Background and Aim: This study investigates nanoemulsion formulation of Eucalyptus globulus essential oil to overcome volatility and low solubility, enhancing its physicochemical properties for pharmaceutical and medical applications.
Materials and Methods: In this study, nanoemulsions were prepared by spontaneous emulsification using a mixture of an aqueous phase (distilled water) and an organic phase composed of eucalyptus oil and non-ionic surfactants, TWEEN® 20 or TWEEN® 80 as emulsifiers, at different proportions. The different formulations were prepared using two main methods: heat treatment and simple mixing. Particle size analysis, zeta potential and polydispersity index (PDI) were studied on the freshly prepared mixtures. The stability was assessed using the centrifugation.
Results: The prepared nanoemulsions exhibited a transparent appearance with a nanometric globule size distribution, confirming their good homogeneity. Among the tested formulations, F1 presented the smallest droplet size (35.7 nm), while the others ranged between 35.7 and 1487 nm. The zeta potential values were between -1.02 and -3.67 mV, indicating a moderate electrostatic stabilization. However, F1 showed weak physical stability over time, which can be attributed to the use of a single surfactant, leading to phase separation under stress conditions.
Conclusion: The results confirm that the formulations obtained by spontaneous emulsification meet the physicochemical criteria of nanoemulsions in terms of droplet size, appearance, and homogeneity. Their physical stability remains limited, particularly for F1, due to the formulation strategy. Future research may focus on the optimization of surfactant/co-surfactant systems and the incorporation of stabilizing agents to improve long-term stability and broaden potential pharmaceutical applications.