title: Spray freeze drying as an alternative technique for lyophilization of polymeric and lipid-based nanoparticles.
abstract: The use of nanoparticles for drug delivery is still restricted by their limited stability when stored in an aqueous medium. Freeze drying is the standard method for long-term storage of colloidal nanoparticles; however the method needs to be elaborated for each formulation. Spray freeze drying (SFD) is proposed here as a promising alternative for lyophilizing colloidal nanoparticles. Different types of polymeric and lipid nanoparticles were prepared and characterized. Afterwards, samples were spray freeze dried by spraying into a column of cold air with a constant concentration of different cryoprotectants, and the frozen spherules were collected for further freeze drying. Similar samples were prepared using the commonly used technique, freeze drying, as controls. Using SFD, fast-dissolving, spherical and porous nanocomposite microparticles with remarkably high flowability (CI≤10) were produced. On the contrary to similar samples prepared using the freeze drying technique, the investigated polymeric and lipid nanoparticles were completely reconstituted (Sf/Siratio <1.5) after SFD. SFD proved to be an effective platform for improving the long-term stability of colloidal nanoparticles.
authors.affiliation: Department of Pharmaceutics, Institute of Pharmacy, University of Bonn, Bonn, Germany; Department of Industrial Pharmacy, Faculty of Pharmacy, Assiut University, Assiut, Egypt. Electronic address: ehabali@uni-bonn.de.
authors.forename: Mohamed Ehab
authors.initials: ME
authors.lastname: Ali
authors.affiliation: Department of Pharmaceutics, Institute of Pharmacy, University of Bonn, Bonn, Germany; FDE (EA4267), University of Burgundy/Franche-Comté, Besançon, France.
authors.forename: Alf
authors.initials: A
authors.lastname: Lamprecht
mesh_terms: D002626:Chemistry, Pharmaceutical / Q000379:methods; D003102:Colloids; D016503:Drug Delivery Systems; D004355:Drug Stability; D004356:Drug Storage; D005612:Freeze Drying; D008055:Lipids / Q000737:chemistry*; D053758:Nanoparticles; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D012995:Solubility
chemical_list: D003102:Colloids; D008055:Lipids; D011108:Polymers
keywords: Freeze drying; Lipid nanocapsules; Liposomes; Polymeric nanoparticles; Solid lipid nanoparticles; Spray freeze drying; Stability