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Study of the emulsion‐diffusion of solvent: preparation and characterization of nanocapsules
Author(s) -
Guinebretière Sandra,
Briançon Stéphanie,
Lieto Joseph,
Mayer Christian,
Fessi Hatem
Publication year - 2002
Publication title -
drug development research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.582
H-Index - 60
eISSN - 1098-2299
pISSN - 0272-4391
DOI - 10.1002/ddr.10054
Subject(s) - nanocapsules , emulsion , polymer , differential scanning calorimetry , particle size , solvent , chemical engineering , aqueous solution , aqueous two phase system , chemistry , materials science , microparticle , analytical chemistry (journal) , chromatography , polymer chemistry , nanoparticle , organic chemistry , nanotechnology , physics , engineering , thermodynamics
The objective of this work was to obtained stable nanocapsules (NC), that is to say a core shell structure by a recently patented method, the emulsion diffusion of solvent. To study the capacity of encapsulation, the aim was first to control the nanocapsules size distribution before the characterization of the membrane. Nanocapsules (NC) were prepared by an emulsion‐diffusion method. The emulsion was prepared using a high‐speed stirrer (Ultraturrax T25), and the droplet size distributions were determined. The mechanism of particle formation is based on the diffusion of the solvent followed by the deposition of the polymer around the oil droplet. The solvent partially soluble in the water and included in oil droplets diffuses into the outer aqueous medium after the emulsion dilution with water. It is then removed under reduced pressure. In order to control the NC sizes, we studied the effect of various emulsion parameters such as the nature and the concentration of the polymer, the stabilizer, the organic/aqueous phases ratio on NC morphology and size. The mean size of NC was about 500 nm, but we could have NC with diameter size between 200 to 1,000 nm. Size distributions were found to be function of the polymer/oil ratio in the organic phase, and of the solvent volume in the droplet. The suspension of nanocapsules were characterized by Transmission Electron Microscopy (TEM), Nuclear Magnetic Resonance (NMR), density gradient centrifugation, and Differential Scanning Calorimetry (DSC). The formation of nanocapsules involves mass transfer of solvent, polymer, and oil between phases. The physicochemical properties of the system can be classified into transport parameters such as solvent diffusion into the non‐solvent and interaction parameters such as solvent solubility in the water and the polymer. The mechanism of NC formation was investigated experimentally by monitoring the solvent concentration as a function of time in the continuous phase after different dilutions. The solvent elimination in the NC was complete after a dilution step followed by an evaporation under reduced pressure. This NC study gave some important information on their structure (core shell). The mechanism of formation based on the diffusion of solvent towards the aqueous phase was very rapid and depended on the volume of water at a kinetic level. We also showed that the state of the polymer changes and that the polymer forms the shell around the oil. Drug Dev. Res. 57:18–33, 2002. © 2002 Wiley‐Liss, Inc.