Chirality-dependent antibacterial activity of copper-cysteine nanoparticles enables functional silk sutures for enhanced wound healing.

Traditional silk sutures are widely used in clinical practice due to their excellent mechanical properties and biocompatibility. However, their intrinsic lack of bioactivity limits their efficacy in combating bacterial infections and managing excessive inflammation during wound healing. To address these challenges, we synthesized two chiral copper-cysteine nanoparticles (Cu-L-Cys and Cu-D-Cys NPs) and systematically evaluated their chirality-dependent biological functions. Although both NPs exhibited comparable enzyme-like activities, Cu-D-Cys NPs exhibited superior antibacterial activity against both Gram-positive and Gram-negative bacteria compared to Cu-L-Cys NPs. Moreover, Cu-D-Cys NPs demonstrated excellent cytocompatibility, effective intracellular reactive oxygen species (ROS) scavenging capability and pronounced angiogenic activity within the therapeutic concentration range for tissue repair. Leveraging these properties, Cu-D-Cys NPs were stably immobilized onto silk sutures through physical adsorption. In vivo animal experiments further showed that these functionalized silk sutures significantly accelerated infected wound closure and improved tissue repair by promoting the formation of granulation tissue, re-epithelialization, angiogenesis, and orderly collagen deposition. Overall, this work presents a robust strategy for developing chiral bioactive sutures, highlighting their promising potential for functional surgical and tissue repair applications.