Comparative antibacterial potential of silver nanoparticles prepared via chemical and biological synthesis

New and improved approaches are urgently needed to fight the increasing number of multi-drug resistant bacteria. The antibacterial effect of silver nanoparticles (AgNPs) prepared by standardized chemical and biological syntheses is compered here. Biological systems included extracts of Opuntia ficus-indica mucilage and extracellular growth broth of Aspergillus niger and Bacillus megaterium. The nanoparticles were characterized by infrared spectroscopy, IR, and transmission electron microscopy. All of the AgNPs shared characteristic IR peaks and had an average size of 20–60 nm. The AgNPs were mainly spherical regardless of synthetic path. The synthesis based on the extracellular broth of the fungus, due to the highest biomass and active compounds concentration, resulted in a high yield of nanoparticle formation. These AgNPs also exhibited the highest inhibition zone against Salmonella typhimurium and Staphylococcus aureus. The syntheses reported here have no significant influence on AgNPs physical characteristics, as compared to literature, but represent processes with shorter reaction time. Additionally, the fungal based nanoparticles have superior antibacterial characteristics.     

Effect of Curcuma longa tuber powder extract on size of silver nanoparticles prepared by green method

Biosynthesis of noble metal nanoparticles is a vast developing area of research. In the present study, silver nanoparticles (Ag-NPs) were synthesized from aqueous silver nitrate through a simple and biosynthetic route using water extract of Curcuma longa (C. longa) tuber powder, which acted simultaneousl as a reductant and stabilizery. The as-prepared samples are characterized using UV–Visible, XRD, TEM, SEM, EDXF, and FT-IR techniques. The formation of Ag-NPs is evidenced by the appearance of the signatory brown color of the solution and UV–vis spectra. Formation of Ag/C. longa was determined by UV–Vis spectroscopy where surface plasmon absorption maxima can be observed at 457–415 nm from the UV–Vis spectrum. The XRD analysis shows that the Ag-NPs are of a face-centered cubic structure. Well-dispersed Ag-NPs with anisotropic and isotropic morphology for 5, 10, and 20 mL of C. longa water extract having a size less than 10 nm are seen in TEM images. The optimum volume extraction to synthesize smallest particle size was 20 mL with mean diameter and standard division 4.90 ± 1.42 nm. FT-IR spectrum indicates the presence of different functional groups in capping the nanoparticles with C. longa. The zeta potential analysis results indicated that the charge of C. longa was negative and increased in Ag/C. longa emulsion with increasing of volumes of extract used (10–20 mL). The most needed outcome of this work will be the development of value-added products from C. longa for biomedical and nanotechnology-based industries.     

Catalytic and antibacterial evaluation of silver nanoparticles synthesized by a green approach

In this work, silver nanoparticles were synthesized using Salvia microphylla Kunth leaves extract as reducing agent and stabilizing agent. The effect of reaction time and plant extract amount on the biosynthesized nanoparticles were studied. The UV–Vis spectrum indicated that silver nanoparticles show a characteristic surface plasmon resonance at 427 nm. X-ray diffraction experiments show that the silver nanoparticles have a face-centered cubic crystal structure. The density of nanoparticles increases with increasing extract concentration and reaction time. TEM and SEM observations showed well-dispersed quasi-spherical nanoparticles sized in the range of 15–45 nm. The FT-IR analysis suggested the involvement of phenolic compounds in the reduction and stabilization of silver nanoparticles. Synthesized silver nanoparticles showed good antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Finally, the catalytic properties of silver nanoparticles were demonstrated through the degradation of congo red and methyl orange.     

Investigation of physicochemical properties of CuSn-based PAN nanofibers prepared via electrospinning method

Copper-tin (CuSn) nanomaterials have been receiving substantial attention due to their excellent thermal, electrical, and optical properties. However, how such properties are affected based on heat treatment temperature and chemical composition of copper and tin is still not very well understood. In this paper, CuSn nanofibers were fabricated by electrospinning a precursor solution of polyacrylonitrile, copper, and tin. Calcination temperatures were selected using thermogravimetric/differential thermal analysis (TG/DTA) and Fourier transform infrared (FT-IR) results. Analytical techniques such as scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet photoelectron spectroscopy (UPS) were employed to investigate the physicochemical properties of the CuSn nanofibers. SEM images and EDS revealed the formation of pores on the nanofibers and high concentrations of tin were in the core, while copper was located on the surface. XRD results confirmed the monoclinic phase of Cu₆Sn₅ for the CuSn nanofibers because peaks for diffraction angles at 27.6°, 53.4°, and 60.0° were observed. XPS results showed that Cu―C and Sn―C bonds occur at binding energies around 932 and 484 eV, respectively. The work function of the CuSn NF heat treated at 150°C was calculated from the UPS spectra, and the value was 4.19 eV.     

Alga-mediated facile green synthesis of silver nanoparticles: Photophysical,catalytic and antibacterial activity

A facile, convenient and green method has been employed for the synthesis of silver nanoparticles (AgNPs) using dried biomass of a green alga, Chlorella ellipsoidea. The phytochemicals from the alga, as a mild and non-toxic source, are believed to serve as both reducing and stabilizing agents. The formation of silver nanoparticles was confirmed from the appearance of a surface plasmon resonance band at 436 nm and energy dispersive X-ray spectroscopy. The transmission electron microscopy images showed the nanoparticles to be nearly spherical in shape with different sizes. A dynamic light scattering study revealed the average particle size to be 220.8 ± 31.3 nm. Fourier transform infrared spectroscopy revealed the occurrence of alga-derived phytochemicals attached to the outer surface of biogenically accessed silver nanoparticles. The powder X-ray diffraction study revealed the face-centred cubic crystalline structure of the nanoparticles. The as-synthesized biomatrix-loaded AgNPs exhibited a high photocatalytic activity for the degradation of the hazardous pollutant dyes methylene blue and methyl orange. The catalytic efficiency was sustained even after three reduction cycles. A kinetic study indicated the degradation rates to be pseudo-first order with the degradation rate being 4.72 × 10⁻² min⁻¹ for methylene blue and 3.24 × 10⁻² min⁻¹ for methyl orange. The AgNPs also exhibited significant antibacterial activity against four selected pathogenic bacterial strains.     

Highly antibacterial hydrogels prepared from amino cellulose,dialdehyde xylan,and Ag nanoparticles by a green reduction method

Cellulose - Hydrogels with antibacterial activity have attracted more and more attention in the wound dressing area. Here, we developed antibacterial hydrogels directly from cellulose, xylan, and...     

Waste-grass-mediated green synthesis of silver nanoparticles and evaluation of their anticancer,antifungal and antibacterial activity

Grass waste was used for transform an inexpensive waste into health. Silver nanoparticles (AgNPs) have been synthesized using waste material (dried grass). The average size of silver nanoparticles observed in transmission electron images was estimated to be about 15?nm. The anticancer, antifungal and antibacterial effect of AgNPs were studied in vitro. The minimum inhibitory concentration of AgNPs against Pseudomonas aeruginosa and Acinetobacter baumannii was calculated about 3?µg/ml. The highest level of inhibitory effect of AgNPs against Fusarium solani was close to 90% at a concentration of 20?μg/ml of AgNPs. An inhibitory effect on the cancer cell growth is reach, by increasing the concentration of AgNPs to 5?µg/ml; the cancer cells’ survival decreases about 30%. Western results showed that the expression of Cyclin D1 protein of MCF-7 cell line decreased after treatment with the effective concentration of AgNPs.     

Honey mediated green synthesis of silver nanoparticles

The paper reports the pH controlled synthesis of silver nanoparticles using honey as reducing and stabilizing agents. By adjusting the pH of the aqueous solution containing metal ions and honey, nanoparticles of various size could be obtained at room temperature. The nanoparticles were characterized by UV–visible, high-resolution TEM, XRD and FTIR measurements. The colloid obtained at a pH of 8.5 is found to consist of monodispersed and nearly spherical silver nanoparticles of size ～4 nm which is a significant advancement in biosynthesis. The high crystallinity with fcc phase is evidenced by clear lattice fringes in the high-resolution TEM image and peaks in the XRD pattern corresponding to (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) planes. FTIR spectrum indicates that the nanoparticles are bound to protein through the carboxylate ion group.     

Preparation of antibacterial polyimide films containing silver nanoparticles

Polyimide/silver composite films were successfully prepared by in situ polymerization. A precursor, AgNO₃ was used as the source of the silver nanoparticles. The structure and morphology of resulting films were characterized by FTIR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Consequently, the silver nanoparticles were well dispersed in polyimide matrix. Meanwhile, thermal properties from thermal gravimetric analyses (TGA) and mechanical properties from tensile test which confirmed composites were kept good performance as compared to pure polyimide. In addition, the antimicrobial activity of polyimide/silver composite films against three different bacteria, B. subtilis, S. aureus, and E. coil, illustrated excellent activity. This composite is potential useful as antimicrobial material with good thermal performance in a wide variety of biomedical and general use applications.     

Construction of multifunctional UV-resistant,antibacterial and photothermal cotton fabric via silver/melanin-like nanoparticles

Cellulose - As a kind of melanin-like nanoparticles, poly(levodopa) nanoparticles have abundant reactive catechol groups, which provide the basis for the structure design of melanin-like...     

Nature-inspired biogenic synthesis of silver nanoparticles for antibacterial applications

In recent decades, nanotechnology has been empowered as a new and developing interdisciplinary region of science and innovation that coordinates material science and biology. Nanoscience and nanotechnology open up new streets of examination that are helpful in synthesizing novel nanomaterials with remarkable applications. Among different metal nanomaterials, silver nanoparticles (AgNPs) attracted the attention of researchers due to their versatile antibacterial characteristics and biological properties. Biogenically synthesizing AgNPs from plants and microorganisms seems to be a highly promising alternative for developing a technology that is both environmentally benign and fast. Plants and microorganisms' ability to synthesize AgNPs has mostly remained untapped, and the lack of investigation is due to the vast variety of plants and microorganisms. This review aims to describe the current progress in various synthetic techniques for AgNPs and their potential for antibacterial applications. It discusses biogenic synthetic approaches, the role of various metabolites in the growth processes of AgNPs with antibacterial implications, bactericidal mechanisms, and the influence of operational parameters on AgNPs synthesis. Furthermore, the present status, critical challenges, and future outlook of AgNPs will be explored, which will definitely affect their present and future scenarios. We believe that by focusing readers' attention on nature-inspired, biogenically synthesized AgNPs and their bactericidal applications, this review will enable them to formulate a new perspective.     

LLM-105 nanoparticles prepared via green ball milling and their thermodynamics and kinetics investigation

Journal of Thermal Analysis and Calorimetry - 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) has drawn extensive attention because of its heat resistance and insensitivity properties. In this...     

Green synthesis of antibacterial chitosan films loaded with silver nanoparticles

An eco-friendly chemical reduction method was successfully used for the preparation of chitosan (CTS) composite films loaded with silver nanoparticles (AgNPs) by self assembly method using poly(ethylene glycol) as both reducing and stabilizing agent. UV-Vis spectra of the prepared chitosan loaded silver nanoparticles (CTSLAg) films reveal that full reduction of silver ions to silver nanoparticles takes place at 90 °C. The effect of reaction conditions on the silver nanoparticles formation was investigated using UV-Vis spectrophotometer. The morphology of the films was tested by scanning electron microscopy (SEM). The DSC curves showed that the CTSLAg film had a favorable compatibility and heat stability. AgNPs were confirmed by XRD and UV-Vis spectroscopy. The TEM findings revealed that the silver nanoparticles synthesized were spherical in shape with uniform dispersal, and by increasing CTS:PEG ratio larger silver nanoparticles could be obtained. The results of antibacterial study reveal that the prepared nanocomposite films exhibited potential inhibition.     

XPS study of silver and copper nanoparticles demonstrated selective anticancer,proapoptotic, and antibacterial properties

Silver and copper nanoparticles were produced by an ecologically safe metal vapor synthesis (MVS) method using acetone as an organic dispersion medium. Transmission electron microscopy (TEM) showed that the specimens are spherical and polydisperse, and their average size is 2.5 nm for silver nanoparticles (Ag NPs) and 2.6 nm for copper nanoparticles (Cu NPs). X-ray photoelectron spectroscopy analyses showed that the state of silver in the nanoparticles is close to that of silver in the Ag⁰ state, whereas copper black contains two oxidized states of the metal—Cu⁺ and Cu²⁺. Biological in vitro studies demonstrated that the nanoparticles have antibacterial activity against Gram-positive and Gram-negative bacterial species. Cu NPs exhibited more prominent antibacterial effects and induced significant growth inhibition of Bacillus cereus and Escherichia coli. Both types of nanoparticles showed anticancer properties in vitro. Cu NPs induced intense cytotoxicity in cancer and normal fibroblasts in vitro cultures, but their inhibitory effect against noncancerous cells was milder compared with cancer cell lines. Ag NPs demonstrated selective cytotoxicity against human lung and cervical adenocarcinoma cell lines. Further in vitro studies indicated that the mechanism of Ag NPs and Cu NPs anticancer effects involves induction of apoptosis. The present study describes a green synthesis approach for production of biologically active silver and copper nanoparticles and highlights their potential for medical application.     

Impact of silver nanoparticles synthesized by green method and microemulsion loaded with the nanoparticles on the development of cress

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A new green method for the synthesis of silver nanoparticles and their antibacterial activities against gram‐positive and gram‐negative bacteria

This study aims to evaluate the capability of Ageratum conyzoides and Mikania micrantha extracts to synthesize silver nanoparticles (AgNPs) and their antibacterial capability against gram‐positive and gram‐negative bacteria. Several properties of the synthesized AgNPs, including plasmonic, biomolecule bonding, shape, size, and antibacterial, were investigated. Ultraviolet–visible (UV–vis) spectroscopy was employed for characterizing their plasmonic properties. Functional groups on the produced AgNPs were investigated by Fourier‐transform infrared (FT‐IR) spectroscopy. The size and shape of the AgNPs were identified using the field‐emission scanning electron microscopy (FESEM). Inhibition zone measurement was carried out for evaluating the antibacterial capability. This study showed that the extracts of A. conyzoides and M. micrantha were able reducing agents as evidenced by the formation of the spherical AgNPs. UV–vis spectroscopy, FT‐IR spectroscopy, and FESEM confirmed the physicochemical characteristics of AgNPs. AgNPs that were synthesized using M. micrantha were slightly smaller than those produced using A. conyzoides. In general, the present work establishes that the synthesized AgNPs have antibacterial capability depending on their size and synthesis procedure.     

Investigation of photocatalytic activity of metal-doped TiO2 nanoparticles prepared by Pechini method

M-doped TiO₂ (M = Ag²⁺, Al³⁺, Ce⁴⁺, Nb⁵⁺) with different dopant contents have been prepared by the Pechini method using titanium IV isopropoxide as precursor. The effect of doping concentration on the photocatalytic activity for methyl orange (MO) photodegradation was investigated using UV radiation. The photocatalysts were characterized by surface area, X-ray diffraction and UV–Vis diffuse reflectance spectroscopy. An increase in the photoactivity of TiO₂ nanoparticles was confirmed by MO photocatalytic degradation experiments, when the transition metal ions were incorporated into the semiconductor crystalline lattice, which could be attributed to an increase in the charge separation and reduction of e^?/h⁺ recombination as a function of the substitutional defect generated at very low levels.     

Cytotoxicity,antifungal, antioxidant,antibacterial and photodegradation potential of silver nanoparticles mediated via Medicago sativa extract

The biosynthesis of metallic nanoparticles is on a sharp rise as they have growing applications in environmental and biomedical sciences. This study reports an eco-friendly and cost-effective methodology for synthesizing biogenic silver nanoparticles (AgNPs) using the extract of Medicago sativa (M. sativa) cultivated in South Khorasan. The parameters used in the synthesis process were optimized to obtain uniformly distributed AgNPs in suitable sizes. The morphological, structural, and bonding characteristics of M. sativa extract-based AgNPs (MSE-AgNPs) were explored using FTIR, FESEM, EDS, TEM, XRD, UV–Vis, and DLS techniques. UV–Vis spectroscopy confirmed the formation of MSE-AgNPs by observing the typical surface plasmon resonance (SPR) peak at 419 nm. XRD, FESEM, TEM, and DLS analyses confirmed the formation of face-centered cubic (fcc) crystalline structure, spherical/elliptical morphology, the average particle size of 15–35 nm, and highly stable MSE-AgNPs. Green synthesized MSE-AgNPs indicated a significant antioxidant activity (78%) compared to M. sativa extract (32%). As such, the synthesized MSE-AgNPs revealed a potential antioxidant activity towards the DPPH radicals. The biologically synthesized MSE-AgNPs exhibited highly potential antibacterial and antifungal activities against Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Staphylococcus epidermidis, Enterococcus faecalis, Staphylococcus aureus, and Candida albicans with the minimum inhibitory concentration (MIC) values of 62.5, 125, 125, 1000, 125, 1000, and 31.25 µg/mL, respectively. In vitro cytotoxicity of the MSE-AgNPs against human fibroblast (HF) cells indicated a dose–response activity (with IC50 value of 18 µg/mL). Moreover, the AgNPs revealed efficient photocatalytic degradation of thymol blue (TB) as an anionic dye and malachite green (MG) as a cationic dye under sunlight and UV irradiations. Up to 94.37% and 90.12% degradation rates were obtained for MG and TB within only 100 min of UV irradiation. These observations signify that synthesized MSE-AgNPs can have great potential for biological and environmental applications.     

溶剂热法制备银纳米晶

以聚乙烯吡咯烷酮(PVP)作为表面活性剂,利用乙二醇溶剂热法成功制备了银纳米颗粒;利用场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)分析了样品的形貌和晶体结构,并考察了溶剂组成等因素对银纳米颗粒形貌的影响.研究结果表明所得银纳米晶粒径均一,直径约为90nm;增大PVP的加入量会降低产物的粒径,溶剂中水的引入会影响银纳米晶的形貌.