Resorufin-based fluorescent probe with elevated water solubility for visualizing fluctuant peroxynitrite in progression of inflammation.

Inflammation is a significant protective response in biological systems and associated with various diseases. Peroxynitrite (ONOO-) as a highly active oxidant participates in the inflammatory process of organisms. Thus, it is necessary to construct novel fluorescent probes for exploring inflammation-related diseases through detecting endogenous ONOO-. Resorufin-based fluorescent probes for testing ONOO- were rare and suffered from poor water solubility. In this work, we elaborately designed three resorufin-based incorporating isatin derivatives probes RF-ITs and successfully obtained two highly selective probes RF-IT-OC and RF-IT-EG for ONOO-. Comparing the other two probes, RF-IT-EG containing triethylene glycol monomethyl ether on isatin moiety displayed better water solubility (3.2 mg/L), faster response rate (60 s), larger signal-to-noise ratio (103-fold) and lower detection limit (87 nM) for monitoring ONOO-. The cells imaging results manifested that probe RF-IT-EG could be applied to trace endogenous ONOO- with inappreciable cytotoxicity. Moreover, the RF-IT-EG was capable of tracking the fluctuation of endogenous ONOO- in LPS-stimulated inflamed mouse leg models. This work will provide a faithful and promising probe for illustrating the roles of ONOO- in various inflammation-related diseases.