Characterization of DNA/Buffer/H 2 O System Through Electrochemical Impedance Spectroscopy (EIS)

Abstract

In this work we present a study of transitional behavior of calfthymusDNA molecules in solution in a concentration range from0.01 to 2.5 mg mL-1 at different temperatures (10, 20, 30 and 40ºC) and a pH of 7.3 using Electrochemical ImpedanceSpectroscopy (EIS). The results are interpreted with amethodology similar to the one used in studies of linear-rheology.The Zo modulus and the characteristic time constant of the process(τc) were obtained through a variation of Bode graphics. From theanalysis of these parameters as a function of DNA concentration itis possible to determine the overlap (C*) and entanglement (Ce)concentrations of the system. These concentrations allowidentifying conditions where interactions and entanglementsbetween DNA molecules are present. An interpretation of thecharacteristic time constant values is proposed according to thestructural rearrangement of the electrochemical double-layer.