Fluorescence Switching of Conjugated Polyelectrolyte based on Polydiphenylacetylene

Polydiphenylacetylene (PDPA) derivatives are a class of conjugated polymer that contain intramolecular excimer emission originating the intramolecular stack structure. In contrast with conventional conjugated polymer, the fluorescence property of PDPA significantly depends on the intramolecular stack structure. In this regard, herein, we investigated new fluorescence switching mechanism of conjugated polyelectrolyte (CPE) based on PDPA. The developed CPE showed relatively weak fluorescence emission in water, while the polymer exhibited a great fluorescence amplification behavior by electrostatic complex with proteins. In addition, the CPE is highly sensitive to binding with a little protein despite of turn-on type fluorescence response. We found that the fluorescence switching of the CPE closely relate to a perturbation of the intramolecular stack structure. The new fluorescence switching mechanism of the CPE is very useful for protein assays and discrimination and it also would be provide new sensing approaches as basic sensing mechanism.