Enzyme-induced multicolor colorimetric and electrochemiluminescence sensor with a smartphone for visual and selective detection of Hg.

In this study, we developed a novel dual-analytical platform for the visual, sensitive, and reliable analysis of mercury ions (Hg) in environmental water samples. Importantly, thymine (T)-rich DNA probes were utilized to form T-Hg-T base pairs in the presence of Hg to ensure the specificity of the method. We synthesized new luminescent tris(4,4'-dicarboxylicacid-2,2'-bipyridyl) ruthenium (II) dichloride (Ru(dcbpy))-modified metal-polydopamine frameworks (MPFs@Ru), which were then applied to construct an electrochemiluminescence (ECL) system for the first time, and it achieved accurate and sensitive quantitative detection of Hg. To achieve rapid on-site determination, a multicolorimetric system based on a smartphone was established by inducing deposition of silver shells on gold nanorods (Au NRs). Under optimized conditions, the dual-modal assay showed an excellent response for Hg in the linear range of 2 pmol L to 500 nmol L, with a low detection limit of 0.32 pmol L. Moreover, the proposed method demonstrated satisfactory selectivity, stability, and acceptable reproducibility for the detection of Hg. The recovery of lake water samples ranged from 98.53% to 111.97% for the ECL method and from 95.04% to 106.11% for the colorimetric method, indicating the potential applicability of the proposed method for monitoring environmental water samples.