Multifunctional 1,3-benzoxazole-merocyanine-based probe for the ratiometric fluorescence detection of pH/HSO3−/viscosity in mitochondria.

[Display omitted] • A ratiometric probe for detecting pH, HSO 3 − and viscosity in the mitochondria was developed. • Probe 1 exhibited rapid response, large Stokes shift, good optical performance, high selectivity, and high sensitivity in solution. • Multifunctional-detection in the mitochondria of C6 cells and zebrafish. • Detection can be achieved using a smartphone with a chromaticity APP. pH, HSO 3 −, and viscosity are crucial bio-markers for evaluating the status of mitochondria in the cell micro-environment. With this research, we developed a ratiometric mitochondria-targeting fluorescent probe 1 that was responsive toward bisulphite, pH and viscosity. Hydroxylphenyl 1,3-benzoxazole (D) acted as a pH recognition unit; benzo[ e ]indolium (A) acted as a fluorescent rotor to achieve a viscosity response; the C = C bond constructed by bridging D and A was susceptible to nucleophilic attack and hence responded to HSO 3 −. Probe 1 exhibits significant ratiometric signal changes, high sensitivity, outstanding selectivity, and good stability for detecting pH, viscosity, and SO 2 in solution. Probe 1 was used for imaging pH, viscosity, and SO 2 derivatives in live cells and zebrafish, indicating its potential for identifying mitochondrial dysfunctions. [ABSTRACT FROM AUTHOR]