Hybrid polyetherimide-CuS layer coated nanoporous titanium implants: NIR-II laser-driven antibacterial strategy

Abstract

Although titanium-based artificial bioimplants are considered viable, they are not effective in combating bacterial-associated infections. In this perspective, the near-infrared (NIR) photothermal treatment (PTT) approach is suitable for eradicating bacteria due to its distinct characteristics. The present work aims to fabricate the NIR-II (1064 nm) laser-active CuS nanoparticles (NPs) incorporated within a polyetherimide (PEI) matrix as a hybrid coating on the nanoporous structured Ti surface (CuS-PEI/OH-Ti) to enhance the antibacterial efficacy. The formation of the CuS NPs, the alkali treatment of the Ti sample to create a nanoporous structure, and the subsequent coating of the hybrid CuS-PEI layer on OH-Ti were carried out by solvothermal and casting methods, respectively. The CuS NPs formed, nanoporous Ti surface, and the CuS-PEI hybrid coating on the OH-Ti surface with better adhesion were confirmed by comprehensive surface characterization studies. The antibacterial efficacy of CuS NPs (at 100 μg mL⁻¹) and their CuS-PEI coated OH-Ti was enhanced against S. aureus and E. coli under NIR-II laser irradiation, reaching over 88 % and 83 %, respectively through the cell membrane damage mechanism. Minimal cytotoxicity was observed in the presence of the L929 and MC3T3-E1 cell lines. Furthermore, the electrochemical results in a simulated body fluid revealed that the coated Ti is compatible with the in-vivo electrochemical potential range. The antibacterial efficacy (>97 % against S. aureus) of the CuS-PEI/OH-Ti implant, as well as its biocompatibility and stability, were confirmed using an in vivo subcutaneous mouse model. The results indicate that the application of a photoactive hybrid CuS-PEI layer on the nanoporous Ti improves the antibacterial properties without compromising the biocompatibility.