Small Molecule Quinoxaline Fluorescent Probe for AcO⁻ Real-Time Detection in Vivo

Fluorescent probes to detect biologically important acetate ion (AcO⁻) are essential for regulating substance metabolism, alleviating inflammatory symptoms, reducing cancer incidence, and diagnosing early diseases. However, the relatively small charge-to-atomic radius ratio in AcO⁻ and its triangular spatial structure pose challenges in recognition and often lead to interference from other anions in detection methods. Herein, we introduce a quinoxaline fluorescent probe, o-(4-(2-(3-oxo-3,4 -dihydroqui-noxalin-2-yl)vinyl)phenyl) dimethylaminothiophene ester (QPDMT), specifically design and synthetic for the accurate detection of AcO⁻. This probe leverages molecular nucleophilicity and electron transfer to undergo a reaction that releases the fluorophore upon cleavage of the thioformyl ether bond, exhibiting a turn-on fluorescence response at 530 nm. QPDMT exhibits an impressively low detection limit of 30 nM, a rapid response time of 20 min, a robust linear response in the 1–9 µM range and excellent fluorescence quantum yield, 0.32. Importantly, this probe demonstrates low cytotoxicity, making it an ideal candidate for endogenous AcO⁻ detection in living cells and organisms.