Preparation of a fluorescence sensor based on molecularly imprinted polymers coated with quantum dots for specific recognition and selective determination of quercetin in red wine samples†

A highly efficient and practical molecularly imprinted fluorescence sensor (MIP-QDs) was successfully synthesized through the simple reverse micro-emulsion method employing quercetin as the template molecule, quantum dots (QDs) as the fluorescent carrier and APTES as the functional monomer. The surface morphologies and structures of MIP-QDs were well characterized and examined in detail using several techniques. The fluorescence measurements were performed to investigate the fluorescence quenching capability of MIP-QDs for quercetin. Benefitting from the thin surface-imprinting layer and predefined binding sites on the surface of MIP-QDs, the prepared MIP-QDs sensor not only exhibited remarkable fluorescence quenching properties, outstanding optical stability and favorable reusability, but also had excellent sensitivity and selectivity towards quercetin. Under the optimized conditions, the fluorescence intensity of the designed MIP-QDs showed a linear decrease with the increasing quercetin concentration in the range of 0.1–150 μg mL⁻¹. Moreover, the proposed fluorescence sensor was effectively applied to determine quercetin in real samples. Satisfactory recoveries ranging from 94.8% to 102.8% with the relative standard deviations (RSDs) below 5.0% in red wine samples were achieved using the fabricated MIP-QDs sensor. Therefore, it can be used as an efficient and cost-effective approach with excellent application potential for selective recognition and quantitative detection of quercetin in actual samples.