A Rhodol-Derived Probe for Intracellular Biothiols Imaging and Rapid Labelling of Sulfhydryl-Containing Proteins

Biological thiols are crucial in biological processes. Therefore, a probe capable of targeting and imaging biothiols in living cells, as well as rapidly labelling the thiols in proteins, is desirable and imperative. Herein, we designed and synthesized FRB-T containing α , β -unsaturated ketones to recognize thiols for detecting biothiols and selectively labelling the sulfhydryl-containing proteins. The probe initially exhibited weak fluorescence and then performed 1, 4-Michael addition reaction between its α , β -unsaturated ketone and thiols, along with the spiro ring-opening, leading to remarkable fluorescence enhancement and colour changes. The specificity of FRB-T towards thiols was high, and its detection limits were 70 nM for cysteine (Cys) and 1.51 μg/mL for ovalbumin (OVA). Furthermore, FRB-T has also been successfully applied to biothiols imaging in Hela cells, and rapid labelling of the sulfhydryl-containing proteins without washing step. • A biothiol-specific probe with strong fluorescence enhancement and colorimetric response. • The probe owns low LOD of 70 nM and 1.51 μg/mL for Cys and OVA respectively. • A new type of reagent for labelling sulfhydryl-containing proteins without washing.