title: Fluorescent dye labeled iron oxide/silica core/shell nanoparticle as a multimodal imaging probe.
abstract: OBJECTIVE
  To develop an MRI/optical multimodal imaging probe based on dye-conjugated iron oxide/silica core/shell nanoparticle, and investigate the distance-dependent fluorescence quenching through careful control of the distance between the iron oxide core and fluorescent dyes.
  
  
  METHODS
  Different size of core/shell nanoparticles were prepared by varying the silica shell width. PEGylation on the surface of silica shell was followed to improve the stability of particles in the physiological condition. In vitro cytotoxicity was evaluated by the MTT assay on a HeLa cell line and in vivo imaging of subcutaneous SCC7 xenografted mice was performed using MRI/optical imaging modalities.
  
  
  RESULTS
  Diameter and ζ-potential of the nanoparticles were measured, and TEM images demonstrated the mono-disperse nature of the particles. Quenching efficiency of the dyes on the surface was nearly 100% in the smallest nanoparticle, while almost no quenching effect was observed for the largest nanoparticle. In vitro cytotoxicity showed nearly 90% cell viability at 0.15 Fe mg/mL, a comparable concentration for clinical use. The tumor area was significantly darkened after the nanoparticle injection due to the high transverse relaxivity value of the nanoparticles. Fluorescence signal was affected by the particle size due to the distance-dependent quenching/dequenching behaviour.
authors.affiliation: Advanced Materials Educational Institute, Kumoh National Institute of Technology, Sanho-ro 77, Yangho, Gumi, 730-701, South Korea.
authors.forename: Eue Soon
authors.initials: ES
authors.lastname: Jang
authors.forename: Seung Yong
authors.initials: SY
authors.lastname: Lee
authors.forename: Eui-Joon
authors.initials: EJ
authors.lastname: Cha
authors.forename: In-Cheol
authors.initials: IC
authors.lastname: Sun
authors.forename: Ick Chan
authors.initials: IC
authors.lastname: Kwon
authors.forename: Dukjoon
authors.initials: D
authors.lastname: Kim
authors.forename: Young Il
authors.initials: YI
authors.lastname: Kim
authors.forename: Kwangmeyung
authors.initials: K
authors.lastname: Kim
authors.forename: Cheol-Hee
authors.initials: CH
authors.lastname: Ahn
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D003287:Contrast Media; D005290:Ferric Compounds / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D051379:Mice; D064847:Multimodal Imaging / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011092:Polyethylene Glycols; D012822:Silicon Dioxide / Q000737:chemistry*; D013778:Tetrazolium Salts; D013844:Thiazoles; D023041:Xenograft Model Antitumor Assays
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; D005456:Fluorescent Dyes; D013778:Tetrazolium Salts; D013844:Thiazoles; C000499:ferric oxide; D011092:Polyethylene Glycols; D012822:Silicon Dioxide; C022616:thiazolyl blue