Hossam E. Emam

Production of antibacterial colored viscose fibers using in situ prepared spherical Ag nanoparticles

In situ incorporation technique was used for coloration and acquiring excellent antibacterial properties for viscose fibers by silver nanoparticles (AgNPs). AgNPs were prepared in situ and incorporated in viscose matrix directly without using any other reducing and stabilizing agents. The main objective of this research was to successfully employ the reducing and stabilizing features of cellulose to produce nanosilver-viscose composites. Coloration of fibers after in situ AgNPs incorporation is related to surface plasmon resonance of silver. Colorimetric data were recorded as a function of washings to characterize the final colored fibers. Fastness properties and silver release were all measured to study the washable and wear off properties. Depending on the silver concentration, yellowish colored fibers with different shades were produced. Good fastness properties were obtained after 20 washings without using any crosslinker or binder. The colored fibers had excellent antibacterial activities against Escherichia coli, even after 20 washings.

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.

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.

Copper inclusion in cellulose using sodium D-gluconate complexes.

Copper containing cellulose material is of growing interest, e.g. offering alternative in the field of antimicrobials. Solutions of copper d-gluconate complexes (Cu(2+)-DGL) were used to introduce copper ions into a swollen cellulosic matrix. A ligand exchange mechanism forms the chemical basis of the sorption process. Copper sorption in cellulose was studied in the range between pH 6 and 13. An estimate for the complex stabilities of the Cu-cellulose system could be derived from the calculated species distribution of the different Cu(2+)-DGL complexes present. Spectrophotometry and cyclic voltammetry of Cu(2+)-DGL complex solution were used to confirm the presence of different species participating in the ligand exchange reaction. The pH dependent uptake of Cu(2+) ions in the cellulose matrix can be explained on the basis of the relative stabilities of Cu(2+)-DGL complex vs. Cu(2+)-cellulose complexes. In comparison to pH 10, higher copper content was observed at pH 6 and 13. Copper content was limited by carboxyl content of cellulosic materials, thus in analogy to the structure of Cu(2+)-DGL complexes participation of the carboxyl group as complex forming site is proposed. At high Cu(2+)-concentration and longer time of immersion in the copper complex solutions formation of solid deposits was observed on the surface of the treated fibres.

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.

Influence of silver nanoparticles on the fabrics functions prepared by in-situ technique

Abstract The development of multifunctional fabrics is an important purpose for their application in many fields. This study provided a simple approach for innovative textile design by applying the optical properties of Plasmonic noble metal nanoparticles. The utilization of feasible technique to functionalize both semi-synthetic and synthetic fabrics namely viscose and acrylic fabric has been accomplished. Where, fabrics functions have been developed by in situ synthesis of silver nanoparticles (Ag NPs) into their surface using trisodium citrate as multifunctional agent (reductant, stabilizer, and linker). The silver NPs incorporated into fabrics has been characterized by UV–visible spectroscopy, scanning electron microscopy, energy dispersive X-ray, and X-ray photoelectron spectroscopy. The mechanism of assembling Ag NPs in situ incorporated fabric matrix has been discussed. The influence of silver nanoparticles on the coloration, UV-protection, and antibacterial properties of the fabrics has also been examined. The overall results indicated that, the in situ Ag NPs-incorporated into fabrics has been applied as a colorant for both viscose and acrylic fabrics effectively beside the improvement for UV-blocking and anti-bacterial properties.

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.

Self-assembled AuNPs for ingrain pigmentation of silk fabrics with antibacterial potency

Nanogold was self-assembled for ingrain pigmentation of silk fabric with antibacterial properties. The functional groups of silk macromolecular polymeric chains were exploited for generation and stabilization of nanogold. Hydrogen peroxide was used for activation of silk molecular chains through increasing their reactivity and accessibility to be functionalized as manufacturer of nanogold without using any external agents. Effect of procedure sequencing was studied through addition of peroxide firstly (group A) and with Au salt (group B). Self-assembly of nanogold inside fabric was confirmed by electron microscope, X-ray diffraction and absorbance spectra. The particle size of the nanogold within fabric was estimated to be in range of 22-66nm (group A) and 18-49nm (group B). Due to LSPR of nanogold, silk fabrics were acquired violet color with good fastness properties. In distilled water and artificial sweat, 33.5-41.0% and 46.2-50.4% of Au was leached out from silk fabric, respectively after 24h. Very good antibacterial properties were estimated for ingrain colored fabric against E. coli and S. aureus via using the optical density measurements. Quite simplicity, timelessness and energy saving are advantages which were realized in the current work for silk functionalization.