Dissolution-enhanced emission of 1,3,6,8-tetrakis(p-benzoic acid)pyrene for selectively detecting protamine and “on-to-on” heparin detection in water

Abstract

We developed a small organic molecule, 1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy), as a facile turn-on fluorescence probe for selectively detecting the basic protein protamine in water with a low detection limit of 24.14 ng mL⁻¹. The TBAPy–protamine system could be further used as an “on-to-on” probe to detect the heparin protein with great fluorescence enhancement and simultaneous color change from green to blue. It can be explained by dissolution-enhanced emission (DEE) that the insoluble TBAPy probe is deprotonated to form the anionic species and dissolve in water, which suppresses the aggregation-caused quenching by electrostatic repulsion interactions. This DEE phenomenon is different from the widely reported aggregation-induced emission (AIE). These facile fluorescence “turn-on” and “on-to-on” methods for protein detection suggest that the DEE phenomenon is a very useful strategy for biosensing and can be potentially applied in food safety, disease diagnosis and healthcare.