Multiplexed sensing of mercury(II) and silver(I) ions: A new class of DNA electrochemiluminescent-molecular logic gates

Most of the DNA logic gates employ fluorescent or colorometric signals as their outputs, which were limited by the cumbersome handling procedures, lack of portability and lower sensitivity. To the best of our knowledge, the logic gates with electrochemiluminescent (ECL) signal as their outputs have not been reported. In response, we report here the construction of DNA molecular logic gates that produce ECL signals as their outputs, having the advantages of versatility, low background and simplified optical setup. The logic gates are based on the T-rich or C-rich oligonucleotides for the selective analysis of Hg2+ and Ag+ ions using energy or electron transfer-quenching path. Efficient and stable quenching of ECL of Ru bis(2,2′-bipyridine) (2,2′-bipyridine-4,4′-dicarboxylic acid) N-hydroxysuccinimide ester by oxidizing ferrocene at the Au electrode enabled us to use Hg2+ and Ag+ ions as inputs that activate logic gates, and to execute ECL of Ru(II) as readout signals for logic gate operations.