Analysis of DNA Electrochemistry with Electrochemical Impedance Spectroscopy

DNA electrochemistry has proven beneficial for understanding fundamental charge transport features of DNA, DNA-protein interactions, enzymatic kinetics, and DNA-damaging anticancer drug activity. Still, fundamental insight on the overall electrical and electrochemical behavior of DNA electrochemistry is elusive due to the interplay of ionic and electronic effects. Electrochemical Impedance Spectroscopy (EIS) is a useful tool in analyzing the ionic and electronic features of electrochemical systems. Here, we use EIS with equivalent circuit modeling to develop a fundamental and consistent equivalent circuit to represent our DNA electrochemistry system. When analyzing a working electrode modified with electrochemically active DNA monolayers and a mercaptohexanol backfilling agent, key capacitive and resistive elements were identified. Frequency-dependent capacitance and conductance of the system were also analyzed. Additional mechanistic insight was revealed through protein studies with DNA helicases. These experiments provide a different outlook on the ionic and electronic features of DNA, giving a better understanding of how DNA reacts to charge.