Investigation of DNA damage treated with perfluorooctane sulfonate (PFOS) on ZrO2/DDAB active nano-order film

Abstract

The interactions between DNA and small molecules with planar heterocyclic structure were indicated in previous researches. This study investigated the interactions between PFOS with linear chain structure and DNA. A new phenomenon of DNA damage due to PFOS using electrochemistry technique was proved. The data was obtained on a modified glassy carbon electrode, on which didodecyldimethylammonium bromide (DDAB), ZrO2 and calf thymus DNA were immobilized layer-by-layer. Electrochemical response of DNA damage caused by PFOS was detected by differential pulse voltammetry (DPV) using methylene blue (MB) as electro-active indicator. The current of MB attenuated obviously after DNA/ZrO2/DDAB/GCE were incubated in PFOS. The shift of MB reduction peak potential indicates that PFOS is bound with DNA in groove probably by the first step of hydrophobic interaction and then the second step of intercalation into the base of DNA. X-ray photoelectron spectroscopic (XPS) was used to elucidate in detail the intercalation of PFOS into DNA and the formation of hydrogen bond between PFOS and DNA base. Electrochemical quartz crystal microbalance (EQCM) proved the formation of adducts of DNA and PFOS. Moreover, electrochemical impedance spectroscopy (EIS) indicates that the PFOS influence DNA structure and attenuate DNA charge transport. These results demonstrate that PFOS intercalated into DNA do induce DNA base damage.