Sensing Reactive Oxygen and Nitrogen Species Using Selective Fluorescent Probes

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generally thought to be important mediators of various pathological conditions. Since fluorescent probes are promising tools for clarifying the functions of biomolecules in biological systems as demonstrated by the case of Ca2+ fluorescent probes, interest in the use of fluorescent probes for sensing ROS/RNS is increasing. Although fluorescent probes such as 2',7'-dichlorodihydrofluorescein (DCFH) and dihydrorhodamine 123 (DHR123) have traditionally been used for sensing ROS/RNS, many reports suggest that such probes are not suitable for sensing specific ROS/RNS individually but for whole oxidative stresses caused by ROS/RNS due to their lack of selectivity for ROS/RNS. However, it is quite important to detect specific ROS/RNS with a high selectively because each ROS/RNS has its own physiological activities and has unique characteristic roles. To achieve such specificity, novel functional fluorescent probes that can distinguish specific ROS/RNS individually with high selectivity, have been developed in recent years. The purpose of this review is to highlight recent advances in the design and development of such selective ROS/RNS fluorescent probes that should have a great potential for evaluating the unique roles of individual ROS/RNS in biological processes.