Invertase-labeling gold-dendrimer for in situ amplified detection mercury(II) with glucometer readout and thymine-Hg2+-thymine coordination chemistry

A simple, low-cost transducer with glucometer readout was designed for sensitive detection of mercury(II) (Hg2+), coupling with thymine-Hg2+-thymine (T-Hg2+-T) coordination chemistry and invertase-functionalized gold-dendrimer nanospheres for the signal amplification. Initially, nanogold-encapsulated poly(amidoamine) dendrimers (Au DENs) were synthesized by in-situ reduction of gold(III). Thereafter, the as-prepared Au DENs were utilized for the labeling of invertase and T-rich signal DNA probe. In the presence of target Hg2+, the functionalized Au DENs were conjugated to capture DNA probe-modified electrode via T-Hg2+-T coordination chemistry. Accompanying the Au DENs, the labeled invertase could hydrolyze sucrose into glucose, which could be quantitatively monitored by an external personal glucometer (PGM). The PGM signal increased with the increasing target Hg2+ in the sample. Under the optimal conditions, our designed sensing platform exhibited good PGM responses toward target Hg2+, and allowed the detection of Hg2+ at a concentration as low as 4.2 pM. This sensing system also displayed remarkable specificity relative to target Hg2+ against other competing ions, and could be applied for reliable monitoring of spiked Hg2+ into the environmental water samples with satisfactory results. With the advantages of cost-effectiveness, simplicity, portability, and convenience, our strategy provides a tremendous potential to be a promising candidate for point-of-use monitoring of non-glucose targets by the public.