Construction of acidic microenvironment by Cu-TCPP nanozyme composited deprotonatable polymeric nanofibers for efficient antibacterial activity

• Cu-TCPP nanozyme and deprotonated polymer were composited into nanofibrous membranes. • Localized acidic microenvironments were constructed to enhance the activity of nanozyme . • Nanofibrous membranes exhibited excellent antibacterial activity under weakly alkaline. The issue of bacterial resistance caused by conventional antibiotics has emerged as a major challenge in clinical treatment. Nanozymes, based on catalysis and devoid of bacterial resistance, provide a novel approach to eradicating bacteria. However, the practical potential of these nanozymes is limited by their low and readily pH-affected catalytic activity. Herein, the enzyme activity was optimized starting from the synthesis of nanozyme and the selection of carboxylate-containing polymers for the matrix. Specifically, various copper-tetrakis (4-carboxyphenyl) porphyrin (Cu-TCPP) were initially synthesized employing three copper sources, and among them, Cu-TCPP derived from Cu 2 O with higher catalytic activity was preferred. Subsequently, Cu-TCPP composite fibrous membranes were further obtained by electrospinning from their blend solutions with different polymers with distinct deprotonation capabilities. Thus, an acidic microenvironment conducive to the exertion of enzyme activity was constructed. The fabricated composite nanofibrous membrane could dissociate hydrogen ions to construct a localized acidic microenvironment even under weakly alkaline conditions, thereby enhancing the enzyme activity and improving the antibacterial effect. Further, in vivo experiments demonstrated its favorable antibacterial ability and accelerated wound healing effect. The enhancement strategy of enzyme activity in this study brings inspiration for the design of nanozyme composited wound dressings and holds significant potential for clinical antibacterial applications.