Bactericidal Silver Nanoparticles Research Articles

Studies of Mercaptosuccinic Acid-Crosslinked Chitosan Hydrogel with Grafted Cinnamaldehyde and Silver Nanoparticles for Antibacterial Biomedical Application

For the effective clinical antibacterial application of biomaterials, such as for wound management and tissue repair, the biomaterials need to show proper antibacterial capability as well as non-cytotoxicity. Furthermore, the material needs to have suitable mechanical characteristics for further medical use. Chitosan hydrogel is a potential candidate for various antibacterial biomedical applications due to its amine functionalities that lead to antimicrobial characteristics. Nevertheless, its antimicrobial capability is dependent upon the degree of protonation of amine groups caused by the pH value. Moreover, its mechanical compressive strength may not be high enough for clinical use if not chemically or physically crosslinked. This study utilized a novel chemical crosslinker, mercaptosuccinic acid, to improve its mechanical characteristics. The natural antibacterial agent, cinnamaldehyde, was grafted onto the crosslinked chitosan to improve its antimicrobial capability. Meanwhile, to take advantage of the thiol functionality in the mercaptosuccinic acid, the bactericidal silver nanoparticles were incorporated through silver-thiol covalent bounding. NMR analyses indicated the chitosan was successfully mercaptosuccinic acid-crosslinked and grafted with cinnamaldehyde at different ratios. Combined the results from the mechanical assessment, swelling experiments, antimicrobial assessment, and cytotoxicity assay, the chitosan hydrogel with the highest crosslinked degree and grafted with cinnamaldehyde and silver nanoparticles is of great promise for further clinical uses.

Dual action of pyroligneous acid in the eco-friendly synthesis of bactericidal silver nanoparticles

In the present study, we demonstrate that pyroligneous acid (PA), also known as wood vinegar, functions efficiently as both reducing and stabilizing agent in the synthesis of silver nanoparticles (AgNPs). The synthesis and stabilization of AgNPs take place in the following fashion: 1) in alkaline environment, oxygenated species (phenols in the present case) contained in PA reduce silver ions to metallic silver; 2) acetic acid, abundantly present in PA, adsorb onto the AgNPs conferring electrostatic stabilization. This mechanism is supported by GC-MS and RAMAN analysis, with the former revealing the compounds lacking in PA after nanoparticle synthesis and the latter demonstrating acetic acid adsorbed on the nanoparticles. The AgNPs produced via this method were quite stable up to 150 days (zeta potential = -56 mV). The AgNPs were then found to inhibit the growth of Escherichia coli and Staphylococcus aureus. Concerning PA, we showed that it displays bactericidal properties only under acidic conditions. This study contributes to the development of more environmentally benign routes to produce nanomaterials.

Bactericidal Anti-Adhesion Potential Integrated Polyoxazoline/Silver Nanoparticle Composite Multilayer Film with pH Responsiveness.

Bacterial infections occur frequently during the implantation of medical devices, and functional coating is one of the effective means to prevent and remove biofilms. In this study, three different hydrophilic polyoxazolines with carboxyl groups (aPOx: PT1, PT2 and PT3) and bactericidal silver nanoparticles (AgNPs) were synthesized successfully, and an aPOx-AgNP multilayer film was prepared by electrostatic layer-by-layer self-assembly. The effect of charge density and assembly solution concentration was explored, and the optimal self-assembly parameters were established (PT2 1 mg/mL and AgNPs 3 mg/mL). The hydrophilicity of the surface can be enhanced to resist protein adhesion if the outermost layer is aPOx, and AgNPs can be loaded to kill bacteria, thereby realizing the bactericidal anti-adhesion potential integration of the aPOx-AgNP multilayer film. In addition, the aPOx-AgNP multilayer film was found to have the characteristic of intelligent and efficient pH-responsive silver release, which is expected to be used as a targeted anti-biofilm surface of implantable medical devices.

Dual Action of Pyroligneous Acid in the Eco-Friendly Synthesis of Bactericidal Silver Nanoparticles

Dual Action of Pyroligneous Acid in the Eco-Friendly Synthesis of Bactericidal Silver Nanoparticles

Bactericidal Silver Nanoparticles by Atmospheric Pressure Solution Plasma Processing.

Silver nanoparticles have applications in plasmonics, medicine, catalysis and electronics. We report a simple, cost-effective, facile and reproducible technique to synthesise silver nanoparticles via plasma-induced non-equilibrium liquid chemistry with the absence of a chemical reducing agent. Silver nanoparticles with tuneable sizes from 5.4 to 17.8 nm are synthesised and characterised using Transmission Electron Microscopy (TEM) and other analytic techniques. A mechanism for silver nanoparticle formation is also proposed. The antibacterial activity of the silver nanoparticles was investigated with gram-positive and gram-negative bacteria. The inhibition of both bacteria types was observed. This is a promising alternative method for the instant synthesis of silver nanoparticles, instead of the conventional chemical reduction route, for numerous applications.

Facile production of silver-reduced graphene oxide nanocomposite with highly effective antibacterial performance

Reduced graphene oxide (rGO) has broad applications based upon its superior electronic properties. In many cases, an additional antibacterial function of these materials requests physical or chemical modification, such as incorporating silver nanoparticles into rGO to produce silver-reduced graphene oxide (Ag/rGO) composite. Most of the previous methods of preparing Ag/rGO are top-down techniques starting from graphite exfoliation into graphene oxide (GO), to the reduction of a mixture of silver nitrate and GO into the Ag/rGO nanocomposite. This method is flawed by its high cost, tedious treatments, and heavy pollution from generated wastes. Herein, we manifest a novel bottom-up strategy of growing Ag/rGO totally from a cellulose acetate and silver nitrate precursor in one step without tedious solution exfoliation and chemical treatment steps. The produced Ag/rGO nanocomposite maintains highly effective antibacterial activity, which is ascribed to the synergy between the effect of rGO size and incorporated bactericidal silver nanoparticles. Our strategy is promising for industrial production from sustainability and cost-effectiveness perspectives.

Development of Multimodal Antibacterial Surfaces Using Porous Amine-Reactive Films Incorporating Lubricant and Silver Nanoparticles.

Anti-biofouling has been improved by passive or active ways. Passive antifouling strategies aim to prevent the initial adsorption of foulants, while active strategies aim to eliminate proliferative fouling by destruction of the chemical structure and inactivation of the cells. However, neither passive antifouling strategies nor active antifouling strategies can solely resist biofouling due to their inherent limitations. Herein, we successfully developed multimodal antibacterial surfaces for waterborne and airborne bacteria with the benefit of a combination of antiadhesion (passive) and bactericidal (active) properties of the surfaces. We elaborated multifunctionalizable porous amine-reactive (PAR) polymer films from poly(pentafluorophenyl acrylate) (PPFPA). Pentafluorophenyl ester groups in the PAR films facilitate creation of multiple functionalities through a simple postmodification under mild condition, based on their high reactivity toward various primary amines. We introduced amine-containing poly(dimethylsiloxane) (amine-PDMS) and dopamine into the PAR films, resulting in infusion of antifouling silicone oil lubricants and formation of bactericidal silver nanoparticles (AgNPs), respectively. As a result, the PAR film-based lubricant-infusedAgNPs-incorporated surfaces demonstrate outstanding antibacterial effects toward both waterborne and airborne Escherichia coli, suggesting a new door for development of an effective multimodal anti-biofouling surface.

Spectroscopic investigation on interaction of biogenic, Croton bonplandianum leaves extract mediated potential bactericidal silver nanoparticles with human hemoglobin and human serum albumin

The green synthesis of nanoparticles has received increasing attention due to the growing demand to produce safe, cost-effective, and eco-friendly technology for nanomaterials synthesis. We report on the use of aqueous Croton bonplandianum (Family: Euphorbiaceae, Genus: Croton) leaves extract for the preparation of silver nanoparticles (AgNPs) without using any external reducing and stabilizing agent. Ultraviolet–visible spectroscopy showed maximum absorbance at 446 nm due to surface plasmon resonance of AgNPs. Energy dispersive X-ray spectra also supported the existence of AgNPs. An average diameter (d = ~17.4 nm) of the spherical AgNPs was determined from the transmission electron microscopic images. Hydrodynamic size (d = ~21.1 nm) was determined by dynamic light scattering. Fourier transform infrared analysis designed that the functional groups like O–H, N–H, , CONH2, and COOH participated in the AgNPs formation. The negative zeta potential value (−19.3 mV) of the AgNPs indicated its dispersion and stability. The AgNPs exhibited strong antibacterial activity against Escherichia coli ATCC 25922 and 1.5 nM proved to be minimum inhibitory concentration for it. Hemolysis assay demonstrated the blood compatibility of the AgNPs toward human RBCs. The binding affinity of the AgNPs toward human hemoglobin and human serum albumin (HSA) was also determined by means of fluorescence spectroscopy. The circular dichroism spectroscopy revealed that the native structures of human hemoglobin and HSA remain unchanged, but its secondary structures were slightly changed upon interaction with AgNPs. Overall, it can be concluded that the AgNPs may be applied in the area of nanomedicines.

Photochemically assisted one-pot synthesis of PMMA embedded silver nanoparticles: antibacterial efficacy and water treatment

Achievement of simultaneous reduction of bactericidal silver nanoparticles andin situpolymerization by photo irradiation is beneficial for water treatment.

The Application of Bactericidal Silver Nanoparticles in Wound Treatment

Even with the prevalence of wounds, the medical technology for efficiently managing skin damage is still primitive. The disruption of any of the numerous healing processes can lead to problems in the time-sensitive healing actions of the dermal and epidermal layers. Bacterial infection is one of the major obstacles to proper wound healing as it poses a danger of causing long-term negative effects. Keeping the wound free of bacteria is imperative to the proper and hasty repair of dermal wounds. Silver has been widely used to treat wounds for its bactericidal properties. Although the mechanism of silver's antibacterial action is not fully understood, it exhibits a significant antimicrobial efficacy against a wide spectrum of bacterial species. A number of different approaches to the mechanism are reported and presented in this review. Silver nanoparticles (AgNPs) have been reported to exhibit enhanced antibacterial activity due to their increased surface-area-to-volume ratio. AgNPs are capable of various modifications, significantly broadening the therapeutic properties of the material as a result. This review explores the different aspects of silver and silver nanoparticles, and their antibacterial properties, which can be applied in the field of wound treatments.

New generation of bactericidal silver nanoparticles against different antibiotic resistant Escherichia coli strains

Biosynthesis of silver nanoparticles (AgNPs) with ecofriendly plant extracts contains different phytochemicals act as both reducing and capping agents forming stable and shape-controlled AgNPs. The present study deals with the synthesis of AgNPs using the aqueous leaf extract of Coleus aromaticus and to evaluate the bactericidal activity against three antibiotic resistant Escherichia coli strains. The AgNPs are characterized using UV–Visible Spectroscopy, Scanning Electron Microscope coupled with X-ray Energy Dispersive Spectroscopy, Fourier transform-infrared spectroscopy, and Atomic force microscope. The synthesized AgNPs were crystalline in nature, spherical in shape with an average of 48 ± 5 nm in size, and the stability of AgNPs is due to its high negative Zeta potential −65.7 mV. The AgNPs have outstanding bactericidal activity against three antibiotic resistant E. coli strains. This is the first report of antibacterial activity against antibiotic resistant strains using AgNPs by green route.

Fabrication of Biogenic Antimicrobial Silver Nanoparticles by Streptomyces aegyptia NEAE 102 as Eco-Friendly Nanofactory

The current research was focused on the extracellular biosynthesis of bactericidal silver nanoparticles (AgNPs) using cell-free supernatant of a local isolate previously identified as a novel Streptomyces aegyptia NEAE 102. The biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102 was quite fast and required far less time than previously published strains. The produced particles showed a single surface plasmon resonance peak at 400 nm by UV-Vis spectroscopy, which confirmed the presence of AgNPs. Response surface methodology was chosen to evaluate the effects of four process variables (AgNO3 concentration, incubation period, pH levels, and inoculum size) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. Statistical analysis of the results showed that the linear and quadratic effects of incubation period, initial pH, and inoculum size had a significant effect (p < 0.05) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. The maximum silver nanoparticles biosynthesis (2.5 OD, at 400 nm ) was achieved in runs number 5 and 14 under the conditions of 1 mM AgNO3 (1-1.5% (v/v)), incubation period (72-96 h), initial pH (9-10), and inoculum size (2-4% (v/v)). An overall 4-fold increase in AgNPs biosynthesis was obtained as compared with that of unoptimized conditions. The biosynthesized silver nanoparticles were characterized using UV-VIS spectrophotometer and Fourier transform infrared spectroscopy analysis, in addition to antimicrobial properties. The biosynthesized AgNPs significantly inhibited the growth of medically important pathogenic gram-positive (Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa) and yeast (Candida albicans).

Synthesis and characterization of bactericidal silver nanoparticles using cultural filtrate of simulated microgravity grown Klebsiella pneumoniae

Silver nanoparticles were synthesized by biological method using cultural filtrate of Klebsiella pneumoniae cultured under simulated microgravity and silver nitrate solution as precursor. The nanoparticles exhibited typical plasmon absorption maximum of silver nanoparticles between 405 and 407nm. Spherical silver nanoparticles were found to have size between 15 and 37nm by TEM analysis. XRD pattern corresponding to planes (111), (200), (220) (311) revealed the crystalline nature of the biosynthesized silver nanoparticles. FTIR spectrum proposed stabilization of silver nanoparticles by the protein molecules present in the cultural filtrate. The silver nanoparticles exhibited high bactericidal activity against Salmonella enterica, Escherichia coli and moderate bactericidal activity against Streptococcus pyogenes.

Mangrove Streptomyces sp. BDUKAS10 as nanofactory for fabrication of bactericidal silver nanoparticles

Biosynthesis has led to the development of various biomimetic approaches for the fabrication of nanoscale materials. The present study reveals a unique procedure for the biosynthesis of bactericidal silver nanoparticles (AgNPs) using a novel Streptomyces sp. BDUKAS10, an isolate of mangrove sediment. Aqueous silver nitrate (AgNO3) solution was treated with cell free supernatant (CFS) of the isolate to synthesize bactericidal silver nanoparticles. Initial characterization was performed by visual observation for color change to intense brown color. UV–visible spectrophotometry (UV–vis) for measuring surface plasmon resonance indicated a maximum absorption peak at 441nm. Fourier Transform Infrared Spectroscopy (FTIR) analysis provides evidence for proteins as possible reducing, and capping agents. Energy dispersive X-ray (EDAX) spectroscopy analysis showed elemental silver as major signal. Transmission Electron Microscopy (TEM) study indicated spherical silver nanoparticles in the size range of 21–48nm. Compared to the CFS, the biosynthesized AgNPs exemplified superior bactericidal efficacy towards the tested bacterial strains. Results from this study suggested that Streptomyces sp. BDUKAS10 can be advantageous for the synthesis of AgNPs by extracellular method in the view of sustainable and ecofriendly approach.

Photochemical synthesis of highly bactericidal silver nanoparticles

In this work we describe an experimental technique that makes it possible to obtain highly bactericidal silver nanoparticles (NPs). Synthesis was carried out using nontoxic reagents, and the technique consisted of reducing silver by glucose via UV irradiation in the presence of oleic or myristic acids as stabilizers. The size of the NPs fell in the range of 4–18 nm, and the average diameter was about 7 ± 1 nm (oleic acid) and 4 ± 1 nm (myristic acid). Unlike previous reports, where the Tollens reaction was used only with the assistance of thermal activation, we conducted the UV reduction of a silver nitrate solution, glucose, and the stabilizer at room temperature for the first time. The minimum inhibition concentration of nanosized silver against a gram-negative Escherichia coli was 1 μg/ml. Thus, the activity of the NPs appeared to be considerably higher than that of nanosilver samples that are currently known.

Green synthesis of finely-dispersed highly bactericidal silver nanoparticles via modified Tollens technique

In this article, we represent a versatile and effective technique which using non-toxic chemicals to prepare stable aqueous dispersions of silver nanoparticles (NPs) via modified Tollens process. It was shown that as-prepared silver colloids consisted of finely-dispersed NPs with average diameter about 10 nm and a relatively narrow size distribution. Moreover, they could be stored very stable after several months without observation of aggregates or sedimentation. In comparison with previous works where Tollens process was being used, we for the first time applied UV-irradiation simultaneously with glucose reduction of silver salt through NPs preparation. The colloidal solutions of silver NPs were found to exhibit a high antibacterial activity against gram-negative Escherichia coli. The concentration of silver leading to a complete inhibition of bacteria growth was revealed as low as at 1.0 μg ml −1 and found much lower compared to earlier reports. These advantages of aqueous dispersions of silver NPs make them ideal for green industrial, medicinal, microbiological and other applications.