A Facile and General Method for the Encapsulation of Different Types of Imaging Contrast Agents Within Micrometer-Sized Polymer Beads

Authors

  • Meng-Yi Bai,

    1. Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO 63130, USA
    Current affiliation:
    1. Graduate Institute of Biomedical Engineering, National Taiwan University of Science and Technology, Taipei 10673, Taiwan
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  • Christine H. Moran,

    1. Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO 63130, USA
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  • Lei Zhang,

    1. Department of Medicine, Washington University Medical School, Saint Louis, MO 63110, USA
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  • Changjun Liu,

    1. Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO 63130, USA
    Current affiliation:
    1. School of Electronics and Information Engineering, Sichuan University, Chengdu 610064, China
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  • Yu Zhang,

    1. Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO 63130, USA
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  • Lihong V. Wang,

    1. Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO 63130, USA
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  • Younan Xia

    Corresponding author
    1. Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO 63130, USA
    • Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO 63130, USA.

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Abstract

Polystyrene (PS) hollow beads with holes on the surfaces are employed as containers for quick loading and encapsulation of a variety of contrast enhancement agents: saline solutions for thermoacoustic tomography, iodinated organic compounds for micro-computed tomography, and perfluorooctane for magnetic resonance. Because of the hole on the surface of the PS hollow bead, the contrast agent to be encapsulated could quickly enter the hollow interior via direct flow rather than slow diffusion through the wall. After loading, the hole on the surface is conveniently sealed by annealing the sample at a temperature (e.g., 95 °C) slightly above the glass-transition temperature of PS. In vitro methods are also used to investigate the effectiveness of encapsulation by quantifying the contrast enhancement enabled by the contrast agents.

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