Pluronic®/casein micelles for ophthalmic delivery of resveratrol: In vitro, ex vivo, and in vivo tests

Ocular health may strongly benefit from the supply of antioxidant agents that counteract free radicals and reactive oxygen species responsible for long-term eye diseases. Additionally, natural antioxidants like resveratrol can inhibit bacteria growth and restore natural microbiota. However, their use is hindered by limited solubility, fast degradation, and low ocular permeability. This work aimed to overcome these limitations by preparing single and mixed micelles of Pluronic® F127 and casein that serve as resveratrol nanocarriers. Single and mixed (0.1 % casein) micelles (0.0 to -17.0 mV; 2.4 to 32.7 nm) increased 50-fold resveratrol solubility, remained stable for one month at 4 °C, withstood fast dilution, underwent sol-to-gel transitions in the 23.9-27.1 °C range, and exhibited potent antioxidant properties. All formulations successfully passed the HET-CAM assay but showed Pluronic®-casein dose-dependent toxicity in the zebrafish embryo model. Resveratrol-loaded single and mixed micelles (10-15 mM Pluronic® F127) displayed antimicrobial activity against S. aureus and P. aeruginosa. The micelles favored resveratrol accumulation in cornea and sclera, but mixed micelles showed larger lag times and provided lower amount of resveratrol permeated through sclera. In vivo (rabbit) tests confirmed the safety of resveratrol-loaded single micelles and their capability to supply resveratrol to anterior and posterior eye segments.