A Simple Fluorescent Probe for Biothiol Detection and Its Application Based on a Phthalimide Derivative

ABSTRACT A novel fluorescent probe PSH was developed for the specific detection of biothiols, using phthalimide as the fluorophore and the 2,4‐dinitrobenzenesulfonyl (DNBS) group as the recognition moiety. The DNBS group causes fluorescence quenching of PSH , while biothiols trigger a nucleophilic substitution reaction that restores strong green fluorescence. PSH demonstrates superior analytical performance: it possesses favorable water solubility, high selectivity and sensitivity (LODs: 25 nM for GSH, 36 nM for Cys, 54 nM for Hcy), a large Stokes shift (120 nm), rapid response (≤ 3 min), and a wide linear detection range. Furthermore, the quantitative determinations of GSH in PBS buffer and cotton kits were achieved via the smartphone using PSH as the probe. Notably, it achieves successful biothiol detection in both serum samples and living cells, suggesting its suitability for biological sample analysis and intracellular imaging of biothiols.