Brown Cotton Fibers Self-Produce Ag Nanoparticles for Regenerating Their Antimicrobial Surfaces

To produce textiles that regenerate antimicrobial surfaces wash after wash, we synthesized and immobilized antimicrobial silver nanoparticles (Ag NPs) within brown cotton fibers. This composite formation is based on utilizing brown cotton fiber as a nanoreactor─natural condensed tannins reduce Ag ions, and the swollen microfibrillar structure controls and stabilizes particle growth. A simple one-step process involving heating brown cotton in an aqueous solution of Ag ions actuates the self-synthesis of Ag NPs. Transmission electron microscopy (TEM) images of the fiber cross-section confirm the formation of Ag NPs (diameter of 8–21 nm, weight fraction of 12 800 mg/kg) throughout the entire volume of the fiber with a unique size distribution. The Ag NPs present within the cotton fiber were found to be leach-resistant against typical textile wet processing and prolonged laundering while serving as a reservoir of Ag ions. After 50 laundering cycles, cotton retains approximately 85% of the total Ag embedded and persistently inhibits 99.99% of both Gram-positive and Gram-negative bacteria. The fabrication of true cotton nanocomposite fibers holds promise for binder-free and permanent functionalization.