A Ratiometric Fluorescence Sensing for Carboxylesterase Based on Semiconducting Polymer Quantum Dots / 分析化学

ABSTRACT

A carboxylesterase ( CaE ) ratiometric fluorescent probe based on semiconducting Poly ( 9 , 9-dioctylfluorenyl-2,7-diyl) (PFO) polymer quantum dots (Pdots) was prepared. The negatively charged PFO Pdots and the positively charged polyethyleneimine ( PEI) formed a nanocomposite Pdots@PEI by electrostatic interaction, and emitted fluorescence at 440 nm and 467 nm. In the presence of CaE, the substrate fluorescein diacetate ( FDA ) was hydrolyed into negatively charged fluorescein molecule, and could get closer to the positively charged Pdots@PEI due to electrostatic interactions, which could induce resonance energy transfer, resulting in the energy donor Pdots@ PEI fluorescence intensity gradually weakened and the fluorescence intensity of the FDA hydrolysis product increased. Based on the fluorescence intensity ratio of Pdots@PEI and the fluorescence enhancement of FDA hydrolysis products, a new method for selective detection of CaE was established. Under the optimal conditions, the linear range of the method on CaE testing was 0. 75-50 U/L with detection limits of 0 . 75 U/L ( S/N=3 ) . This method was used for the detection of the content of CaE in rabbit blood with satisfactory results.