title: Physicochemical parameters associated with nanoparticle formation in the salting-out, emulsification-diffusion, and nanoprecipitation methods.
abstract: OBJECTIVE
  The aim of this work was to relate the physicochemical properties of the aqueous and organic phases used for nanoparticle (NP) preparation to the formation of NP produced by salting-out, emulsification-diffusion, and nanoprecipitation.
  
  
  METHODS
  Methacrylic acid copolymer and poly(vinyl alcohol) (PVAL) were selected as NP polymer and emulsifying agent, respectively. Salting-out and emulsification-diffusion NP batches were prepared modifying the PVAL content in the aqueous phase. For nanoprecipitation, NP were produced with variation of the polymer content and type of solvent in the organic phase.
  
  
  RESULTS
  For salting-out and emulsification-diffusion, NP formation was discussed in terms of the emulsification theory. The nanoemulsion obtained during NP preparation was visualized by scanning electron microscopy. Aqueous and organic phases used for NP preparation were characterized by their viscosity and surface tension. NP characteristics such as particle mean size, residual surfactant, suspendability in water after freeze-drying, and morphology were explained in terms of these properties. For nanoprecipitation, NP formation was analyzed considering the diffusion-stranding phenomenon.
  
  
  CONCLUSIONS
  NP formation by salting-out and emulsification-diffusion was related to PVAL chain interactions at the droplet interface (e.g., reduction in the interfacial tension, mechanical stabilization, and steric stabilization) and in the bulk solution (hydrodynamic stabilization). For nanoprecipitation, chi(solvent-water) and delta(delta solvent-water) of the organic phase solvents were well related to the NP characteristics.
authors.affiliation: Pharmapeptides, Geneva-Lyon Interuniversity Centre, 74166 Archamps, France.
authors.forename: Sergio
authors.initials: S
authors.lastname: Galindo-Rodriguez
authors.forename: Eric
authors.initials: E
authors.lastname: Allémann
authors.forename: Hatem
authors.initials: H
authors.lastname: Fessi
authors.forename: Eric
authors.initials: E
authors.lastname: Doelker
mesh_terms: D004058:Diffusion; D004655:Emulsions / Q000138:chemical synthesis; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D011109:Polymethacrylic Acids / Q000737:chemistry; D011142:Polyvinyl Alcohol / Q000032:analysis / Q000737:chemistry; D013500:Surface Tension; D014783:Viscosity
chemical_list: D004655:Emulsions; D011109:Polymethacrylic Acids; D011142:Polyvinyl Alcohol