Solid Lipid Nanoparticles
Solid lipid nanoparticle (SLN) is another delivery platform instead of nanoemulsions and nanoliposomes that has attracted much attention since it was introduced in 1991. SLNs are mainly made from solid lipids including fatty acids (e.g., palmitic acid), triglycerides (e.g., trilaurin), steroids (e.g., cholesterol), partial glycerides (e.g., glyceryl monosterate), and waxes (Fig. 5.2C) (Zhang et al., 2010). Surfactants are also needed to stabilize the lipid dispersions. The basic production methods for SLN include the high-pressure homogenization, cold precipitation, spray-drying, high-shearing homogenization, and ultrasonication (MuEller et al., 2000). Although most studies considered SLNs ideal carriers for cosmetic and pharmaceutical applications, their unique properties including the composition of physiological compounds, the possibility for loading both lipophilic and hydrophilic compounds into the solid matrix and large-scale production have also attracted the attention to use them as carriers of food antimicrobials (MuEller et al., 2000). Nisin was entrapped in the SLN by high-pressure homogenization and showed a sustained release to inhibit the growth of L. monocytogenes and L. plantarum over at least 15—20 days (Prombutara et al., 2012). Clove extract (eugenol) was encapsulated in Compritol-based solid lipid carriers by spraydrying and showed a high retention in the formulation (Cortes-Rojas et al., 2014).