Influence of precursor chemistry on CVD grown TiO2 coatings: differential cell growth and biocompatibility

Abstract

Nanocrystalline titanium oxide (TiO₂) coatings with different phases and surface topographies were deposited using chemical vapor deposition (CVD) of different homo- and heteroleptic titanium precursors of general formula [XTi(OⁱPr)₃] (X = Cl (1), –NEt₂ (2), –N(SiMe₃)₂ (3), –C₅H₅ (4), –OⁱPr (5) and –O^tBu (6)) to elucidate the influence of molecular configuration on resulting material properties. The interdependence of precursor chemistry and materials features of the CVD deposits was verified by performing film growth under similar conditions using different precursor molecules (1–6). Studies on composition (XPS), structure (SEM, XRD) and bio-functional properties (cell tests) revealed that the decomposition process is markedly influenced by the auxiliary ligands, which led to incorporation of heteroelements (Si, Cl, N) in the films. Cell tests performed to evaluate the biocompatibility of the coatings towards the growth of bone cells showed a pronounced correlation between cell adhesion and surface morphology as well as the chemical composition. Growth of osteoblast cells was strongly enhanced on films obtained using [Ti(OⁱPr)₄] and [CpTi(OⁱPr)₃], whereas TiO₂ coatings produced by [ClTi(OⁱPr)₃] significantly inhibited the cell growth and their proliferation due to Cl contamination. Also, the nanomorphological features of the films were found to stimulate the cell adhesion and growth.