A Fluorescent Probe for Selective Facile Detection of H(2)S in Serum Based on an Albumin-Binding Fluorophore and Effective Masking Reagent

[Image: see text] A fluorescent probe (4-(2-(4-(diethylamino)phenyl)-4-methyl-5-oxo-4,5-dihydrothieno[3,2-b]pyridin-7-yl)phenyl 2,4-dinitrobenzenesulfonate, KF-DNBS) for facile detection of H(2)S in serum was developed based on the combination of an environment-sensitive fluorophore (2-(4-(diethylamino)phenyl)-7-(4-hydroxyphenyl)-4-methylthieno[3,2-b]pyridin-5(4H)-one, KF) with albumin and the 2,4-dinitrobenzene sulfonyl (DNBS) group as a recognition unit for H(2)S. KF-DNBS showed remarkable fluorescence enhancement due to H(2)S-triggered thiolysis followed by the formation of a fluorescent fluorophore (KF)-albumin complex. The H(2)S detection limit of KF-DNBS was estimated to be 3.2 μM, and KF-DNBS achieves a high selectivity to H(2)S over biothiols by employing 2-formyl benzene boronic acid (2-FBBA) as an effective masking reagent. Furthermore, under optimized sensing conditions, KF-DNBS could be applied to accurately determine spiked H(2)S in human serum without the need for any further procedure for the removal of serum proteins.