Abstract
A bacterial target-specific titanium oxide (TiO2) photocatalyst was developed for the enhancement of selective inactivation of targeted bacteria. An antibacterial composition comprising TiO2 particles immobilized with a bacterial-specific antibody having affinity to bacteria of interest was prepared via a carbodiimide hydrochloride/N-hydroxysulfosuccinimide (EDC/NHS) coupling reaction between polyacrylic acid (PAA) coated TiO2 and an antibody. As a model case, an antibody to Escherichia coli was conjugated with the PAA-coated TiO2 (TiO2-AbE). We evaluated the enhancement of the antibacterial effect of TiO2-AbE against target E. coli, compared with its effect on other bacteria that lack affinity for the antibody used. The TiO2-AbE inactivated approximately 90% of the E. coli at 15 min, whereas the raw TiO2 inactivated approximately 20% of the E. coli after the same period of time under UV irradiation. The TiO2-AbE did not show an enhanced antibacterial effect against non-target bacteria. We infer that close contact between TiO2 particles and E. coli, as a result of the specificity of the antibody, can enhance the direct transfer of reactive oxygen species (ROS) generated by TiO2 particles to the cellular surface under UV irradiation and result in rapid and efficient inactivation of the targeted bacteria. The strategy presented here will facilitate the combination of other receptors and TiO2 particles for the preparation of highly selective and photocatalytic composites to prevent or remediate contamination by unwanted bacteria in a wide variety of natural and man-made systems.