title: [Preparation and characterization of stearic acid-grafted chitosan oligosaccharide polymeric micelles].
abstract: OBJECTIVE
  To prepare the micelles of stearic acid-grafted chitosan oligosaccharide and investigate the drug release from micelles.
  
  
  METHODS
  Mediated by a 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), stearic acid (SA) was covalently attached to chitosan oligosaccharide (CSO), and the graft polymer (CSO-SA) was obtained. The critical aggregation concentration (CAC) of the CSO-SA was determined by measuring the fluorescence intensity of pyrene as a fluorescent probe. The effect of various pH dispersed media and concentration of tripolyphosphate sodium (TPP) on the micellar size distribution and zeta-potential measured by light scattering and electrophoretic mobility, was investigated. In buffers of different pH, the release profiles of methotrexate (MTX) from micelles were evaluated.
  
  
  RESULTS
  The CAC value of CSO-SA in deionized water was 0.05 g x L(-1). The mean diameter of CSO-SA micelles was 26.7 nm and the zeta potential was (55.9 +/- 0.1) mV. With the increase of TPP concentration, the size and MTX encapsulation of CSO-SA micelles increased, while the zeta-potential decreased. With the decrease of pH value of dispersed media, the size and zeta-potential of CSO-SA micelles increased, and the MTX encapsulation in CSO-SA micelles decreased. While the enhancement of drug release from the micelles was observed.
  
  
  CONCLUSIONS
  The graft polymer of CSO-SA provides polymeric micelles, which possessed a low CAC value in aqueous media. The drug release in vitro from CSO-SA micelles was affected by the pH of delivery media.
authors.affiliation: College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310031, China.
authors.forename: Yi-qing
authors.initials: YQ
authors.lastname: Ye
authors.forename: Fu-qiang
authors.initials: FQ
authors.lastname: Hu
authors.forename: Hong
authors.initials: H
authors.lastname: Yuan
mesh_terms: D048271:Chitosan / Q000008:administration & dosage* / Q000737:chemistry; D004337:Drug Carriers; D016503:Drug Delivery Systems; D006863:Hydrogen-Ion Concentration; D008727:Methotrexate / Q000008:administration & dosage* / Q000737:chemistry; D008823:Micelles; D009844:Oligosaccharides / Q000008:administration & dosage* / Q000737:chemistry; D010316:Particle Size; D011108:Polymers; D011122:Polyphosphates; D012995:Solubility; D013229:Stearic Acids / Q000008:administration & dosage* / Q000737:chemistry
chemical_list: D004337:Drug Carriers; D008823:Micelles; D009844:Oligosaccharides; D011108:Polymers; D011122:Polyphosphates; D013229:Stearic Acids; C031183:stearic acid; D048271:Chitosan; C005692:triphosphoric acid; D008727:Methotrexate