DNA Interaction with 17α-Ethinylestradiol Studied Using Electrochemical Biosensors and Biosensing in Solution

The synthetic estrogen 17 alpha-ethinylestradiol (EE2) is an active component of oral contraceptives. It is considered as an endocrine disrupting compound that, once incorporated into an organism, affects the hormonal balance of animals and humans. In this study we characterized the DNA-EE2 interaction using an electrochemical biosensor and biosensing in solution phase with the double stranded DNA from salmon sperm and deoxyguanosine monophosphate (dGMP). Differential pulse voltammetry method has been applied based on voltammetric anodic responses of the deoxyguanine (dGuo) and deoxyadenine (dAdo) as well as EE2 in the medium of phosphate buffer solution pH 7.0. Binding of EE2 to the nucleobases leads to a decrease of their anodic signals. Association constant for DNA-EE2 interaction has been estimated to be about 1.1.10(3) L mol(-1) and 1.4.10(3) L mol(-1) for dGuo and dAdo responses, respectively. The association is reversible as indicated by decrease of the EE2 response in pure buffer solution due to leaching of EE2 from the surface attached DNA. The DNA-EE2 association has been confirmed also by UV-vis spectrometric experiments.