Two new rhodamine-based fluorescent probes with thiophen/selenophene acrylate group for selective detection of Cys in living cells

Cysteine (Cys), one of the biological thiols, has long been an important sensing target. In this work, two new rhodamine-based fluorescent probes with thiophen/selenophene acrylate group (Rh–S and Rh–Se) have been obtained and fully characterized. Their sensing behaviors have been researched by UV–Vis absorption and fluorescence spectra, which display high sensitivity and good selectivity for the detection of Cys with low detection limit (0.268/0.270 μM) and fast response time (30/40 min), and exhibit a "turn on" response toward Cys. The possible sensing mechanism has been proposed and confirmed by HRMS and 1H NMR. Biological studies reveal that probe Rh–S has low cytotoxicity and good biocompatibility, thereby could be further used to determine Cys in living cells.