Selective fluorometric determination of microcystin-LR using a segment template molecularly imprinted by polymer-capped carbon quantum dots

Abstract

Microcystin-LR (MC-LR) is a virulent hepatotoxin that is pervasive in rivers and lakes. The contamination of water with MC-LR poses a significant threat to human life and the water ecology. Therefore, it is of great interest developing a reliable, quick, and sensitive method for the detection of MC-LR. Herein, a novel type of molecularly imprinted polymer-coated carbon quantum dot (MIP@CQDs@SiO2) fluorescence sensor is developed for the selective and sensitive determination of MC-LR. The MIP@CQDs@SiO2 fluorescence sensor was fabricated via sol–gel polymerization using L-leucine as the segment template molecule, carbon quantum dots (CQDs) as the signal materials, 3-aminopropyltriethoxysilane as the monomer, and tetraethylorthosilicate as the crosslinker. The specific recognition sites in the polymer layers could selectively adsorb MC-LR molecules, which caused fluorescence-quenching behavior of CQDs via an electron transfer process. Under optimal conditions, the linear response associated with MC-LR was 1–1000 μg/L with a limit of detection (LOD) of 0.0093 μg/L. The imprinting factor was 5.0, and the adsorption ability was 3.23 mg/g. The proposed method was proved to efficiently detect MC-LR in real water samples. In addition, the fluorescence sensor proposed in this work shows good stability in a complex matrix, excellent selectivity and sensitivity to MC-LR in real sample analysis, and remarkable potential in practical applications.