Characterization and stability assessment of geraniol self-nanoemulsifying drug delivery systems (SNEDDS): A novel approach using dielectric spectroscopy Academic Article in Scopus uri icon

abstract

  • The stability of emulsions is essential for proper formulation and effective performance of these colloidal systems in biomedical applications. In this study, an oil-in-water geraniol nanoemulsion was created using Self-Nanoemulsifying Drug Delivery Systems (SNEDDS), with different concentrations of oil and surfactants (Labrasol, Cremophor EL, and Labrafil M 1944 CS). The stability was monitored over 60 days using techniques such as dynamic light scattering, viscosity measurements, Fourier-transform infrared spectroscopy, and dielectric spectroscopy in the GHz range. Results indicated that the formulation with high surfactant levels and a droplet size near 25 nm remained stable throughout storage. Conversely, the formulation with twice the geraniol concentration and less surfactant had larger droplets (~45 nm) and exhibited signs of phase separation due to creaming; however, its initial properties were restored after stirring. The viscosity depended on geraniol concentration, droplet size, and interfacial volume fraction. The interfacial volume and layer thickness were estimated from dielectric spectroscopy data using a three-phase model that considers water as the continuous phase, oil droplets as the dispersed phase, and the surfactant-coated interfacial layer as the third phase. These findings confirm that dielectric spectroscopy in the GHz frequency range is a sensitive and non-destructive method for evaluating the structural properties and stability of nanoemulsions, beneficial for analyzing phase separation mechanisms. © 2025 Elsevier B.V.

publication date

  • January 1, 2025