ABSTRACT
Nanoemulsions (NEs) can be de ned as extremely small droplet emulsions. They are termed miniemulsions (Constantinides et al., 2008; Solans et al., 2005), ultra ne emulsions (Guglielmini, 2008), submicron emulsions (Benita, 1999; Klang and Benita, 1998), and translucent emulsions (Fernandez et al., 2004; Tadros et al., 2004). These systems have also been called microemulsions (MEs; Koo et al., 2005). There are two types of NEs: thermodynamically stable systems (classic MEs) and metastable systems. Both types can be classi ed as NEs. The distinction between a thermodynamically stable system and a metastable system is not always made clear (Sarker, 2005). Unlike classic MEs, the stability of metastable NEs depends on the method of preparation (Wang et al., 2007). NEs may possess high kinetic stability and optical transparency resembling MEs (Porras et al., 2004). Despite their metastability, NEs can persist over many months or years because of the presence of stabilizing surfactant micelles (Chiesa et al., 2008).
