First Characterization of a Biosensor for Large DNA Molecules using Quartz Crystal Microbalance and Impedance Spectroscopy

The hybridization of large DNA molecules has been investigated using quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS). 20-base DNA probes bearing thiol groups were immobilized on the gold-quartz surface and gold electrode. Confirmation of this irreversible surface modification was obtained using cyclic voltammetry (CV). After the immobilization step, the probe was hybridized with a 100-base DNA that includes the 20-base complementary sequence, and significant changes in resonant frequency values and electrochemical values were observed. The hybridization reactions were found to be completely reversible and specific. These methods of detection open the way for further use in biological applications.