ELECTROCHEMICAL CHARACTERIZATION OF DNA PROBES IMMOBILIZED ON GOLD SURFACES. Adam B. Steel, Building 221, Room A303, NIST, Gaithersburg, MD USA address NIST Bldg 221, Room A303. (301-975-3107, email:adam.steel@nist.gov)

DNA probe arrays are of increasing interest for DNA sensor and sequencing applications. Characterization of surface-confined DNA molecules is crucial to the development of these technologies. Electrochemical methods are particularly well suited to characterize this system. DNA-coated surfaces are prepared by sequential exposure of a clean gold substrate to a thiol-derivitized single strand DNA probe molecule and an inert, diluent hydroxyalkanethiol, mercaptohexanol (MCH). The capacitance of the resultant two component monolayer coated gold surface/electrode shows that the mixed DNA/MCH surface is well-packed with low solvent (water) permeability. Cyclic voltammetry of solution redox molecules further probes the packing and permeability of the DNA monolayer. Quantitation of the amount of DNA on the electrode is afforded by chronocoulometric methods. Preliminary results indicate that the surfaces created by the sequential exposure method are more ordered than those of a pure DNA monolayer. Electrochemical characterization of DNA monolayer coated gold electrodes produces a more detailed understanding of the structure-function relationship of surface-immobilized DNA, a prerequisite for intelligent application design.