Polyetheretherketone (PEEK) implant functionalization with magnetron-sputtered SrTiO3 for regenerative medicine

Polyetheretherketone (PEEK) is a polymer material widely used for artificial bone implants but known to exhibit a low affinity for bone tissue and lack osteoconductivity and osseointegration. Because strontium (Sr) is known to enhance bone growth, PEEK implants coated with strontium titanate (SrTiO3, STO) is expected to improve the bone growth around them. In this study, STO was deposited on model PEEK implants by magnetron sputtering deposition and its ability to release Sr2+ ions to a surrounding phosphate-buffered saline (PBS) solution was examined. It is found that, in an early stage of the deposition process, STO on a PEEK surface exhibits irregular surface structures with many holes. The amount of Sr stored in the STO film increases with the increasing film thickness but the release rate of Sr2+ ions from the STO film to the surrounding PBS also increases with the film thickness, limiting the duration of effectiveness of the STO-coated PEEK films. It is found, however, that a three-layer titanium (Ti)-STO-Ti film deposited on PEEK allows a steady release of Sr2+ ions to the surrounding PBS for an extended period.