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Issue 8, 2004
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Synthesis and characterization of multi-functional nanoparticles possessing magnetic, up-conversion fluorescence and bio-affinity properties

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Abstract

Multi-functional nanoparticles possessing magnetic, up-conversion fluorescence and bio-affinity properties were synthesized and characterized. The particles have a core/shell structure. Iron oxide nanoparticles of 5–15 nm diameter were synthesized as the magnetic core. The core was covered with ytterbium and erbium co-doped sodium yttrium fluoride (NaYF4:Yb,Er), an efficient infrared-to-visible up-conversion phosphor. The phosphor shell was prepared by co-precipitation of the rare-earth metal salts with fluoride in the presence of EDTA and the magnetic nanoparticle. After the magnetic/fluorescent hybrid particle was coated with SiO2 and activated with glutaraldehyde, streptavidin was immobilized on the particle. The magnetic/fluorescent nanoparticles were found by transmission electron microscopy to be well-dispersed spherical particles with an average diameter of 68 nm. Both energy dispersive X-ray microanalysis and X-ray fluorescence spectra revealed the existence of iron in the particle. Measurements performed on a vibrating sample magnetometer obtained a strong magnetic response for the particle and fluorescence measurements demonstrated its up-conversion property. X-Ray diffraction analysis suggests the phosphor shell has the same structure as the pure NaYF4:Yb,Er nanoparticles we prepared in a previous study (G. S. Yi, H. C. Lu, S. Y. Zhao, Y. Ge, W. J. Yang, L. H. Guo, D. P. Chen and J. Cheng, submitted). Streptavidin-coated magnetic/fluorescent particles were found to bind specifically to a glass slide spotted with biotinylated IgG and emit up-conversion fluorescence, confirming the successful coating of the protein and retention of its optical activity and bio-affinity.

Graphical abstract: Synthesis and characterization of multi-functional nanoparticles possessing magnetic, up-conversion fluorescence and bio-affinity properties

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Publication details

The article was received on 21 Nov 2003, accepted on 13 Feb 2004 and first published on 04 Mar 2004


Article type: Paper
DOI: 10.1039/B315103D
Citation: J. Mater. Chem., 2004,14, 1336-1341
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    Synthesis and characterization of multi-functional nanoparticles possessing magnetic, up-conversion fluorescence and bio-affinity properties

    H. Lu, G. Yi, S. Zhao, D. Chen, L. Guo and J. Cheng, J. Mater. Chem., 2004, 14, 1336
    DOI: 10.1039/B315103D

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