Surface Modification of Carbon Fiber-Reinforced Polyetheretherketone with MXene Nanosheets for Enhanced Photothermal Antibacterial Activity and Osteogenicity

Ideal bone implant materials need to provide multiple functions such as biocompatibility, non-cytotoxicity, and bone tissue regeneration guidance. To tackle this challenge, according to our previous work, carbon fiber (40 mm)-reinforced polyetheretherketone (CFPEEK) composites were developed by using 3D needle-punched CFPEEK preform molding technology. Because of the excellent mechanical properties, the CFPEEK needled felt matrix composites have a broad application prospect in orthopedic internal fixation and implant materials. In order to expand the application range of composite materials, it is very necessary to improve the surface bioactivity of composite materials. The surface modification of CFPEEK with 2D titanium carbide (MXene) nanosheets (sulfonated CFPEEK (SCFPEEK)-polydopamine (PDA)-Ti3C2Tx) for enhanced photothermal antibacterial activity and osteogenicity was explored in this study. Here, the new composites we constructed are composed of Ti3C2Tx nanosheets, PDA, and biologically inert SCFPEEK, which gave the bio-inert composites bimodal therapeutic features: photothermal antibacterial activity and in vivo osseointegration. To our knowledge, this is the first time that a CFPEEK implant with a bioactive surface modified by Ti3C2Tx nanosheets was demonstrated. Due to the synergistic photothermal therapy (PTT) treatment of Ti3C2Tx/PDA, SCFPEEK-PDA-Ti3C2Tx (SCP-PDA-Ti) absorbed heat and the temperature increased to 40.8–59.6 °C─the high temperature led to bacterial apoptosis. The SCP-PDA-Ti materials could effectively kill bacteria after 10 min of near-infrared (NIR) irradiation at 808 nm. SCP-PDA-Ti (2.5) and SCP-PDA-Ti (3.0) achieved a 100% bacteriostasis rate. More importantly, the multifunctional implant SCP-PDA-Ti shows good cytocompatibility and an excellent ability to promote bone formation in terms of cytotoxicity, diffusion, alkaline phosphatase activity, alizarin red activity, real-time polymerase chain reaction analysis, and in vivo bone defect osteogenesis experiments. This provides a more extendable development idea for the application of carbon fiber-reinforced composites as orthopedic implants.