Topical delivery of Niaouli essential oil nanoemulsion via Chitosan: Polyvinyl alcohol patches: A promising antimicrobial strategy for potential biomedical applications

Niaouli essential oil (NEO), selected as a bioactive compound, is a volatile oil known for its antiviral, antifungal, antibacterial, and antioxidant activities. To overcome the limitations associated with direct use of NEO, nanoemulsion formulations were developed, aiming for stability, long-term release, and controlled use. In this study, NEO nanoemulsions (NEO-NEs) were prepared, incorporated into a polymeric matrix, and evaluated for their potential use as antimicrobial patches. Three different oil-in-water emulsion formulations were produced, and the droplet size analyses were performed. Thin polymeric films were produced as carrier matrices for the optimal NEO-NEs formulation. Polymer matrices based on chitosan (CS) and polyvinyl alcohol (PVA) were physicochemically characterized in the presence of different volumes of NEO-NEs (10, 20, and 30 mu L). The sample containing 20 mu L of NEO-NEs exhibited a homogeneous morphology and achieved a swelling ratio of approximately 300 times its initial weight without compromising structural stability. Both direct and indirect cytotoxicity tests demonstrated that the NEO-NEs additive had no adverse effect on the biocompatibility. GC-MS analysis identified the main components of NEO, revealing a rich terpenoid composition that exhibited timedependent antioxidant activity. Release studies showed a controlled, stable, and sustained release profile over 48 h. Microbiological evaluations showed high antifungal activity, particularly against Candida albicans. Overall, the findings of this study highlight the significant potential of NEO-incorporated polymeric adhesive patches for the prevention of fungal infections.