In situ synthesis and deposition of AgNPs on the alkali-pretreated cotton/flax blended denim fabric for antibacterial efficacy

In this study, cotton/flax blended denim fabric was pretreated with NaOH to activate the surface hydroxyl groups of the cellulosic denim fabric to provide active sites for Ag + ions resulting enhance silver nanoparticles (AgNPs) deposition onto the fabric surface. AgNPs were synthesized and deposited onto denim fabrics by in situ process, using tri-sodium citrate as both reducing and stabilizing agent. Particle size distribution, zeta-potential and X-ray diffraction measurement confirmed the formation of AgNPs, its stability in the colloidal dispersion and crystallinity, respectively. Fourier transform infrared spectroscopy revealed chemical interaction between the fabric and deposited AgNPs. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (EDAX) and X-ray photoelectron spectroscopy analysis was used to study the treated fabric’s morphology and surface characteristics, revealing the chemical state of AgNPs and AgNPs deposition on the fabric surface. Antibacterial activity of AgNPs finished denim fabric was assessed against both gram-positive and gram-negative bacterial strains, namely S. aureus and E. coli . The result showed significant inhibitory action of 90% against S. aureus and 85% against E. coli . After five and ten wash cycles, the treated fabric exhibited significant antibacterial activity, indicating low leaching rate of AgNPs from treated fabrics; however, repeated washing cycle reduces the antibacterial activity to some extent. The results of the tests on cell viability showed negligible cytotoxicity on human fibroblast cell lines. Graphical Abstract