Enhanced antibacterial activity through photothermal therapy of copper nanoparticles on titanium-based implants

Implant-related infections caused by drug-resistant bacteria pose a significant clinical concern for orthopedic surgeons. Therefore, developing an effective antibacterial coating to modify implant surfaces is crucial for preventing implant-related infections. In this study, we utilized a simple self-assembly method to prepare an antibacterial composite coating (Cu-NPs/PDA/PNIPAM) on larger pore-sized titanium dioxide nanotubes (TNTs) by combining copper nanoparticles (Cu-NPs) coated with polydopamine (PDA) and poly (N-isopropylacrylamide) (PNIPAM). Copper nanoparticles functioned as a photothermal transduction agent, converting light energy into heat under near-infrared (NIR) light irradiation, and acted as a source for releasing copper ions. The findings of the photothermal properties indicated that the composite coating may produce a substantial quantity of reactive oxygen species (ROS) when exposed to 808 nm NIR laser irradiation, exhibiting a photothermal conversion efficiency of 30.9 %. Moreover, the inhibitory efficacy of Cu-NPs/PDA/PNIPAM composite coating against Escherichia coli and S. aureus attained 100 % following NIR irradiation, in contrast to the non-irradiation group. This approach addressed the constraints of single-model photothermal therapy (PTT) and solely Cu-based antibacterial strategies, resulting in a synergistic antibacterial effect. Additionally, this antibacterial composite covering demonstrated superior cytocompatibility and biocompatibility, enhancing the osteogenic differentiation of osteoblasts and promoting bone apposition. This platform provided an effective and pragmatic approach to attain superior antibacterial activity and presented a viable alternative for combating harmful microorganisms.