Preparation of Polymeric Micelles of Poly(Ethylene Oxide-b-Lactic Acid) and their Encapsulation With Lavender Oil

Abstract

Nanoparticles comprised of the poly(ethylene oxide)-b-poly (lactic acid) diblock copolymer (PEO-b-PLA) with and without the incorporation of lavender oil were prepared by nanoprecipitation. Diblock copolymers based on a fixed PEO block (5 KDa ) and two different PLA segments (4.5 or 10 KDa ) were used. The morphology, encapsulation efficiency, essential oil-polymer interaction and the release kinetics of the active agent in the nanoparticles, were evaluated. The hydrodynamic radius of the nanoparticles determined by light scattering was affected by the size of the poly(lactic acid) (PLA) block. The lavender essential oil encapsulation efficiency (at a concentration of 0.4 μL mL -1 ) determined by UV-VIS spectroscopy was in the range of 70-75%. The in vitro release suggests that the polymeric barrier is able to control the oil release.

Encapsulation of Essential Oils via Nanoprecipitation Process: Overview, Progress, Challenges and Prospects

“…In a study carried out by Christofoli and coworkers, Zanthoxylum rhoifolium L. EO from poly-ε-caprolactone-NP have reached a level of maximal release (81.9%) at 72 h [87]. The release kinetic profile of Zanthoxylum rhoifolium L. EO showed an initial burst effect, followed by a slow release after 12 h. Similar biphasic release profile was already described [57,73,88]. As reported earlier, the initial burst release was related to the molecules that are adsorbed to the polymeric wall, while the second release phase was attributed to the EO molecules present in the core of the nanocapsules which make more time to diffuse through the polymeric wall [57].…”

“…The nanoprecipitation method involves the use of an organic solvent, which is completely soluble in the external aqueous phase, inducing immediate polymer precipitation. According to the Table 1, several organic solvents could be used like, dimethyl sulfoxide [67], ethanol [75], acetic acid [72][73][74]81,82], isopropanol:acetone [68,70], tetrahydrofuran [86]; while acetone is the mostly used [55,57,65,66,71,87,88].…”

“…Pluronic ® F68 [57,65], Tween 80 [66,87] and polyvinyl alcohol [68] are examples of used surfactants. While, water was the most used non-solvent [55,57,[66][67][68]71,75,87,88,90]. Methanol was also used by other work studies [73,74,81,82].…”

“…Currently, several reports highlighted the negligible effect of surfactant on the physicochemical properties of the developed NP. In this context, several EO have been efficiently entrapped in polymeric NP without adding any surfactant to stabilize the system [55,67,[69][70][71][72]74,75,81,82,86,88]. In some cases, some EO played the role of surfactant-like substance facilitating the formation of NP [55,71].…”

“…This was explained by the fact that carvacrol is more hydrophilic than thymol, thus in contact with water, more release is expected for carvacrol [73]. Moreover, Popiolski and coworkers reported that Lavandula dentata L. EO release from polyethylene oxide-b-polylactic acid (PEO-b-PLA) copolymers based-NP depends on polylactide molecular weight [88]. For instance, the release of Lavandula dentata L. EO from PEO5KDa-b-PLA10KDa nanoparticles was about 40% and this percentage remained the same for 24 h of releasing process.…”