FRET-based ratiometric detection of Hg2+ and biothiols using naphthalimide–rhodamine dyads

Abstract

A new naphthalimide–rhodamine-based dyad 1 in CH₃CN–HEPES (1 : 1) buffer solution exhibits fluorescence resonance energy transfer (FRET) from naphthalimide to the rhodamine moiety on addition of only Hg²⁺ ions and allows ratiometric absorption and fluorimetric estimation of Hg²⁺ ions between 50 nM (10 ppb) to 2 μM (0.4 ppm). FRET-induced fluorescence changes were recovered again by the subsequent addition of thiol amino acids via reverse FRET. The interconversion of probe 1 and 1·Hg²⁺2+2+via the complexation/decomplexation by the modulation of Hg²⁺/Cys exhibited a selective probe for biothiols in real samples.