Creation of nanoporous TiO₂ surface onto polyetheretherketone for effective immobilization and delivery of bone morphogenetic protein

This study evaluated the utility of the creation of a nanoporous TiO ₂ surface to enhance the in vitro biocompatibility and in vivo osseoconductivity of polyetheretherketone (PEEK) implants by providing favorable sites for the effective immobilization of bone morphogenetic protein-2 (BMP-2). A uniform nanoporous TiO₂ layer with a pore diameter of ∼70 nm was successfully created by anodizing a Ti film, which had been deposited onto a PEEK substrate via electron beam (e-beam) evaporation technique. This nanoporous, hydrophilic TiO₂ surface enabled the efficient immobilization of BMP-2, resulting in a remarkable enhancement in in vitro biocompatibility that was assessed in terms of cell attachment, proliferation, and differentiation. The in vivo animal tests also confirmed that the nanoporous TiO₂ surface immobilized with BMP-2 could significantly enhance the osseoconductivity of PEEK implants. The BMP-immobilized PEEK implant with the nanoporous TiO₂ surface showed much higher bone-to-implant contact (BIC) ratio (60%) than the bare PEEK (30%), PEEK with the nanoporous TiO ₂ surface (50%) and even BMP-immobilized PEEK without the nanoporous TiO₂ surface (32%). © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 793-800, 2014.