Photocatalytic effect on plasmid DNA damage under different UV irradiation time

Microbiological contaminants such as mold and mould (both of them fungi), pathogenic bacteria, viruses that widely exist in indoor environment can cause respiratory allergic reactions, asthma, and infectious diseases ranging from influenza to Legionnaires disease. Photocatalytic oxidation (PCO) by TiO2 is a technology that can decompose a wide range of chemical pollutants and disinfect microbiological contaminants by utilizing a semiconductor catalyst such as TiO2 and near-UV (ultraviolet) radiation. In this research, a solution of supercoiled plasmid DNA was used to demonstrate photodynamic DNA strand-breaking and hydroxylation activity at photocatalyst surfaces. Index of DNA damage degree induced by a commercial TiO2 and a non-commercial nanocatalyst were compared, with the UV irradiation time as the controlled variable. Results show that as irradiation time increased, the photocatalytic effect on DNA also increased, and the nanocatalyst has a better photocatalytic effect on plasmid DNA than P25 under the same test conditions. For the irradiation time as short as five seconds, plasmid DNA damage occurred. This fundamental research provides quantitative information for further evaluation of PCO in destructing microbiological pollutants.