Effect of oxidation treatment and UV irradiation of titanium on surface properties and yeast adhesion

In bioreactors that use microorganisms as catalysts, it is important to retain a high density of microorganisms on the support material. Initial adhesion of microorganisms is the first step in the formation of a robust biofilm. In this study, we evaluated the potential of titanium oxide as a microbial carrier by controlling the surface properties of titanium through oxidation and UV irradiation. Furthermore, we attempted to clarify the effect of changes in the surface properties of titanium oxide on the initial adhesion of yeast. When polished titanium is heat-treated or anodized, the number of yeast cells attached to anodized titanium increases significantly, indicating that anodized titanium may be a promising microbial carrier. No significant effect of UV irradiation on yeast adhesion is observed. UV irradiation increases the surface free energy of titanium oxide, which is decreased when polished titanium or heat-treated titanium is immersed in a culture medium due to adsorption of the medium components. Anodized titanium adsorbs more medium components than the other titanium samples, but maintains its superhydrophilicity and surface free energy even after immersion. These results suggest that the characteristics of the adsorption layer formed on the material surface strongly affect the adhesion of materials and microorganisms.