Chameleonic Dye Adapts to Various Environments Shining on Macrocycles or Peptide and Polysaccharide Aggregates

This work describes latent fluorescence particles (LFPs) based on a new environmentally sensitive carbazole compound aggregated in water and their use as sensors for probing various cavitands and the different stages of aggregating systems. Cyclodextrins (CDs), cucurbit[n]urils (CB[n], n = 6, 7, 8), and a resorcinarene capsule were used to study the dynamic nature of the LFPs. The fluorescence was dramatically enhanced by a proposed disaggregation-induced emission enhancement (DIEE) mechanism with specific features for CB[n]. Then, the aggregated states of the dipeptides Leu-Leu, Phe-Phe, and Fmoc-Leu-Leu (vesicles, crystals, fibers) were studied by fluorescence spectroscopy and confocal fluorescence microscopy thanks to the adaptive and emissive behavior of the LFPs, allowing us to study an interesting polymorphism phenomenon. The LFPs have then been used in the sensing of the aggregation of the polysaccharide alginate, for which distinct fluorescence turn-on is detected upon stepwise biopolymer assembly...