Chemical Modification Strategy to Improve Biological Activity of Carbon Fiber-Reinforced Poly(ether ether ketone) Implants

Carbon fiber-reinforced poly­(ether ether ketone) (CFRPEEK) composite materials, with good biocompatibility and human cortical bone-like elastic modulus, are considered as possible orthopedic implants. However, the inert surface caused inadequate osseointegration, which has limited the clinical application of CFRPEEK in the field of bone implants. To address this issue, a surface chemical modification strategy is proposed to construct a simvastatin (SIM) sustained-release system on the surface of CFRPEEK to promote angiogenesis and osteogenesis. Based on the Friedel–Crafts reaction between PEEK and succinic anhydride, carboxylated CFRPEEK is prepared to adsorb SIM through the surface pore structure, then chitosan/amino-terminated poly­(ethylene glycol) (CS/PEG-NH₂) (CPN) as a biocoating is covalently grafted on the surface to prevent the rapid diffusion of SIM (SCP/SIM/CPN). <i>In vitro</i> assays indicate that SCP/SIM/CPN exhibits the long-term sustained-release capability of SIM, good hydrophilicity, biomineralization capability, and excellent angiogenesis and bone regeneration/osseointegration. In addition, the rat subcutaneous implantation model confirms that surface modification improves the immunofluorescence intensity of VEGF and CD31 in the surrounding tissues of the implant by 1.65 and 1.60 times after 7 days of implantation, respectively. The rat cranial defect model further substantiates that, compared to the unmodified group, the bone mineral density and bone volume/total volume of the SCP/SIM/CPN group, respectively, increase by 1.84-fold and 1.58-fold after 12 weeks of implantation. This study has attempted to construct a drug sustained-release system on the surface of CFRPEEK by the chemical modification strategy to improve its osseointegration and angiogenesis features, and SCP/SIM/CPN as prepared has potential application in bone tissue engineering.