Multifunctional gold nanoclusters with red fluorescence as nanoantibiotics for imaging-guided infected wound healing.

The increasing emergence of multidrug-resistant (MDR) bacteria threatens the health of the global population by perpetuating microbial infections. Therefore, accelerating the development of nondrug-resistant antimicrobial substances is crucial to combat drug-resistant bacterial infections. Herein, we report a simple one-pot, microwave-assisted strategy for designing ultrasmall lysozyme-functionalized gold nanoclusters (L-Au NCs) through the one-step assembly of natural lysozyme and metal ions (e.g., Au3+) in aqueous solution. Compared with free lysozyme, L-Au NCs efficiently disrupted the membranes of MDR bacteria and induced the formation of reactive oxygen species within bacterial cells, demonstrating potent broad-spectrum antibacterial activity against Gram-positive (e.g., methicillin-resistant Staphylococcus aureus (MRSA)) and Gram-negative (e.g., MDR Escherichia coli) bacteria. In addition, the red-emitting L-Au NCs exhibited fluorescence labeling capability against MDR bacteria. In mouse infection models, L-Au NCs exhibited good biocompatibility and promoted healing of MRSA-infected skin wounds by eradicating bacterial infection and reducing inflammation without causing systemic damage. These findings provide insights into the antibacterial properties of metal-natural enzyme materials and highlight the potential of rationally designed broad-spectrum antibacterial strategies to treat intractable bacterial infections.