Micro-arc oxidation treatment enhanced the biological performance of human osteosarcoma cell line and human skin fibroblasts cultured on titanium–zirconium films

• Ti and Zr oxide films with porous structures were synthesized by micro-arc oxidation.
• Besides TiO2, tetragonal and monoclinic ZrO2 were obtained for the MAO-treated TiZr coatings.
• High cell viability of MG-63 and SKF cells was found in MAO-treated TiZr films.
• MAO-treated TiZr films are suitable for MG-63 and SKF cell growth and differentiation.

Development of oxide films on metallic implants with a desirable combination of mechanical properties and biocompatibility can greatly improve its functionality and application to the medical implant field. The present work is aimed to fabricate titanium (Ti) or zirconium (Zr) oxide films with porous structures onto Ti substrates by micro-arc oxidation (MAO) procedure. Before the MAO treatment, a series of TiZr alloy films were deposited on polished pure Ti substrates using a cathodic arc deposition system with different deposition cathode current ratios of Zr/Ti. The post-MAO-treated surface layers were characterized for its composition, crystalline structure, bonding states, surface morphology, and wettability. The results showed that porous crystalline titanium and zirconium oxides were formed using the MAO treatment for the TiZr films. To evaluate the bioactivity, cell viability and gene expression of human osteosarcoma cell line (MG-63) and human skin fibroblast cell line (SKF) cultured on different TiZr oxide films were determined. The results of MTT tests showed that the higher cell viability of MG-63 and SKF cells was found in MAO-treated TiZr films with higher Zr content. Gene expression data by RT-PCR and agarose gel electrophoresis showed that MG-63 cells and SKF cells exhibited notable osteogenic gene expression, such as Runx2, ALP, Dlx-5, OCN, BMP-2 and BMPR1A. The cell adhesion-related genes, such as fibronectin, collagen types I and III, and laminin were also remarkably expressed in the gel imaging. It suggested that the MAO-treated TiZr films were suitable for bone tissue- or soft tissue-derived cell growth and differentiation. The design and fabrication of TiZr oxide films with specific composition and porous surface layer with MAO treatment may provide a better material environment for cell bonding, living, and differentiation in dental and orthopedic implants.