N-halamine modified cotton dressing with thermosensitive antibacterial-antifouling switchable surface for wound healing.

Surface biofouling of cotton gauze dressings greatly promotes biofilm formation and delays wound healing. Herein a reversibly thermoresponsive switchable biointerface strategy is proposed to regulate the antibacterial and antifouling activity of cotton dressings for promoting wound healing. Poly(ethylene glycol) (PEG) brushes are covalently grafted onto cotton fibers to form a durable antifouling underlayer, followed by in situ polymerization of poly(N-isopropylacrylamide) (PNI) and subsequent chlorination to generate N-halamine antibacterial groups of N-Cl. In the initial antibacterial state, the outer chlorinated PNI layer releases available active chlorine upon bacterial contact, enabling fast disinfection and efficient biofilm disruption. After chlorine consumption, the PNI recovers its thermosensitive structure and collapses at wound-relevant temperature, exposing the PEG brushes underlayer and switching the interface to an antifouling state. The resulting dressing exhibited rapid and rechargeable antibacterial activity, effective biofilm disruption, excellent biocompatibility, and markedly accelerated healing of infected wounds. This bilayer architecture provides a practical route to reconcile rapid disinfection with sustained antifouling at wound biointerface.