title: Physicochemical characterization of nebulized superparamagnetic iron oxide nanoparticles (SPIONs).
abstract: BACKGROUND
  Aerosol-mediated delivery of nano-based therapeutics to the lung has emerged as a promising alternative for treatment and prevention of lung diseases. Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted significant attention for such applications due to their biocompatibility and magnetic properties. However, information is lacking about the characteristics of nebulized SPIONs for use as a therapeutic aerosol. To address this need, we conducted a physicochemical characterization of nebulized Rienso, a SPION-based formulation for intravenous treatment of anemia.
  
  
  METHODS
  Four different concentrations of SPION suspensions were nebulized with a one-jet nebulizer. Particle size was measured in suspension by transmission electron microscopy (TEM), photon correlation spectroscopy (PCS), and nanoparticle tracking analysis (NTA), and in the aerosol by a scanning mobility particle sizer (SMPS).
  
  
  RESULTS
  The average particle size in suspension as measured by TEM, PCS, and NTA was 9±2 nm, 27±7 nm, and 56±10 nm, respectively. The particle size in suspension remained the same before and after the nebulization process. However, after aerosol collection in an impinger, the suspended particle size increased to 159±46 nm as measured by NTA. The aerosol particle concentration increased linearly with increasing suspension concentration, and the aerodynamic diameter remained relatively stable at around 75 nm as measured by SMPS.
  
  
  CONCLUSIONS
  We demonstrated that the total number and particle size in the aerosol were modulated as a function of the initial concentration in the nebulizer. The data obtained mark the first known independent characterization of nebulized Rienso and, as such, provide critical information on the behavior of Rienso nanoparticles in an aerosol. The data obtained in this study add new knowledge to the existing body of literature on potential applications of SPION suspensions as inhaled aerosol therapeutics.
authors.affiliation: 1 Institute for Work and Health, University of Lausanne and Geneva , 1066 Epalinges-Lausanne, Switzerland .
authors.forename: Halshka
authors.initials: H
authors.lastname: Graczyk
authors.forename: Louise C
authors.initials: LC
authors.lastname: Bryan
authors.forename: Nastassja
authors.initials: N
authors.lastname: Lewinski
authors.forename: Guillaume
authors.initials: G
authors.lastname: Suarez
authors.forename: Geraldine
authors.initials: G
authors.lastname: Coullerez
authors.forename: Paul
authors.initials: P
authors.lastname: Bowen
authors.forename: Michael
authors.initials: M
authors.lastname: Riediker
mesh_terms: D000280:Administration, Inhalation; D000336:Aerosols; D006397:Hematinics / Q000008:administration & dosage* / Q000737:chemistry; D016014:Linear Models; D058185:Magnetite Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry; D009038:Motion; D009330:Nebulizers and Vaporizers; D010316:Particle Size
chemical_list: D000336:Aerosols; D006397:Hematinics; D058185:Magnetite Nanoparticles
keywords: Rienso; SPIONs; aerosol distribution; characterization; inhaled therapy; nebulizer