An off-on quinoxaline-based fluorescent probe for lighting up biothiols in living cells and zebrafish

A novel fused four-ring quinoxaline fluorophore and a maleimide receptor were firstly integrated into one molecule to develop a novel, sensitive and highly effective probe for biothiols detection. The fluorescence of quinoxaline fluorophore was quenched by the maleimide group via the photoinduced electron transfer (PET) mechanism. After the Michael addition of the biothiols towards maleimide, the PET process was blocked and the fluorescence restored. The above sensing mechanisms were confirmed by the mass spectroscopy and explained by density functional theory (DFT) calculations, ensuring QX9M as a highly selective probe towards biothiols over other amino acids. Moreover, the probe featured a good linearity range and a low detection limit to Cys, Hcy and GSH. For the practical applications, the probe can be used to monitor the biothiols not only in living cells but also in zebrafish with an off-on process.(c) 2023 Elsevier Ltd. All rights reserved.

Automated summary

In this study, a novel and highly effective probe for biothiols detection was developed by integrating a four-ring quinoxaline fluorophore and a maleimide receptor into one molecule for the first time. The fluorescence of the quinoxaline fluorophore was quenched by the maleimide group through the photoinduced electron transfer (PET) mechanism. The PET process was then blocked and the fluorescence restored after the Michael addition of the biothiols to the maleimide. The probe demonstrated high selectivity towards biothiols over other amino acids, and it exhibited a good linearity range and low detection limit to Cys, Hcy, and GSH. Furthermore, the probe could be used for monitoring biothiols in living cells and zebrafish. (c) 2023 Elsevier Ltd. All rights reserved.