Efficient delivery of quercetin after binding to beta-lactoglobulin followed by formation soft-condensed core-shell nanostructures.

Nature-made inherent transporting property of beta-lactoglobulin (BLG) was exploited to develop delivery systems for quercetin. After binding to BLG, quercetin was nanoencapsulated within soft-condensed nanostructures of BLG and sodium alginate (ALG). Fluorimetry results revealed that quercetin could bind to BLG even at acidic conditions. The amounts of stoichiometry binding (n) were 1.24 and 1.62 at pH values of 4 and 7, respectively. Formation of core-shell type nanostructures was confirmed by transmission electron microscopy. Quercetin was efficiently entrapped (>93%). The ejection from the carrier was very limited over time (<1% during 1month). The protection of nanoencapsulated quercetin was at least 3 times better than that of free quercetin. Quercetin was not released (<3.5% during 6h) in simulated gastric fluids (pH 1.2 and 4); while, a sustained release (77% during 12h) was observed in simulated intestinal fluid (pH 7.4).