A new quinoxaline-based fluorescent probe capable of naked eye recognition and cell imaging for biothiols

Maintaining biothiols homeostasis is extremely important for the health of organisms. In this work, a pair of fluorescent probes (Acr-QX8A and Acr-QX9A) was designed and synthesized to monitor biothiols. The two probes applied the same fused four ring quinoxaline as the skeleton, benzyl carbamate as the linker and acryloyl group as the recognition site, whose only difference was the amino group’s position on the skeleton. By comparing the optical properties, Acr-QX9A exhibited superior performances than Acr-QX8A and chosen for further studies. Probe Acr-QX9A displayed 180-fold, 135-fold and 69-fold fluorescence intensity enhancements upon interactions with Cys, Hcy and GSH respectively, owing to the release of fluorophore QX9A and the restoration of intramolecular charge transfer (ICT) process. Acr-QX9A showed good selectivity and excellent anti-interference, which could be served as the naked-eye colorimetric probe for biothiols detection. More importantly, the probe exhibited high sensitivity towards biothiols with outstanding detection of limits (75.2 nM for Cys, 92.7 nM for Hcy and 370 nM for GSH). Encouraged by the appreciable results in solutions, probe Acr-QX9A was then successfully applied as a promising tool for monitoring both endogenous and exogenous biothiols in living cells.