Smart Bactericidal Capsules Based on Cationic Luminescent Nanoclusters for Controllable Treatment of Drug-Resistant Bacterial Infection

Effective treatment of drug-resistant bacteria infected wound has been a longstanding challenge for healthcare systems. In particular, the development of novel strategies for controllable delivery and smart release of antimicrobial agents is greatly demanded. Herein, the design of biodegradable microcapsules carrying bactericidal gold nanoclusters (AuNCs) as an attractive platform for the effective treatment of drug-resistant bacteria infective wounds is reported. AuNC capsules are fabricated via the well-controlled layer-by-layer strategy, which possess intrinsic near-infrared fluorescence and good biocompatibility. Importantly, these AuNC capsules exhibit strong, specific antibacterial activity toward both S. aureus and methicillin-resistant S. aureus (MRSA). Further mechanistic studies by fluorescence confocal imaging and inductively coupled plasma mass spectrometry reveal that these AuNC capsules will be degraded in the S. aureus environment rather than E. coli, which then controllably release the loaded cationic AuNCs to exert antibacterial effect. Consequently, these AuNC capsules show remarkable therapeutic effect for the MRSA infected wound on a mouse model, and intrinsic fluorescence property of AuNC capsules enables in situ visualization of wound dressings. This study suggests the great potential of microcapsule-based platform as smart carriers of bactericidal agents for the effective treatment of drug-resistant bacterial infection as well as other therapeutic purposes.