Amyloid-like Protein-Metal Sulfide Nanocoatings for Synergistic Photothermal and Antibacterial Implant Surface Protection

Preventing bacterial adhesion and biofilm formation is essential for the long-term success of biomedical implants. Implant-associated infections remain a significant clinical challenge, underscoring the urgent need for effective and durable antimicrobial surface strategies. This study develops a nanocoating with dual antibacterial adhesion and photothermal antibacterial properties for biomedical surface modification. Bovine serum albumin-templated metal sulfide (MS@BSA) nanocomposites are synthesized and converted into a stable nanofilm via phase-transitioned BSA (PTB) self-assembly. The MS@PTB coating adheres to various substrates and demonstrates broad-spectrum antibacterial activity. In vitro assays show that the copper sulfide@PTB (CuS@PTB) coating significantly reduces bacterial attachment and suppresses biofilm development upon 808 nm near-infrared irradiation. RNA sequencing identifies differentially expressed genes in common pathogens, indicating disrupted respiration, energy metabolism, and virulence pathways as well as stress responses to heat and copper ions. In vivo experiments using rat subcutaneous infection and abdominal wall defect models demonstrate that CuS@PTB markedly reduces bacterial load and inflammatory responses while accelerating tissue regeneration and maintaining excellent biocompatibility. The results demonstrate the synergistic antibacterial effects of photothermal heating and Cu ion release, supporting CuS@PTB as a promising antimicrobial surface coating for implantable biomaterials.