Coating thickness of magnetic iron oxide nanoparticles affects R 2 relaxivity

Leslie E W LaConte, Nitin Nitin, Omar Zurkiya, Daniela Caruntu, Charles J. O'Connor, Xiaoping Hu, Gang Bao

Research output: Contribution to journalArticle

170 Citations (Scopus)

Abstract

Purpose: To evaluate the effect of coating thickness on the relaxivity of iron oxide nanoparticles. Materials and Methods: Monocrystalline superparamagnetic iron oxide nanoparticles (MIONs), coated with a polyethylene glycol (PEG)-modified, phospholipid micelle coating, with different PEG molecular weights, were prepared. The particle diameters were measured with dynamic light scattering (DLS) and electron microscopy (EM). The R1 and R2 of MIONs were measured using a bench-top nuclear magnetic resonance (NMR) relaxometer. pH was varied for some measurements. Monte Carlo simulations of proton movement in a field with nanometer-sized magnetic inhomogeneities were performed. Results: Increasing the molecular weight of the PEG portion of the micelle coating increased overall particle diameter. As coating thickness increases, the R2 decreases and the R1 increases. Changing pH has no effect on relaxivity. The Monte Carlo simulations suggest that the effect of coating size on R2 relaxivity is determined by two competing factors: the physical exclusion of protons from the magnetic field and the residence time for protons within the coating zone. Conclusion: Coating thickness can significantly impact the R2, and the R2/R1 ratio, of a MION contrast agent. An understanding of the relationship between coating properties and changes in relaxivity is critical for designing magnetic nanoparticle probes for molecular imaging applications using MRI.

Original languageEnglish (US)
Pages (from-to)1634-1641
Number of pages8
JournalJournal of Magnetic Resonance Imaging
Volume26
Issue number6
DOIs
StatePublished - Dec 2007
Externally publishedYes

Fingerprint

Nanoparticles
Protons
Micelles
Molecular Weight
Molecular Imaging
Magnetic Fields
Contrast Media
Phospholipids
Electron Microscopy
Magnetic Resonance Spectroscopy
monocrystalline iron oxide nanoparticle
ferric oxide
Dynamic Light Scattering

Keywords

  • Coating thickness
  • Molecular imaging
  • MRI contrast agent
  • Relaxivity
  • Superparamagnetic nanoparticle

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology

Cite this

LaConte, L. E. W., Nitin, N., Zurkiya, O., Caruntu, D., O'Connor, C. J., Hu, X., & Bao, G. (2007). Coating thickness of magnetic iron oxide nanoparticles affects R 2 relaxivity. Journal of Magnetic Resonance Imaging, 26(6), 1634-1641. https://doi.org/10.1002/jmri.21194

Coating thickness of magnetic iron oxide nanoparticles affects R 2 relaxivity. / LaConte, Leslie E W; Nitin, Nitin; Zurkiya, Omar; Caruntu, Daniela; O'Connor, Charles J.; Hu, Xiaoping; Bao, Gang.

In: Journal of Magnetic Resonance Imaging, Vol. 26, No. 6, 12.2007, p. 1634-1641.

Research output: Contribution to journalArticle

LaConte, LEW, Nitin, N, Zurkiya, O, Caruntu, D, O'Connor, CJ, Hu, X & Bao, G 2007, 'Coating thickness of magnetic iron oxide nanoparticles affects R 2 relaxivity', Journal of Magnetic Resonance Imaging, vol. 26, no. 6, pp. 1634-1641. https://doi.org/10.1002/jmri.21194
LaConte LEW, Nitin N, Zurkiya O, Caruntu D, O'Connor CJ, Hu X et al. Coating thickness of magnetic iron oxide nanoparticles affects R 2 relaxivity. Journal of Magnetic Resonance Imaging. 2007 Dec;26(6):1634-1641. https://doi.org/10.1002/jmri.21194
LaConte, Leslie E W ; Nitin, Nitin ; Zurkiya, Omar ; Caruntu, Daniela ; O'Connor, Charles J. ; Hu, Xiaoping ; Bao, Gang. / Coating thickness of magnetic iron oxide nanoparticles affects R 2 relaxivity. In: Journal of Magnetic Resonance Imaging. 2007 ; Vol. 26, No. 6. pp. 1634-1641.
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