Abstract
A fluorescence and solid phase extraction (SPE) adsorption nanomaterials of molecularly imprinted polymers (MIPs) based on quantum dot-grafted covalent organic frameworks (QD-grafted COFs) was prepared by one-pot surface-imprinting synthesis method. Amino groups of silane reagent were at the surface of QDs to coordinate COFs efficiently by Schiff-base reactions, providing thermal and chemical stability to MIPs. It also reacted with the phenolic hydroxyl groups of ferulic acid (FA) through non-covalent interactions. The nanomaterials were used as fluorescence sensing and SPE adsorption toward determination of ferulic acid. The MIPs based on QD-grafted COFs had good fluorescence response ability, and quenching linearly at concentrations of ferulic acid from 0.03 to 60 mg kg−1, with a detection limit of 5 µg kg−1. At the same time, it exhibited a good SPE adsorption ability, and the FA extraction was from 1.63 to 3.11 mg kg−1 in grain by-products by SPE coupled with high performance liquid chromatography/mass spectrometry (HPLC/MS). The fluorescence and SPE-HPLC/MS were used for the efficient detection of ferulic acid in real samples with recovery values of 88–114% and 90–97%, respectively. Furthermore, the nanomaterials of MIPs based on QD-grafted COFs were used for FA detection with high sensitivity and selectivity, and it also increased the recycling of waste resources.
Highlights
Quantum dots are solution-processable semiconductor nanocrystals [1] with size dependent optical characteristics, probably the most attractive property of II-VI semiconductor nanocrystals [2], with the advantage of narrow emission linewidths, near-unity-photoluminance quantum yield and inherent photophysical stability [3]
We have reported the introduction of the quantum dots on the surface of the molecularly imprinted polymers to improve the fluorescence quantum yield of core-shell complex [12]
The preparation of molecularly imprinted polymers (MIPs) based on QD-grafted covalent organic frameworks (COFs) used a one-pot surface-imprinting synthesis method (Figure 1)
Summary
Quantum dots are solution-processable semiconductor nanocrystals [1] with size dependent optical characteristics, probably the most attractive property of II-VI semiconductor nanocrystals [2], with the advantage of narrow emission linewidths, near-unity-photoluminance quantum yield and inherent photophysical stability [3]. The variable surface chemistry determined by capping ligands have extensively been used in the modification of quantum dots as luminescent species for imaging, detection, and biolabeling [4]. Many of the fluorescent labeling based on quantum dots are core-shell structures with two approaches for preparation. One example incorporates quantum dots into the core of a modified layer. Many researchers report core-shell fluorescent labeling of quantum dots capped by modified layer to enhance detection selectivity and sensitivity [6,7,8,9,10,11]
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