Fluorescence resonance energy transfer-based ratiometric fluorescent assay for highly sensitive and selective determination of sulfide anions

Abstract

A novel and effective ratiometric fluorescence strategy was developed for rapidly, sensitively and selectively probing sulfide anions (S²⁻). A dual-emission nanosensor was prepared by covalently attaching fluorescent carbon nanoparticles (CNPs) to gold nanoclusters (Au NCs), triggering the sensing mechanism of fluorescence resonance energy transfer (FRET) from CNPs (donor) to Au NCs (acceptor). Once S²⁻ was added, considerable fluorescence recovery of CNPs and quenching of Au NCs were observed due to the inhibition of FRET progress via the formation of Au₂S. The ratiometric probe showed good, specific S²⁻ sensing behavior and high sensitivity with a detection limit of 18 nM. Significantly, the assay was successfully employed to determine the S²⁻ content in biological and water samples, presenting immense promise in the biological and environmental fields.