AVS 52nd International Symposium
    DNA Topical Conference Monday Sessions
       Session DN+BI-MoM

Paper DN+BI-MoM11
New Approach in Electrochemical DNA Hybridization Detection with Adjacent Impedance Probing

Monday, October 31, 2005, 11:40 am, Room 311

Session: DNA Structures and Surfaces
Presenter: K.S. Ma, University of California, Irvine
Authors: K.S. Ma, University of California, Irvine
H. Zhou, University of California, Irvine
J. Zoval, University of California, Irvine
M. Madou, University of California, Irvine
Correspondent: Click to Email
Over the past two decades, the rapidly progressing development of electrochemical DNA biosensors have attracted substantial research efforts. Within the large number of electrochemical detection approaches, self-assembled monolayers (SAM) have been shown to be a convenient technique for immobilization of oligonucleotides probes on the gold electrodes. With this type of surface preparation, thiol-labeled ssDNA spontaneously adsorbs onto the gold surface, however, both via thiol-gold linkage (specific) and via non-specific interactions, thus introducing undesirable random orientations of the ssDNA molecules. These random orientations are undesirable because of the resulting non-perfectly-polarized membrane on the electrode. To avoid the problems caused by non-specific adsorption of probes on electrode surface, many methods have been studied intensively. Paleek et al. worked on a new assay method called the "two-surface strategy". In our current study, a unique method was employed for DNA hybridization detection. Using micro-fabrication processes, the two-surface concept was proved to be feasible in the same spatial domain. In this case, the DNA hybridization microspot is made for the bio-recognition event and a bare adjacent conductor electrode is designed for generating the impedance change through insulator deposition. The Electrochemical Impedance Spectroscopy was employed for the measurements. At medium frequency, a noticeable increase of impedance modulus appeared in the Bode plot. For non-complementary measurement, there was no change of impedance modulus. By this biosensor, upon DNA hybridization and subsequent deposition of the enzymatic reaction product, we had found significant improvement on the signal of DNA hybridization detection. Further studies such as lowest detection limitation are required before any practical applications.