Today, nanotechnology is recognized as enabling the manipulation of matter at the atomic and molecular level to create new materials with functional characteristics that are markedly different from conventional materials. Nanoemulsions, for example, can be used to control the rate at which assets are delivered to the skin. This control is achieved by incorporating materials within the nanoemulsion according to their compatibility with it, which obviously relies on their physical-chemical structure. Indeed, a great deal of attention has been dedicated recently to colloidal systems for the delivery of active ingredients because they significantly reduce the side effects of drugs and increase their bioavailability.
Besides delivery, nanoemulsions exhibit improved stability over conventional systems, such as liposomes or solid lipid nanoparticles, since their small particle sizes are less affected by gravity and less inclined to settle during storage, thus preventing flocculation and increasing shelf life. The particles also prevent coalescence due to their uniform shape. Furthermore, the significant thickness of the particle film, relative to the particle diameter, prevents its thinning or rupture; and wetting, spreading and penetration can be improved as a result of the low surface tension.
The size of nanoemulsion particles is a key factor in their efficient transdermal delivery; their large surface area and small size ensure uniform deposition on skin, thus increasing the rate of skin absorption and hydration potential. In order to reduce particle size, physical means are used. High pressure homogenization is the preferred technology since it can be used on a wide range of compositions. This pressure typically is applied in two stages—high pressure at first, followed by low pressure. High pressure homogenizers are manufactured by various companies and the end product will vary with the brand and model used.
Besides pressure, the number of homogenization cycles or passes used during the two stages can affect the particle size in the end product. The chemical composition and concentration of emulsifier used can also impact the nanoemulsion. Finally, the temperature at which the nanoemulsion is homogenized influences its production; Aubrun et al. and Liedtke et al. observed that higher homogenization temperatures resulted in smaller particles. Thus, the objective of the present work was to examine formulations prepared with similar oil fractions but different emulsifier systems and process parameters to determine why their behaviors differ. Understanding these dynamics would thus determine which conditions, among those studied, is optimal for formulating nanoemulsions.