title: Nebulised siRNA encapsulated crosslinked chitosan nanoparticles for pulmonary delivery.
abstract: OBJECTIVE
  To explore the potential of crosslinked chitosan nanoparticles as carriers for delivery of siRNA using a jet nebuliser.
  
  
  METHODS
  Nanoparticles encapsulating siRNA were prepared using an ionic crosslinking technique at chitosan to siRNA weight/weight ratios of 10:1, 30:1 and 50:1. Particles were characterised for their size, charge, morphology, pH stability and siRNA encapsulation efficiency. Gel electrophoresis was used to assess the association and stability of siRNA with nanoparticles, including after aerosolisation using a Pari LC Sprint jet nebuliser. The aerosolisation properties of FITC labelled chitosan nanoparticles were investigated using a two-stage impinger. Cell viability was performed with H-292 cells using a WST-1 assay.
  
  
  RESULTS
  Positively charged spherical nanoparticles were produced with mean diameters less than 150 nm, at all chitosan to siRNA ratios. Nanoparticles were non-aggregated at the pH of the airways and showed high siRNA encapsulation efficiency (>96%). Complete binding of siRNA to chitosan nanoparticles was observed when the w/w ratio was 50:1. Nebulisation produced fine particle fractions of 54±11% and 57.3±1.9% for chitosan and chitosan:siRNA (10:1 w/w) nanoparticles respectively. The stability of chitosan-encapsulated siRNA was maintained after nebulisation. Cell viability was high (>85%) at the highest chitosan concentration (83 μg/ml).
  
  
  CONCLUSIONS
  The results suggest that crosslinked chitosan nanoparticles have potential for siRNA delivery to the lungs using a jet nebuliser.
authors.affiliation: UCL, School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK.
authors.forename: Ketan
authors.initials: K
authors.lastname: Sharma
authors.forename: Satyanarayana
authors.initials: S
authors.lastname: Somavarapu
authors.forename: Agnes
authors.initials: A
authors.lastname: Colombani
authors.forename: Nayna
authors.initials: N
authors.lastname: Govind
authors.forename: Kevin M G
authors.initials: KM
authors.lastname: Taylor
mesh_terms: D000280:Administration, Inhalation; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D048271:Chitosan / Q000737:chemistry*; D004337:Drug Carriers / Q000008:administration & dosage* / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry / Q000648:ultrastructure; D009330:Nebulizers and Vaporizers; D010316:Particle Size; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000737:chemistry
chemical_list: D004337:Drug Carriers; D034741:RNA, Small Interfering; D048271:Chitosan
keywords: Chitosan; Inhalation; Nanocarrier; Nanoparticle; Nebuliser; siRNA