Antioxidant-Loaded Mucoadhesive Nanoparticles for Eye Drug Delivery: A New Strategy to Reduce Oxidative Stress

There are several approaches to treat ocular diseases, which can be invasive or non-invasive. Within the non-invasive, new pharmaceutical strategies based on nanotechnology and mucoadhesive polymers are emerging methodologies, which aim to reach an efficient treatment of eye diseases. The aim of this work was the development of novel chitosan/hyaluronic acid nanoparticle systems with mucoadhesive properties, intended to encapsulate antioxidant molecules (e.g., crocin) aiming to reduce eye oxidative stress and, consequently, ocular disease. An ultraviolet (UV) absorber molecule, actinoquinol, was also added to the nanoparticles, to further decrease oxidative stress. The developed nanoparticles were characterized and the results showed a mean particle size lower than 400 nm, polydispersity index of 0.220 ± 0.034, positive zeta potential, and high yield. The nanoparticles were also characterized in terms of pH, osmolality, and viscosity. Mucoadhesion studies involving the determination of zeta potential, viscosity, and tackiness, showed a strong interaction between the nanoparticles and mucin. In vitro release studies using synthetic membranes in Franz diffusion cells were conducted to unravel the drug release kinetic profile. Ex vitro studies using pig eye scleras in Franz diffusion cells were performed to evaluate the permeation of the nanoparticles. Furthermore, in vitro assays using the ARPE-19 (adult retinal pigment epithelium) cell line showed that the nanoparticles can efficiently decrease oxidative stress and showed low cytotoxicity. Thus, the developed chitosan/hyaluronic acid nanoparticles are a promising system for the delivery of antioxidants to the eye, by increasing their residence time and controlling their delivery.