title: Different approaches for determination of the attachment degree of polyethylene glycols to poly(anhydride) nanoparticles.
abstract: OBJECTIVE
  The aim of the study was to find an appropriate method for determination of the attachment degree of polyethylene glycol (PEG) to poly(anhydride) nanoparticles.
  
  
  METHODS
  The nanoparticles were modified with hydroxy-functionalized or with amino-functionalized PEGs. Three methods for their determination were applied and examined: in particular colorimetry, nuclear magnetic resonance ( (1) H-NMR), and elemental analysis (EA).
  
  
  RESULTS
  The attachment degrees determined by (1) H-NMR and colorimetry were similar. The associated amounts of PEGs estimated on the basis of EA differed significantly than those determined by colorimetry and (1) H-NMR.
  
  
  CONCLUSIONS
  The colorimetric determination was considered fast and simple technique, but (1) H-NMR contributed to more precise results.
authors.affiliation: Department of Pharmaceutical Technology, Faculty of Pharmacy, Sofia, Bulgaria. krassi.yoncheva@gmail.com
authors.forename: K
authors.initials: K
authors.lastname: Yoncheva
authors.forename: I
authors.initials: I
authors.lastname: Doytchinova
authors.forename: J M
authors.initials: JM
authors.lastname: Irache
mesh_terms: D001665:Binding Sites; D016503:Drug Delivery Systems / Q000379:methods; D053758:Nanoparticles / Q000737:chemistry*; D049388:Polyanhydrides / Q000737:chemistry* / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D049388:Polyanhydrides; D011092:Polyethylene Glycols