Electrochemiluminescence Enhanced by Restriction of Intramolecular Motions (RIM): Tetraphenylethylene Microcrystals as a Novel Emitter for Mucin 1 Detection.

Apart from the reported energy transfer mechanism of aggregation-induced electrochemiluminescence (AI-ECL) enhancement, a new strategy named restriction of intramolecular motions-driven ECL (RIM-ECL) enhancement is first proposed based on the phenomenon of a very strong electrochemiluminescence observed on the hexagonal tetraphenylethylene microcrystals (TPE MCs) in aqueous solution. Compared to TPE in molecule-isolation state with faint ECL, TPE in aggregate state (TPE MCs) showed a significantly enhanced ECL that was due to the restriction of intramolecular motions (RIM). Inspired by the unique luminescence characteristic of TPE MCs, we integrated the novel ECL emitter of TPE MCs and target-activated bipedal DNA walker together to fabricate a sensitive "off-on" ECL biosensor for Mucin 1 (MUC1) assay, which exhibited desirable linear response for a concentration scope from 1 fg/mL to 1 ng/mL with a low detection limit of 0.29 fg/mL. The RIM enhanced ECL demonstrated by the TPE MCs provides a new chapter in the exploration of aggregated organic emitters for further applications.