Aggregation of thioflavin T and its new derivative in the presence of anionic polyelectrolyte

Abstract

Spectral properties of aqueous solutions of thioflavin T (ThT) and its new derivative, trans-2-[4-(dimethylamino) styryl]-3-ethyl-1,3-benzothiazolium perchlorate (DMASEBT) were studied in the presence of anionic polyelectrolyte sodium polystyrene sulfonate (PSS). It was shown that PSS promote the dye dimerization process. Quantum–chemical analysis of DMASEBT in monomer and dimer forms allowed to suggest that the dimers have a sandwich-like structure, i.e. H-aggregates can be formed. DMASEBT dimer formation in the presence of PSS leads to a 40 nm hypsochromic shift of the dye absorption spectrum and to quenching of its fluorescence. The PSS interaction with the monomeric dye leads to a 26 nm bathochromic shift of the absorption spectrum and to one order of magnitude increase in its fluorescence.