The interaction of DNA with several surfactants was investigated by cyclic voltammetry, UV-vis spectrum and ac impendance, using MB as the redox probe. It was found that all anionic, cationic and non-ionic surfactants can bind to DNA immobilized on the electrode surface, changing the surface state of DNA, thus affects the electrostatic behavior of the probe. The interaction between DNA and anionic surfactants is attributed to electrostatic repulsion and hydrophobic binding, which makes the peak current of MB decrease. Non-ionic surfactants bind to DNA weakly, but they can partly change the conformation of surface DNA because they changed the solution properties. While cationic surfactants bind to DNA via hydrophobic interaction and electrostatic attraction. This interaction is influenced by the length of the hydrophobic carbon chain and the size of the polar headgroup of cationic surfactants. Among them, cetyltrimethylammonium bromide and dodecyltrimethylammonium chloride can improve the electrochemical response of the probe in certain concentration range, while cetylpyridinium bromide and octadecyltrimethylammonium bromide depress the probe's response.

Key words: INTERACTIONS, DEOXYRIBONUCLEIC ACID, SURFACTANTS, GOLD, ELECTRODE, ELECTROCHEMISTRY, ULTRAVIOLET SPECTROSCOPY