Phosphinate-based mitochondria targeted fluorescent probe for in vitro and in vivo detection of superoxide anion

Superoxide anion has attracted great attention because it is the precursor of other reactive oxygen species (ROS). Herein, we prepared a new fluorescent probe based on phosphinate, consisting of a fluorescein, a superoxide anion responsive group, and a mitochondrial-targeted site, triphenylphosphonium salt (PF-MitoSOX). The probe PF-MitoSOX was synthesized and characterized by FTIR, 1H-NMR, 31P-NMR, and CIMS. The dose-dependent fluorescence enhancement of PF-MitoSOX showed a good linearity with the detection limit of 4.6 pM for superoxide anion. The specificity of PF-MitoSOX was examined by measuring its fluorescence response after expose to various analytes. Except superoxide anion, PF-MitoSOX did not show apparent fluorescence increase in the presence of other ROS or relevant substances, including hydrogen peroxide, singlet oxygen, nitric oxide, hpochlorite, hydroxy radical, glutathione. These results suggested that PF-MitoSOX was highly selective for superoxide anion. Moreover, the fluorescent imaging results illustrated that PF-MitoSOX not only can detect intracellular superoxide anion, but also can conveniently visualaize changes in superoxide anion concentration in cells and C.elegans .