Preparation of nanoemulsions by phase inversion temperature (PIT)

Over the last decade, nanoemulsion-based delivery systems have been gained interest in the pharmaceuticals1-4, food and beverage5-8, cosmetics9-11, agrochemicals12-14 and other15 industries. The main purposes are to encapsulate, protect, and deliver lipophilic components such as drugs, vitamins, food supplements, antioxidants, antimicrobials, pesticides. In general, it is desirable to utilize nanoemulsions with very small droplet sizes, typically < 100 nm, since they have several potential benefits, including increased bioavailability1,2, enhanced long-term stability16 and high optical clarity17. These can be explained by the particle properties regarding surface area, kinetic property and optical property which are related to their particle sizes. The percentage of surface molecules in particles, particle settling velocities, and Brownian motion of the particles are summarized in Table 1. It is interesting to see that compared to a 10-μm particle, a large percentage of the molecules are present on the surface of nanoparticles. Hence, the dissolution rate of nanoparticles is much higher than microparticles. When the particles are of nanometer length scale, surface irregularities can play an important role in adhesion. Therefore, the smaller diameter of nanoemulsions leading to an increase in surface area enables nanoemulsions to exhibit greater biological activity per given mass