A two-photon fluorescent probe for HNO rapid visualization in endoplasmic reticulum

Nitroxyl (HNO) is a one-electron reduction product of nitric oxide (NO), which mainly exists in protonated form during physiological processes. As a kind of reactive nitrogen species (RNS), HNO has significant correlations with many physiological and pathological pathways. In this study, we report a two-photon fluorescent probeR2, which can detect HNO based on the reaction with a triarylphosphine group. Upon exposure to HNO, the probe R2 holds naked eye recognition, high selectivity and fast response (2 min). These excellent spectral properties promoted the detection of exogenous and endogenous HNO in MCF-7 cells. Furthermore, the probe could be selectively located in the endoplasmic reticulum (ER) with high biocompatibility and successfully apply to visualize NO/H2S cross-talk to generate HNO. These results support that R2 will provide a powerful tool to elucidate the physiological and pathological functions of HNO in the ER.