DNA QUANTIFICATION WITH AN ELECTROCHEMILUMINESCENCE MICROCELL

The detection and quantification of DNA strands using an electrochemil uminescence (ECL) instrument with a microfabricated excitation/detecti on cell is presented. The microcell is a vertical assembly of silicon and glass substrates, containing thin film Pt electrodes and micromach ined fluid channels. A silicon PIN diode photodetector completes the c ell assembly. The DNA strands are labeled with an electrochemically ex ited, luminescing molecule: tris (2,2' bipyridyl) ruthenium (TBR). The labeled DNA strands are bound to paramagnetic beads with a biotin-str eptavidin linkage. The magnetic beads are attracted to the Pt electrod e surface with an external magnet, where ECL is excited. With a 1 cm(2 ), Pt anode, a detection limit of 40 fmol of DNA is obtained with a si licon PIN diode photodetector operating at room temperature. The overa ll size of the microcell is only 1.5 cm x 2 cm x 0.2 cm and supports a sample volume of 150 mu l. This is the first demonstration of DNA qua ntification using an ECL microinstrument. (C) 1998 Elsevier Science S. A. All rights reserved.