Innovative formulation technology
- Development of a new α-gel emulsification method that provides increased comfort and wrinkle reduction capabilities-
Podium 65
Presented by: Junya Hiyoshi
Introduction
Moisturizers and emollients are essential ingredients of cosmetics used to maintain skin beauty and health. Since their discovery 60 years ago, α-gels, formed by combining surfactants and higher alcohols, have been used to stabilize formulations containing these ingredients. However, to provide sufficient moisturizing power and skin-conditioning effect, these ingredients are highly blended, which results in stickiness and decreased comfort. This stickiness arises from the increased system viscosity because a large amount of the aqueous phase is incorporated between the stacked bilayer structure of the α-gel. To overcome this problem, we developed a new α-gel by controlling the surface spacing of the laminated structure. These new α-gels contained a larger quantity of moisturizing ingredients than conventional gels. They also showed high skin-conditioning effects as well as a unique and comfortable texture. We found it surprising that for the new α-gel, the interlayer spacing of the laminated structure did not widen when a two-chain nonionic surfactant was used as the fatty alcohol. Using this new α-gel, we developed a new emulsification method and a prototype skincare emulsion, which unexpectedly displayed strong wrinkle-improvement capabilities.
Experimental
The novel α-gel was obtained by mixing various hydrophilic surfactants, polyoxyethylene (6 mol) distereate (POE-6), and ion-exchanged water at 70 °C. Small- and wide-angle X-ray scattering (SWAXS) was used to determine the structure of the α-gel, and differential scanning calorimetry (DSC) was used to measure the melting point and enthalpy.
Both human trials and home use tests were conducted to evaluate user sensation and skin-conditioning effects, and the new α-gel containing a large amount of emollient and humectant was compared with our commercially available emulsion. During human trials, comparisons were performed before use, immediately after single use, and after 1 week of continuous use. The home use tests were conducted over 2 weeks with a total of 60 participants in their 40s and 60s.
Results
Through SWAXS, the self-assembling gels formed by mixing various hydrophilic surfactants, POE-6, and ion-exchanged water were found to have an α-gel structure. Aqueous dispersions of various hydrophilic surfactants either had a lamellar liquid crystal or α-gel structure. As the concentration of POE-6 increased, the melting point and melting enthalpy of the gel increased, although the hexagonal structure of the α-gel was found to become more rigid. Furthermore, because this α-gel did not widen the surface spacing even when the water content increased and was insoluble in polar oil and water, it was possible to prepare a low-viscosity emulsion by adhering it to the oil-water interface.
This novel α-gel emulsion did not become sticky to the touch even when it was blended with a large amount of humectant or emollient. Furthermore, when this formulation containing a large amount of moisturizer and emollient was continuously used for 2 weeks by healthy middle-aged and elderly women, significant softening of the stratum corneum and improvement of the wrinkle appearance were observed. Compared with conventional products, this product, containing a large amount of humectant and emollient, softened the stratum corneum to a high degree. Skin texture was also found to improve with single and continuous use. A strong wrinkle-improving effect was observed, and a correlation was observed between skin softness and wrinkle improvement.
Discussion
According to a report by Ogura et al. presented at IFSCC 2020, wrinkles are formed from hardening of the stratum corneum and softening of the dermis layer with aging. This formulation contains 2 to 3 times more emollient than conventional formulations and enhances the flexibility of the stratum corneum without making it feel sticky. Because the skin texture is improved when the stratum corneum is softened, texture improvement can eliminate distortion of the large stratum corneum that causes wrinkles. Thus, wrinkles are effectively reduced.
Conclusion
In this study, a new type of α-gel was developed by mixing a hydrophilic nonionic surfactant with a two-chain nonionic surfactant. The physical properties and usability of the new α-gel are significantly different from those of the conventional α-gel. In particular, the new α-gel can contain a greater moisturizer and emollient content than the conventional α-gel without feeling sticky. Moreover, formulations using the new α-gel show strong wrinkle-reduction capability. This new α-gel can lead to the creation of new cosmetics featuring comfort and functionality to increase customer satisfaction.
Moisturizers and emollients are essential ingredients of cosmetics used to maintain skin beauty and health. Since their discovery 60 years ago, α-gels, formed by combining surfactants and higher alcohols, have been used to stabilize formulations containing these ingredients. However, to provide sufficient moisturizing power and skin-conditioning effect, these ingredients are highly blended, which results in stickiness and decreased comfort. This stickiness arises from the increased system viscosity because a large amount of the aqueous phase is incorporated between the stacked bilayer structure of the α-gel. To overcome this problem, we developed a new α-gel by controlling the surface spacing of the laminated structure. These new α-gels contained a larger quantity of moisturizing ingredients than conventional gels. They also showed high skin-conditioning effects as well as a unique and comfortable texture. We found it surprising that for the new α-gel, the interlayer spacing of the laminated structure did not widen when a two-chain nonionic surfactant was used as the fatty alcohol. Using this new α-gel, we developed a new emulsification method and a prototype skincare emulsion, which unexpectedly displayed strong wrinkle-improvement capabilities.
Experimental
The novel α-gel was obtained by mixing various hydrophilic surfactants, polyoxyethylene (6 mol) distereate (POE-6), and ion-exchanged water at 70 °C. Small- and wide-angle X-ray scattering (SWAXS) was used to determine the structure of the α-gel, and differential scanning calorimetry (DSC) was used to measure the melting point and enthalpy.
Both human trials and home use tests were conducted to evaluate user sensation and skin-conditioning effects, and the new α-gel containing a large amount of emollient and humectant was compared with our commercially available emulsion. During human trials, comparisons were performed before use, immediately after single use, and after 1 week of continuous use. The home use tests were conducted over 2 weeks with a total of 60 participants in their 40s and 60s.
Results
Through SWAXS, the self-assembling gels formed by mixing various hydrophilic surfactants, POE-6, and ion-exchanged water were found to have an α-gel structure. Aqueous dispersions of various hydrophilic surfactants either had a lamellar liquid crystal or α-gel structure. As the concentration of POE-6 increased, the melting point and melting enthalpy of the gel increased, although the hexagonal structure of the α-gel was found to become more rigid. Furthermore, because this α-gel did not widen the surface spacing even when the water content increased and was insoluble in polar oil and water, it was possible to prepare a low-viscosity emulsion by adhering it to the oil-water interface.
This novel α-gel emulsion did not become sticky to the touch even when it was blended with a large amount of humectant or emollient. Furthermore, when this formulation containing a large amount of moisturizer and emollient was continuously used for 2 weeks by healthy middle-aged and elderly women, significant softening of the stratum corneum and improvement of the wrinkle appearance were observed. Compared with conventional products, this product, containing a large amount of humectant and emollient, softened the stratum corneum to a high degree. Skin texture was also found to improve with single and continuous use. A strong wrinkle-improving effect was observed, and a correlation was observed between skin softness and wrinkle improvement.
Discussion
According to a report by Ogura et al. presented at IFSCC 2020, wrinkles are formed from hardening of the stratum corneum and softening of the dermis layer with aging. This formulation contains 2 to 3 times more emollient than conventional formulations and enhances the flexibility of the stratum corneum without making it feel sticky. Because the skin texture is improved when the stratum corneum is softened, texture improvement can eliminate distortion of the large stratum corneum that causes wrinkles. Thus, wrinkles are effectively reduced.
Conclusion
In this study, a new type of α-gel was developed by mixing a hydrophilic nonionic surfactant with a two-chain nonionic surfactant. The physical properties and usability of the new α-gel are significantly different from those of the conventional α-gel. In particular, the new α-gel can contain a greater moisturizer and emollient content than the conventional α-gel without feeling sticky. Moreover, formulations using the new α-gel show strong wrinkle-reduction capability. This new α-gel can lead to the creation of new cosmetics featuring comfort and functionality to increase customer satisfaction.