Nanostructured lipid carriers: effect of solid phase fraction and distribution on the release of encapsulated materials.
Emulsions, solid lipid nanoparticles (SLN), and nanostructured lipid carriers (NLC) containing a mix of liquid and solid domains are of interest as encapsulation vehicles for hydrophobic compounds. Studies of the release rate from these particles yield contradictory results: Some find that increasing the fraction of solid phase increases the rate of release and others the opposite. In this paper we study the release of encapsulated materials from lipid-based nanoparticles using Monte Carlo simulations. We find that, quite surprisingly, the release rate is largely insensitive to the size of solid domains or the fraction of solid phase. However, the distribution of the domains significantly affects the rate of release: Solid domains located at the interface with the surrounding solution inhibit transport, while nanoparticles where the solid domains are concentrated in the center enhance it. The latter can lead to release rates in NLCs that are faster than in the equivalent emulsions. We conclude that controlling the release rate from NLCs requires the ability to determine the location and distribution of the solid phase, which may be achieved through choice of the surfactants stabilizing the particles, incorporation of nucleation sites, and/or the cooling rates and temperatures.
Department of Chemical and Biological Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States.
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D004337:Drug Carriers / Q000737:chemistry*; D004655:Emulsions; D008055:Lipids / Q000737:chemistry*; D008956:Models, Chemical; D053758:Nanoparticles / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
D004337:Drug Carriers; D004655:Emulsions; D008055:Lipids; D013501:Surface-Active Agents