Optimisation of the hydrogen peroxide pre-treatment of titanium: surface characterisation and protein adsorption

Background: Researchers have attempted to enhance titanium osseointegration by modifying its surface properties, including via H2O2 pre-treatment, with reported treatment regimes varying from minutes/hours, to weeks. Objective: This study examined the effects of various H2O2 treatments on titanium surface topography/roughness, chemical composition/oxide thickness, hydrophilicity and plasma protein adsorption. Materials and methods: Titanium discs were treated with 30% H2O2 for 0–24 h or 1–4 weeks and subjected to atomic force microscopy (AFM), scanning electron microscopy (SEM), profilometry, X-ray photon spectroscopy and contact angle analysis. For protein adsorption, whole plasma and FITC-conjugated serum albumin were added to 0–24 h and 1–4 week H2O2-treated discs and examined by SEM and fluorescence microscopy, respectively. Results: AFM, SEM and profilometry demonstrated that 1–6 h H2O2-treated discs exhibited subtle alterations in surface topography/roughness at the nanometre scale, although 24 h and 1–4 week H2O2-treated discs exhibited much greater increases in surface roughness, in the micrometre range. Maximal increases in surface oxide thickness and chemical modification were identified between 1 h–4 weeks and 3 h–4 weeks, respectively, although no increases in oxygen/titanium (O1s : Ti2p) molar ratio or in hydrophilicity were evident. Plasma and serum albumin adsorption increased on 1–24 h H2O2-treated discs, with further increases on 1–4 week H2O2-treated discs. Conclusions: Based upon the present data and previous findings, this study supports the concept that surface topography/roughness and oxide composition/thickness, are more significantly modified by H2O2 treatment and more influential to protein adsorption than hydrophilicity. Additionally, it can be hypothesized that the 24 h H2O2 treatment of titanium surfaces, which induced micrometre scale changes in roughness and protein adsorption, to those associated with enhanced osteoblast attachment/behaviour, mineralisation and subsequent implant osseointegration, would be most beneficial