Enhanced osteogenic activity and antibacterial performance in vitro of polyetheretherketone by plasma-induced graft polymerization of acrylic acid and incorporation of zinc ions

Abstract

Polyetheretherketone (PEEK) has been widely used in the fields of orthopedics and trauma, but weak osteointegration and bacterial infection affect its long-term stability and repair effects. Surface modification is an effective way to improve the osteogenic and antibacterial activity of PEEK implants. In the present study, a layer of acrylic acid (AA) polymer coating loaded with zinc ions (Zn²⁺) was constructed on the surface of PEEK (PEEK-AA-Zn) using a strategy of combining plasma-induced graft polymerization with a chemical immersion technique. Successful construction of the AA coating remarkably enhanced the hydrophilicity of PEEK, and effectively loaded and released Zn²⁺. In vitro cell culture using MC3T3-E1 preosteoblasts showed that the Zn²⁺ released from PEEK-AA-Zn promoted cell proliferation and elevated gene expression levels of alkaline phosphatase (ALP), osteocalcin (OCN) and bone sialoprotein (BSP). Antibacterial tests revealed that PEEK-AA-Zn efficiently inhibited the proliferation of Staphylococcus aureus (S. aureus). These results suggest that the combined method of graft polymerization and ion incorporation endows PEEK with excellent osteogenic and antibacterial activity, which provides a wide range of possibilities for developing PEEK implants with multifunctional properties for bone tissue repair.