Fabrication and characterization of bioactive nanoemulsion-based delivery systems

Abstract

In this work, a nanoemulsion-based delivery system was developed by encapsulation of different concentrations (0.5%, 0.75% and 1% v/v) of oregano essential oil (OEO) within poly-vinyl alcohol. The delivery systems (oregano essential oil loaded nanoemulsion systems, OEO NESs) were characterized in terms of size distribution, zeta potential, thermal, molecular, micro-structural and antifungal properties. The average droplet diameter values were determined in the range of 70–75 nm while zeta potential values were recorded in the range of 3.13-19.90 mV. Increase in the OEO concentration did not affect size distribution of nanoemulsions. Change in the concentrations showed no visible differences in FTIR spectra; however, for the concentrations of 0.5, 0.75 and 1%, endothermic peak temperatures were recorded as 94, 105 and 117°C, respectively. The antifungal activity of NESs against mycelial growth of Aspergillus niger was evaluated, revealing a significant enhancement in the antifungal activity in comparison to that of free OEO. The zone diameter of mycelial growth could be reduced by around 20, 55 and 65% using NESs at the levels of 0.5, 0.75 and 1% v/v, respectively over 6 days of incubation time. The results of this study revealed the stronger antifungal efficiency of OEO by its encapsulation into NESs as compared to that of free OEO.