Using Quercetin to Construct Molecularly Imprinting Polymer in the Preparation and Enrichment of Flavonol and Flavonoid Compounds.

Flavonol and flavonoid compounds are important natural compounds with various biomedical activities. Therefore, it is of great significance to develop a strategy for the specific extraction of flavonol and flavonoid compounds. Quercetin is a well-studied flavonoid possessing many health benefits. This compound is a versatile antioxidant known to possess protective abilities against body tissue injury induced by pathological situations and various drug toxicities. Although quercetin is widely distributed in many plants, its content generally is not very high. Therefore, the specific extraction of quercetin as well as other flavonol and flavonoid compounds has profound significance. In this work, the quercetin molecularly imprinting polymer (QMIP) was successfully prepared, in which a typical flavonol quercetin was selected as the template molecule. QMIP was synthesized by performing the surface molecular imprinting technology on the surface of NH2-MIL-101(Fe). Our study results showed that QMIP exhibited quick binding kinetic behavior, a high adsorption capacity (57.04[Formula: see text]mg/g), and the specific recognition ability toward quercetin compared with structurally distinct compounds (selective [Formula: see text]). The specific adsorption ability of quercetin by QMIP was further explained using computation simulation that molecules with non-planar 3D conformations hardly entered the molecularly imprinted cavities on QMIP. Finally, QMIP was successfully used for the specific extraction of quercetin and five other flavonol and flavonoid compounds in the crude extracts from Sapium sebiferum. This study proposes a new strategy to synthesize the molecularly imprinted polymer based on a single template for enriching and loading a certain class of active ingredients with similar core structures from variable botanicals.

An edible molecularly imprinted material prepared by a new environmentally friendly deep eutectic solvent for removing oxalic acid from vegetables and human blood.

A novel deep eutectic solvent-magnetic molecularly imprinted polymer (DES-MMIP) for the specific removal of oxalic acid (OA) was prepared by an environmentally friendly deep eutectic solvent, consisting of betaine, citric acid, and glycerol, which acted as the functional monomer for polymerization. The structure and morphology of DES-MMIPs were studied by X-ray diffraction, scanning and transmission electron microscopy, thermal gravimetric analysis, Fourier transform infrared spectroscopy, and vibrating sample magnetometer. DES-MMIPs had a core-shell structure, with magnetic iron oxide as the core, and showed good thermal stability and high adsorption capacity (18.73 mg/g) for OA. The adsorption process of OA by DES-MMIPs followed the pseudo-second-order kinetic model and Langmuir isotherm model. DES-MMIPs had significant selectivity for OA and their imprinting factor was 3.26. When applied to real samples, high performance liquid chromatography analysis showed that DES-MMIPs could remove OA from both spinach and blood serum. These findings provide potential methods for removal of OA from vegetables and for specific removal of OA in renal dialysis.

Synergistic recognition of transferrin by using performance dual epitope imprinted polymers.

Transferrin (Trf) is a new type of active drug targeting carrier and disease biomarker that regulates the balance of iron ions in human body. The recognition and isolation of Trf is of great significance for disease diagnosis and treatment. Thus, a new type of magnetic dual affinity epitope molecularly imprinted polymer coated on Fe3O4 nanoparticles (Fe3O4@DEMIP) was successfully prepared for specific recognition of Trf. C-terminal nonapeptide and Trf glycan were selected as bi-epitope templates for metal chelation and boron affinity immobilization, respectively. 4-vinylphenylboric acid (4-VP), N-isopropyl acrylamide (NIPAM) and zinc acrylic were used as functional monomers. Results showed that Fe3O4@DEMIP exhibited excellent specific recognition ability adsorption capacity toward Trf, with an adsorption of 43.96 mg g-1 (RSD = 3.28%) and a more satisfactory imprinting factor (about 6.60) than that of other reported imprinting methods. In addition, Fe3O4@DEMIP displayed pH, temperature and magnetic sensitivity properties to realize temperature and pH-controlled recognition and release of target proteins and magnetic rapid separation. Furthermore, the Fe3O4@DEMIP coupled with high-performance liquid chromatography (HPLC) analysis was successfully used for specific recognition of Trf in biosamples. This study provides a reliable protocol for preparing metal chelation and boron affinity dual affinity bi-epitope molecularly imprinted polymers for synergistic and efficient recognition of biomacromolecules in the complex biological systems.

Specific adsorption and determination of aspartame in soft drinks with a zein magnetic molecularly imprinted modified MGCE sensor.

In this work, an efficient and sensitive magnetic molecularly imprinted polymer with zein and deep eutectic solvents (ZDM-MIPs) was designed and synthesized to exclusively adsorb and detect aspartame (ASP). We used zein, together with deep eutectic solvents (DESs) and Fe3O4 as the cross-linker, functional monomer and support material, respectively. A magnetic glassy carbon electrode (MGCE) modified with ZDM-MIPs was used for selective recognition of ASP. The electrochemical response of the ZDM-MIPs-MGCE for quantification of ASP was evaluated with a portable electrochemical detection station with differential pulse voltammetry and cyclic voltammetry. The responses of ZDM-MIPs-MGCE signified a good linear relationship with ASP concentrations in the range of 0.1-50 µg mL-1. The sensor systems showed good accuracy and precision, with recovery percentages between 84% and 107%. These results suggested that the obtained ZDM-MIPs exhibited good adsorption performance for ASP in soft drinks, and this method could be used to determine ASP content in actual food samples.