Influences of niobium pentoxide on roughness, hydrophilicity, surface energy and protein absorption, and cellular responses to PEEK based composites for orthopedic applications

Abstract

To improve the bio-performances of polyetheretherketone (PEEK) for orthopedic applications, submicro-particles of niobium pentoxide (Nb₂O₅) were synthesized using a sol–gel method, and PEEK/Nb₂O₅ composites (PNC) with a Nb₂O₅ content of 25v% (PNC25) and 50v% (PNC50) were fabricated by utilizing a process of pressing–sintering. The results showed that the Nb₂O₅ particles were not only dispersed in the composites but also exposed on the surface of the composites, which formed submicro-structural surfaces. In addition, the hydrophilicity, surface energy, surface roughness and absorption of proteins of the composites were improved with increasing Nb₂O₅ content. Moreover, the release of Nb ions with the highest concentration of 5.01 × 10⁻⁶ mol L⁻¹ from the composite into the medium displayed no adverse effects on cell proliferation and morphology, indicating no cytotoxicity. Furthermore, compared with PEEK, the composites, especially PNC50, obviously stimulated adhesion and proliferation as well as osteogenic differentiation of bone mesenchymal stem cells of rats. The results suggested that the incorporation of Nb₂O₅ submicro-particles into PEEK produced novel bioactive composites with improved surface properties, which played important roles in regulating cell behaviors. In conclusion, the composites, especially PNC50 with good cytocompatibility and promotion of cellular responses, exhibited great potential as implantable materials for bone repair.