Impact of trace elements on biocompatibility of titanium scaffolds

A titanium oxide scaffold has recently been reported with high compressive strength (>2 MPa) which may allow its use in bone. However, would it be possible to enhance the scaffolds' performance by selecting a titanium oxide raw material without elemental contamination? Elements in implant surfaces have been reported to provoke implant failure. Thus, this study aims to compare different commercial titanium dioxide powders in order to choose the appropriate powder for scaffold making. The x-ray photoelectron spectroscopy (XPS) analysis identified the trace elements, mainly Al, Si, C, Ca and P. Cellular response was measured by cytotoxic effect, cell growth and cytokine secretion from murine preosteoblasts (MC3T3-E1) in vitro. The XPS data showed that traces of carbon-based molecules, silicon, nitrogen and aluminium in the powder were greatly reduced after cleaning in 1 M NaOH. As a result, reduction in cytotoxicity and inflammatory response was observed. Carbon contamination seemed to have a minor effect on the cellular response. Strong correlations were found between Al and Si contamination levels and the inflammatory response and cytotoxic effect. Thus, it is suggested that the concentration of these elements should be reduced in order to enhance the scaffolds' biocompatibility.