Many biosensors have been developed and used in recent years, and to enhance the sensitivity and stability of enzyme biosensors, immobilization of the enzymes on material surfaces is a necessary and important step. Therefore, there has been considerable interest in understanding how material interfaces affect enzyme adsorption. In this study, the influence of the crystallinity of titanium dioxide (TiO2) films on the quantity and activity of the immobilized enzyme, i.e., formaldehyde dehydrogenase (FDH), was investigated. It was found that TiO2 films with high crystallinity, which were annealed at 550 degrees C, showed higher enzyme immobilization and activity compared with the non-annealed TiO2 film. These results suggest that the activity of enzymes could be affected by the crystallinity of surface materials. (C) 2014 Elsevier B.V. All rights reserved.