title: Amorphous silica coatings on magnetic nanoparticles enhance stability and reduce toxicity to in vitro BEAS-2B cells.
abstract: BACKGROUND
  Nanoparticles are being rapidly assimilated into numerous research fields and consumer products. A concurrent increase in human exposure to such materials is expected. Magnetic nanoparticles (MNPs) possess unique and beneficial features, increasing their functionality and integrative potential. However, MNP toxicity characterization is limited, especially in regards to the human respiratory system. This study aimed to assess the in vitro effects of airborne MNPs on BEAS-2B cells. Uncoated iron oxide was compared with two amorphous silica-coated MNPs, hypothesizing the coatings reduced toxicity and increased particle stability.
  
  
  METHODS
  BEAS-2B cells were cultured at an air-liquid interface and exposed to airborne MNPs using a fabricated exposure device. Indices of cytotoxicity, inflammatory response, oxidative stress, and iron homeostasis were monitored postexposure via cell viability assays and qRT-PCR. Concentrations of soluble iron-associated with different MNPs were also examined before and after contact with several aqueous organic and inorganic acids.
  
  
  RESULTS
  The silica-coated MNPs had reduced soluble iron concentrations. This result indicates that the silica coating provides a barrier to and prevents the mobilization of soluble iron from the particle to the cell, thereby reducing the risk of oxidative stress or alterations of iron homeostasis. Cells exposed to MagSilica50 and MagSilica50-85® showed little to no indications of cytotoxicity or induction of inflammatory response/oxidative stress at the examined delivery concentrations.
  
  
  CONCLUSIONS
  MNPs coated with amorphous silica are protected from acidic erosion. Correspondingly, the particle stability translates into reduced cytotoxicity and cellular influence on human airway epithelial cells.
authors.affiliation: Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL, USA.
authors.forename: Ori
authors.initials: O
authors.lastname: Baber
authors.forename: Myoseon
authors.initials: M
authors.lastname: Jang
authors.forename: David
authors.initials: D
authors.lastname: Barber
authors.forename: Kevin
authors.initials: K
authors.lastname: Powers
mesh_terms: D000336:Aerosols; D018929:Cell Culture Techniques; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects; D005290:Ferric Compounds / Q000737:chemistry / Q000633:toxicity; D006801:Humans; D058185:Magnetite Nanoparticles / Q000737:chemistry / Q000592:standards / Q000633:toxicity*; D008855:Microscopy, Electron, Scanning; D008962:Models, Theoretical; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry*; D012995:Solubility; D013499:Surface Properties
chemical_list: D000336:Aerosols; D005290:Ferric Compounds; D058185:Magnetite Nanoparticles; C000499:ferric oxide; D012822:Silicon Dioxide