Facile preparation of fluorescent water-soluble non-conjugated polymer dots and fabricating an acetylcholinesterase biosensor

Abstract

Acetylcholinesterase (AChE) has been demonstrated as a crucial enzyme in the development and treatment of Alzheimer's disease (AD). The present work reported the preparation of high fluorescence emission, water-soluble, non-conjugated polymer dots (NCPDs) via Schiff base reaction, and its self-assembly between hyperbranched poly(ethylenimine) (PEI) and pyrogallol in aqueous solutions. A one-pot method was introduced, which made the preparation process of the NCPDs more convenient, energy-efficient, and environmentally friendly. The mechanism of the inherent fluorescence of NCPDs and its fluorescence properties were investigated. This study, for the first time, explored the application of NCPDs to a nanoquencher biosensing system, discovering the reversible quenching effect of MnO₂ nanosheets for NCPDs. Furthermore, the quenching mechanism of MnO₂ for NCPDs was demonstrated to be an inner filter effect (IFE). The NCPDs–MnO₂ biosensing system showed a broader detection range from 12.3 to 3675 U L⁻¹ for AChE and the limit of detection (LOD) was as low as 4.9 U L⁻¹. The sensing system has been applied to screen AChE inhibitors, and the result of the positive drug was highly consistent with previous studies. The established method showed a promising prospect in screening for leading compounds in new drug discoveries for AD.