This study was jointly carried out by Tokyo University of Science (TUS) and Miyoshi Oil and Fat. Led by Dr Kenichi Sakai, the team synthesised an α-gel using an oleic acid-based surfactant.
Alpha-gels are viscous substances formulated by mixing surfactants with fatty alcohol and water. They are commonly used in skin care products because of their ability to retain water well.
The study claims that this alpha-gel has a structure similar to natural ceramide. Ceramide plays an important role in helping skin retain moisture. It is found in the lipid layer of the skin and forms a ‘lamellar gel’ with cholesterol, fatty acids, and water.
Sakai said one of his interests was to develop alpha-gels using two-tailed and two-headed surfactants to discover how their structural and physical properties would be different.
The properties of this new alpha-gel were evaluated using the small- and wide-angle X-ray scattering (SWAXS) technique, nuclear magnetic resonance (NMR) spectroscopy, and an optical microscope.
SWAXS measurements revealed that the alpha-gel had a ‘sheet-like’ structure. The structure remained highly ordered even when 90% of the mixture by weight was water.
Further analyses found that increasing the molar content of the fatty alcohol in the mixture could increase the space between the molecular bilayers in the stacked-structure of the alpha-gel.
The scientists concluded that increasing the space between the bilayers happens when the water content increases.
The NMR spectroscopy showed that increasing fatty alcohol molar content also caused a decrease in the movement of protons within the molecular bilayers, similar to characteristics lamellar gels are known to have.
Using an optical microscope, the researchers studied the shear thinning of the α-gel and show progressive and specific changes in the structure of the alpha-gel with an increase in fatty alcohol content.
The study concluded that this alpha-gel has the ability to retain water and spread evenly over surfaces, making it suitable for skin care products such as skin creams.
According to Sakai, the characteristics of this alpha-gel indicate that it can be used to develop environmentally-friendly skin care products at low-energy costs.
This is because as an oleic acid-based surfactant, it is readily soluble in water, explained Sakai.
"It is an environment-friendly functional organic material because even when it is added in small amounts, it exhibits surface chemical functions not inferior to those of conventional surfactants."