Ultrasonic homogenization used for the nanoemulsion preparation.
•
Nanoemulsion was used as a template for the nanocapsule preparation.
•
Controlled sonication helped to prepare uniformly-dispersed multi-layered nanocapsules.
•
Formation of polymeric shell around nanoemulsion droplet confirmed by microscopy.
•
More efficient disruption of flocs through sonication than conventional homogenization.
Abstract
In this study, biodegradable polymeric nanocapsules were prepared by sequential deposition of food-grade polyelectrolytes through the self-assembling process onto the oil (medium chain triglycerides) droplets enriched with curcumin (lipophilic bioactive compound). Optimum conditions were used to prepare ultrasound-assisted nanoemulsions stabilized by octenyl-succinic-anhydride (OSA)-modified starch. Negatively charged droplets (−39.4 ± 1.84 mV) of these nanoemulsions, having a diameter of 142.7 ± 0.85 nm were used as templates for the fabrication of nanocapsules. Concentrations of layer-forming cationic (chitosan) and anionic (carboxymethylcellulose) biopolymers were optimized based on the mean droplet/particle diameter (MDD/MPD), polydispersity index (PDI) and net charge on the droplets/capsules. Prepared core–shell structures or nanocapsules, having MPD of 159.85 ± 0.92 nm, were characterized by laser diffraction (DLS), ζ-potential (ZP), atomic force microscopy (AFM), transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Furthermore, physical stability of curcumin-loaded nanocapsules in suspension was determined and compared at different storage temperatures. This study may provide information regarding the formation of ultrasound-assisted polymeric nanocapsules from the nanoemulsion templates which could be helpful in the development of delivery systems for lipophilic food bioactives.
