Nail Lacquer with Origanum vulgare Essential Oil and Biogenic Silver Nanoparticles for Onychomycosis: Development, Characterization, and Antifungal Effectiveness

Onychomycosis is a common fungal nail infection for which new antibiotics are needed to overcome antifungal resistance and other limitations of conventional treatments. This study reports the development of antifungal nail lacquers containing oregano essential oil (OEO), rosemary essential oil (REO), and/or biogenic silver nanoparticles (bioAgNP). The formulations (F) were tested against dermatophytes by agar diffusion, ex vivo nail infection, and scanning electron microscopy techniques. They were evaluated pharmacotechnically and by FTIR-PAS to access permeation across the nail plate. F-OEO and F-OEO/Ag were promising for the final nail lacquer formulation, they permeated through the nail plate and showed antifungal efficacy against dermatophytes-contaminated nails after 5 days of treatment. The treated nails had decreased hyphae and spores compared to untreated control; the hyphae were atypically flattened which indicates loss of cytoplasmic content due to damage to cytoplasmic membrane. Formulations were stable after centrifugation and thermal stress, maintaining organoleptic and physicochemical characteristics. F-OEO and F-OEO/Ag had pH compatible with the nail, and drying time (59-90 s) within the reference for nail lacquer. For the first time, OEO and bioAgNP were incorporated in a nail lacquer, resulting in a natural and nanotechnological antifungal product for onychomycosis that may combat microbial resistance.