Dual-entropy-driven catalytic amplification reaction for ultra-sensitive and visible detection of Hg2+ in water based on thymine–Hg2+–thymine coordination chemistry

Abstract

An ultra-sensitive and visible Hg²⁺ detection strategy was established. It was based on T–Hg²⁺–T coordination chemistry and a dual-entropy-driven catalytic reaction (EDCR). The dual EDCR was initiated by T–Hg²⁺–T coordination chemistry, resulting in the release of a G-rich sequence to form a hemin/G-quadruplex-HRP-mimicking DNAzyme, and then catalyzing 3,3′,5,5′-tetramethylbenzidine (TMB) into TMB⁺, with a color change from colorless to blue. This method showed great sensitivity and excellent selectivity, and the limit of detection reached 0.6 pM. The feasibility of this method was demonstrated by real water samples. Moreover, the visible color change provided the possibility of ultra-sensitive detection of Hg²⁺ by the naked eye.