Engineered Theranostic Magnetic Nanostructures: Role of Composition and Surface Coating on Magnetic Resonance Imaging Contrast and Thermal Activation

Vikas Nandwana, Soo Ryoon Ryoo, Shanthi Kanthala, Mrinmoy De, Stanley S. Chou, Pottumarthi V. Prasad, Vinayak P. Dravid*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Magnetic nanostructures (MNS) have emerged as promising functional probes for simultaneous diagnostics and therapeutics (theranostic) applications due to their ability to enhance localized contrast in magnetic resonance imaging (MRI) and heat under external radio frequency (RF) field, respectively. We show that the "theranostic" potential of the MNS can be significantly enhanced by tuning their core composition and architecture of surface coating. Metal ferrite (e.g., MFe2O4) nanoparticles of ∼8 nm size and nitrodopamine conjugated polyethylene glycol (NDOPA-PEG) were used as the core and surface coating of the MNS, respectively. The composition was controlled by tuning the stoichiometry of MFe2O4 nanoparticles (M = Fe, Mn, Zn, ZnxMn1-x) while the architecture of surface coating was tuned by changing the molecular weight of PEG, such that larger weight is expected to result in longer length extended away from the MNS surface. Our results suggest that both core as well as surface coating are important factors to take into consideration during the design of MNS as theranostic agents which is illustrated by relaxivity and thermal activation plots of MNS with different core composition and surface coating thickness. After optimization of these parameters, the r2 relaxivity and specific absorption rate (SAR) up to 552 mM-1 s-1 and 385 W/g were obtained, respectively, which are among the highest values reported for MNS with core magnetic nanoparticles of size below 10 nm. In addition, NDOPA-PEG coated MFe2O4 nanostructures showed enhanced biocompatibility (up to [Fe] = 200 μg/mL) and reduced nonspecific uptake in macrophage cells in comparison to other well established FDA approved Fe based MR contrast agents.

Original languageEnglish (US)
Pages (from-to)6953-6961
Number of pages9
JournalACS Applied Materials and Interfaces
Issue number11
StatePublished - Mar 30 2016


  • biomedical applications
  • hyperthermia
  • magnetic nanoparticles
  • magnetic nanostructures
  • magnetic resonance imaging contrast
  • nanomedicine
  • theranostics
  • thermal activation

ASJC Scopus subject areas

  • Materials Science(all)


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