Instead of only using surfactants to help combine the oil and water components in an emulsion, the team at the University of South Australia led by Dr Nasrin Ghouchi-Eskandar is investigating adding silica nanoparticles.
This can help both the stability of active ingredients within the formulation as well as controlling and improving their delivery, she explained.
“Coating the tiny emulsion droplets with silica increases the stability of the mixture, and makes it less likely the active compounds inside will degrade or be released until we want that to happen,” she said.
Enhance ingredient penetration
The silica nanoparticles can enhance the penetration of the ingredient through different mechanisms.
“The way that silica improves the skin delivery is a combination of different effects ranging from affecting skin integrity to increasing skin hydration by forming a thin layer on the skin surface,” she told CosmeticsDesign-Europe.com.
In addition, using the silica in the formulation can significantly lower the surfactant levels needed to produce a stable emulsion. Formulas can be designed using between 10 and 20 per cent of the usual surfactant levels, Ghouchi-Eskandar said.
“We can keep this low concentration of surfactants since they have shown a synergistic effect with silica nanoparticles in stabilising emulsions,” she added.
Controlling delivery
Furthermore, where the ingredient is delivered can also be controlled, according to the researcher.
Choosing the type of surfactant as well as modifying the hydrophobicity and concentration of silica nanoparticles can all control where in the skin the ingredient ends up.
Although pig skin studies have shown that the silica nanoparticles did not pass through the full thickness of the skin, Ghouchi-Eskandar did say further human studies would be needed to investigate potential toxicity.
Sunscreens as well as dermal drug delivery are some of the potential applications noted for the technology.