Development of Optimized Colloidal Dispersion Containing Nanoemulsified Quercetin

Quercetin (Qct) is a flavonoid belonging to the subclass of flavonol with recognized biological activities. However, such activities are limited due to its poor aqueous solubility and low stability. Nanoemulsions (NE) are metastable colloidal dispersions formed by a fluid lipid core that can be loaded with hydrophobic biomolecules. Therefore, this study aimed to optimize and characterize NE containing quercetin. NE formulations were prepared using phase inversion temperature method and characterized relating to size, polydispersity index (PdI), physical stability, incorporation efficiency (IE), and in vitro release. Initially, five unloaded NE formulations were prepared having different compositions (wt. %) of oil blend, nonionic surfactants, and aqueous external phase. For these unloaded NE, droplet sizes ranged from 65 to 470 nm and PdI values between 0.09 and 0.63. Qct-containing NE (Qct-NE) showed average diameter of 60.6 nm (± 4.08) and PdI 0.085 (± 0.005) demonstrating that nanosized oil droplets were formed with narrow size distribution. Stability study was performed by analytical photocentrifugation method. According this testing, NE formulations were physically stable with lower droplet migration velocities and instability index values below 0.1. Additionally, quercetin was efficiently incorporated in NE reaching 85.4% (± 0.87) of this flavonol inside the oily core. In vitro release experiments were carried out using dialysis technique. Following 156 h of experiment, 71.4% (± 8.12) and 8.9% (± 1.25) of nanoemulsified and free quercetin, respectively, were released in receptor medium. In summary, we have successfully developed a stable NE containing quercetin using a cost-effective and ecofriendly emulsification approach.