Stable and Monodisperse Iron Nitride Nanoparticle Suspension for Magnetic Diagnosis and Treatment: Development of Synthesis and Surface Functionalization Strategies

Kai Wu, Jinming Liu, Renata Saha, Bin Ma, Diqing Su, Vinit K Chugh, Jian Ping Wang

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


The past decade has seen tremendous progress in the synthesis and surface functionalization of iron oxide nanoparticles (IONPs) for a variety of biomedical applications. However, there is still a growing demand on magnetic nanoparticles with higher magnetic moments for more sensitive diagnosis and lower dose treatments in magnetic bioassays, imaging, and therapies. In view of this need, the γ′-Fe4N nanoparticle, with around 3 times higher saturation magnetizations than IONPs, becomes one promising alternative for these applications. However, the large and non-uniformly distributed sizes of γ′-Fe4N nanoparticles hinder the biomedical applications. These synthesized γ′-Fe4N nanoparticles are not suitable for biomedical applications at the current stage. Herein, we have developed and demonstrated a wet ball milling method along with different surface-active media to produce ultrastable, monodispersed, uniformly sized, and sub-100 nm γ′-Fe4N nanoparticles in solvents. Different standard characterization methods such as transmission electron microscopy, nanoparticle tracking analysis, and Fourier-transform infrared spectroscopy are carried out to measure the physicochemical properties of these surface-functionalized γ′-Fe4N nanoparticles. It is confirmed that the functional chemical groups have been successfully anchored on our purified sub-100 nm γ′-Fe4N nanoparticles, which allows for convenient subsequent conjugation of proteins, nucleic acids, and drugs for future in vitro and in vivo biomedical applications.

Original languageEnglish (US)
Pages (from-to)4409-4418
Number of pages10
JournalACS Applied Nano Materials
Issue number5
StatePublished - Apr 23 2021

Bibliographical note

Funding Information:
This study was financially supported by the Institute of Engineering in Medicine of the University of Minnesota through the FY18 IEM Seed Grant Funding Program. This study was also financially supported by the U.S. Department of Agriculture-National Institute of Food and Agriculture (NIFA) under award no. 2020-67021-31956. Portions of this work were conducted in the Minnesota Nano Center, which is supported by the National Science Foundation through the National Nano Coordinated Infrastructure Network (NNCI) under award no. ECCS-1542202. Portions of this work were carried out in the Characterization Facility, University of Minnesota, a member of the NSF-Funded Materials Research Facilities Network ( ) via the MRSEC program.

Publisher Copyright:
© 2021 American Chemical Society.


  • colloidal stability
  • iron nitride
  • monodispersed
  • surface functionalization
  • surface-active media


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