title: Biodistribution of newly synthesized PHEA-based polymer-coated SPION in Sprague Dawley rats as magnetic resonance contrast agent.
abstract: OBJECTIVE
  The purpose of this study was to observe the pharmacokinetic behavior of newly synthesized biocompatible polymers based on polyhydroxyethylaspartamide (PHEA) to be used to coat an iron oxide core to make superparamagnetic iron oxide nanoparticles (SPION).
  
  
  METHODS
  The isotopes [(14)C] and [(59)Fe] were used to label the polymer backbone (CLS) and iron oxide core (FLS), respectively. In addition, unradiolabeled cold superparamagnetic iron oxide nanoparticles (SPION/ULS) were synthesized to characterize particle size by dynamic light scattering, morphology by transmission electron microscopy, and in vivo magnetic resonance imaging (MRI). CLS and FLS were used separately to investigate the behavior of both the synthesized polymer and [Fe] in Sprague Dawley (SD) rats, respectively. Because radioactivity of the isotopes was different by β for CLS and γ for FLS, synthesis of the samples had to be separately prepared.
  
  
  RESULTS
  The mean particle size of the ULS was 66.1 nm, and the biodistribution of CLS concentrations in various organs, in rank order of magnitude, was liver > kidney > small intestine > other. The biodistribution of FLS concentrations was liver > spleen > lung > other. These rank orders show that synthesized SPION mainly accumulates in the liver. The differences in the distribution were caused by the SPION metabolism. Radiolabeled polymer was metabolized by the kidney and excreted mainly in the urine; [(59)Fe] was recycled for erythrocyte production in the spleen and excreted mainly in the feces. The MR image of the liver after intravenous injection demonstrated that [Fe] effectively accumulated in the liver and exhibited high-contrast enhancement on T2-weighted images.
  
  
  CONCLUSIONS
  This newly synthesized, polymer-coated SPION appears to be a promising candidate for use as a liver-targeted, biocompatible iron oxide MR imaging agent.
authors.affiliation: Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, Republic of Korea ; College of Pharmacy, Chungnam National University, Daejeon, Republic of Korea.
authors.forename: Junsung
authors.initials: J
authors.lastname: Park
authors.forename: Wonkyung
authors.initials: W
authors.lastname: Cho
authors.forename: Hee Jun
authors.initials: HJ
authors.lastname: Park
authors.forename: Kwang-Ho
authors.initials: KH
authors.lastname: Cha
authors.forename: Dae-Chul
authors.initials: DC
authors.lastname: Ha
authors.forename: Youn-Woong
authors.initials: YW
authors.lastname: Choi
authors.forename: Ha-Young
authors.initials: HY
authors.lastname: Lee
authors.forename: Sun-Hang
authors.initials: SH
authors.lastname: Cho
authors.forename: Sung-Joo
authors.initials: SJ
authors.lastname: Hwang
mesh_terms: D061605:Administration, Intravenous; D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage / Q000032:analysis / Q000737:chemistry / Q000493:pharmacokinetics*; D005260:Female; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D058185:Magnetite Nanoparticles / Q000008:administration & dosage / Q000737:chemistry*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution
chemical_list: D003287:Contrast Media; D058185:Magnetite Nanoparticles
keywords: SPION; liver; pharmacokinetic; polyhydroxyethylaspartamide; radiolabeled