Design, Synthesis And Application Research Of Coumarin-based Ratiometric Fluorescent Probes

Hydrogen sulfide (H2S), as a member of the reactive sulfur species (RSS), has drawn more attention to its virulence over the centuries. Hydrogen sulfide, which is small molecule with biological activity, plays an important role in the life activities. Endogenous H2S is produced from L-cysteine by separate enzymes:cystathionine β-synthetase (CBS) and cystathionineg y-lyase (CSE). H2S is involved in many physiological and pathological processes in the organisms. Endogenous H2S is associated with diverse physiological processes, such as neuromodulation in the brain, vasodilation, against myocardial ischemia injury and antioxidant. However, abnormal H2S levels are implicated in many diseases such as Alzheimer’s disease, liver cirrhosis, gastric mucosal injury and arterial hypertension. Therefore, detecting of the concentration of H2S inside living cells is of great significance in physiological and pathological processes.Fluorescent probes possess many advantages, including fast response, high sensitivity and selectivity, pervasive application in living cells, bringing about the rapid development of probes for detecting H2S. A major limitation of intensity-based probes is that background interference, probe distribution and instrumental sensitivity are problematic for quantitative measurements. Compared to intensity-based probes, the ratiometric fluorescent probes can overcome the above drawbacks. So, we devote to designing and synthesizing the ratiometric fluorescent probes for detecting H2S.This paper is mainly divided into the following parts:Chapter 1, we reviewed the recognition mechanisms of fluorescent probes and the research progress of fluorescent probes.Chapter 2, we developed a ratiometric fluorescent probe CPC for sensing H2S based on a coumarin-merocyanine dyad. The FRET based probe was constructed by integrating a coumarin fluorophore as a donor into the merocyanine fluorophore as an acceptor. The probe has two emission peaks at 474 nm and 587 nm, respectively. Upon addition of H2S, emission band at 587 nm decreased distinctly, meanwhile the band at 474 nm increased obviously. So, the ratiometric detection of H2S was achieved. The probe CPC has many advantages, such as fast response, high sensitivity and selectivity, cell membrane permeability. Probe CPC is capable of detecting exogenous and endogenous H2S in living cells. Furthermore, probe CPC can be used for ratiometric tracking of H2S in mitochondria (Pearson’s coefficient 0.924).