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

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)₃²⁺)-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 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.