Oleic Acid-Shelled Solid Lipid Nanocomplexes for Enhanced Quercetin Delivery with Improved Antioxidant and Stability Properties

Quercetin (Que), a bioactive flavonoid with anti-inflammatory and antioxidant effects, faces limited use due to its poor solubility and instability. To overcome these limitations, a novel glyceryl monostearate (GM)-based solid lipid nanocomplex was developed, incorporating oleic acid (OA) to improve stability and Que delivery. GM, aided by positively charged octadecylamine, encapsulated Que (forming LNP@Que), which was then electrostatically coated with OA to yield LNP@Que/OA. Optimizing the GM-to-OA mass ratio to 9:1 yielded a nanocomplex with a particle size of 183.3 ± 20.6 nm and a reduced zeta potential. The OA modification significantly improved the antioxidant properties, degradation resistance, and overall stability of the Que nanocomplex. Notably, LNP@Que/OA (10% OA + 90% GM) demonstrated the highest encapsulation efficiency (97.49%) and enabled effective controlled release of Que during in vitro simulated digestion. This study highlights the potential of LNP@Que/OA for pharmaceutical applications.