An insight into the recognition mechanisms of Molecularly Imprinted Polymers (MIPs) for flavonoids quercetin, kaempferol and hydroxytyrosol

Molecularly Imprinted Polymers (MIPs) are synthesized in the presence of a template (quercetin, kaempferol and hydroxytyrosol) which results in the formation of specific recognition cavities complementary to the template in shape and chemical functionality. This successful preparation provides an innovative opportunity for the development of advanced separation materials, with applications in the field of wine and fermentation analysis. Also, compared to their biological counterparts, MIPs offer different advantages, such as simplicity in manufacturing and durability. All polymers were created via thermally initiated polymerization using methacrylic acid and ethylene glycol dimethacrylate as functional monomer and cross-linker, respectively. The developed flavonoid-MIPs enabled selective extraction of the template even from complex mixtures, demonstrating the potential for designing biomimetic recognition materials with improved selectivity for biomolecules with tunable functionality. The capillary electrophoresis analytical data provided enough evidence for the percentage of the recognition ability of the above-mentioned polymers toward the respective functional. Molecular analysis such as ¹H NMR was used for experimentally confirming the prevalent template-monomer interactions at the pre-polymerisation mixture, yielded further information on the nature of the complexes formed prior to the polymerization step. These results demonstrated hydrogen-bonding interactions of methacrylic acid and the respective functional molecule. The present work also demonstrates the utility of this strategy toward analyzing complex non-covalent interaction mechanisms between small bioactive molecules.

Acknowledgements: We thank Prof. Skaltsounis team (U. of Athens, Greece) for providing the NMR data. This work is funded by a research grant PEP-Crete (KR-19, co-financed by the E.U.-European Regional Development Fund, the Regional Authority of Crete and the Greek Ministry of Development-General Secretariat Research & Technology).