title: Influence of co-surfactants on crystallization and stability of solid lipid nanoparticles.
abstract: OBJECTIVE
  The purpose of this study was to find a suitable co-surfactant to replace non-food grade bile salts in solid lipid nanoparticle (SLN) formulations. The hypothesis was that the molecular structure and physical properties of co-surfactant modulate the stabilization of SLNs upon polymorphic transition.
  
  
  METHODS
  Tristearin SLNs were prepared by using two main surfactants: saturated high-melting lecithin, and unsaturated low-melting lecithin. As co-surfactants we used sodium taurodeoxycholate (i.e. bile salt), Pluronic F68, Tween 60 and 80, and amino acids tyrosine, tryptophan, and phenylalanine. The influence of co-surfactants on crystallization behavior and physical stability of SLNs was investigated by differential scanning calorimetry and static light scattering, respectively.
  
  
  RESULTS
  The results showed that the aromatic amino acids had optimal structures and properties to act as effective co-surfactants in SLNs. Our study suggests that ideal co-surfactants are amphiphilic with pronounced hydrophobic areas, but highly water soluble so that they can have a reservoir of molecules readily available for interfacial stabilization. They adsorb fast to the interfaces, but without inducing polymorphic transition. This work demonstrates how the right structure can facilitate the desired function.
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany. Electronic address: hanna.salminen@uni-hohenheim.de.
authors.forename: Hanna
authors.initials: H
authors.lastname: Salminen
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany. Electronic address: helgason01@gmail.com.
authors.forename: Thrandur
authors.initials: T
authors.lastname: Helgason
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany. Electronic address: Susanne.Aulbach@gmx.de.
authors.forename: Susanne
authors.initials: S
authors.lastname: Aulbach
authors.affiliation: Faculty of Food Science and Nutrition, University of Iceland, Eiriksgötu 2, 101 Reykjavik, Iceland. Electronic address: bhk1@hi.is.
authors.forename: Bjarki
authors.initials: B
authors.lastname: Kristinsson
authors.affiliation: Faculty of Food Science and Nutrition, University of Iceland, Eiriksgötu 2, 101 Reykjavik, Iceland. Electronic address: kk@hi.is.
authors.forename: Kristberg
authors.initials: K
authors.lastname: Kristbergsson
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany. Electronic address: j.weiss@uni-hohenheim.de.
authors.forename: Jochen
authors.initials: J
authors.lastname: Weiss
mesh_terms: D002152:Calorimetry, Differential Scanning; D003460:Crystallization; D008055:Lipids / Q000737:chemistry*; D053758:Nanoparticles; D013501:Surface-Active Agents / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D008055:Lipids; D013501:Surface-Active Agents
keywords: Aromatic amino acids; Co-surfactant; Crystallization; Lecithin; Pluronic F68; Polymorphic transition; Solid lipid nanoparticles; Stability; Tween 60; Tween 80