title: The impact of polymer coatings on magnetite nanoparticles performance as MRI contrast agents: a comparative study.
abstract: BACKGROUND
  Superparamagnetic iron oxide nanoparticles (SPIONs) are the most commonly used negative MRI contrast agent which affect the transverse (T2) relaxation time. The aim of the present study was to investigate the impact of various polymeric coatings on the performance of magnetite nanoparticles as MRI contrast agents.
  
  
  METHODS
  Ferrofluids based on magnetite (Fe3O4) nanoparticles (SPIONs) were synthesized via chemical co-precipitation method and coated with different biocompatible polymer coatings including mPEG-PCL, chitosan and dextran.
  
  
  RESULTS
  The bonding status of different polymers on the surface of the magnetite nanoparticles was confirmed by the Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The vibrating sample magnetometer (VSM) analysis confirmed the superparamagnetic behavior of all synthesized nanoparticles. The field-emission scanning electron microscopy (FE-SEM) indicated the formation of quasi-spherical nanostructures with the final average particle size of 12-55 nm depending on the type of polymer coating, and X-ray diffraction (XRD) determined inverse spinel structure of magnetite nanoparticles. The ferrofluids demonstrated sufficient colloidal stability in deionized water with the zeta potentials of -24.2, -16.9, +31.6 and -21 mV for the naked SPIONs, and for dextran, chitosan and mPEG-PCL coated SPIONs, respectively. Finally, the magnetic relaxivities of water based ferrofluids were measured on a 1.5 T clinical MRI instrument. The r2/r1 value was calculated to be 17.21, 19.42 and 20.71 for the dextran, chitosan and mPEG-PCL coated SPIONs, respectively.
  
  
  CONCLUSIONS
  The findings demonstrated that the value of r2/r1 ratio of mPEG-PCL modified SPIONs is higher than that of some commercial contrast agents. Therefore, it can be considered as a promising candidate for T2 MRI contrast agent.
authors.affiliation: Department of Physics, Faculty of Science, University of Zanjan, Zanjan, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Khalkhali
authors.affiliation: Zanjan Pharmaceutical Nanotechnology Research Center, Zanjan University of Medical Sciences, Zanjan, Iran. rostaimzadeh@gmail.com.|Department of Medicinal Chemistry, School of Pharmacy, Zanjan University of Medical Sciences, Postal Code 45139-56184, Zanjan, Iran. rostaimzadeh@gmail.com.
authors.forename: Kobra
authors.initials: K
authors.lastname: Rostamizadeh
authors.affiliation: Zanjan Pharmaceutical Nanotechnology Research Center, Zanjan University of Medical Sciences, Zanjan, Iran.|Department of Pharmaceutical Biomaterials, School of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran.
authors.forename: Somayeh
authors.initials: S
authors.lastname: Sadighian
authors.affiliation: Department of Physics, Faculty of Science, University of Zanjan, Zanjan, Iran.
authors.forename: Farhad
authors.initials: F
authors.lastname: Khoeini
authors.affiliation: Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mehran
authors.initials: M
authors.lastname: Naghibi
authors.affiliation: Zanjan Pharmaceutical Nanotechnology Research Center, Zanjan University of Medical Sciences, Zanjan, Iran.
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Hamidi
mesh_terms: D003287:Contrast Media / Q000737:chemistry*; D008279:Magnetic Resonance Imaging; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D011108:Polymers / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D003287:Contrast Media; D058185:Magnetite Nanoparticles; D011108:Polymers