A sulfydryl-based near-infrared ratiometic fluorescent probe for assessment of acute/chronic mercury exposure via associated determination of superoxide anion and mercury ion in cells and in vivo

Mercury exposure is associated with severe oxidative stress especially superoxide anion radicals (O2−). Mercury exposure is common in the clinic, but it is difficult to track. Although many researchers have tried to reveal the mechanism of mercury exposure, it is still remain vague that the differences between acute mercury exposure and chronic mercury exposure as well as the fluctuations in O2− during mercury ion (Hg2+) stress. Thus effective tool for O2− and Hg2+ associated-detection is needed urgently. Herein we have developed a stable near-infrared ratiometric fluorescent probe, HCy-SH, for O2− and Hg2+ associated-detection. Probe HCy-SH was designed and synthesized based on a heptamethine cyanine fluorophore and a thiol-responsive group. The probe HCy-SH can be used for mercury poisoning detection in HEK 293 cells and mice models with low detection limits of 65 nM for O2− and 72 nM for Hg2+. Relying on the probe HCy-SH, we found that O2− burst was much severer in acute mercury exposure than chronic mercury exposure, especially in heart, and Hg2+ mainly accumulated in kidney no matter acute mercury exposure or chronic mercury exposure. The experimental results indicated that the probe HCy-SH was a potential candidate for accurate diagnosis and efficacy evaluation of mercury exposure.