Effects of nanoparticles on stability of cell DNA studied by SRCD

To investigate influence of different-sized nanoparticles on stability of cell DNA, RAW264.7 strains were incubate with 30 nm and 50 nm COOH-labeled polystyrene beads (COOH-PBs). Synchrotron radiation circular dichroism spectroscopy (SRCD) was used to analyze possible transformation of the secondary structure of DNA, which was further confirmed by means of comet assay. The CD spectra indicated that both particles could reduce helicity of the DNA and increase the degree of DNA single strands. The 30 nm-PBs treatment did more damage than the 50 nm-PBs treatment. This suggests a size-dependent influence. It is demonstrated that SRCD provides a reliable method to investigate the stability of cell DNA influenced by nanoparticles.