Selective recovery and preconcentration of catechins from wine industry residues using molecularly imprinted polymers: an eco-friendly solid phase extraction approach

Molecularly imprinted polymers (MIPs) are engineered materials that provide exceptional selectivity and stability for target molecule recognition. While most previous catechin-imprinted polymer (CAT-MIP) studies have focused on tea matrices, the present study applies CAT-MIP technology to wine industry residues, particularly grape seeds, which represent sustainable and underutilized sources of bioactive compounds. CAT-MIP was synthesized using CAT as the template molecule and polymerization parameters including functional monomer type, porogen composition, and template-to-monomer-to-crosslinker molar ratios were systematically optimized. Among the tested conditions, 4-vinylpyridine (4-VP) and an acetonitrile: dimethyl sulfoxide (ACN: DMSO, 98:2, v/v) solvent system provided the most favorable imprinting performance. Adsorption studies revealed heterogeneous binding behavior consistent with the Freundlich model, while Langmuir parameters were used for comparative evaluation. The optimized CAT-MIP was successfully applied as a molecularly imprinted solid-phase extraction (MISPE) sorbent, achieving selective recovery of 69.20 ± 2.45% for CAT and 52.50 ± 1.77% for epicatechin (ECAT) from white grape seed extracts, with comparable performance observed for red grape seed extracts. This MISPE based approach offers the first comprehensive study applying CAT-MIP technology to wine industry waste valorization, comparing red and white grape varieties, and establishing a fully validated HPLC-PDA (high performance liquid chromatography-photodiode array detection) method for CAT quantification. The eco-friendly approach addresses the growing need for sustainable extraction of valuable high-value natural antioxidants. from agro-industrial byproducts.