J. Cosmet. Sci., 65, 225–238 (July/August 2014) 225 Address all correspondence to Nabila Belhaj at Nabila.belhaj@lucasmeyercosmetics.com. Development of a new resistant liposome coated with polysaccharide fi lm for cosmetic application NABILA BELHAJ, JEAN PIERRE ARNAUD, ESTELLE LOING, and CARINE BÉZIVIN, Lucas Meyer Cosmetics, ZA les Belles Fontaines, 91160 Champlan, France (N.B., J.P.A., C.B.), and Lucas Meyer Cosmetics, Place de la Cité, Tour de la Cité # 900, Québec G1V 4W2, Canada (E.L.). Accepted for publication May 22, 2014. Synopsis The aim of our study was to elaborate a resistant liposome that can be used in cosmetic formulations containing high amounts of surfactants and electrolytes. The stability of liposomes was increased via hydrophobized polysac- charide (Stearoyl Inulin) by anchoring its stearic acid tail into liposome bilayer. Coated and noncoated liposomes were prepared under the same conditions and their morphology, size, and resistance to surfactants and electrolytes were evaluated. We established that coated liposomes were more resistant to surfactants and electrolytes. It seems that a coating of polysaccharides prevents liposome destabilization in the presence of high amounts of surfactants and electrolytes. Moreover, the ability of coated liposomes to improve the skin delivery of active molecules was evaluated. Coated liposomes increased the effi cacy of magnesium chloride by improving its skin availability. INTRODUCTION Liposomes are mainly used for the encapsulation of bioactive molecules in cosmetics, pharmaceutics, nutraceutics, and in food sciences. Both hydrophilic and lipophilic bioac- tive molecules can be incorporated into liposomes to enhance their skin penetration and thus to improve their effi cacy. Because of their biocompatibility with skin composition, liposomes have been principally used in the cosmetic industry since the eighties (1–3). Liposomes are incorporated into different cosmetic products such as creams, lotions, and gels. However, even if they are very interesting delivery systems for the cosmetic industry, they still have some limitations. For example, various cosmetic ingredients decrease the stability of liposomes and therefore their effi cacy to deliver bioactive molecules. Maherani et al. (4) have reported that physicochemical stability of liposomes depends mainly on the lipid composition, the rigidity of the membrane, and the ability of liposomes to maintain the entrapment effi ciency despite changing external conditions (pH, electrolytes, surfac- tants, and so on).

JOURNAL OF COSMETIC SCIENCE 226 In cosmetics and toiletries, electrolytes have an important role on the sensorial properties of fi nal products because they infl uence the gel formation. They are largely used in sham- poo, deodorants, and as water in oil emulsion stabilizers. Also, several studies reported the benefi cial effect of some salts on human cutaneous barrier functions (5,6) and on bio- logical mechanisms (7). Moreover, surfactants are widely used in personal care products for emulsion stabilization and for their several properties such as detergency, solubilization, conditioning, thicken- ing, and emolliency (8). Surfactants are also used in toiletries formulations as rheology controllers to modify the viscoelastic properties and thus the sensorial characteristics of the fi nal product (9). Deo et al. (10) have reported that liposomes made of phosphatidyl- choline and phosphatidic acid are very sensitive to surfactants. In the presence of dodecyl sulfonate, the size of liposomes increased until complete solubilization. It has been reported from several studies that the stability of liposomes can be enhanced by modifi cation of their surfaces using a coating process with natural polysaccharides (i.e., mannan, pullulan, amylopectin, dextran, chitosan) (11). However, the adsorption of these polysaccharides to the liposome membrane seemed to be thermodynamically unstable (12). The use of chemically modifi ed polysaccharides for coating liposomes may avoid this stability problem (13–15). Good stability could be obtained by coating the outermost surface of liposomes with derivatives of polysaccharides (16–18). Fatty acids are chemi- cally grafted to natural polysaccharides to make them amphiphilic. The hydrophobic al- kyl chains of modifi ed polysaccharides were then anchored into the bilayer membrane of liposomes. The fi rst part of our study was the physicochemical characterization of modifi ed polysac- charide coated liposomes compared to classical noncoated liposomes. Then, we evaluated the resistance of coated liposomes versus noncoated ones to different concentrations of ionic/ nonionic surfactants and electrolytes. In order to evaluate the delivery property of coated liposomes, magnesium chloride (MgCl2), a divalent salt, was chosen as the bioactive mole- cule which is implicated in P-glycoprotein (P-gp) transporter activity. Natural MgCl2 has interesting cosmetic properties as it plays an important role in the expulsion of wastes out of cells and then avoids the accumulation of reactive oxygen species. Detoxifi cation of cells was regulated by P-gp transporter it is a magnesium-dependent transmembrane pump. In this way, 12% of MgCl2 was entrapped in coated liposomes. These coated liposomes loaded with MgCl2, called magnesium chloride-coated liposomes (MCCL), were physico- chemically characterized. The MgCl2 release from MCCL was then measured in an acry- late gel formula whose viscosity is known to be very sensitive to divalent ions. The delivery property of this resistant liposome was evaluated by an ex vivo study on human skin explants. MATERIALS AND METHODS MATERIALS Two soybean lecithins (Emulmetik™ 930 and Emulmetik™ 900) distributed by Lucas Meyer Cosmetics were used for the preparation of liposomes. They are composed of about 92% and 45% of phosphatidylcholine, respectively.