Decomposition-assembly of tetraphenylethylene nanoparticles with uniform size and aggregation-induced emission property

Tetraphenylethylene (TPE)-substituted poly(allylamine hydrochloride) (PAH-g-TPE) is synthesized by a Schiff base reaction between PAH and TPE-CHO. The PAH-g-TPE forms micelles in water at pH 6, which are further transformed into pure TPE-CHO nanoparticles (NPs) with a diameter of ≈300 nm after incubation in a solution of low pH value. In contrast, only amorphous precipitates are obtained when TPE-CHO methanol solution is incubated in water. The aggregation-induced emission feature of the TPE molecule is completely retained in the TPE NPs, which can be internalized into cells and show blue fluorescence. Formation mechanism of the TPE NPs is proposed by taking into account the guidance effect of linear and charged PAH molecules, and the propeller-stacking manner between the TPE-CHO molecules.