Hanan B. Ahmed

Characterization of nanosilver coated cotton fabrics and evaluation of its antibacterial efficacy

An ecological and viable method for coating of cotton fabrics with silver nanoparticles (AgNPs) has been carried out. Nanocoated fabrics were characterized by scanning electron microscopy, energy dispersive X-ray and infrared spectroscopy. Color coordinates and silver release were assessed and the impact of repeated washings was evaluated. Silver contents were measured using atomic absorption spectroscopy and were 109.07 and 97.85 mg/kg for the fabrics treated with 100 ppm of AgNPs in presence and absence of binder respectively. Antibacterial activities of the cotton fabrics coated by AgNPs were evaluated qualitatively and quantatively, and the results explored that, regardless of the concentration of AgNPs used, the biocidability was always higher without washing. However, for all coated fabrics, a sufficient antibacterial action still observed after 20 washings. The results revealed that valuable antibacterial textiles which are required in different medical textile fields could be successfully produced.

Surface modification of cotton fabrics for antibacterial application by coating with AgNPs-alginate composite.

In recent years nano-sized particles have been focused on bacteriostasis. We investigated antimicrobial activities by applying AgNPs-alginate composite on cotton fabric, using a simple one-step rapid synthetic route by reduction of silver nitrate using alkali hydrolyzed alginate solution which acts as both reducing and capping agent. FTIR spectra, color coordinates, silver content, silver release percent and SEM images of treated fabric samples confirmed the successful physical deposition of AgNPs-alginate composite on the fabric. The treated fabrics demonstrated an excellent antibacterial activity against the tested bacteria, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. A slight decrease in the antibacterial feature of the cotton fabrics was observed after successive washings. However, an efficient antibacterial activity still remained on the fabrics.

Facile size-regulated synthesis of silver nanoparticles using pectin.

Monodispersed silver nanoparticles capped by pectin were prepared by the reaction of silver nitrate with alkali hydrolyzed pectin at 70 °C for 30 min. Spherical and size-regulated silver nanoparticles were prepared using alkali hydrolyzed pectin as a reducing and particle-stabilizing agent. This approach is facile, effective, rapid, and convenient for the large scale preparation of silver nanoparticles. UV-visible spectral analysis confirmed that the nanoparticles consisted of metallic silver. Transmission electron microscopy (TEM) was used to estimate particle size and size distribution of the produced silver nanoparticles. Transmission electron microscopy and size distribution analysis revealed the presence of spherical silver nanoparticles with a main diameter of 5-10nm and have a narrow size distribution. The concentration of reducing sugars was monitored by using dinitrosalicylic acid. A comprehensive schematic mechanism for the formation of silver nanoparticles using pectin is proposed.

Layer by layer assembly of nanosilver for high performance cotton fabrics

High performance cellulosic fabrics are of increasing attention as a wearable fabric with special functions. The current report deals with preparation of multifunctional cotton fabrics by using simple and facile layer by layer technique. Firstly, silver nitrate was reacted with carboxymethyl cellulose to prepare Ag nanoparticles-carboxymethyl cellulose composite. Multi-layers of the so-obtained composite were applied on the cotton fabrics using pad-dry-cure method. Ag nanoparticles were deposited with mean size of 18.2 nm onto cotton fabrics which served as a cross linker between carboxymethyl cellulose macromolecules and cotton macromolecular blocks. Application of composite multilayers brought new properties for the finished cloths such like coloration, ultraviolet resistance, electrical resistance and biocidal action. The ultraviolet transmission radiation was significantly reduced to 7-10 % after applying ten composite layers. Valuable antibacterial textiles which are required in different medical purposes could be successfully produced, as excellent antibacterial activities were achieved by using the reported method. The developed process can be easily adapted to the existing textile machinery, making it industrially viable to produce fabric’s versatility.

Alginate mediate for synthesis controllable sized AgNPs

A new method to prepare silver nanoparticles was reported. Alginate colloidal solution containing chemically synthesized silver nanoparticles (AgNPs) was investigated regarding the nanoparticles stabilization and possibilities for production of alginate based nanoparticles. The formation of AgNPs has been confirmed by UV-visible spectroscopy and monitoring of reducing sugars in the reaction was carried out. The morphology of synthesized silver nanoparticles was characterized by transmission electron microscopy (TEM). The results showed that the morphology of Ag nanoparticles is spherical and the main size is about 1-4 nm.

Room temperature synthesis of metallic nanosilver using acacia to impart durable biocidal effect on cotton fabrics

Effective one-pot and large scale strategy for rapid synthesis and stabilization of Ag0 nanoparticles (AgNPs) at room temperature, using acacia gum has been reported. Acacia gum played a dual rule as reducing agent for Ag+ and as stabilizing agent for the net produced AgNPs. Concentration of reducing sugars produced in the reaction medium was monitored. Formation of AgNPs has been detected by UV-Vis spectra and confirmed by transmission electron microscopy. Size distribution was 4–8 nm and mean size was 6 nm for AgNPs prepared at room temperature. Finishing of Cotton fabrics by solutions of AgNPs - acacia composite was utilized. Presence of Ag on the coated Cotton was confirmed by using energy dispersive X-ray spectroscopy. The influence of coating with that composite on color of fabrics and on biocidal properties as well as laundering durability of obtained effects was studied. Coated Cotton fabrics exhibited excellent antibacterial action with good durability as after 20 washing cycles, 99 % of bacteria was completely killed. The presented method contains neither complicated systems nor hazard chemicals, which makes the coated fabrics with AgNPs - acacia composite sterile and can be used in medical purposes to prevent or minimize infection with pathogenic bacteria.

In-situ deposition of Cu2O micro-needles for biologically active textiles and their release properties

Metal/metal oxide containing fibres are gradually increasing in textile industrialization recently, owing to their high potential for application as antimicrobial textiles. In this study, the reducing properties of cellulose were applied to synthesize cuprous oxide in-situ. The direct formation of Cu2O on viscose fabrics was achieved via quite simple technique in two subsequent steps: alkalization and sorption. Cu contents in fabrics before and after rinsing ranged between 45.2-86.4mmol/kg and 18.1-67.7mmol/kg, respectively. Uniform micro-needles of Cu2O were obtained with regular size and dimensions of 1.60±0.20μm in length and 0.13±0.03μm in width. Release of Cu1+/2+ ions from selected samples was studied in water, physiological fluid and artificial sweat. Copper containing fabrics exhibited a percent of 96.8-97.8% and 85.5-89.0% for reduction in microbial viability, which was tested for S. aureus (as gram positive bacteria), E. coli (as gram-negative bacteria) and C. albicans and A. niger (as fungal species), respectively after 24h contact time.

Heatless synthesis of well dispersible Au nanoparticles using pectin biopolymer.

Due to its potency to utilize in enormous applications, preparation of nanogold is of interest. Moreover, getting of highly dispersed nanogold with small size is extremely needful in specific fields. Herein, Au nanocolloid was prepared using alkali catalyzed pectin biopolymer. Pectin was concurrently used as reductant for Au ions and stabilizer for the produced Au nanoparticles (AuNPs). Reducing sugars were evaluated in the colloidal solution reflecting the role alkali in catalytic degradation of pectin to produce much powerful reducing moieties. The obtained Au nanocolloid was monitored via changing in color, UV-visible spectral and transmission electron microscopy. Using of NaOH as strong alkali achieving rapid rate of degradation reaction, resulted in 0.45g/L reducing sugars from 0.2g/L pectin which produced AuNPs with mean size of 6.5nm. In case of Na2CO3 which attained slow degradation rate led to, slightly low reducing sugar content (0.41g/L), fabricated comparatively size of AuNPs (7.5nm). In both cases, well distributed AuNPs was obtained with suitable stabilization up to 5 months and Na2CO3 exhibited higher stability. The current successful method used to produce small sized AuNPs with high dispersion is an innovative, one-step, easily, costless, energy saving and eco-friendly method.

One-pot fabrication of AgNPs, AuNPs and Ag-Au nano-alloy using cellulosic solid support for catalytic reduction application

The current report provides a simple, green and inexpensive route for one-pot fabrication of AgNPs, AuNPs, and Ag-Au nano-alloy individually onto cellulosic solid support. Cellulosic solid support was naturally extracted from plant and then was used for deposition of nanoparticles. The manufacturing was carried out through redox reaction between metal ions and alcoholic groups of cellulose, resulting in production of metallic/bimetallic nanostructures. AuNPs was obtained in size of 26.1nm smaller than AgNPs (36.3nm). Controlling in size of bimetallic nanostructures was achieved by tuning the concentrations, mass ratios of nanometal precursors and their addition sequencing in reaction liquor. Immobilization of nanoparticles/bimetallic nanostructures was frequently speeded up the reduction reaction of p-nitro-aniline, however, bimetallic nanostructures exhibited much better catalytic reactivity, where, 87.2% from p-nitro-aniline was reduced to p-phenylene-di-amine only in 20min in the presence of Ag-Au bimetallic nano-alloy.

Green-assisted tool for nanogold synthesis based on alginate as a biological macromolecule

Large-scale biomedical applications of nanogold reflect the challenge faced by recent researches in the investigation of green synthesis methodologies, which are mostly complicated and/or expensive processes. The present report offers a totally green method using a quite simple and costless technique for the manufacture of Au nanoparticles based on alginate macromolecules. Hydrogen peroxide was used for the oxidative degradation of alginate at room temperature to produce more accessible fragments, beneficial for the reduction of Au ions to Au0 and as a stabilizer for the produced nanogold. The competence of the mentioned procedure was tested by comparison with the alkali/glucose/alginate system, in which glucose and alginate were used as a reducer and stabilizer, respectively. For both the systems, surface plasmon resonance peaks for nanogold were detected and similar absorbance spectra were observed. Using either 30 mmol L−1 H2O2 or 1 g L−1 glucose, similar reducing sugar content (0.32 g L−1) resulted from 1 g L−1 alginate. Nanogold manufactured by H2O2 exhibited smaller size (3.7 ± 1.1) with narrower size distribution (1.5–8.0 nm) than that produced in the case of glucose. However, enlarged nanogold was observed after storage for 5 months, which still maintained the nano dimension. The produced nanogold via the completely green technique using H2O2/alginate could be safely used in biomedical applications.