DNA quantification with an electrochemiluminescence microcell

The detection and quantification of DNA strands using an electrochemiluminescence (ECL) instrument with a microfabricated excitation/detection cell is presented. The microcell is a vertical assembly of silicon and glass substrates, containing thin film Pt electrodes and micromachined fluid channels. A silicon PIN diode photodetector completes the cell assembly. The DNA strands are labeled with an electrochemically exited, luminescing molecule: tris (2,2' bipyridyl) ruthenium (TBR). The labeled DNA strands are bound to paramagnetic beads with a biotin-streptavidin linkage. The magnetic beads are attracted to the Pt electrode 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 silicon PIN diode photodetector operating at room temperature. The overall 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 quantification using an ECL microinstrument. (C) 1998 Elsevier Science S.A. All rights reserved.