Sustained ocular drug delivery via polydopamine chitosan curcumin nanocomposite coatings

Traditional methods of ocular drug delivery (i.e.) eye drops, have limited effectiveness, with only ∼ 5% the administered dose reaching deeper ocular tissues due to rapid drainage and barriers like the corneal epithelium and blood-retinal barriers. Alternatives such as ocular implants, gels, microneedles, and iontophoresis can improve bioavailability but often cause patient discomfort, invasiveness, or require specialized equipment. Silicone hydrogel contact lenses are utilized in this study for sustained drug delivery using polydopamine (PDA) coatings combined with curcumin-loaded chitosan nanoparticles (NPs). Optimized PDA coatings, achieved with a 0.1 M dopamine hydrochloride solution 10 h immersion, resulted in a uniform 1-3 μm thickness and functioned as a therapeutic neutral-density. Reaction time influenced nanoparticle distribution. Shorter times (1 h) yield narrower size distributions and reduced aggregation. At a chitosan and tripolyphosphate (TPP) ratio of 2:1, particles averaged 167.3±1.9 nm with a low polydispersity index (PDI) of 0.15-0.25, indicating uniformity. Ethanol minimized aggregation, resulting in a narrower size distribution subsequently and creating a smooth nanocomposite film. Curcumin's anti-inflammatory and antioxidant properties are protected from thermal degradation within chitosan NPs, and the hydrophilic PDA coating further stabilized the lenses. We created a convenient, non-invasive alternative to traditional methods, potentially improving therapeutic outcomes and patient compliance in ocular drug delivery.