Abstract:Nitroyl or nitrosoyl hydrogen (Nitroxyl, HNO) is the protonated form of the single electron reduction product of nitric oxide (NO). As a reactive nitrogen species, HNO exhibits a distinct chemical reactivity from NO, attracting much attention for its unique roles in many biological functions and pathological activities. Although great progress has been made in understanding the chemical biology of HNO, HNO is still highly challenging due to its high reactivity and short life span, so it is crucial to develop reliable methods to detect HNO. Recently, fluorescent probes have been widely used in life sciences and other fields due to their high sensitivity, simple operation, real-time monitoring and non-invasive advantages, and those for detecting HNO have also made great progress. This paper summarized four existing design types of HNO fluorescent probes, focusing on the progress of fluorescent probes with the diphenylphosphonic group as the recognition site, to provide a reference for the future design of new HNO probes, the challenges and developments in the field are also prospected.