Magnetic Molecularly Imprinted Polymer Synthesis and Application for Selective Separation of Quercetin

Abstract

Quercetin (QUE) is the most active compound in the flavone family, commonly found in the leaves, fruits, and flowers of many plants. The separation of QUE from various plant matrices has been a key research area due to its antioxidant, anti-inflammatory, antiviral, and antitumor properties. In this study, the conditions for synthesizing MMIPs and their use in QUE recovery were examined. Iron (II) chloride tetrahydrate (FeCl<inf>2</inf>·4H<inf>2</inf>O) and iron (III) chloride hexahydrate (FeCl<inf>3</inf>·6H<inf>2</inf>O) were used to prepare magnetic nanoparticles, and Fe<inf>3</inf>O<inf>4</inf> was synthesized. Tetraethyl orthosilicate (TEOS) was used to coat the resulting Fe<inf>3</inf>O<inf>4</inf> surface with silica. [3-(methacryloxy)propyl] trimethoxysilane (γ-MPS) was used to functionalize the surface of the formed Fe<inf>3</inf>O<inf>4</inf>@TEOS structure. The synthesis was carried out using QUE as the template molecule; tetrahydrofuran (THF), ethanol (EtOH), and a solvent mixture of acetone and acetonitrile (ACN) (3:1, v/v) served as porogen solvents; acrylamide (AM), methacrylic acid (MAA), and 4-vinylpyridine (4-VP) were used as functional monomers; ethylene glycol dimethacrylate (EDMA) served as the cross-linker, and 2,2’-azobisisobutyronitrile (AIBN) was used as the initiator at different molar ratios (T:M:CrL, 1:4:20, 1:8:20, and 1:8:40). The recognition and selectivity properties of these polymers were evaluated based on absorbance values at 370 nm obtained through equilibrium assays, which used QUE solutions prepared in THF, ACN, and 50% (v/v) EtOH solvent mixtures at different ratios. It was established that the magnetic imprinted polymer prepared with a 50% (v/v) EtOH solvent mixture and molar ratios of 1:8:40 (QUE:4-VP:EDMA) exhibited the highest adsorption capacity and imprinting factor. Using the prepared QUE-MMIP, QUE was recovered with 33% efficiency from red onion peel extract. © 2025 Elsevier B.V., All rights reserved.