Use of Double Gelled Microspheres to Improve Release Control of Cinnamon-Loaded Nanoemulsions

Abstract

The use of nanoemulsions as encapsulation systems for active ingredients, such as cinnamon oil, has been studied. A surfactant based on polyoxyethylene glycerol esters from coconut/palm kernel oil has been used. The nanoemulsions were obtained by the two most commonly low-energy emulsification methods, the composition inversion phase (PIC) and the temperature inversion phase (PIT) methods. Nanoemulsions were successfully obtained by both methods, with very small droplet sizes (5–14 nm) in both cases, but a greater stability was observed when the PIT method was used. Nanoemulsions were encapsulated by external gelation using two different polysaccharides, alginate or chitosan, dissolved in the continuous phase of the nanoemulsion. Then, the nanoemulsion was dropped into a bath with a gelling agent. To improve the release control of cinnamon oil and avoid the burst effect, beads prepared with one of the polysaccharides were coated with the second polysaccharide and then gelled again. Double gelled beads were successfully obtained, the core with chitosan and the outer layer (shell) with alginate. SEM images showed the morphology of the single beads presenting high porosity. When the beads were coated, the porosity decreased because the second polysaccharide molecules covered the pre-existing pores. The smoother surface was obtained when this second layer was, in turn, gelled. The release patterns at pH = 2 and pH = 7 were studied. It was observed that the double gelled bead provided a more gradual release, but maintained approximately the same amount of final released oil. The release patterns were fitted to the Korsmeyer-Peppas model. The fitting parameters reflected the effect of the different coating layers, correlating with different diffusion mechanisms according to the bead core and shell materials.

Formulation of a Novel Hesperetin-Loaded Nanoemulsion and Its Promising Effect on Osteogenesis

“…Our study demonstrates a rapid release within 10 h, which may be attributed to its higher viscosity, rendering it a promising therapy for local applications, since it presents a controlled release that does not take a long time, and formulates properly to systemic functions. Taking into account the mathematical models, in the consistent Korsmeyer–Peppas model, used in various studies [ 50 , 51 ], the k and n values, in this context, represent the release rate to the encapsulated compound through the release system and mean important parameters in the drug release from the nanoparticle system [ 50 ]. This way, the obtained n value of 0.7485 indicates that the HT release from the NE probably is following a non-Fickian or anomalous diffusion mechanism, suggesting that the release process is influenced not only by the compound diffusion but also by other factors, such as the release matrix structure and the HT and NE interaction.…”