6.2.2.5　Nano-emulsions

Nano-emulsions are stable dispersion systems，in which the oil phase in the form of nano-droplets disperse in water stabled by surfactants.Like nano-capsules，drugs are dissolved in oil droplets and the drug loading depends on the solubility of drugs in the oil phase.Diameter of oil droplets is between 1-100 nm and the uniformity is different owing to the preparation methods，but most of them are not good as spherical micelles.Cooking oil can be chosen as oil droplets and surfactant is supposed to be biodegradable amphiphilic polymer with good biocompatibility.Hydrophobic chains of surfactant in nano-emulsions face oil droplets while hydrophilic chains spread in the water phase，but the accumulate intensity of polymer chains is smaller than polymer nano-spheres/capsules and polymer micelles/vesicles.Therefore，the release speed of drugs from nano-emulsion could be very fast.(https://www.daowen.com)