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FeCo/graphitic-shell nanocrystals as advanced magnetic-resonance-imaging and near-infrared agents

Nature Materials volume 5, pages 971–976 (2006)Cite this article

Abstract

Nanocrystals with advanced magnetic or optical properties have been actively pursued for potential biological applications, including integrated imaging, diagnosis and therapy1,2,3,4,5,6,7,8,9. Among various magnetic nanocrystals10,11,12,13,14,15, FeCo has superior magnetic properties, but it has yet to be explored owing to the problems of easy oxidation and potential toxicity10,16,17. Previously, FeCo nanocrystals with multilayered graphitic carbon, pyrolytic carbon or inert metals have been obtained15,18,19, but not in the single-shelled, discrete, chemically functionalized and water-soluble forms desired for biological applications. Here, we present a scalable chemical vapour deposition method to synthesize FeCo/single-graphitic-shell nanocrystals that are soluble and stable in water solutions. We explore the multiple functionalities of these core–shell materials by characterizing the magnetic properties of the FeCo core and near-infrared optical absorbance of the single-layered graphitic shell. The nanocrystals exhibit ultra-high saturation magnetization, r1 and r2 relaxivities and high optical absorbance in the near-infrared region. Mesenchymal stem cells are able to internalize these nanoparticles, showing high negative-contrast enhancement in magnetic-resonance imaging (MRI). Preliminary in vivo experiments achieve long-lasting positive-contrast enhancement for vascular MRI in rabbits. These results point to the potential of using these nanocrystals for integrated diagnosis and therapeutic (photothermal-ablation) applications.

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Figure 1: Structural analysis of FeCo/GC nanocrystals.
Figure 2: Advanced magnetic, chemical and near-infrared properties of FeCo/GC nanocrystals.
Figure 3: MR measurements and imaging of functionalized FeCo/GC nanocrystals, Feridex and Magnevist solutions.
Figure 4: Biological applications.

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References

  1. Lewin, M. et al. Tat peptide-derivatized magnetic nanoparticles allow in vivo tracking and recovery of progenitor cells. Nature Biotechnol. 18, 410–414 (2000).

    Article  Google Scholar 

  2. Alivisatos, P. The use of nanocrystals in biological detection. Nature Biotechnol. 22, 47–52 (2004).

    Article  Google Scholar 

  3. Kim, S. et al. Near-infrared fluorescent type II quantum dots for sentinel lymph node mapping. Nature Biotechnol. 22, 93–97 (2004).

    Article  Google Scholar 

  4. Hirsch, L. R. et al. Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance. Proc. Natl Acad. Sci. USA 100, 13549–13554 (2003).

    Article  Google Scholar 

  5. Liao, H. W. & Hafner, J. H. Gold nanorod bioconjugates. Chem. Mater. 17, 4636–4641 (2005).

    Article  Google Scholar 

  6. Huang, X., El-Sayed, I. H., Qian, W. & El-Sayed, M. A. Cancer cell imaging and photothermal therapy in the near-infrared region by using gold nanorods. J. Am. Chem. Soc. 128, 2115–2120 (2006).

    Article  Google Scholar 

  7. Chen, C.-C. et al. DNA-gold nanorod conjugates for remote control of localized gene expression by near infrared irradiation. J. Am. Chem. Soc. 128, 3709–3715 (2006).

    Article  Google Scholar 

  8. Kopelman, R. et al. Multifunctional nanoparticle platforms for in vivo MRI enhancement and photodynamic therapy of a rat brain cancer. J. Magn. Magn. Mater. 293, 404–410 (2005).

    Article  Google Scholar 

  9. McCarthy, J. R., Jaffer, F. A. & Weissleder, R. A macrophage-targeted theranostic nanoparticle for biomedical applications. Small 2, 983–987 (2006).

    Article  Google Scholar 

  10. Hütten, A. et al. New magnetic nanoparticles for biotechnology. J. Biotechnol. 112, 47–63 (2004).

    Article  Google Scholar 

  11. Dinega, D. P. & Bawendi, M. G. A solution-phase chemical approach to a new crystal structure of cobalt. Angew. Chem. Int. Edn. 38, 1788–1791 (1999).

    Article  Google Scholar 

  12. Puntes, V. F., Zanchet, D., Erdonmez, C. K. & Alivisatos, A. P. Synthesis of hcp-Co nanodisks. J. Am. Chem. Soc. 124, 12874–12880 (2002).

    Article  Google Scholar 

  13. Sun, S., Murray, C. B., Weller, D., Folks, L. & Moser, A. Monodisperse FePt nanoparticles and ferromagnetic FePt nanocrystal superlattices. Science 287, 1989–1992 (2000).

    Article  Google Scholar 

  14. Park, J. et al. Ultra-large-scale syntheses of monodisperse nanocrystals. Nature Mater. 3, 891–895 (2004).

    Article  Google Scholar 

  15. Desvaux, C. et al. Multimillimetre-large superlattices of air-stable iron–cobalt nanoparticles. Nature Mater. 4, 750–753 (2005).

    Article  Google Scholar 

  16. Bardos, D. I. Mean magnetic moments in bcc Fe–Co alloys. J. Appl. Phys. 40, 1371–1372 (1969).

    Article  Google Scholar 

  17. Reiss, G. & Hütten, A. Magnetic nanoparticles: applications beyond data storage. Nature Mater. 4, 725–726 (2005).

    Article  Google Scholar 

  18. Turgut, Z., Scott, J. H., Huang, M. Q., Majetich, S. A. & McHenry, M. E. Magnetic properties and ordering in C-coated FexCo1−x alloy nanocrystals. J. Appl. Phys. 83, 6468–6470 (1998).

    Article  Google Scholar 

  19. Bai, J. & Wang, J.-P. High-magnetic-moment core-shell-type FeCo-Au/Ag nanoparticles. Appl. Phys. Lett. 87, 152502 (2005).

    Article  Google Scholar 

  20. Tuinstra, F. & Koenig, J. L. Raman spectrum of graphite. J. Chem. Phys. 53, 1126–1130 (1970).

    Article  Google Scholar 

  21. Lu, Y., Zhu, Z. & Liu, Z. Carbon-encapsulated Fe nanoparticles from detonation-induced pyrolysis of ferrocene. Carbon 43, 369–374 (2005).

    Article  Google Scholar 

  22. Li, Y. et al. Growth of single-walled carbon nanotubes from discrete catalytic nanoparticles of various sizes. J. Phys. Chem. 105, 11424–11431 (2001).

    Article  Google Scholar 

  23. Kam, N. W. S., Liu, Z. & Dai, H. Functionalization of carbon nanotubes via cleavable disulfide bonds for efficient intracellular delivery of siRNA and potent gene silencing. J. Am. Chem. Soc. 127, 12492–12493 (2005).

    Article  Google Scholar 

  24. Kam, N. W. S., O’Connell, M., Wisdom, J. A. & Dai, H. Carbon nanotubes as multifunctional biological transporters and near-infrared agents for selective cancer cell destruction. Proc. Natl Acad. Sci. USA 102, 11600–11605 (2005).

    Article  Google Scholar 

  25. Cataldo, F. An investigation on the optical properties of carbon black, fullerite, and other carbonaceous materials in relation to the spectrum of interstellar extinction of light. Full. Nanotubes Carb. Nanostruct. 10, 155–170 (2002).

    Article  Google Scholar 

  26. Jung, C. W. & Jacobs, P. Physical and chemical properties of superparamagnetic iron oxide MR contrast agents: ferumoxides, ferumoxtran, ferumoxsil. Magn. Reson. Imag. 13, 661–674 (1995).

    Article  Google Scholar 

  27. Kellar, K. E. et al. NC100150 injection, a preparation of optimized iron oxide nanoparticles for positive-contrast MR angiography. J. Magn. Reson. Imag. 11, 488–494 (2000).

    Article  Google Scholar 

  28. Huang, D.-M. et al. Highly efficient cellular labeling of mesoporous nanoparticles in human mesenchymal stem cells: implication for stem cell tracking. FASEB J. 19, 2014–2016 (2005).

    Article  Google Scholar 

  29. Kam, N. W. S. & Dai, H. Carbon nanotubes as intracellular protein transporters: Generality and biological functionality. J. Am. Chem. Soc. 127, 6021–6026 (2005).

    Article  Google Scholar 

  30. Bianco, A., Kostarelos, K., Partidos, C. D. & Prato, M. Biomedical applications of functionalised carbon nanotubes. Chem. Commun. 571–577 (2005).

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Acknowledgements

This work was supported in part by a Korea Research Foundation Grant (KRF-2005-214-C00074), a Ludwig Translational Research Grant at Stanford University, a NIH-NCI Cancer Center for Nanotechnology Excellence-Therapy Response (CCNE-TR) grant (# 1 U54 CA119367-01) at Stanford, a NIH RO1 grant (#HLO78678), and the National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, which is supported by the US Department of Energy, supported this work in part. We thank H. Li for help with TEM.

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Authors and Affiliations

  1. Department of Chemistry and Laboratory for Advanced Materials, Stanford University, Stanford, California, 94305, USA

    Won Seok Seo, Xiaoming Sun, David Mann, Zhuang Liu & Hongjie Dai

  2. Department of Electrical Engineering, Stanford University, Stanford, California, 94305, USA

    Jin Hyung Lee & Dwight G. Nishimura

  3. Division of Cardiovascular Medicine, Stanford University, Stanford, California, 94305, USA

    Yoriyasu Suzuki, Masahiro Terashima, Philip C. Yang & Michael V. McConnell

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  1. Won Seok Seo
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Contributions

W.S.S., D.M. and H.D. carried out the design and experiments of synthesis, characterization and functionalization. X.M.S. and Z.L. carried out cytotoxicity assays. P.Y. and Y.S. participated in the stem cell experiment. M.T. and M.V.M carried out rabbit injections. J.H.L. and D.G.N. carried out MRI experiments. H.D., W.S.S. and J.H.L. designed the research and wrote the paper.

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Correspondence to Hongjie Dai.

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The authors declare no competing financial interests.

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Seo, W., Lee, J., Sun, X. et al. FeCo/graphitic-shell nanocrystals as advanced magnetic-resonance-imaging and near-infrared agents. Nature Mater 5, 971–976 (2006). https://doi.org/10.1038/nmat1775

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