Introduction

“Microemulsions are dispersions made of water, oil, and surfactant(s) that are isotropic and thermodynamically stable systems with dispersed domain diameter varying approximately from 1 to 100 nm, usually 10 to 50 nm.”

https://en.wikipedia.org/wiki/Microemulsion

Microemulsions (also known as nano-emulsions) are a new generation of skincare formulation systems that offer multiple advantages over traditional skincare formulation types^​1​. Microemulsions are clear, optically isotropic and thermodynamically stable systems generally composed of a blend of oil, water and surfactant(s)^​2​. They have nano-sized micelle droplets (10-100nm) which can be used to combine water and oil soluble active ingredients in the one formulation. Their small droplet size partly explains their stability and their enhanced skin penetrating ability for active ingredients.

Unlike most cosmetic formulation types, microemulsions are described as low energy formation systems^​3​. Also known as “cold-processing”, this means that energy (such as heat) is not required to form microemulsions. Once the formulation conditions are met, microemulsions form spontaneously and are thermodynamically stable. Low energy formation offers environmental energy usage advantages as well as advantages in formulating with heat sensitive natural ingredients (such as Vitamin C).

“In spite of what the name suggests, microemulsions are nanocarriers, and their use as topical delivery systems derives from their multiple advantages compared to other dermatological formulations, such as ease of preparation, thermodynamic stability and penetration-enhancing properties.”^​1​

Benefits of Microemulsion Systems

Recent interest in microemulsions as topical/transdermal delivery systems results from the multiple benefits that these systems present^​4​. These multiple benefits include:^​5​

• Microemulsions are thermodynamically stable system and the stability allows self-emulsification of the system

• Microemulsions normally have enhanced ability to dissolve active ingredients

• The mean diameter of droplets in microemulsions is 10-100nm, an order of magnitude smaller that other cosmetic formulations

• Microemulsions can carry both water soluble and oil soluble ingredients

• Microemulsions are easy to prepare and require no significant energy contribution during preparation

• Microemulsions have low viscosity compared to other emulsions.

• Microemulsions as delivery systems can improve the penetration efficacy of an ingredient, allowing the total dose to be reduced and thus minimizing side effects

• Microemulsion formation is dynamic and reversible which also leads to greater formulation stability

“The small size of the particles in these kinds of delivery systems (r < 100 nm) means that they have a number of potential benefits for certain applications: enhanced long-term stability; high optical clarity; and, increased bioavailability.”^​3​

Microemulsions in Cosmetic Applications

Microemulsions are increasingly used in skincare formulations and the following are examples of applications:

1. Microemulsions have been found to be effective dermal and transdermal delivery systems for oil soluble and water soluble drugs^​7,8​.
2. Microemulsions have been used to formulate sunscreens^​9​.
3. Microemulsions have been successfully formulated to combine Vitamin C and Vitamin E in single, stable cosmetic formulations^​10​.
4. Microemulsions deliver the synergistic benefits of Vitamin C and Vitamin E in a combined skincare treatment^​11​.
5. The stability of both Vitamin C and Vitamin E was enhanced by inclusion in a microemulsion formulation^​12​.
6. Microemulsion formulations were found to increase the skin penetration of Vitamin C and Vitamin E is a single formulation^​13​.

“The widespread influence of nanocarrier in the cosmetics industry is due to the fact that nanocarriers can effectively promote the percutaneous penetration and significantly increase skin retention of active components in functional cosmetics.”^​6​

Discussion

Due to their multiple skincare benefits offered by microemulsions over traditional formulation systems, they are finding increasing cosmetic applications^​6​. Their superior formulation stability, enhanced skin penetration ability and ease of low energy formation means they are becoming a preferred skincare formulation method.

Our proprietary Green Micelle™ formulation system uses nano-emulsions (microemulsions) to entrap and stabilise active skincare ingredients in nano-size micelles. Using our proprietary microemulsifying techniques we have been able to develop a range of stable, skin penetrating, cold-processed cosmetic skincare products. Unlike other microemulsion systems, we developed our unique Green Micelle™ system uses organic, all-natural and sustainable surfactants rather than synthetic, potentially dangerous ingredients. Our products are stable, effective AND environmentally friendly.

References