Surface Functionalization of Polyetheretherketone With Immobilized γ-Polyglutamic Acid for Enhanced Apatite Formation

Polyetheretherketone (PEEK) is a lightweight, chemically stable, thermoplastic polymer with excellent strength and wear resistance. Therefore, it is used clinically as a restorative material for the spine, skull, and dental crowns. However, PEEK has the drawback of not directly bonding to bone in vivo. Previously reported surface modifications for bone bonding have mostly used inorganic materials, with few examples using organic materials. In this study, we attempted to impart bone-bonding properties by immobilizing γ-polyglutamic acid (γ-PGA) on the surface of PEEK via a solution process. When UV irradiation was used to hydrophilize PEEK, more γ-PGA was immobilized compared with acetic acid pretreatment. Samples with γ-PGA immobilized following UV treatment tended to exhibit enhanced apatite growth in a simulated body fluid and peeling resistance. However, further improvement of the adhesion between the apatite layer and the substrate is required.