Electrochemical detection of DNA hybridization using a change in flexibility

A novel electrochemical method of detecting DNA hybridization is presented based on the change in flexibility between the single and double stranded DNA. A recognition surface based on gold nanoparticles (GNPs) is firstly modified via mixing self-assembled monolayer of thiolated probe DNA and 1,6-hexanedithiol. The hybridization and electrochemical detection are performed on the surface of probe-modified GNPs and electrode, respectively. Here in our method the charge transfer resistance (R-ct) signal is enhanced by blocking the surface of electrode with DNA covered GNPs. The GNPs will be able to adsorb on the gold electrode when covered with flexible single stranded DNA (ssDNA). On the contrary, it will be repelled from the electrode, when covered with stiff double stranded DNA (dsDNA). Therefore, different R-ct signals are observed before and after hybridization. The hybridization events are monitored by electrochemical impedance spectroscopy (EIS) measurement based on the R-ct signals without any external labels. This method provides an alternative route for expanding the range of detection methods available for DNA hybridization. (C) 2011 Elsevier B.V. All rights reserved.