Micelle-induced multiple performance improvement of fluorescent probes for H2S detection

In this paper, two colorimetric and turn-on fluorescent probes N-[2-(2-hydroxy)-ethoxy] ethyl-4-azido-1,8-naphthalimide (SS1) and N-butyl-4-azido-1,8-naphthalimide (SS2) for selective recognition of H2S were designed and synthesized. The probes were constructed by incorporating an azido group into the naphthalimide fluorophore as a specifical reaction group for sulfide utilizing its reducing property. Once treated with H2S, the azido groups of the probes were converted to amino groups and the solutions' color changed from colorless to yellow companied with a strong yellow-green fluorescence. Rapid and sensitive responses of the probes towards H2S were achieved in the presence of cationic surfactant cetyltrimethyl ammonium bromide (CTAB): the reaction was completed within 10min in CTAB compared to more than 4h in buffer solution, and the detection limit decreased from 0.5μM to 20nM. High selectivity and good competition of both probes towards H2S over other 11 ions and 2 reducing agents were realized in CTAB micelle. An overall linear concentration range of 0.05μM to 1mM was achieved with the assistance of differently charged surfactants CTAB and sodium dodecyl sulfate (SDS). The probes were applied to rapidly and sensitively detect H2S levels in fetal bovine serum without any pretreatment of the sample.