Ratiometric fluorescent probes based on fluorogenic reactions of o-phenylenediamine for multiple sensing applications

In recent years, construction of ratiometric fluorescent probes based on the in-situ fluorescence reaction of o-phenylenediamine (OPD) is more convenient, simple and efficient for sensing various targets, which has attracted widespread attention from researchers. However, there is still a lack of systematic summary of its design strategies and applications, which may prevent its further development in this field. In this review, we will focus on the construction and application of ratiometric probes based on the in-situ fluorescence reaction of OPD. In addition, construction strategies of ratiometric fluorescent probes are divided into three main categories according to the different generated fluorescent products via in-situ fluorescence reaction of OPD. The first category of construction ratiometric fluorescent probe is based on the yellow fluorescence product. The second category of construction ratiometric fluorescent probe is based on the blue fluorescence product. The third category of construction ratiometric fluorescent probe is combined blue with yellow fluorescent products mentioned-above. Meanwhile, the multiple applications of the three types ratiometric fluorescent probes are summarized. This will provide us in-depth idea for the multiple-function development of ratiometric fluorescent probes in terms of the in-situ fluorescence reaction of OPD, and promote its research in broader fields in the future.