title: Formulation of solid lipid nanoparticles (SLN): the value of different alkyl polyglucoside surfactants.
abstract: Alkyl polyglycosides (APGs) represent a group of nonionic tensides with excellent skin compatibility. Thus they seem to be excellent stabilizers for lipid nanoparticles for dermal application. To investigate this, different APGs were selected to evaluate their influence on the formation and characteristics of solid lipid nanoparticles (SLN). Contact angle analysis of the aqueous solutions/dispersions of the APGs on cetyl palmitate films revealed good wettability for all APG surfactants. Cetyl palmitate based SLN were prepared by hot high pressure homogenization and subjected to particle size, charge and inner structure analysis. 1% of each APG was sufficient to obtain SLN with a mean size between 150 nm and 175 nm and a narrow size distribution. The zeta potential in water was ∼ -50 mV; the values in the original medium were distinctly lower, but still sufficient high to provide good physical stability. Physical stability at different temperatures (5°C, 25°C and 40°C) was confirmed by a constant particle size over an observation period of 90 days in all dispersions. In comparison to SLN stabilized with classical surfactants, e.g., Polysorbate, APG stabilized SLN possess a smaller size, improved physical stability and contain less surfactant. Therefore, the use of APGs for the stabilization of lipid nanoparticles is superior in comparison to classical stabilizers. Further, the results indicate that the length of the alkyl chain of the APG influences the diminution efficacy, the final particle size and the crystallinity of the particles. APGs with short alkyl chain led to a faster reduction in size during high pressure homogenization, to a smaller particle size of the SLN and to a lower recrystallization index, i.e., to a lower crystallinity of the SLN. The crystallinity of the SLN increased with an increase in the alkyl chain length of APGs. Therefore, by using the tested APGs differing in the alkyl chain length, not only small sized and physically stable but also SLN with different sizes and crystallinity can be obtained. An optimized selection of these stabilizers might therefore enable the production of lipid nanoparticles with "tailor-made" properties.
authors.affiliation: Applied Pharmacy Division, University of Applied Sciences Kaiserslautern, Campus Pirmasens, Carl-Schurz-Strasse 10-16, Pirmasens 66953, Germany; Institute of Pharmacy, Department of Pharmaceutics, Biopharmaceutics and NutriCosmetics, Free University of Berlin, Kelchstr. 31, Berlin 12169, Germany. Electronic address: cornelia.keck@fh-kl.de.
authors.forename: Cornelia M
authors.initials: CM
authors.lastname: Keck
authors.affiliation: University of Belgrade - Faculty of Pharmacy, Department of Pharmaceutical Technology and Cosmetology, Vojvode Stepe 450, P.O. Box 146, Belgrade 11221, Serbia.
authors.forename: Andjelka
authors.initials: A
authors.lastname: Kovačević
authors.affiliation: Institute of Pharmacy, Department of Pharmaceutics, Biopharmaceutics and NutriCosmetics, Free University of Berlin, Kelchstr. 31, Berlin 12169, Germany.
authors.forename: Rainer H
authors.initials: RH
authors.lastname: Müller
authors.affiliation: University of Belgrade - Faculty of Pharmacy, Department of Pharmaceutical Technology and Cosmetology, Vojvode Stepe 450, P.O. Box 146, Belgrade 11221, Serbia.
authors.forename: Snežana
authors.initials: S
authors.lastname: Savić
authors.affiliation: University of Belgrade - Faculty of Pharmacy, Department of Pharmaceutical Technology and Cosmetology, Vojvode Stepe 450, P.O. Box 146, Belgrade 11221, Serbia.
authors.forename: Gordana
authors.initials: G
authors.lastname: Vuleta
authors.affiliation: University of Belgrade - Faculty of Pharmacy, Department of Pharmaceutical Technology and Cosmetology, Vojvode Stepe 450, P.O. Box 146, Belgrade 11221, Serbia.
authors.forename: Jela
authors.initials: J
authors.lastname: Milić
mesh_terms: D005960:Glucosides / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D012995:Solubility; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D005960:Glucosides; D008055:Lipids; D011108:Polymers; D013501:Surface-Active Agents
keywords: Alkyl polyglucosides; Crystallinity; Physical stability; SLN; Size; Solid lipid nanoparticles