An aptamer cocktail-functionalized photocatalyst with enhanced antibacterial efficiency towards target bacteria.

We developed TiO2 particles conjugated with an Escherichia coli surface-specific ssDNA aptamer cocktail (composed of three different aptamers isolated from E. coli) for targeted and enhanced disinfection of E. coli. We examined the target-specific and enhanced inactivation of this composite (TiO2-Apc), which were compared to those of TiO2 conjugated with a single aptamer (one of the three different aptamers, TiO2-Aps) and non-modified TiO2. We found that TiO2-Apc enhanced the inactivation of targeted E. coli under UV irradiation compared to both the non-modified TiO2 and TiO2-Aps. A higher number of TiO2-Apc than TiO2-Aps particles was observed on the surface of E. coli. The amount of TiO2-Apc required to inactivate ∼99.9% of E. coli (10(6) CFU/ml) was 10 times lower than that of non-modified TiO2. The close proximity of functionalized particles with E. coli resulting from the interaction between the target surface and the aptamer induced the efficient and fast transfer of reactive oxygen species to the cells. In a mixed culture of different bacteria (E. coli and Staphylococcus epidermidis), TiO2-Apc enhanced the inactivation of only E. coli. Taken together, these results support the use of aptamer cocktail-conjugated TiO2 for improvement of the target-specific inactivation of bacteria.