Enzyme-induced multicolor colorimetric and electrochemiluminescence sensor with a smartphone for visual and selective detection of Hg2+

In this study, we developed a novel dual-analytical platform for the visual, sensitive, and reliable analysis of mercury ions (Hg2+) in environmental water samples. Importantly, thymine (T)-rich DNA probes were utilized to form T-Hg2+-T base pairs in the presence of Hg2+ to ensure the specificity of the method. We synthesized new luminescent tris(4,4'-dicarboxylicacid-2,2'-bipyridyl) ruthenium (II) dichloride (Ru(dcbpy)(3)(2+))-modified metalpolydopamine 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 Hg2+. 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 Hg2+ in the linear range of 2 pmol L-1 to 500 nmol L-1, with a low detection limit of 0.32 pmol L-1. Moreover, the proposed method demonstrated satisfactory selectivity, stability, and acceptable reproducibility for the detection of Hg2+. 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.

Automated summary

In this study, a novel dual-analytical platform was developed for visual, sensitive, and reliable analysis of mercury ions in environmental water samples. The method utilized thymine-rich DNA probes and luminescent metalpolydopamine frameworks to achieve accurate detection of Hg2+, with potential applicability for monitoring environmental water samples. Additionally, a multicolorimetric system based on a smartphone was established for on-site determination.