Electrochemiluminescence DNA sensor array for multiplex detection of biowarfare agents

Development of a fully automated electrochemiluminescence (ECL) DNA assay for multiplex detection of six biowarfare agents is described. Aminated-DNA capture probes were covalently immobilised on activated-carbon electrodes and subsequently hybridised to target strands. Detection was achieved via a sandwich-type assay after Ru(bpy)3 2+-labelled reporter probes were hybridised to the formed probe–target complexes. The assay was performed in an automated microsystem in a custom-designed ECL detection box with integrated fluidics, electronics, and movable photomultiplier detector. The obtained limits of detection were 0.6–1.2 nmol L−1 for six targets ranging from 50 to 122 base pairs in size, with linear range 1–15 nmol L−1. Non-specific adsorption and cross-reactivity were very low. Detection of six targets on a single chip was achieved with subnanomolar detection limits.