Dual-Functional Silent-Region SERS Nanoplatform for Real-Time Bacterial Tracking and Wound Healing Therapy

Bacterial wound infections, particularly those caused by Escherichia coli and Pseudomonas aeruginosa, are difficult to treat due to biofilm formation, multidrug resistance, and chronic inflammation. Here, we report a multifunctional nanoplatform based on a surface-enhanced Raman scattering (SERS) probe that enables simultaneous photodynamic therapy, antibiotic delivery, and real-time infection monitoring. The probe comprises gold nanoparticles coated with Prussian blue, which acts both as a near-infrared photosensitizer and a Raman reporter in the spectroscopically silent region, further loaded with colistin sulfate and stabilized with bovine serum albumin. Upon irradiation with a 650 nm laser, the probe produces reactive oxygen species, and, in combination with antibiotic release, achieves enhanced eradication of Gram-negative bacteria (>90% reduction) using a significantly reduced antibiotic dose. The SERS signal in the silent region enables background-free, in situ discrimination and quantification of bacterial load during treatment. In both normal and diabetic mouse wound models, the probe accelerates bacterial clearance, facilitates M2 macrophage polarization, and promotes angiogenesis and collagen deposition, thereby resulting in improved wound healing. Analysis of 36 clinical wound samples demonstrates sensitive and specific Gram-positive and negative bacterial identification. This approach establishes a clinically translatable strategy for precise infection management, real-time monitoring, and enhanced wound repair.