title: Solvent exchange method: a novel microencapsulation technique using dual microdispensers.
abstract: OBJECTIVE
  A new microencapsulation method called the "solvent exchange method" was developed using a dual microdispenser system. The objective of this research is to demonstrate the new method and understand how the microcapsule size is controlled by different instrumental parameters.
  
  
  METHODS
  The solvent exchange method was carried out using a dual microdispenser system consisting of two ink-jet nozzles. Reservoir-type microcapsules were generated by collision of microdrops of an aqueous and a polymer solution and subsequent formation of polymer films at the interface between the two solutions. The prepared microcapsules were characterized by microscopic methods.
  
  
  RESULTS
  The ink-jet nozzles produced drops of different sizes with high accuracy according to orifice size of a nozzle, flow rate of the jetted solutions, and forcing frequency of the piezoelectric transducers. In an individual microcapsule, an aqueous core was surrounded by a thin polymer membrane; thus, the size of the collected microcapsules was equivalent to that of single drops.
  
  
  CONCLUSIONS
  The solvent exchange method based on a dual microdispenser system produces reservoir-type microcapsules in a homogeneous and predictable manner. Given the unique geometry of the microcapsules and mildness of the encapsulation process, this method is expected to provide a useful alternative to existing techniques in protein microencapsulation.
authors.affiliation: Departments of Pharmaceutics and Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Yoon
authors.initials: Y
authors.lastname: Yeo
authors.forename: Alvin U
authors.initials: AU
authors.lastname: Chen
authors.forename: Osman A
authors.initials: OA
authors.lastname: Basaran
authors.forename: Kinam
authors.initials: K
authors.lastname: Park
mesh_terms: D002214:Capsules; D003692:Delayed-Action Preparations; D004339:Drug Compounding / Q000295:instrumentation / Q000379:methods*; D006016:Glycolates / Q000737:chemistry; D007773:Lactates / Q000737:chemistry; D019344:Lactic Acid; D018613:Microscopy, Confocal; D010316:Particle Size; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry; D012212:Rheology; D012997:Solvents
chemical_list: D002214:Capsules; D003692:Delayed-Action Preparations; D006016:Glycolates; D007773:Lactates; D011108:Polymers; D012997:Solvents; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid