Effects of nano-TiO2 on Chlamydomonas reinhardtii cell surface under UV, natural light conditions

Abstract

Cell surface of aquatic organisms constitutes a primary site for the interaction and a barrier for the nano-TiO2 biological effects. In the present study, the biological effects of nano-TiO2 on a unicellular green algae Chlamydomonas reinhardtii were studied by observing the changes of the cell surface morphology and functional groups under UV or natural light. By SEM, the cell surface morphology of C. reinhardtii was changed under UV light, nano-TiO2 with UV light or natural light, which indicated that photocatalysis damaged cell surface. It was also observed that cell surface was surrounded by TiO2 nanoparticles. The ATR-FTIR spectra showed that the peaks of functional groups such as C-N, -C=O, -C-O-C and P=O, which were the important components of cell wall and membrane, were all depressed by the photocatalysis of nano-TiO2 under UV light or natural light. The photocatalysis of nano-TiO2 promoted peroxidation of functional groups on the surface of C. reinhardtii cells, which led to the damages of cell wall and membrane.