Peptide-Induced AIEgen Self-Assembly: A New Strategy to Realize Highly Sensitive Fluorescent Light-Up Probes.

Fluorescent light-up probes with aggregation-induced emission (AIE) characteristics have recently attracted great research interest due to their intelligent fluorescence activation mechanism and excellent photobleaching resistance. In this work, we report a new, simple, and generic strategy to design and prepare highly sensitive AIE fluorescent light-up bioprobe through facile incorporation of a self-assembling peptide sequence GFFY between the recognition element and the AIE luminogen (AIEgen). After the bioprobes respond to the targets, the peptide GFFY is capable of inducing the ordered self-assembly of AIEgens, yielding close and tight intermolecular steric interactions to restrict the intramolecular motions of AIEgens for excellent signal output. Using two proof-of-concepts, we have demonstrated that self-assembling peptide-incorporating AIE light-up probes show much higher sensitivity in sensing the corresponding targets in both solutions and cancer cells as compared to those without GFFY induced self-assembly. Taking the probe TPE-GFFYK(DVEDEE-Ac), for example, a detection limit as low as 0.54 pM can be achieved for TPE-GFFYK(DVEDEE-Ac) in caspase-3 detection, which is much lower than that of TPE-K(DVED-Ac) (3.50 pM). This study may inspire new insights into the design of advanced fluorescent molecular probes.