A hybrid binder of carboxymethyl chitosan and l-methionine enables a slight amount of Ag NPs to be durably effective on antibacterial cotton fabrics

This work proposes a facile approach to improve the durability of antibacterial cotton fabric by using carboxymethyl chitosan (CMC) and l -methionine (Met) as a combination binder to immobilize silver nanoparticles (Ag NPs). The durable antibacterial function is achieved by grafting CMC and Met molecules onto a cotton fabric by a simple pad-dry-cure process, followed by the preparation of Ag NPs on the modified surface. This surface modification process provides the cotton fabric with an excellent antibacterial effect and outstanding laundering durability. Structural analyses of the modified surface revealed that the covalent bonds between Met, CMC, and cotton fibers were formed, and the thioether groups caused the stable immobilization of the Ag NPs. Notably, the modification process does not significantly damage the original fiber structure. The desired cotton properties such as vapor permeability, water absorptivity, and flexibility of the modified fabric were very close to the original cotton. Moreover, the safety to human skin was verified by cytotoxicity tests using fibroblast cells.