Preparation and antibacterial evaluation of two-layered aluminum anodic oxide film electrodeposited titanium dioxide

Abstract

Aluminum anodic oxide film with a two-layer structure was successfully prepared by a two-step anodic oxidation process in two solutions of phosphoric acid (H3PO4) and sulfuric acid (H2SO 4). The two-layer structure consists of the upper layer with wide pores and the lower layer with narrow pores. Subsequently, titanium dioxide (TiO2) was electro-deposited into wide pores in upper layer. The TiO2 content in the obtained sample depended on the concentration of TiO2 sol, pH and the migration voltage during electrodeposition. The hardness, corrosion resistance and sealing degree of the sample with TiO 2 were almost the same as that of the sealed sample without TiO 2. On the other hand, the electron spin resonance (ESR) measurement indicated that hydroxyl radicals (·OH) were generated from the prepared sample by the irradiation of ultraviolet light. Furthermore, antimicrobial activity to Escherichia coli of the anodic oxide film of aluminum electrodeposited TiO2 was higher than that without TiO2. These results suggested that the two-layered anodic oxide film of aluminum electrodeposited with TiO2 would be a novel photocatalytic antimicrobial material.