Small‐Molecule Quenchers for Förster Resonance Energy Transfer: Structure, Mechanism, and Applications

For fluorogenic probes, Förster resonance energy transfer (FRET) is one of the most widely used mechanisms to realize the detection of biochemical activities. Dark quenchers relax from the excited state to the ground state non-radiatively, and are promising alternatives to fluorescent FRET acceptors. Small-molecule (dark) quenchers have been widely used as acceptors in FRET-based probes to monitor various physiological processes with minimum background signal. Herein, we summarize the relevant advances of small-molecule quenchers that are used in FRET-based probes. This Review is intended to provide suggestions regarding the rationale design and selection of appropriate fluorophore-quencher FRET pairs, which are fully compatible with challenging analytical applications in various biological systems. Finally, an outlook of the future biomedical applications and developments of this field is presented.