One-pot synthesis of cellulose / silver nanoparticle fibers and their antibacterial application

A simple, novel method was developed for synthesizing cellulose (CE) fibers doped with silver nanoparticles (Ag NPs) in the green solvent tetrabutylammonium hydroxide / dimethyl sulfoxide / H2O at room temperature. Tetrabutylammonium hydroxide accelerated the reduction of Ag+ to Ag by the cellulose chains, yielding Ag NPs in cellulose solution stabilized using polyethyleneimine (PEI). After 24 h, almost all the Ag+ was reduced to Ag NPs. The influences of silver nitrate concentration, reaction time, and stabilizer on the formation of Ag NPs were investigated by UV-vis spectrophotometry. The prepared smooth and dense cellulose / Ag NP fibers showed high mechanical properties, with a tensile strength of 304.3 MPa and an elongation at break of 22.1%. The fibers exhibited excellent antibacterial activities against Escherichia coli and Staphylococcus aureus, with more than 99% of E. coli bacteria killed by Ag NP / cellulose fibers. The synthesis procedure offers a general and mild approach to designing materials of almost any shape.

Optimization and Characterization of Paper-based SERS Substrates for Detection of Melamine

A flexible low-cost paper-based surface enhanced Raman scattering (SERS) substrate was successfully manufactured by a direct chemical reduction of silver nanoparticles (AgNPs) onto a common commercially available filter paper. Characterization of fabricated paper-based SERS substrate and the influences of the silver nitrate concentration, type of paper on SERS signal were systematically investigated. In order to fabricate SERS substrates with the highest quality, a suitable one from four different types of filter papers was chosen. The prepared SERS substrates have capability for detecting food toxic chemicals. The test of detecting melamine in aqueous solution was successfully demonstrated with the limit of detection for melamine is 10-7M.

Biosynthesis of silver nanoparticles using citrus sinensis peel extract and their application as antibacterial agent

Silver nanoparticles (Ag-NPs) have attracted huge importance due to their distinctive chemical, biological and physical properties. Silver nanoparticles are widely synthesized by the chemical method, which involves the use of toxic chemicals which affects its applications. The bio-reduction method, in comparison with chemical method is more economic and eco-friendly. In the present work, the bio-based production of Ag-NPs was done by using peel extract of orange (citrus sinensis), which played a role of reducing and stabilizing agent. The biosynthesis of silver nanoparticles was optimized by one factor at a time (OFAT) with respect to peel extract concentration, silver nitrate concentration and reaction temperature. The green synthesized silver nanoparticles were characterized by UV-visible spectroscopy, Fourier transforms infrared (FT-IR) spectroscopy, Scanning electron microscopy (SEM) and X-ray diffraction (XRD). Disk diffusion method was used for the study of antibacterial activity of the bio-synthesized silver nanoparticles against the bacteria Escherichia coli and Staphylococcus aureus. The results showed that at a peel extract concentration of 6%, the temperature of 60oC and silver nitrate concentration of 0.1M, the synthesis of Ag-NPs was effective. The orange peel synthesized Ag-NPs showed effective antibacterial activity against both bacteria. However better activity was observed against bacterium Staphylococcus aureus. The results confirmed the synthesis of Ag-NPs using peel extract of citrus sinensis and its role as antibacterial agent.

Supercritical Phase Inversion: A Powerful Tool for Generating Cellulose Acetate-AgNO3 Antimicrobial Membranes

Antimicrobial composite membranes, formed by cellulose acetate loaded with AgNO3 particles, were produced by supercritical phase inversion. Different cellulose acetate concentrations were tested (15%, 20%, 30%(w/w)), whereas the active agent (i.e., silver nitrate) concentration was fixed at 0.1%(w/w) with respect to the quantity of polymer used. To determine the influence of the process parameters on membranes morphology, the pressure and temperature were varied from 150 to 250 bar and from 55 to 35 °C, respectively. In all cases, regularly porous membranes were produced with a uniform AgNO3 distribution in the membrane matrix. Silver release rate depended on membrane pore size, covering a time interval from 8 to 75 h.

Bactericidal Effect of Cotton Fabric Treated with Polymer Solution Containing Silver Nanoparticles of Different Sizes and Shapes

Stable silver nanoparticles in solutions of sodium-carboxymethylcellulose (Na-CMC) were synthesized and their structure and physico-chemical properties were evaluated. The form and sizes of silver nanoparticles formed in solutions of CMC and cotton fabrics were studied using UV-VIS spectroscopy, atomic force microscopy and transmission electron microscopy methods. It was found that silver nitrate concentration increase in sodium carboxymethylcellulose solutions, as well as photoirradiation of the hydrogel lead to the changes of the silver nanoparticles size and shape. Investigations have also shown that spherical silver nanoparticles with sizes of 5-35 nm and content of 0.0086 mass% in cotton fabrics possess high bactericidal activity. Stabilization of silver nanoparticles has preserved bactericidal and bacteriostatic activities during the washing of cotton fabrics and textiles on their base.

Antibacterial Activity of Silver Nanoparticles Capped by p-Aminobenzoic Acid on Escherichia coli and Staphylococcus aureus

This paper describes the antibacterial performance of silver nanoparticles (AgNPs) which have been synthesized by using p-aminobenzoic acid as reducing and stabilizing agent simultaneously. The silver nitrate with various concentrations was reacted with pH 11-adjusted p-aminobenzoic acid with a concentration of 5 × 10–3 mol L–1 for 30 min in a boiling water bath. The synthesized AgNPs were characterized by UV-Vis spectrophotometry, Transmission Electron Microscope (TEM), and Particle Size Analyzer (PSA). The antibacterial performance of the synthesized AgNPs was evaluated by agar well diffusion method on Escherichia coli and Staphylococcus aureus. The higher silver nitrate concentration, the bigger the nanoparticle size, the wider particle size distribution, and the higher number of AgNPs formed. AgNPs synthesized from higher silver nitrate concentration had higher antibacterial activity. It is an indication that the antibacterial activity of AgNPs is mainly controlled by the silver ion concentration which influences the AgNPs particle size and existence of silver ion in the AgNPs colloidal solution

A New Approach to Produce Eco-friendly Antibacterial and Antistatic Polyamide Yarns

In this paper, we reported on environmental technique of developing for the deposition of silver nanoparticles onto polyamide (PA) fibers. A new composite PA yarn with carboxyl methyl starch (CMS) including silver nanoparticles (AgNPs) has been synthesized. The influence of silver nitrate concentration on the morphological and spectrophometeric properties was investigated. SEM images showed the distribution of silver nanoparticles and nanolayer formation on the surface. Electrical conductivity of composite yarns was measured by four point probe technique and was changed from 1.574x10-7 to 2.630x10-4 S/cm. The antibacterial activities of the composite yarns have been investigated against Escherichia coli and determined considerable antibacterial properties.

Biosynthesis of Silver Nanoparticles from Eucalyptus corymbia Leaf Extract at Optimized Conditions

This study reports the biosynthesis of narrow range diameter silver nanoparticles at optimum conditions usingEucalyptus corymbiaas a reducing and stabilizing agent. Optimal conditions for biosynthesis of silver nanoparticles (AgNPs) were found to be; an extraction temperature of 90°C, pH of 5.7 a Silver Nitrate concentration of 1mM and AgNO3to plant extract ratio of 4:1. UV-Visible spectroscopy monitored the formation of colloidal AgNPs. The UV-Visible spectrum showed a peak around 425 nm corresponding to the Plasmon absorbance of the AgNPs. The size and shape characterization of the AgNPs was done using Transmission Electron Microscopy (TEM) techniques which revealed narrow range diameter (18-20 nm), almost monodispersed AgNPs, spherical in nature and with minimal agglomeration. Energy Dispersive X-ray (EDX) results showed the presence of two peaks at 3.0 and 3.15 keV in the silver region. The Fourier Transform Infrared-Spectra (FTIR) of the plant extract and the AgNPs gave rise to vibrational peaks at 3260 and 1634 wavenumbers which are due to the presence of OH and –C=C-functional groups respectively.