PHOTOCATALYTIC EFFECT ON PLASMID DNA DAMAGE UNDER DIFFERENT UV IRRADIATION TIME

摘要

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 new 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 has been 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 illumination time as the controlled variable. Results show that as illumination 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. Even for the 1 minute illumination time, plasmid DNA damage appeared, which has significant implication to application of the PCO techniques when the factor of short residence time of microbes in PCO reactor is considered.