Preparation And Characterization Of TiO₂ Micropatterns By Soft Lithography

The effects of implant surface topography and chemistry on biomineralization and cell behavior have been a research focus because of their potential importance in orthopedic and bone replacement applications. While a vast amount of research is focusing on chemical modified surfaces and rough surfaces, little attention has been paid to the well-defined micropatterned surface effects on calcium phosphate mineralization process due to the difficulties in preparing microfabricated biomaterial surfaces. This work focus on the effects of microgrooved TiO2 surfaces on the calcium phosphate mineralization process and its biocompatibilty.We developed a new process that can prepare microgrooved TiO2 coatings on glass substrates using the soft-lithography and sol-gel technology. TiO2 sol-gel precursor solution was prepared using a mixture of tetrabutyltitanate/ethanol/hydrochloric acid/distilled water/1,5-pentanediol with a molar ratio of 1/30/0.2/2/2. Polydimethylsiloxane (PDMS) microstamps were used to transfer micropatterns from the silicon wafer to the TiO2 gel. Then microgrooved TiO2 surfaces were used to induce Ca-P mineralization under biomimetic conditions. The results revealed that topography dominated the growth and distribution of mineralization at the initial days and then the effect of topography become weak with the extended immersion days. The surface energies of the TiO2 surfaces were in range ofγ12μm<γ20μm<γ40μm<γflat surfaces.The effect of microgrooved TiO2 surfaces on osteoblast behavior was also evaluated. Osteoblasts (MC3T3-E1) were cultured on the as-prepared microgrooved and flat TiO2 surfaces. Optical microscopy and scanning electron microscopy (SEM) were used to analyze adherent cell behavior by examining the cell morphology. Orientation angle (OA) analysis indicated that cells tended to align along with the microgrooves and this tendency was strong on the microgrooves with small width and became weak with the increase of the width. Alamar blue assay indicated that the microgrooves restricted the growth of cells and alkaline phosphatase (ALP) assay revealed that microgrooves limited the proliferation rate. This restriction increased with the decrease of the width of microgrooves. Osteoblast proliferation and differentiation on micropatterned titanium oxide surfaces was correlated with the surface energy.