Functionalization of Polymer Networks to Target Trans‐Resveratrol in Winemaking Residues Supported by Statistical Design of Experiments

Abstract

The present work aims to produce functionalized polymer networks to target the bioactive molecule trans‐resveratrol found in winemaking residues, specifically at grape stems. The synergistic choice of photoinitiation, polymerization composition, and molecular imprinting approach allows the functionalization of these materials. Experimental design is applied to methodically perform the syntheses. The amount of crosslinker, the total monomer's concentration, and the ratio of trans‐resveratrol to the functional monomer 4‐vinylpyridine (4VP) are the factors selected for this experimental design. The binding capacities and the selectivity of the synthesized materials are assessed through sorption experiments in acetonitrile and hydroalcoholic media. Consequently, a multivariate linear regression analysis leads to describe the uptake of trans‐resveratrol by the materials in both media. The crosslinker content and the ratio of trans‐resveratrol to 4VP are found to be impactful parameters while designing such materials. These studies allow the identification of working conditions for sorption/desorption processes combining a high retention capability of the adsorbents with selectivity. Furthermore, four materials are selected to enrich trans‐resveratrol from grape stems extracts in a continuous process of solid‐phase extraction. The results show that the functionalized materials are able to enrich 12‐fold the content of trans‐resveratrol in some fractions demonstrating the interest of such polymers.

Surface Molecularly Imprinted Cellulose‐Synthetic Hybrid Particles Prepared via ATRP for Enrichment of Flavonoids in Olive Leaf

“…Characteristic peaks for 4VP monomer at 1600 cm −1 (C=C pyridyl), 1418 cm −1 (C=N), 820 and 755 cm −1 (both correspond to the C-H bending in the pyridine ring) are all potential indicators for incorporation of this monomer, particularly the 1418 cm −1 assignment. Note that, in comparison with other works, [8][9][10][11][12] a weaker signal for these 4VP peaks is here expected due to the lower incorporation of this monomer in the final products. The presence of EGDMA in polymer materials is usually confirmed by analyzing assignments at 1720 and 1130 cm −1 (C=O and C-O groups, respectively).…”

“…Also, the polymerization conditions, namely, the kind and concentrations of all initial components in the reaction mixture (functional monomer(s), template, crosslinker, initiator, solvent(s)), reaction temperature, or initiation mechanism strongly affect the molecular imprinting process. [8] The purposes of molecular imprinting above described are depicted in Figure 1b for the surface phenomena here seek. A thin synthetic shell with imprinted cavities is intended, via ATRP polymerization, for core cellulose particles.…”

“…Due to the high number of different parameters involved in molecular imprinting recipes, although it is possible to use molecular simulation, and/or of experimental design to help with designing tasks, [8] some rules established by solubility constraints, expected thermodynamic effects, and so on, are important for the planning of the experimental runs. Obviously, the selection of the template depends on the application pursued.…”

“…The ratio of functional monomer/template is known to play an important role in imprinting efficiency. [8] However, as pointed before, solubility constraints also define the maximum amount of template that can be used. The concentrations for quercetin in Table 1 are a consequence of that kind of analysis for the present MIPs synthesis runs.…”

“…The selection of 4VP as functional monomer was driven by previous results concerning the development of MIPs for different kinds of polyphenols. [8][9][10][11][12] Indeed, 4VP can establish a strong binding with polyphenols, even at low extent of hydrophobic effects, due to the particular features for the -N= group in the pyridyl moiety. Specifically, one extra electron pair that is not involved in the ring conjugation system that is able to participate in strong H-bonding mechanisms, as well as to bind with protons.…”