“One stone, two birds”: a mitochondria-targeted fluorescent probe for the detection of viscosity and HSO3− in living cells

Abstract

The material transport and physiological events of mitochondria need to be supported by a suitable microenvironment. For example, high viscosity will seriously hinder material exchange, and SO₂, as the precursor of HSO₃⁻, is an endogenous signal molecule that plays a key role in information transmission. It is very important to detect viscosity and HSO₃⁻ in mitochondria. Here, we developed a dual-responsive fluorescent probe (named Hcy-NT) to image the changes in mitochondrial viscosity and HSO₃⁻ in a “killing two birds with one stone” manner. Hcy-NT showed an OFF–ON fluorescence signal for the increase in cell viscosity induced by nystatin, while an ON–OFF fluorescence signal for intracellular and endogenous HSO₃⁻. Its limits of detection for HSO₃⁻ were calculated by both absorption and fluorescence methods, which were 1.200 and 1.291 μM, respectively. This work provides a valuable tool for the study of viscosity and HSO₃⁻ related physiological processes and the diagnosis of potential diseases.