On-site quantitative Hg2+ measurements based on selective and sensitive fluorescence biosensor and miniaturized smartphone fluorescence microscope

Mercury is a bio-accumulative and toxic pollutant causing severe damages to human health and environment. Since Hg2+ is the most stable form of mercury, selective and sensitive Hg2+ detection is required. Though classical approaches can realize accurate Hg2+ detection, the complicated instruments and the time-consuming operations inevitably limit their on-site applications. Here, we design a smart Hg2+ detection approach using the fluorescence biosensor, the smartphone fluorescence microscope and the smartphone application for Hg2+ on-site detection. Based on the thymine-Hg2+-thymine coordination chemistry, a selective and sensitive fluorescence biosensor is designed for capturing Hg2+ in aqueous solution; besides, a miniaturized smartphone fluorescence microscope for fluorescence signal collection and an image processing application for quantitative Hg2+ measurements are constructed. A highly specific detection of Hg2+ with a linear relation between 1 nM and 1 μM with a limit of detection of 1 nM is obtained using the smart Hg2+ detection approach. Considering it can realize selective and sensitive quantitative Hg2+ measurements in high precision with simple operations and cost-effective system, it is believed the proposed smart Hg2+ detection approach owns great potentials in Hg2+ detection for routine uses at home and in the field.