Enhancing the surface affinity with silver nano-particles for antibacterial cotton fabric by coating carboxymethyl chitosan and L-cysteine

This study evaluates the durability and antibacterial function of silver nanoparticle (SP) coatings on natural cotton fabrics via a combination of carboxymethyl chitosan (CMCS) and L-cysteine (Cys). Surface modification is accomplished by grafting CMCS on the cotton fabric followed by immobilizing SP via amidation reaction with Cys. The X-ray photoelectron spectroscopic (XPS) results show that the amine and thiol groups of Cys form coordination bonds with SP. Durability experiments show that the antibacterial function of the modified fabrics is sustained even after 180 cycles of washing with bacterial reduction rates (BR) > 97% for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Surface characterization results reveal that the combination of the two binders (CMCS and Cys) allows for a stable dispersion of SP on the modified fiber surfaces with > 89% of the silver coating layer preserved after 180 rounds of washing. Moreover, cytotoxicity assays performed on the leachate of the modified fabric show insignificant effects on human immortalized keratinocyte (Hacat) cells indicating that the material is safe to wear against human skin. The results collectively demonstrate that the modified fabric has great potential for use in textile applications.