The development of Cu-incorporated micro/nano-topographical bio-ceramic coatings for enhanced osteoblast response

In order to take advantages of the structural complexity of hierarchical topography and benefits of Cu, novel Cu-incorporated micro/nano-topographical coatings were developed on titanium (Ti) substrates using micro-arc oxidation (MAO) and hydrothermal treatment. A post heat treatment was employed to alter the morphology of the nanostructures and modulate the release of Cu2+. The structural evolution, phase composition, surface wettability, ion release and protein adsorption of the coatings were investigated. The results showed that the MAO-fabricated coating (denoted as MAO surface) was composed of porous TiO2 matrix distributed with CaO, SiO2 and CaSiO3 amorphous compounds. After hydrothermal treatment, a thin layer of nano-particles (20 nm in diameter) composed of CuO and calcium silicate hydrate formed on MAO surface (denoted as MAO-HT surface). These nano-particles grew to larger ones (65 nm in diameter) composed of crystallized CaO center dot 3CuO center dot 4TiO(2) and CaO center dot TiO2 center dot SiO2 after post heat treatment (denoted as MAO-HT2 surface). Moreover, the ion release rate and surface hydrophilicity of various coatings followed the trend: MAO surface > MAO-HT surface > MAO-HT2 surface. The amounts of adsorbed proteins were comparable on all surfaces. Furthermore, SaOS-2 cell response to various surfaces was investigated. The results showed that the viability of cells was significantly inhibited on MAO-HT surface due to the cyto-toxicity of high concentration Cu2+ release. However, the attachment, proliferation and differentiation of SaOS-2 cells were enhanced on MAO-HT2 surface compared to MAO surface. The results indicate that modifying Ti surface with hierarchical micro/nano-topography could lead to enhanced osteoblast response.