Single‐Molecule‐Sensitive Fluorescent Sensors Based on Photoinduced Intramolecular Charge Transfer

Triggered by ions and antibodies: Fluorescent sensors based on intramolecular photoinduced electron transfer (PET) enable the monitoring of individual recognition and binding events at the single-molecule level with high optical and temporal resolution. The fluorophore can be directly involved in the binding process or act as reporter sensitive to binding-induced conformational changes, for example, conformational changes within a peptide induced by antibody binding (see scheme).