Discrimination of biothiols in different media with NBD-F as the probe

Abstract

Abstract 4-Fluoro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-F) was employed as a colorimetric probe for differential detection of biothiols in different media. The spectral response and the selectivity of NBD-F toward thiols were significantly improved by surfactant micelles. Mercapto group exhibited high reactivity in all the solvents (including Tris–HCl buffer solution, CTAB and SDS micelles). The 4-thioether derivatives of NBD-F reacting with Cys and Hcy but not GSH could transfer to the corresponding 4-amino-substituents via intramolecular nucleophilic aromatic substitution, thus, GSH could be discriminated from Cys/Hcy. In CTAB micelles, the reaction product of NBD-F with Cys is non-fluorescent and it absorbs in long-wavelength region. According to the spectral responses of NBD-F toward different low-molecular-weight thiols, we could identify Cys, Hcy and GSH from each other.