Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs): recent advances in drug delivery

Solid lipid-based nanoparticles (SLBNs) were developed as potential alternatives to other conventional drug delivery systems such as polymeric nanoparticles, liposomes, and emulsions. In general, SLBNs are divided into two types: solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs). SLNs are distinguishable from NLCs by the composition of solid particle matrix. SLBNs can be prepared by several methods including high pressure homogenization, solvent emulsification (or diffusion)-evaporation, and microemulsion technologies. Then, SLBNs can be characterized in terms of particle size distribution, surface charge, morphology, and crystallinity. SLBNs are well-tolerated and efficient carrier systems for parenteral, oral, inhalational, ocular, and dermal applications. This review provides an overview of the preparation and characterization technologies for SLBNs and focuses on recent advances in drug delivery using SLBNs.