenic nanoparticles was demonstrated against gram-positive Staphylococcus aureus (ATCC 29213), gram-negative Pseudomonas aeruginosa (ATCC 27853), Klebsiella pneumoniae (ATCC 700603), Escherichia coli (ATCC 25922) and Salmonella enterica (ATCC 14028) bacterial strains. Salmonella enterica was found to be the most sensitive strain to the nanoparticles, with a minimum inhibitory concentration and minimum bactericidal concentration of 7 and 15 µg/mL, respectively. Interestingly, at the concentration range in which the AgNPs showed an antibacterial effect, they were not toxic to HaCaT mammalian cells. Thus, green tea synthesized AgNPs could find important biomedical applications in the combat of pathogenic bacteria with low cytotoxicity to normal cells.

Biogenic Nanosilver against Multidrug-Resistant Bacteria (MDRB).

Multidrug-resistant bacteria (MDRB) are extremely dangerous and bring a serious threat to health care systems as they can survive an attack from almost any drug. The bacteria’s adaptive way of living with the use of antimicrobials and antibiotics caused them to modify and prevail in hostile conditions by creating resistance to known antibiotics or their combinations. The emergence of nanomaterials as new antimicrobials introduces a new paradigm for antibiotic use in various fields. For example, silver nanoparticles (AgNPs) are the oldest nanomaterial used for bactericide and bacteriostatic purposes. However, for just a few decades these have been produced in a biogenic or bio-based fashion. This review brings the latest reports on biogenic AgNPs in the combat against MDRB. Some antimicrobial mechanisms and possible silver resistance traits acquired by bacteria are also presented. Hopefully, novel AgNPs-containing products might be designed against MDR bacterial infections.

Cytotoxic Potential and Molecular Pathway Analysis of Silver Nanoparticles in Human Colon Cancer Cells HCT116.

Silver nanoparticles (AgNPs) have gained attention for use in cancer therapy. In this study, AgNPs were biosynthesized using naringenin. We investigated the anti-colon cancer activities of biogenic AgNPs through transcriptome analysis using RNA sequencing, and the mechanisms of AgNPs in regulating colon cancer cell growth. The synthesized AgNPs were characterized using UV–visible spectroscopy (UV–vis), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and transmission electron microscopy (TEM). The AgNPs were spherical with sizes of 2–10 nm. Cytotoxicity assays indicated that the AgNPs in HCT116 colorectal cancer cells were very effective at low concentrations. The viability and proliferation of colon cancer cells treated with 5 µg/mL biogenic AgNPs were reduced by 50%. Increased lactate dehydrogenase leakage (LDH), reactive oxygen species (ROS) generation, malondialdehyde (MDA), and decreased dead-cell protease activity and ATP generation were observed. This impaired mitochondrial function and DNA damage led to cell death. The AgNPs upregulated and downregulated the most highly ranked biological processes of oxidation–reduction and cell-cycle regulation, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that AgNPs upregulated GADD45G in the p53 pathway. Thus, the AgNP tumor suppressive effects were mediated by cell apoptosis following DNA damage, as well as by mitochondrial dysfunction and cell-cycle arrest following aberrant regulation of p53 effector proteins. It is of interest to mention that, to the best of our knowledge, this study is the first report demonstrating cellular responses and molecular pathways analysis of AgNPs in HCT116 colorectal cancer cells.

Antibacterial and Cytotoxic Potential of Biosynthesized Silver Nanoparticles by Some Plant Extracts.

The provision of nanoparticles using biogenic material as a part of green chemistry is an attractive nanotechnology. The current research aimed to test the antimicrobial and cytotoxic efficacy of silver nanoparticles synthesized by extracts of Phoenix dactylifera, Ferula asafetida, and Acacia nilotica as reductant and stabilizing agents in silver nanoparticle formation. Synthesized nanoparticles were evaluated for their antimicrobial activity against Staphylococcus aureus (Gram-positive) and Pseudomonas aeruginosa and Escherichia coli (Gram-negative) using an agar well diffusion assay. Furthermore, cytotoxic ability was investigated against LoVo cells. The potential phyto-constituents of plant extracts were identified by Fourier-transform infrared spectroscopy (FT-IR) techniques. Field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), and zeta potential analyzed the size and morphology of the biogenic nanoparticles. The current study revealed the ability of the tested plant extract to convert silver ions to silver nanoparticles with an average size that ranged between 67.8 ± 0.3 and 155.7 ± 1.5 nm in diameter. Biogenic AgNPs showed significant antibacterial ability (10 to 32 mm diameter) and anticancer ability against a LoVo cell with IC50 ranged between 35.15–56.73 μg/mL. The innovation of the present study is that the green synthesis of NPs, which is simple and cost effective, provides stable nano-materials and can be an alternative for the large-scale synthesis of silver nanoparticles.

Promotion of shoot regeneration of Swertia chirata by biosynthesized silver nanoparticles and their involvement in ethylene interceptions and activation of antioxidant activity

Chemically synthesized silver nanoparticles (AgNP) have been assessed on plant tissue cultures but the impact of biologically synthesized AgNP fabricated by different phytoconstituents has not been sufficiently investigated. In this study biogenic AgNP prepared from leaf extract of Swertia chirata was utilized to address the problems associated with conservation of endangered medicinal plant through plant tissue culture. Endangered as well as economically important medicinal plant considered for this analysis was the same plant S. chirata itself. Excessive deforestation and exploration of this plant had led to complete eradication of the natural reservoir. Thus in vitro plant tissue propagation had attained much importance for maintaining the plant species. Nano-sized particles of diameter 20 nm encapped by different phytochemicals applied on regenerating shoot cultures showed enhanced shoot induction and proliferation. Other forms of silver like AgNO3 (SN) and Ag2S2O3 (STS) showed improved regeneration in comparison to control samples. Ethylene precursors like 1-aminocyclopropane-1-carboxylic acid (ACC) and 2-chloroethylphosphonic acid (CEPA) downregulated the regeneration process considerably. Reactive oxygen species (ROS) status of the treated cultures were evaluated considering hydrogen peroxide and malondialdehyde (MDA) content in treated cells as wells as their antioxidant enzyme activity. Combined manipulation and coordination of ethylene evolution, maintenance of ROS balance and better bio-acceptance of AgNP were responsible for improvement in shoot regeneration of the plant. Phytoencapsulated and nano-dimensioned Ag was capable of changing the chemical reactions of different regulating players of plant regeneration. These findings will facilitate the understanding and future utilization of biofabricated AgNP in agriculture and plant sciences.

Effect of biogenic silver nanocubes on matrix metalloproteinases 2 and 9 expressions in hyperglycemic skin injury and its impact in early wound healing in streptozotocin-induced diabetic mice

Microbial contamination along with over expressions of matrix metalloproteinases 2 and 9 impairs wound healing in diabetic patients. Silver-based antimicrobial agents have been successfully used for treating non-healing chronic wounds associated with infection. However, topical application of silver-ion compounds impairs wound healing process. Thus, usage of biogenic silver nanoparticles appears as a new means to reduce the toxicity of silver compounds in the wound care system. Here, following our previous method, AgNPs was synthesized using the culture filtrate of Brevibacillus brevis KN8(2) then characterized by UV–visible spectrophotometry, TEM, SAED, XRD and DLS measurements. The antibacterial activity of AgNPs was evaluated against the most common wound infecting pathogens Pseudomonas aeruginosa and Staphylococcus aureus by well diffusion assay. Further, the wound healing efficacy of biogenic AgNPs was examined in streptozotocin-induced diabetic mice by measuring wound area closure, histopathology, mRNA and protein expressions of MMP-2, MMP-9. Our results demonstrates that besides antimicrobial activity, biogenic AgNPs decreased the mRNA and protein expression of MMP-2 and MMP-9 in wounded granulation tissues leads to early wound healing in diabetic mice. These findings revealed that biogenic AgNPs synthesized from B. brevis KN8(2) could be an effective therapeutic agent in the management of diabetic foot ulcer with/without infection.

Fulfillment of green chemistry for synthesis of silver nanoparticles using root and leaf extracts of Ferula persica: Solid-state route vs. solution-phase method

Abstract Development of an efficient, one-pot and green preparation method of silver nanoparticles (Ag NPs) is considered in the current investigation. Aqueous extracts prepared from different parts of Ferula persica plant (i.e., root and leaf) could be employed successfully to fabricate Ag NPs, actually via two different bio-reduction approaches. Field emission scanning electron spectroscopy (FESEM) connected energy dispersive X-ray (EDX), X-Ray Diffraction (XRD), fourier transform infra-red spectroscopy (FTIR), as well as transmission electron microscopy (TEM) results evidently demonstrated the proficiency of solid-state route in the production of entirely pure and uniform Ag NPs (10–30 nm) with no aggregation using leaf part of the plant. Conversely, to fabricate Ag NPs using Ferula's root part, the solution-phase method was proposed as the best method of choice. In both methods, the efficiency of bio-reduction reaction in conjunction with the size and purity of produced Ag NPs could be controlled using adapting the weight ratios of plant extract/silver nitrate. Meanwhile, comparing to the chemically synthesized Ag NPs, the biogenic Ag NPs encompassed lower phytotoxicic effects on the germination percentage followed by shoot and root elongation of Matricaria chamomilla and Ocimum basilicum, could be accordingly nominated as an eco-friendly and more safe nano-material either in low- or high-AgNPs-demanded environments. The results, altogether, can open up a new avenue toward cleaner production of bio-compatible, pure and homogeneous Ag NPs with high throughput and low-cost and eventually a reliable way to acquire sustainable/green chemistry.

Multidimensional dose–response toxicity exploration of silver nanoparticles from Nocardiopsis flavascens RD30

In recent decades, silver nanoparticles (AgNPs) are progressively being used in various applications, nevertheless, their environment-based toxicity studies remain deficient. Hence this article shows the toxicity analysis of AgNPs synthesized from Nocardiopsis flavascens RD30 on Chloroccocum humicola, Artemia salina and Swiss albino mouse. AgNPs were extracellularly synthesized from N. flavascens RD30 extract with sunlight irradiation and the synthesized AgNPs were roughly spherical in shape, with the size range between 5 and 50 nm. Further, the toxicity study on green algae proves that, at 50 µg AgNPs concentration, there was no effect on C. humicola, however, increasing the concentration lead to the cell aggregation which is proposed as a defense mechanism by the algal populations. Similarly, in the case of A. salina, the mortality increased with the increasing concentration of AgNPs, wherein abnormalities such as the improper development of mandibles and underdeveloped endopod and endite were observed in concentrations 60 and 70 µg/mL. Finally, the oral toxicity of AgNPs was evaluated in the mouse model which is portrayed through serum biochemistry and histopathological observations of vital organs. There was no major effect on the liver function in the treated mice, while the negligible reaction was observed in kidneys and intestine of the mice treated with AgNPs after 10 days of oral exposure. Overall results indicate that the biogenic AgNPs are less/non-hazardous to the phytoplanktons, zooplanktons and higher animals when released at a minimal concentration and it could be possibly used in human and environmental applications.

NMR Metabolomics Reveals Metabolism-Mediated Protective Effects in Liver (HepG2) Cells Exposed to Subtoxic Levels of Silver Nanoparticles.

The expansion of biomedical and therapeutic applications of silver nanoparticles (AgNPs) raises the need to further understand their biological effects on human cells. In this work, NMR metabolomics has been applied to reveal the metabolic effects of AgNPs toward human hepatoma (HepG2) cells, which are relevant with respect to nanoparticle accumulation and detoxification. Cellular responses to widely disseminated citrate-coated AgNPs (Cit30) and to emergent biogenic AgNPs prepared using an aqueous plant extract as reducing and stabilizing agent (GS30) have been compared with a view to assess the influence of nanoparticle coating on the metabolic effects produced. Subtoxic concentrations (IC5 and IC20) of both nanoparticle types caused profound changes in the cellular metabolome, suggesting adaptations in energy production processes (glucose metabolism and the phosphocreatine system), antioxidant defenses, protein degradation and lipid metabolism. These signatures were proposed to reflect mainly metabolism-mediated protective mechanisms and were found to be largely common to Cit30 and GS30 AgNPs, although differences in the magnitude of response, not captured by conventional cytotoxicity assessment, were detected. Overall, this study highlights the value of NMR metabolomics for revealing subtoxic biological effects and helping to understand cell-nanomaterial interactions.

Green synthesis of silver nanoparticles mediated by Coccinia grandis and Phyllanthus emblica: a comparative comprehension

Fruit extracts also have the potentiality to synthesize silver nanoparticles, which serve as antimicrobial agent in the biological field. At present, the field of biomedical largely depends on the biosynthesized NPs to fight against the multi-drug-resistant pathogens. The fruit residue of Coccinia grandis and Phyllanthus emblica are employed for synthesizing AgNPs by green method. The NPs are further subjected to UV, FTIR, SEM, and XRD measurements. The ten different pathogens were tested against the AgNPs synthesized. The same were tested for early growth of some seed variety too, so as to check the advantages of AgNPs. The UV spectrum analysis showed 442 nm and 423 nm, respectively, and FTIR peaks for the functional group that is responsible for the conversion of NPs were observed at 1640.02 for N–H bond amines (Coccinia grandis) and at 1637.45 for N–H bond amines (Phyllanthus emblica). The SEM results also illustrated that AgNPs are spherical in shape. The XRD patterns indicate the crystalline nature of the AgNPs formed with both these plants. The antimicrobial assay of AgNPs from Coccinia grandis shows maximum zone of inhibition (14 mm) for Vibrio cholerae whereas the AgNPs from Phyllanthus emblica show maximum inhibition at distinct points, namely for Staphylococcus aureus, Vibrio cholerae, Salmonella typhi, and Proteus mirabilis (12 mm). Seed germination initiated by AgNPs is quiet effective and healthier compared to the water-induced seeds. Hence, biogenic AgNPs have various applications in favour of human society.

A nonspecific synergistic effect of biogenic silver nanoparticles and biosurfactant towards environmental bacteria and fungi

The present study focused on the evaluation of a nonspecific synergistic effect of biogenic silver nanoparticles (AgNPs) in combination with biosurfactants against environmental bacteria and fungi. The AgNPs were synthesized in the culture supernatants of the biosurfactant producer Bacillus subtilis grown in brewery effluent, molasses or Luria-Bertani media. Antibacterial activities were tested against Gram-positive and Gram-negative bacteria, while the antifungal activity was tested against phytopathogens. The interactions between biogenic AgNPs and DNA were investigated using a cryo-TEM technique. The presence of biosurfactant significantly increased the stability of biogenic AgNPs and enhanced their antimicrobial activities. The physical properties and antimicrobial activity of biogenic AgNPs were compared with chemically synthesized Ag nanoparticles. Biogenic silver nanoparticles showed a broad spectrum of activity against bacteria and fungi. They were most active against phytopathogenic fungi and Gram-positive bacteria and less active against Gram-negative bacteria. The nonspecific synergistic effect of biogenic AgNPs and biosurfactant on the phytopathogenic fungi was especially observed. In this report, the new roles of biosurfactants as a biogenic AgNPs stabilizer and enhancer of their antimicrobial properties are presented. Our results revealed that the biologically synthesized AgNPs by the biosurfactant-producing bacterium Bacillus subtilis grown on agro-industrial wastes, such as molasses and brewery effluent, could be used as a promising new nanoagent against microbes.

Garcinia indica mediated biogenic synthesis of silver nanoparticles with antibacterial and antioxidant activities.

This reports the optimization of various parameters for biogenic synthesis of Silver nanoparticles using fruit extract of Garcinia indica, popularly known as Kokum. For optimization, the effects of various parameters such as concentration of AgNO3, ratio of AgNO3 to extract, pH, incubation temperature and time were varied and studied for their effect on synthesis. 1.5 mM AgNO3, 1:1 ratio of AgNO3 to Kokum fruit extract, pH 10, incubation of reaction mixtures at 37 °C for 24 h were the optimum parameter for biogenic synthesis. The biogenic AgNPs were then characterized by UV-vis absorption spectroscopy, fourier transform infra-red (FT-IR) spectroscopy, field emission scanning electron microscope (FE-SEM) imaging, energy dispersive X-ray (EDS) spectrometer, X-ray powder diffractometer (XRD), transmission electron microscope (TEM) imaging and the selected area electron diffraction (SAED) pattern. The biogenic AgNPs alone and in combination with Tetracyclin showed antibacterial activity against the four of seven tested bacteria. In addition, biogenic AgNPs also demonstrated good antioxidant activities such as DPPH, hydrogen peroxide, nitric oxide (NO) radical scavenging and reducing power activities. This study demonstrates that Garcinia indica fruit extract can be used for biogenic production of AgNPs with potential antibacterial and antioxidant activities that can be exploited for commercial biomedical application.

Synthesis, characterization and evaluation of antimicrobial and cytotoxic activities of biogenic silver nanoparticles synthesized from Streptomyces xinghaiensis OF1 strain

We report synthesis of silver nanoparticles (AgNPs) from Streptomyces xinghaiensis OF1 strain, which were characterised by UV–Vis and Fourier transform infrared spectroscopy, Zeta sizer, Nano tracking analyser, and Transmission electron microscopy. The antimicrobial activity of AgNPs alone, and in combination with antibiotics was evaluated against bacteria, namely Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis, and yeasts viz., Candida albicans and Malassezia furfur by using micro-dilution method. The minimum inhibitory concentration (MIC) and minimum biocidal concentration of AgNPs against bacterial and yeast strains were determined. Synergistic effect of AgNPs in combination with antibacterial and antifungal antibiotics was determined by FIC index. In addition, MTT assay was performed to study cytotoxicity of AgNPs alone and in combination with antibiotics against mouse fibroblasts and HeLa cell line. Biogenic AgNPs were stable, spherical, small, polydispersed and capped with organic compounds. The variable antimicrobial activity of AgNPs was observed against tested bacteria and yeasts. The lowest MIC (16 µg ml−1) of AgNPs was found against P. aeruginosa, followed by C. albicans and M. furfur (both 32 µg ml−1), B. subtilis and E. coli (both 64 µg ml−1), and then S. aureus and Klebsiella pneumoniae (256 µg ml−1). The high synergistic effect of antibiotics in combination with AgNPs against tested strains was found. The in vitro cytotoxicity of AgNPs against mouse fibroblasts and cancer HeLa cell lines revealed a dose dependent potential. The IC50 value of AgNPs was found in concentrations of 4 and 3.8 µg ml−1, respectively. Combination of AgNPs and antibiotics significantly decreased concentrations of both antimicrobials used and retained their high antibacterial and antifungal activity. The synthesis of AgNPs using S. xinghaiensis OF1 strain is an eco-friendly, cheap and nontoxic method. The antimicrobial activity of AgNPs could result from their small size. Remarkable synergistic effect of antibiotics and AgNPs offer their valuable potential in nanomedicine for clinical application as a combined therapy in the future.

Biogenic synthesis, optical, catalytic, and in vitro antimicrobial potential of Ag-nanoparticles prepared using Palm date fruit extract

Silver nanoparticles (AgNPs) have been synthesized via green route using an aqueous extract of Palm date fruit pericarp extract. The appearance of the yellow color and the surface resonance plasmon (SRP) band at around 400–450nm in UV–Visible spectroscopy initially reveals the formation of AgNPs. The particle size, crystalline nature, and size distribution was confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) ring patterns, energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) techniques. The particles size ranged ca. 3nm to 30nm and are spherical in shape. The microbial activity of biogenic AgNPs was tested on clinical multiple drug resistance Staphylococcus aureus, Escherichia coli and Candida albicans reference strain. Zones of inhibition growth increases with [AgNPs]. The results suggest that the particle tested in this study certainly mediate the inhibition of bacterial and fungus growth. To overcome the serious problems related to environment like discharge of hazardous chemicals to water bodies, AgNPs have been found to be very important in the catalytic degradation of 4-nitrophenol. The rate of degradation strongly depends on the sun light exposure. Based on the chemical and kinetic studies, an attempt has been made to elucidate the mechanism of AgNPs formation.

Facile and eco-friendly fabrication of AgNPs coated silk for antibacterial and antioxidant textiles using honeysuckle extract

Recently, there is a growing trend towards the functionalization of silk through nanotechnology for the prevention of fiber damage from microbial attack and the enhancement of hygienic aspects. Considering sustainable development and environmental protection, the eco-friendly fabrication of silver nanoparticles (AgNPs)-modified silk using natural extracts has currently become a hot research area. This study presents a facile strategy for the fabrication of colorful and multifunctional silk fabric using biogenic AgNPs prepared by honeysuckle extract as natural reductant and stabilizing agents. The influences of pH and reactant concentrations on the AgNPs synthesis were investigated. The color characteristics and functionalities of AgNPs treated silk were evaluated. The results revealed that the particle size of AgNPs decreased with increasing pH. The diameter of AgNPs decreased with increasing amount of honeysuckle extract and reducing amount of silver nitrate. The transmission electron microscopy image showed that the AgNPs were spherical in shape with a narrow size distribution. The treated silk showed excellent antibacterial activities against E. coli and S. aureus, and certain antioxidant activity. Both of the antibacterial and antioxidant activities were well maintained even after 30 washing cycles. This work provides a sustainable and eco-friendly approach to the fabrication of AgNPs coated silk for colorful and long-term multifunctional textiles using honeysuckle extract.

Phytofabrication of silver nanoparticles using Myriostachya wightiana as a novel bioresource, and evaluation of their biological activities

ABSTRACT Nanobiotechnology deals with the properties of nanomaterials and their potential uses. Here we report for the first time novel, cost-effective and eco-friendly method for the rapid green synthesis of silver nanoparticles (AgNPs) using leaf extracts of Myriostachya wightiana. The growth of silver nanoparticles was monitored by UV-vis spectroscopy complemented by Zeta potential, dynamic light scattering technique (DLS), Fourier-transform infrared spectroscopy (FTIR), Transmission electron microscope (TEM) and X-ray diffraction (XRD). The surface plasmon resonance (SPR) band found at 434 nm confirmed the reduction of AgNO 3 to AgNPs. TEM micrographs revealed that AgNPs are irregular in shape with the size range from 15-65 nm. The functional groups responsible for bio-reduction of silver nitrate into silver were analyzed by FTIR and confirmed by X-ray photoelectron spectrum (XPS). Further these biogenic AgNP were evaluated for insecticidal activities against stored product pests, Tribolium castaneum (Flour beetle), Rhyzopertha dominica (F.)(Lesser grain borer) and Sitophilus oryzae L (Rice weevil). The fabricated AgNPs showed moderate activity on stored pests and strong antibacterial activity with varying degrees against Xanthomonas campestris and Ralstonia solanacearum as evidenced by their zone of inhibition at all concentrations. Hence, these AgNP can be used as control agents against agricultural pests and pathogens in future.

Biomimetic synthesis and anticancer activity ofEurycoma longifoliabranch extract‐mediated silver nanoparticles

In the present study, silver nanoparticles (AgNPs) were synthesised by adding 1 mM Ag nitrate solution to different concentrations (1%, 2.5%, 5%) of branch extracts of Eurycoma longifolia, a well known medicinal plant in South–East Asian countries. Characterisation of AgNPs was carried out using techniques such as ultraviolet–visible spectrophotometry, X-ray diffractrometry, Fourier transform infrared–attenuated total reflection spectroscopy (FTIR–ATR), scanning electron microscopy. XRD analysis revealed face centre cubic structure of AgNPs and FTIR–ATR showed that primary and secondary amide groups in combination with the protein molecules present in the branch extract were responsible for the reduction and stabilisation of AgNPs. Furthermore, antioxidant [2,2-diphenyl-1-picrylhydrazyl and 2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulphonic acid)], antimicrobial and anticancer activities of AgNPs were investigated. The highest bactericidal activity of these biogenic AgNPs was found against Escherichia coli with zone inhibition of 11 mm. AgNPs exhibited significant anticancer activity against human glioma cells (DBTRG and U87) and human breast adenocarcinoma cells (MCF-7 and MDA-MB-231) with IC50 values of 33, 42, 60 and 38 µg/ml.