Förster Resonance Energy Transfer-Based Fluorescent Probe for the Selective Imaging of Hydroxylamine in Living Cells

Hydroxylamine (HA) is an important product of cell metabolism and plays a significant role in many biological processes, and therefore, real-time imaging of HA is of great importance for the in-depth study of its physiological and pathological functions. However, a HA-specific fluorescent probe is currently lacking primarily because the highly selective HA-responsive site is undeveloped. To address this critical issue, we present a HA-specific FRET-based fluorescent probe (RhChr) for the selective detection of HA in living systems. Inspired by aza-Michael addition, the unsaturated system appended with an iminium ion was employed as the new HA-specific response site. In response to HA, RhChr provided a ratiometric signal output with excellent selectivity toward HA over biothiols and ammonia. We have demonstrated that RhChr could be applied for the ratiometric imaging of endogenous HA in living cells and the evaluation of xanthine oxidase (XOD) activity in living organs.