Pyridyl-functionalized and surface molecularly imprinted cellulose particles to target bioactive compounds in olive leaf

Hybrid particles consisting of a cellulose core and a 4-vinylpyridine-based cross-linked shell were synthesized in the presence of the quercetin imprinting template by surface-initiated atom transfer radical polymerization (ATRP). The modification of cellulose with the introduction of pyridyl moieties was demonstrated by FTIR, SEM, surface area measurement and quantification of nitrogen in the hybrid particles by elemental analysis. The hybrid materials were assessed for their sorption capacity for standard polyphenols under competitive binding and considering different solvents. It was demonstrated that they exhibited a strong binding capacity for these types of molecules due to favorable interactions with the pyridyl nitrogen, even when loading hydroalcoholic solvents with high alcohol content (e.g. ethanol/water 80/20 v /v) was employed. Adsorbent particles synthesized at the gram scale were packed into HPLC columns, demonstrating their ability to be used in continuous separation processes and the reusability of the materials. Cycling of the packed column with a solvent gradient was performed without observation of a too high backpressure (maximum value observed ~15 bar). Two different industrial olive leaf extracts, characterized by their high polyphenol and triterpene content, were purified by sorption/desorption using the hybrid adsorbent particles. The present study demonstrates that hybrid particles allow the separation of target compounds in olive leaf. Using simple sorption/desorption steps, enrichment factors of about 20 for glycosylated flavonoids and 6 for luteolin were measured with the two olive leaf extracts. • Surface of cellulose particles was functionalized with pyridyl moieties via ATRP. • Strong binding capacity of the functionalized particles for polyphenols has been demonstrated. • Particle reusability and application in continuous separation demonstrated by packaging. • The hybrid particles developed were used to purify two industrial olive leaf extracts. • Enrichment factors for flavonoids up to 20 achieved with simple sorption/desorption processes.