A Janus Adhesive Hydrogel with Integrated Attack and Defense for Bacteria Killing and Antifouling.

Objective: Skin wound exposed to complex external environment for a long time is highly susceptible to bacterial infection. Impact Statement: This work designs a Janus adhesive dual-layer hydrogel containing in situ silver nanoparticles (named PSAP/DXP@AgNPs) with integrated attack and defense to simultaneously kill the existing bacteria and prevent foreign bacterial contamination. Introduction: The current gauze dressing fixed by tape fails to well fit at skin wound and lacks intrinsic antibacterial property, making it highly prone to causing secondary infection. Moreover, foreign bacteria may contaminate the wound dressing during use, further increasing the risk of secondary infection. Methods: In this work, a Janus adhesive dual-layer PSAP/DXP@AgNPs hydrogel is prepared by sequentially building the PSAP gel layer containing zwitterionic poly(sulfobetaine methacrylamide) (PSBMA) on the DXP@AgNPs gel layer containing in situ catechol-reduced AgNPs. Results: The flexible PSAP/DXP@AgNPs can adapt shape change of skin and adhere to skin tissue with interfacial toughness of 153.38 J m^-2 relying on its DXP@AgNPs layer, which is beneficial to build favorable fit. The in situ reduced AgNPs released from the DXP@AgNPs layer of PSAP/DXP@AgNPs exhibit obvious antibacterial effects against Escherichia coli and Staphylococcus aureus, with antibacterial rates of 99% and 88%, respectively. Meanwhile, the hydrated PSAP layer of PSAP/DXP@AgNPs containing PSBMA is able to prevent the bacterial contamination, decreasing the risk of secondary infection. Besides, cell experiments demonstrate that PSAP/DXP@AgNPs is biocompatible. Conclusion: The PSAP/DXP@AgNPs hydrogel with integrated attack and defense simultaneously possessing bacteria-killing and bacteria-antifouling properties is a potential alternative in treating infected skin wound.