title: Chitosan and chitosan/ethylene oxide-propylene oxide block copolymer nanoparticles as novel carriers for proteins and vaccines.
abstract: OBJECTIVE
  The aim of this study was to investigate the interaction between the components of novel chitosan (CS) and CS/ethylene oxide-propylene oxide block copolymer (PEO-PPO) nanoparticles and to evaluate their potential for the association and controlled release of proteins and vaccines.
  
  
  METHODS
  The presence of PEO-PPO on the surface of the nanoparticles and its interaction with the CS was identified by X-ray photoelectron spectroscopy (XPS). The mechanism of protein association was elucidated using several proteins, bovine serum albumin (BSA), and tetanus and diphtheria toxoids, and varying the formulation conditions (different pH values and concentrations of PEO-PPO), and the stage of protein incorporation into the nanoparticles formation medium.
  
  
  RESULTS
  BSA and tetanus and diphtheria toxoids were highly associated with CS nanoparticles partly due to electrostatic interactions between the carboxyl groups of the protein and the amine groups of CS. PEO-PPO also interacted electrostatically with CS, thus competing with the proteins for association with CS nanoparticles. A visible amount of PEO-PPO was projected towards the outer phase of the nanoparticles. Proteins were released from the nanoparticles at an almost constant rate, the intensity of which was closely related to the protein loading. Furthermore, the tetanus vaccine was released in the active form for at least 15 days.
  
  
  CONCLUSIONS
  CS and CS/PEO-PPO nanoparticles prepared by a very mild ionic crosslinking technique are novel and suitable systems for the entrapment and controlled release of proteins and vaccines.
authors.affiliation: Department of Pharmacy and Pharmaceutical Technology, School of Pharmacy, University of Santiago de Compostela, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Calvo
authors.forename: C
authors.initials: C
authors.lastname: Remuñan-López
authors.forename: J L
authors.initials: JL
authors.lastname: Vila-Jato
authors.forename: M J
authors.initials: MJ
authors.lastname: Alonso
mesh_terms: D000818:Animals; D001704:Biopolymers / Q000737:chemistry*; D002417:Cattle; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry; D048271:Chitosan; D003692:Delayed-Action Preparations; D004168:Diphtheria Toxoid / Q000008:administration & dosage / Q000737:chemistry; D004337:Drug Carriers; D004577:Electron Probe Microanalysis; D008854:Microscopy, Electron; D010316:Particle Size; D011095:Polyethylenes / Q000737:chemistry*; D011126:Polypropylenes / Q000737:chemistry*; D011506:Proteins / Q000008:administration & dosage / Q000737:chemistry*; D012709:Serum Albumin / Q000008:administration & dosage / Q000737:chemistry; D013745:Tetanus Toxoid / Q000008:administration & dosage / Q000737:chemistry; D014612:Vaccines / Q000008:administration & dosage / Q000737:chemistry*
chemical_list: D001704:Biopolymers; D003692:Delayed-Action Preparations; D004168:Diphtheria Toxoid; D004337:Drug Carriers; D011095:Polyethylenes; D011126:Polypropylenes; D011506:Proteins; D012709:Serum Albumin; D013745:Tetanus Toxoid; D014612:Vaccines; D002686:Chitin; D048271:Chitosan; C078661:UCON 50-HB-5100