Near-infrared-activated nanohybrid coating with black phosphorus/zinc oxide for efficient biofilm eradication against implant-associated infections

Biofilm infection is the major concern of medical implants, which often causes progressive destruction of surrounding tissues and systemic diseases. However, biofilm resistance significantly increased the difficulty of curing the infectious diseases of medical implants. Herein, we designed an antibacterial phototherapeutic system by combining polydopamine (PDA)-black phosphorus nanosheets (BP NSs)/ZnO nanowires (NWs) on titanium (Ti) substrates to address the infectious concerns. Assisted by the co-efficiency of BP NSs and PDA, remarkable photothermal therapy (PTT) capability was obtained with near-infrared (NIR) irradiation. Note that the photothermal effect not only dissipates the biofilm, but also enhances the Zn2+ release ability of ZnO, greatly improving antibacterial capability. Therefore, with the “dissipating-killing” synergetic strategy, the localized PTT can potently disperse the bacterial biofilms (Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli) and then ZnO NWs can thoroughly kill bacteria in biofilms in vitro with the enhanced sterilization ability. The combination of PTT and antibacterial ZnO NWs achieves an 99.5 % eradication ratio of biofilm in vivo, which is much better than that of PTT or ZnO NWs alone. Importantly, the NIR-triggered synergistic antibacterial strategy has excellent biosafety, which can effectively control the inflammatory response with no damage to normal tissues.