Gold nanorods as molecular contrast agents in photoacoustic imaging: the promises and the caveats

Authors

  • Srirang Manohar,

    Corresponding author
    • Biomedical Photonic Imaging Group, MIRA Institute for Biomedical Technology and Technical Medicine, Faculty of Science and Technology, University of Twente, Enschede, The Netherlands
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  • Constantin Ungureanu,

    1. Biomedical Photonic Imaging Group, MIRA Institute for Biomedical Technology and Technical Medicine, Faculty of Science and Technology, University of Twente, Enschede, The Netherlands
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  • Ton G. Van Leeuwen

    1. Biomedical Photonic Imaging Group, MIRA Institute for Biomedical Technology and Technical Medicine, Faculty of Science and Technology, University of Twente, Enschede, The Netherlands
    2. Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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S. Manohar, Biomedical Photonic Imaging Group, MIRA Institute for Biomedical Technology and Technical Medicine, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.

E-mail: S.Manohar@utwente.nl

Abstract

Rod-shaped gold nanoparticles exhibit intense and narrow absorption peaks for light in the far-red and near-infrared wavelength regions, owing to the excitation of longitudinal plasmons. Light absorption is followed predominantly by non radiative de-excitation, and the released heat and subsequent temperature rise cause strong photoacoustic (optoacoustic) signals to be produced. This feature combined with the relative inertness of gold, and its favorable surface chemistry, which permits affinity biomolecule coupling, has seen gold nanorods (AuNR) attracting much attention as contrast agents and molecular probes for photoacoustic imaging. In this article we provide an short overview of the current status of the use of AuNR in molecular imaging using photoacoustics. We further examine the state of the art in various chemical, physical and biochemical phenomena that have implications for the future photoacoustic applications of these particles. We cover the route through fine-tuning of AuNR synthetic procedures, toxicity reduction by appropriate coatings, in vitro cellular interactions of AuNRs, attachment of targeting antibodies, in vivo fate of the particles and the effects of certain light interactions with the AuNR. Copyright © 2011 John Wiley & Sons, Ltd.

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