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

Carbon fiber-reinforced poly(ether ether ketone) (CFRPEEK)compositematerials, with good biocompatibility and human cortical bone-likeelastic modulus, are considered as possible orthopedic implants. However,the inert surface caused inadequate osseointegration, which has limitedthe clinical application of CFRPEEK in the field of bone implants.To address this issue, a surface chemical modification strategy isproposed to construct a simvastatin (SIM) sustained-release systemon the surface of CFRPEEK to promote angiogenesis and osteogenesis.Based on the Friedel-Crafts reaction between PEEK and succinicanhydride, carboxylated CFRPEEK is prepared to adsorb SIM throughthe surface pore structure, then chitosan/amino-terminated poly(ethyleneglycol) (CS/PEG-NH2) (CPN) as a biocoating is covalentlygrafted on the surface to prevent the rapid diffusion of SIM (SCP/SIM/CPN). In vitro assays indicate that SCP/SIM/CPN exhibits the long-termsustained-release capability of SIM, good hydrophilicity, biomineralizationcapability, and excellent angiogenesis and bone regeneration/osseointegration.In addition, the rat subcutaneous implantation model confirms thatsurface modification improves the immunofluorescence intensity ofVEGF and CD31 in the surrounding tissues of the implant by 1.65 and1.60 times after 7 days of implantation, respectively. The rat cranialdefect model further substantiates that, compared to the unmodifiedgroup, the bone mineral density and bone volume/total volume of theSCP/SIM/CPN group, respectively, increase by 1.84-fold and 1.58-foldafter 12 weeks of implantation. This study has attempted to constructa drug sustained-release system on the surface of CFRPEEK by the chemicalmodification strategy to improve its osseointegration and angiogenesisfeatures, and SCP/SIM/CPN as prepared has potential application inbone tissue engineering.