Voltammetry of osmium end-labeled oligodeoxynucleotides at carbon, mercury, and gold electrodes

Voltammetric behavior of oligodeoxynucleotide (ODN) 5'-T-40 (GAA)(7)-3' end-labeled with osmium tetroxide,2,2-bipyridine [Os(VIII)bipy] was compared with Os(VIII)bipy-base- and with Os(VI)bipy-sugar-modified thymine ribosides. Cyclic voltammograms of Os(VIII)bipy-modified ODN at mercury and carbon electrodes were similar but not identical to those of Os(VIII)bipy-modified thymine riboside. Treatment of the ODN with Os(VI)bipy did not result in the ODN modification, in agreement with the known specificity of the reagent to the sugar cis-diols. We show that in addition to mercury and carbon electrodes, the gold electrode can be used to detect Os(VIII)bipy-labeled ODN. Comparison of voltammetric behavior of end-labeled ODN using three types of electrodes most frequently used in DNA analysis may help to optimize electrochemical DNA sensors.