Paper BI-WeA4
In Situ Study of Ionic Strength and Probe Coverage Influences on DNA Hybridization using Cyclic Voltammetry

Wednesday, October 17, 2007, 2:40 pm, Room 609

Solid-phase hybridization underpins modern microarray and biosensor technologies. While the underlying molecular process, namely sequence-specific recognition between complementary probe and target molecules, is fairly well-understood in bulk solution, this knowledge proves insufficient to adequately understand solid-phase hybridization. Using self-assembled DNA monolayers as a model system for hybridization assays, the influence of ionic strength and probe coverage and their cross-correlation are studied systematically on mm-sized gold electrodes. Electroactive ferrocene and ruthenium compounds were employed to quantify the surface DNA probe and target densities independently. The use of electrochemical labels enables in situ monitoring of the hybridization process as well as quantification of nonspecific versus sequence-specific attachments of targets. Results of these experiments can be summarized in a hybridization "map" as a function of ionic strength and probe coverage. Optimum probe densities that lead to maximum target binding or, alternately, maximum hybridization efficiency under a given set of conditions have been identified. The objective is to obtain better understanding of the physical characteristics of solid-phase hybridization at a more fundamental level and to subsequently use this knowledge to guide DNA microarray and other surface hybridization applications.