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Positive and Negative Lattice Shielding Effects Co-existing in Gd (III) Ion Doped Bifunctional Upconversion Nanoprobes

  1. Feng Chen1,
  2. Wenbo Bu1,*,
  3. Shengjian Zhang2,
  4. Xiaohang Liu2,
  5. Jianan Liu1,
  6. Huaiyong Xing1,
  7. Qingfeng Xiao1,
  8. Liangping Zhou2,
  9. Weijun Peng2,
  10. Lianzhou Wang3,
  11. Jianlin Shi1,*

Article first published online: 28 SEP 2011

DOI: 10.1002/adfm.201101663

Issue

Advanced Functional Materials

Advanced Functional Materials

Volume 21, Issue 22, pages 4285–4294, November 22, 2011

Additional Information

How to Cite

Chen, F., Bu, W., Zhang, S., Liu, X., Liu, J., Xing, H., Xiao, Q., Zhou, L., Peng, W., Wang, L. and Shi, J. (2011), Positive and Negative Lattice Shielding Effects Co-existing in Gd (III) Ion Doped Bifunctional Upconversion Nanoprobes. Adv. Funct. Mater., 21: 4285–4294. doi: 10.1002/adfm.201101663

Author Information

  1. 1

    Group of Mesoporous and Low-Dimensional Nano-materials, State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, P.R. China

  2. 2

    Department of Radiology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, P.R. China

  3. 3

    Chemical Engineering and ARC Centre of Excellence for Functional Nanomaterials, The University of Queensland, St. Lucia, QLD 4072, Australia

*Group of Mesoporous and Low-Dimensional Nano-materials, State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, P.R. China.

Publication History

  1. Issue published online: 16 NOV 2011
  2. Article first published online: 28 SEP 2011
  3. Manuscript Revised: 5 SEP 2011
  4. Manuscript Received: 20 JUL 2011

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Keywords:

  • upconversion;
  • bimodal imaging;
  • lattice shielding effect;
  • MRI

Abstract

Gadolinium (Gd) doped upconversion nanoparticles (UCNPs) have been well documented as T1-MR and fluorescent imaging agents. However, the performance of Gd3+ ions located differently in the crystal lattice still remains debatable. Here, a well-designed model was built based on a seed-mediated growth technique to systematically probe the longitudinal relaxivity of Gd3+ ions within the crystal lattice and at the surface of UCNPs. We found, for the first time, a nearly 100% loss of relaxivity of Gd3+ ions buried deeply within crystal lattices (> 4 nm), which we named a “negative lattice shielding effect” (n-LSE) as compared to the “positive lattice shielding effect” (p-LSE) for the enhanced upconversion fluorescent intensity. As-observed n-LSE was further found to be shell thickness dependent. By suppressing the n-LSE as far as possible, we optimized the UCNPs' structure design and achieved the highest r1 value (6.18 mM−1s−1 per Gd3+ ion) among previously reported counterparts. The potential bimodal imaging application both in vitro and in vivo of as-designed nano-probes was also demonstrated. This study clears the debate over the role of bulk and surface Gd3+ ions in MRI contrast imaging and paves the way for modulation of other Gd-doped nanostructures for highly efficient T1-MR and upconversion fluorescent bimodal imaging.

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