Toward design of magnetic nanoparticle clusters stabilized by biocompatible diblock copolymers for T 2-weighted MRI contrast

Sharavanan Balasubramaniam, Sanem Kayandan, Yin Nian Lin, Deborah F. Kelly, Michael J. House, Robert C. Woodward, Timothy G. St. Pierre, Judy S. Riffle, Richey M. Davis

Research output: Contribution to journalArticlepeer-review

50 Scopus citations


We report the fabrication of magnetic particles comprised of clusters of iron oxide nanoparticles, 7.4 nm mean diameter, stabilized by a biocompatible, amphiphilic diblock copolymer, poly(ethylene oxide-b-d,l-lactide). Particles with quantitative incorporation of up to 40 wt % iron oxide and hydrodynamic sizes in the range of 80-170 nm were prepared. The particles consist of hydrophobically modified iron oxide nanoparticles within the core-forming polylactide block with the poly(ethylene oxide) forming a corona to afford aqueous dispersibility. The transverse relaxivities (r2) increased with average particle size and exceeded 200 s-1 mM Fe-1 at 1.4 T and 37 C for iron oxide loadings above 30 wt %. These experimental relaxivities typically agreed to within 15% with the values predicted using analytical models of transverse relaxivity and cluster (particle core) size distributions derived from cryo-TEM measurements. Our results show that the theoretical models can be used for the rational design of biocompatible MRI contrast agents with tailored compositions and size distributions.

Original languageEnglish (US)
Pages (from-to)1580-1587
Number of pages8
Issue number6
StatePublished - Feb 18 2014

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry


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