Mitochondria-Targeted Reaction-Based Two-Photon Fluorescent Probe for Imaging of Superoxide Anion in Live Cells and in Vivo

A newly synthesized reaction-based two-photon (TP) fluorescence imaging probe, 9-butyltriphenylphosphoniumacylamino-2,7-dibenzothiazolineflurene (MF-DBZH), composed of a superoxide anion (O2 •–) responsive group and a mitochondria-targeted site, has been shown to have high selectivity toward mitochondrial O2 •– fluxes. The fluorescence intensity of MF-DBZH responds proportionally to changes in O2 •– concentrations. Moreover, MF-DBZH was proved to be insensitive toward pH changes and has high photostability. Favorable features of this probe also include convenient cell loading, easy staining of both cells and small animals, and excellent biocompibility. Most importantly, MF-DBZH gives reliable TP fluorescent signal to changes of O2 •– levels in vivo.