Preparation of New Glycerol-Based Dendrimers and Studies on Their Behavior toward Essential Oil Encapsulation

Encapsulation of Vitamin C by Glycerol-Derived Dendrimers, Their Interaction with Biomimetic Models of Stratum corneum and Their Cytotoxicity

Vitamin C is one of the most sensitive cosmetic active ingredients. To avoid its degradation, its encapsulation into biobased carriers such as dendrimers is one alternative of interest. In this work, we wanted to evaluate the potential of two biobased glycerodendrimer families (GlyceroDendrimers-Poly(AmidoAmine) (GD-PAMAMs) or GlyceroDendrimers-Poly(Propylene Imine) (GD-PPIs)) as a vitamin C carrier for topical application. The higher encapsulation capacity of GD-PAMAM-3 compared to commercial PAMAM-3 and different GD-PPIs, and its absence of cytotoxicity towards dermal cells, make it a good candidate. Investigation of its mechanism of action was done by using two kinds of biomimetic models of stratum corneum (SC), lipid monolayers and liposomes. GD-PAMAM-3 and VitC@GD-PAMAM-3 (GD-PAMAM-3 with encapsulated vitamin C) can both interact with the lipid representatives of the SC lipid matrix, whichever pH is considered. However, only pH 5.0 is suggested to be favorable to release vitamin C into the SC matrix. Their binding to SC-biomimetic liposomes revealed only a slight effect on membrane permeability in accordance with the absence of cytotoxicity but an increase in membrane rigidity, suggesting a reinforcement of the SC barrier property. Globally, our results suggest that the dendrimer GD-PAMAM-3 could be an efficient carrier for cosmetic applications.

Synthesis and Activity of Ionic Antioxidant-Functionalized PAMAMs and PPIs Dendrimers

For this study, new dendrimers were prepared from poly(propylene imine) (PPI) and polyamidoamine (PAMAM) dendrimers using an efficient acid-base reaction with various phenolic acids. The syntheses were also optimized in both microwave and microfluidic reactors. These ionic and hydrophilic dendrimers were fully characterized and showed excellent antioxidant properties. Their cytotoxic properties have been also determined in the case of fibroblast dermal cells.

Cinnamomum zeylanicum Essential Oil Formulation with Poly(propylene imine) Dendrimers with Surface-Grafted Glycerol: Release Kinetics of trans-Cinnamaldehyde and Germination Inhibition Effects

The Third-generation glycerodendrimer polypropylenimine (GD-PPI-3) can be used in an aqueous formulation of Cinnamomum zeylanicum essential oil (CEO). The purpose was to give an overview of this innovative method of retaining and releasing essential oils. The formulation consisted of 366 min stirring at 1735 rpm of the aqueous solution of 2 mM GD-PPI-3 with CEO. Some physicochemical properties of these formulations, as well as the release of trans-cinnamaldehyde, have been studied. A bimodal distribution and no concentration or aging effect were observed by optical microscopy. Moreover, the release kinetics showed the retention of volatile molecules in solution under various environmental conditions. The release profile was characterized by an initial burst followed by a steady release. The dendrimers allowed us to reduce this initial burst and extended the release by at least 15 h. In addition, the herbicidal effect was evaluated: inhibition of Arabidopsis thaliana seed germination was obtained for 7 days with a formulation of 12.5 mg/L CEO in a closed space and 360 mg/L CEO in an open space.