Development of a new phosphatidylcholine-like surfactant and its application in cosmetics
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Presented by: Makoto Endo
Introduction
Cosmetic products that are currently on the market exhibit a high degree of functionality, consist of various ingredients, and are produced by using various techniques to ensure a pleasant feel during use. Surfactants are critical components that contribute significantly to the functionality, feel, and stability of cosmetics. Among surfactants, phospholipids, which are present in living organisms, and gemini surfactants, which have characteristics like low critical micelle concentrations, are used for preparing cosmetics. The purpose of this study was therefore to develop a new surfactant that would be easy and safe to handle, similar to phospholipids, while also having excellent stability due to low critical micelle concentration combined with high self-aggregation, similar to gemini surfactants. During the development of this new surfactant, the focus was on phosphatidylcholines, and in particular on stearyl behendimonium ethyl phosphate [PCG(P(18)-N(22))] with a phosphorylcholine group. Following successful synthesis of the surfactant, the functionality of the product was confirmed. The novel surfactant was synthesised by reacting a monohydric alcohol with 2-chloro-2-oxo-1,3,2-dioxaphosphorane, followed by reacting the resulting intermediate with a tertiary amine. In previous studies, it was found that the unsaturated bonds and hydroxyethyl groups(*1) associated with bis(hydroxyethyl)oleylammonium ethyl behenyl phosphate [PCG(P(22)-N(Et)(18:1))] and bis(hydroxyethyl)behenylammonium ethyl oleyl phosphate [PCG(P(18:1)-N(Et)(22))] were associated with their superior ability to reduce interfacial tension and high emulsification stability. Other functionalities and potential applications of these chemicals in cosmetic products were therefore also evaluated in this study.
Methods
During investigations into the potential application of phosphatidylcholine in cosmetic products, its solubility in versatile raw materials like polar and hydrocarbon oils was evaluated. In addition, the emulsification maintenance times of bis(hydroxyethyl)oleylammonium ethyl behenyl phosphate [PCG(P(22)-N(Et)(18:1))] in polar and hydrocarbon oils were also determined.
Since stearyl behendimonium ethyl phosphate [PCG(P(18)-N(22))] can form vesicles, the possibility that the surfactant synthesised here could also form vesicles was further investigated. Therefore, the three-phase diagrams of mixtures containing the fabricated surfactant, water, and glycol were obtained. Small-angle X-ray scattering (SAXS), polarised optical microscopy, and transmission electron microscopy (TEM) analyses were performed on mixtures obtained at various points of the three-phase diagrams.
Results and Discussion
The solubility of bis(hydroxyethyl)oleylammonium ethyl behenyl phosphate [PCG(P(22)-N(Et)(18:1))] in polar and hydrocarbon oils, as well as its corresponding emulsification maintenance times, was remarkable. These results were attributed to the unsaturated bonds in the lipophilic chain and the hydroxyethyl groups of the hydrophilic sites of bis(hydroxyethyl)oleylammonium ethyl behenyl phosphate [PCG(P(22)-N(Et)(18:1))]. Three-phase diagrams of phospholipids, stearyl behendimonium ethyl phosphate [PCG(P(18)-N(22))], and bis(hydroxyethyl)oleylammonium ethyl behenyl phosphate [PCG(P(22)-N(Et)(18:1))] were further obtained and analysed at various points of the diagrams employing SAXS, polarised light microscopy, and TEM. Here the results indicated that the region that form lamellar structures were larger than what could be obtained with phospholipids and stearyl behendimonium ethyl phosphate [PCG(P(18)-N(22))] alone.
(*1) Ayami Kobayashi et al., 60th Annual Society of the Japan Oil Chemistry Society (2021)
Cosmetic products that are currently on the market exhibit a high degree of functionality, consist of various ingredients, and are produced by using various techniques to ensure a pleasant feel during use. Surfactants are critical components that contribute significantly to the functionality, feel, and stability of cosmetics. Among surfactants, phospholipids, which are present in living organisms, and gemini surfactants, which have characteristics like low critical micelle concentrations, are used for preparing cosmetics. The purpose of this study was therefore to develop a new surfactant that would be easy and safe to handle, similar to phospholipids, while also having excellent stability due to low critical micelle concentration combined with high self-aggregation, similar to gemini surfactants. During the development of this new surfactant, the focus was on phosphatidylcholines, and in particular on stearyl behendimonium ethyl phosphate [PCG(P(18)-N(22))] with a phosphorylcholine group. Following successful synthesis of the surfactant, the functionality of the product was confirmed. The novel surfactant was synthesised by reacting a monohydric alcohol with 2-chloro-2-oxo-1,3,2-dioxaphosphorane, followed by reacting the resulting intermediate with a tertiary amine. In previous studies, it was found that the unsaturated bonds and hydroxyethyl groups(*1) associated with bis(hydroxyethyl)oleylammonium ethyl behenyl phosphate [PCG(P(22)-N(Et)(18:1))] and bis(hydroxyethyl)behenylammonium ethyl oleyl phosphate [PCG(P(18:1)-N(Et)(22))] were associated with their superior ability to reduce interfacial tension and high emulsification stability. Other functionalities and potential applications of these chemicals in cosmetic products were therefore also evaluated in this study.
Methods
During investigations into the potential application of phosphatidylcholine in cosmetic products, its solubility in versatile raw materials like polar and hydrocarbon oils was evaluated. In addition, the emulsification maintenance times of bis(hydroxyethyl)oleylammonium ethyl behenyl phosphate [PCG(P(22)-N(Et)(18:1))] in polar and hydrocarbon oils were also determined.
Since stearyl behendimonium ethyl phosphate [PCG(P(18)-N(22))] can form vesicles, the possibility that the surfactant synthesised here could also form vesicles was further investigated. Therefore, the three-phase diagrams of mixtures containing the fabricated surfactant, water, and glycol were obtained. Small-angle X-ray scattering (SAXS), polarised optical microscopy, and transmission electron microscopy (TEM) analyses were performed on mixtures obtained at various points of the three-phase diagrams.
Results and Discussion
The solubility of bis(hydroxyethyl)oleylammonium ethyl behenyl phosphate [PCG(P(22)-N(Et)(18:1))] in polar and hydrocarbon oils, as well as its corresponding emulsification maintenance times, was remarkable. These results were attributed to the unsaturated bonds in the lipophilic chain and the hydroxyethyl groups of the hydrophilic sites of bis(hydroxyethyl)oleylammonium ethyl behenyl phosphate [PCG(P(22)-N(Et)(18:1))]. Three-phase diagrams of phospholipids, stearyl behendimonium ethyl phosphate [PCG(P(18)-N(22))], and bis(hydroxyethyl)oleylammonium ethyl behenyl phosphate [PCG(P(22)-N(Et)(18:1))] were further obtained and analysed at various points of the diagrams employing SAXS, polarised light microscopy, and TEM. Here the results indicated that the region that form lamellar structures were larger than what could be obtained with phospholipids and stearyl behendimonium ethyl phosphate [PCG(P(18)-N(22))] alone.
(*1) Ayami Kobayashi et al., 60th Annual Society of the Japan Oil Chemistry Society (2021)