DNA-Modified Electrochemiluminescent Tris(4,4’-Dicarboxylicacid-2,2’-Bipyridyl)Ruthenium(II) Dichloride and Assistant DNA-Modified Carbon Nitride Quantum Dots for Hg²⁺ Detection

Accurate determination of hazardous Hg2+ is particularly essential for the environment safety and human health. In this work, using Hg2+ as a bridge for the electrochemiluminescence (ECL) reagent and the corresponding coreactant, a new type of self-enhanced ECL nanomaterial was simply and controllably prepared for the first time. In detail, tris (4,4′-dicarboxylicacid-2,2′-bipyridyl) ruthenium(II) dichloride modified with DNA1 (Ru-DNA1) and graphite-like carbon nitride quantum dots linked with DNA2 (QDs-DNA2) were used as the ECL reagent and coreactant, respectively. In the presence of Hg2+, they could be integrated together to form a self-enhanced ECL nanomaterial (Ru-DNA1-Hg2+-QDs-DNA2) via the T-Hg2+-T duplex structure. The ECL signal strength was positively proportional to the concentration of Hg2+. On this basis, sensitive and selective detection of Hg2+ could be achieved by simply modifying the ECL nanomaterial on the electrode surface. Under the optimal experimental conditions, the proposed sensing strategy expressed a superior linear relation with Hg2+ concentration from 10 fM to 1 nM. Moreover, a low detection limit of 3.3 fM with outstanding selectivity, repeatability, and stability for Hg2+ analysis was obtained. In addition, the proposed sensing strategy exhibited reasonable accuracy for real sample assay compared with the atomic fluorescence spectrometry method. From this work, it is suggested that by programming the analytes and the corresponding recognition element, other analytes might also be sensitively and selectively detected using the proposed method.