Insight into mercury ion detection in environmental samples and imaging in living systems by a near-infrared fluorescent probe

Since mercury could accumulate along with the food chains and undermine environment and human health, development of efficient mercury detection tools in water samples, plants and living systems is of great significance. In this work, we designed a hemicyanine-based fluorescent probe HCYS for mercury detection. The probe exhibited distinct near-infrared fluorescence intensity. Based on the spin orbit coupling effect and heavy atom effect of Hg²⁺, a significant fluorescent change was exhibited since Hg²⁺ chelated with the probe by inhibition of the intramolecular charge transfer process in HCYS. The limit of detection (LOD) was calculated to be 1.41 µM. Exploiting the benefits of fast response time (less than 1 min), high selectivity and noninvasively track capacity, the probe has been applied in biological systems. The solid results proved that the probe HCYS is a powerful tool for Hg²⁺ imaging in living cells, zebrafish, pea spouts and water samples.