Amplified electronic transduction of oligonucleotide interactions: novel routes for Tay-Sachs biosensors

Two different configurations for the amplified microgravimetric analysis of oligonucleotides (DNA) are presented. A thiol-tagged oligonucleotide, (1), is assembled on a Au-quartz electrode, and the complementary oligonucleotide (2) is microgravimetrically sensed by the crystal. Formation of the ds-oligonucleotide assembly is amplified using mouse anti-dsDNA antibody and goat anti-mouse Fc antibody. Alternatively, a biotin-labeled oligonucleotide, (4), is used to form the ds-oligonucleotide, Biotin is used to amplify the formation of the ds-complex. An electrochemical method, using cytochrome c as redox probe, to assay the formation of the ds-oligonucleotide assembly, is described. The 5'-carboxylic acid-functionalized oligonucleotide (5) is coupled to a cystamine monolayer associated with an Au-electrode. The electrostatic attraction of cytochrome c to the ds-oligonucleotide complex facilitates the interfacial electron transfer to cytochrome c. Formation of the ds-oligonucleotide assembly is detected electrochemically using differential pulse voltammetry. (C) 1999 Elsevier Science B.V. All rights reserved.