Rational construction of sulfur dioxide and viscosity bifunctional fluorescent probe and its applications in water, food and bioimaging

Abnormal sulfur dioxide (SO2) and microenvironmental viscosity are detrimental to human health, so the effective monitoring of these indicators in relevant foods and organisms is of great significance. The dual-functional fluorescent probes that are sensitive to active sulfur and microenvironment at the subcellular organelle level can link the spatiotemporal changes of different species, which are crucial for understanding complex biological processes. In this work, a high-performance bifunctional red fluorescent probe named Probe 2 was rationally designed and constructed by screening different electron-donating groups. The probe exhibits good chromogenic and turn-on fluorescence responses to SO2 and viscosity, and can target mitochondria well. The probe has been successfully applied for accurate and rapid determination of sulfite content in water and food samples with good recovery (93.2–98.1 % and 94.2–100.4 %). Furthermore, Probe 2 enables real-time tracking and dual-color fluorescence imaging of SO2 and viscosity in cells and zebrafish, especially its high sensitivity to changes in these two parameters during mitochondrial dysfunction and apoptosis.