title: Effect of MePEG molecular weight and particle size on in vitro release of tumor necrosis factor-alpha-loaded nanoparticles.
abstract: OBJECTIVE
  To study the in vitro release of recombinant human tumor necrosis factor-alpha (rHuTNF-alpha) encapsulated in poly (methoxypolyethyleneglycol cyanoacrylate-co-n-hexadecyl cyanoacrylate) (PEG-PHDCA) nanoparticles, and investigate the influence of methoxypolyethyleneglycol (MePEG) molecular weight and particle size.
  
  
  METHODS
  Three sizes (approximately 80, 170, and 240 nm) of PEG-PHDCA nanoparticles loading rHuTNF-alpha were prepared at different MePEG molecular weights (M(r) =2000, 5000, and 10,000) using the double emulsion method. The in vitro rHuTNF-alpha release was studied in PBS and rat plasma.
  
  
  RESULTS
  A higher burst-release and cumulative-release rate were observed for nanoparticles with higher MePEG molecular weight or smaller particle size. A decreased cumulative release of rHuTNF-alpha following the initial burst effect was found in PBS, while the particle sizes remained constant and MePEG liberated. In contrast, in rat plasma, slowly increased cumulative-release profiles were obtained after the burst effect. During a 5-h incubation in rat plasma, more than 50% of the PEG-PHDCA nanoparticles degraded.
  
  
  CONCLUSIONS
  The MePEG molecular weight and particle size had an obvious influence on rHuTNF-alpha release. rHuTNF-alpha released from PEG-PHDCA nanoparticles in a diffusion-based pattern in PBS, but in a diffusion and erosion-controlled manner in rat plasma.
authors.affiliation: Department of Pharmaceutics, School of Pharmacy, Fudan University, Shanghai 200032, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Fang
authors.forename: Bin
authors.initials: B
authors.lastname: Shi
authors.forename: Yuan-Ying
authors.initials: YY
authors.lastname: Pei
mesh_terms: D000818:Animals; D003487:Cyanoacrylates; D008970:Molecular Weight; D036103:Nanotechnology; D010316:Particle Size; D011092:Polyethylene Glycols; D051381:Rats; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D044967:Serum; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage* / Q000378:metabolism / Q000493:pharmacokinetics
chemical_list: D003487:Cyanoacrylates; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; C504655:poly (methoxypolyethyleneglycol cyanoacrylate-co-n-hexadecyl cyanoacrylate); D011092:Polyethylene Glycols