Endogenous pH-responsive induced reversible switching of multifunctional properties of antibacterial cotton fabrics

Antibacterial textiles with switchable properties have made significant progress under the regulation of external stimuli. However, the development of multifunctional and dynamic cotton fabrics (CFs) with endogenous acid-responsive properties to autonomously respond to the microenvironmental changes of bacterial infections remains a challenge. In this work, a sulfonamide-quaternary ammonium zwitterionic polymer P[(2-((2-(methacryloyloxy)ethyl)dimethylammonio)acetyl) (phenylsulfonyl)amide)-co-(2-aminoethyl methacrylate hydrochloride)] (PBA) is designed and synthesized, which is capable of charge reversal in weakly acidic environments. The functional antibacterial cotton fabric (CF-PDA-PBA) with endogenous pH-responsive reversible switching is developed via a Michael addition reaction between PBA and the surface of polydopamine (PDA)-modified CF. The results reveal that CF-PDA-PBA exhibits excellent hydrophilicity and good anti-protein adsorption performance. Furthermore, CF-PDA-PBA shows outstanding durability even after 100 laundering or abrasion cycles. Notably, CF-PDA-PBA surfaces could effectively inhibit bacterial adhesion due to the dense hydration layer provided by the zwitterionic polymer PBA. Upon bacterial infection, the resulting acidification would trigger charge reversal and expose the positively charged quaternary ammonium groups, thereby achieving the conversion from antibacterial adhesion to bactericidal action. After efficient sterilization, the microenvironment gradually returns to neutrality, promoting the release of dead bacteria from the surface. Overall, the versatile antibacterial CF-PDA-PBA enables reversible switching under only endogenous acidic stimulation and possesses good biocompatibility, demonstrating the great potential as a new biomaterial.