Two-Photon Fluorescence Probe for Selective Monitoring of Superoxide in Live Cells and Tissues

The abnormal location or generation of superoxide radical anion (O₂^•-) are implicated in many diseases, including cancers; thus, development of an efficient method to detect O₂^•- is of great importance. Inspired by the fluorophore-governed selective manner to O₂^•- and peroxynitrite (ONOO^-) of previously reported phosphinate-based fluorescence probes, in this contribution, a phosphinothioate-containing probe, TPP, was designed. The probe exhibited easy accessibility through a one-step sequence and good photostability and biocompatibility. Interestingly, TPP showed high specificity and sensitivity to O₂^•- over other reactive oxygen species/nitrogen species including ONOO^-. Furthermore, with the assistance of two-photon microscopy, TPP was successfully applied for imaging endogenous O₂^•- in live cells and tissues.