title: Near infrared with principal component analysis as a novel analytical approach for nanoparticle technology.
abstract: OBJECTIVE
  To progress in the characterization of a poly(MePEGcyanoacrylate-co-hexadecylcyanoacrylate) (poly(PEGCA-co-HDCA) copolymer and the nanoparticles formed from this copolymer.
  
  
  METHODS
  Poly(PEGCA-co-HDCA) at a MePEG/hexadecyl ratio of 1:4 was investigated by 1H-NMR and near infrared spectroscopy. The nanoparticle suspensions, obtained by the methods of nanoprecipitation or emulsion--solvent evaporation, as well as the crude nanoparticles and their dispersion medium--were analyzed by MePEG measurement, 1H-NMR, and near infrared spectroscopy.
  
  
  RESULTS
  The 1H-NMR results showed that the (poly(PEGCA-co-HDCA) copolymer obtained bore lateral hydrophilic MePEG chains and lateral hydrophobic hexadecyl chains in a final ratio of 1:4. However, this ratio, although reproducible from batch to batch, represented only a mean value for different molecular species. Indeed, our results demonstrated the formation of more hydrophobic poly(alkyl-cyanoacrylate) oligomers (with a higher content of hexadecyl chains) and other more hydrophilic oligomers (with a higher MePEG content). Only the more hydrophobic oligomers were able to form solid pegylated nanoparticles. As far as these nanoparticles were concerned, determination of their MePEG content allowed the calculation of a distance of 1.2 nm and 1.05 nm between 2 grafted MePEG chains at the nanoparticle surface, when obtained by nanoprecipitation and emulsion-solvent evaporation, respectively. Moreover, when the same copolymer batch was used, different nanoparticles were obtained according to the preparation method, as seen by near infrared spectroscopy.
  
  
  CONCLUSIONS
  The nanoparticles obtained by nanoprecipitation or emulsion-solvent evaporation of poly(PEGCA-co-HDCA) 1:4 copolymer displayed a different supramolecular organization, as evidenced by the near infrared spectroscopy results. Moreover, these nanoparticles showed surface characteristics compatible with a long circulating carrier.
authors.affiliation: University of Paris-Sud XI, Faculty of Pharmacy, UMR 8612, Châtenay-Malabry, France.
authors.forename: I
authors.initials: I
authors.lastname: Brigger
authors.forename: P
authors.initials: P
authors.lastname: Chaminade
authors.forename: D
authors.initials: D
authors.lastname: Desmaële
authors.forename: M T
authors.initials: MT
authors.lastname: Peracchia
authors.forename: J
authors.initials: J
authors.lastname: d'Angelo
authors.forename: R
authors.initials: R
authors.lastname: Gurny
authors.forename: M
authors.initials: M
authors.lastname: Renoir
authors.forename: P
authors.initials: P
authors.lastname: Couvreur
mesh_terms: D003102:Colloids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D011108:Polymers / Q000737:chemistry*; D019265:Spectroscopy, Near-Infrared / Q000379:methods
chemical_list: D003102:Colloids; D011108:Polymers