Chitosan-Coated Quercetin Nanoemulsion Eye Drops for Sustained Ocular Delivery and Protection of Lens Degeneration from Oxidative Stress

Abstract Quercetin is one of potent antioxidant. Its clinical utility is limited because of its poor solubility and bioavailability. Since oxidative stress is a cause of cataract formation, this study thus developed quercetin-loaded nanoemulsion (QNE) eye drops and further improved their efficacy by preparing in a form of chitosan-coated QNE (CS-QNE). It was found that CS enlarged the droplet size of QNE to 184.33 ± 0.71 nm and shifted the ζ-potential from negative to positive values. CS-QNE had entrapment efficiency of 99.99% with a pH of 6.0 ± 0.0, and shear-thinning behavior. Drug release study demonstrated that the release of quercetin from CS-QNE complied with a zero-order release kinetic. Furthermore, CS-QNE could effectively protect the HLE and HCE-T cells from H2O2-induced oxidative stress. It exhibited strong antioxidant activity with EC50 of 3.15 ± 0.52 μg/mL and 19.48 ± 2.36 μg/mL from the DPPH and ABTS assays, respectively. Cellular uptake studies revealed efficient internalization of CS-QNE in the HLE and HCE-T cells. CS-QNE also showed a trend toward increased Bcl-2 expression, which may contribute to reduced oxidative stress.. The findings suggest that CS-QNE has the ability to protect the HLE and HCE-T cells from oxidative stress that relates to some ocular diseases, including cataract.