Bright chemiluminescent dioxetane probes for the detection of gaseous transmitter H₂S

Hydrogen sulfide (H₂S), the third gaseous transmitter after CO and NO, is a double-edged sword in the human body. A specific concentration of H₂S can attenuate myocardial ischemia-reperfusion injury by preserving mitochondrial function, in contrast, cause illness, including inflammation and stroke. There are already some probes for the real-time monitoring of the level of H₂S in the biological environment. However, they have some disadvantages, such as phototoxicity, low sensitivity, and low quantum yield. In this research, by linking 4-dinitrophenyl-ether (DNP), a specific recognition group for H₂S, with a chemiluminophore 1,2-dioxetane, we designed and synthesized the probe SCL-1. To tackle the barrier that the traditional chemiluminescent group has a short emission wavelength and is not easy to penetrate deep tissues, an acrylonitrile electron-withdrawing substituent was installed to the ortho-position of the 1,2-dioxanol hydroxy group. According to the same design strategy as SCL-1, the probe SCL-2 was designed with the modified chemiluminescent group. Studies have shown that SCL-2 with electron-withdrawing acrylonitrile has higher luminescence quantum yield and high sensitivity than SCL-1, realizing real-time detection of H₂S in vitro and in vivo. The LOD of SCL-2 was 0.185 μM, which was the best among the currently available luminescent probes for detecting H₂S. We envisage that SCL-2 may be a practical toolbox for studying the biological functions of H₂S and H₂S-related diseases.