Development of Molecularly Imprinted Polymers to Target Polyphenols Present in Plant Extracts

Abstract

Abstract:The development of molecularly imprinted polymers (MIPs) to target polyphenols present in vegetable extracts was here addressed. Polydatin was selected as a template polyphenol due to its relatively high size and amphiphilic character. Different MIPs were synthesized to explore preferential interactions between the functional monomers and the template molecule. The effect of solvent polarity on the molecular imprinting efficiency, namely owing to hydrophobic interactions, was also assessed. Precipitation and suspension polymerization were examined as a possible way to change MIPs morphology and performance. Solid phase extraction and batch/continuous sorption processes were used to evaluate the polyphenols uptake/release in individual/competitive assays. Among the prepared MIPs, a suspension polymerization synthesized material, with 4-vinylpyridine as the functional monomer and water/methanol as solvent, showed a superior performance. The underlying cause of such a significant outcome is the likely surface imprinting process caused by the amphiphilic properties of polydatin. The uptake and subsequent selective release of polyphenols present in natural extracts was successfully demonstrated, considering a red wine solution as a case study. However, hydrophilic/hydrophobic interactions are inevitable (especially with complex natural extracts) and the tuning of the polarity of the solvents is an important issue for the isolation of the different polyphenols.

Processing of Onion Skin Extracts with Quercetin-Molecularly Imprinted Adsorbents Working at a Wide Range of Water Content

“…The synthesis of the quercetin-molecularly imprinted polymers (Q-MIP) was performed following procedures similar to those reported in our previous works [12][13][14][15][16]. The precipitation polymerization method was used to produce the adsorbents here addressed, considering ACN/DMF 91/9 v/v or ethanol as solvents.…”

“…Solid-phase extraction (SPE) measurements with onion skin extracts were carried out considering procedures similar to those considered in previous works [12][13][14][15][16]. Briefly, packing extraction cartridges containing the selected adsorbents (e.g., 50 mg of dried products) were first conditioned considering several washing steps [12][13][14][15][16]. Cartridges were then loaded with the selected onion skin extract (5 mL) using a constant percolation flow rate (c.a.…”

“…With MIP3, a high value for Y M (monomers mass fraction) was deliberately used (20%) in order to evaluate its effect on product morphology, since a higher rate of particles coalescence/agglomeration is plausible in these conditions. As discussed elsewhere [12][13][14], other issues such as the mutual initial solubility of ingredients, polymerization retardation due to the polyphenol template, potential interactions FM/T or intended particles size and rigidity also affect the values selected for Y CL (% mole fraction of crosslinker in monomers mixture), Y I (mole fraction of initiator comparatively to monomers × 100) and Y FM∕T (mole ratio FM/T). Notably, besides the sought molecular imprinting effect (see MIP versus NIP comparison in [12] with measurement of imprinting factors in the order of 1.6), the presence of quercetin in the polymerization system can change the particle morphology (particle nucleation is affected by the polyphenol radical scavenging effect) and the incorporation of the template in the polymer network is also possible (Figure S3).…”

Molecularly Imprinted Polymer (MIP) Applications in Natural Product Studies Based on Medicinal Plant and Secondary Metabolite Analysis

“…Due to simplicity and cost-effectiveness, this method can be an alternative to difficult and expensive approaches in identifying paclitaxel [ 41 ] . MIPs have also been successfully used to identify polyphenols in plant extracts [ 42 ] and to extract glucosamine from chicory roots with promising results [ 43 ] .…”

“…In 2018, for the first time, scientists reported the successful production of a paclitaxel made from polysulfone membrane, which improved the separation of such materials [ 41 ] . In preparing MIP to absorb polyphenols, the material obtained from 4VP as a functional monomer, ethylene glycol dimethacrylate as a crosslinker, water/methanol as a solvent, n-heptane as an oil, and Span 80 as a surfactant showed better performance to other forms of MIP in absorption process [ 42 ] .…”