Probing Distance-Dependent Plasmon-Enhanced Near-Infrared Fluorescence Using Polyelectrolyte Multilayers as Dielectric Spacers

Authors

  • Dr. Naveen Gandra,

    1. Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, 1 Brooking Drive, St. Louis, MO 63130 (USA)
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  • Christopher Portz,

    1. Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, 1 Brooking Drive, St. Louis, MO 63130 (USA)
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  • Limei Tian,

    1. Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, 1 Brooking Drive, St. Louis, MO 63130 (USA)
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  • Dr. Rui Tang,

    1. Department of Radialogy, Washington University School of Medicine, St. Louis, MO 63110 (USA)
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  • Dr. Baogang Xu,

    1. Department of Radialogy, Washington University School of Medicine, St. Louis, MO 63110 (USA)
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  • Prof. Samuel Achilefu,

    Corresponding author
    1. Department of Radialogy, Washington University School of Medicine, St. Louis, MO 63110 (USA)
    • Samuel Achilefu, Department of Radialogy, Washington University School of Medicine, St. Louis, MO 63110 (USA)

      Srikanth Singamaneni, Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, 1 Brooking Drive, St. Louis, MO 63130 (USA)

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  • Prof. Srikanth Singamaneni

    Corresponding author
    1. Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, 1 Brooking Drive, St. Louis, MO 63130 (USA)
    • Samuel Achilefu, Department of Radialogy, Washington University School of Medicine, St. Louis, MO 63110 (USA)

      Srikanth Singamaneni, Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, 1 Brooking Drive, St. Louis, MO 63130 (USA)

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  • We acknowledge financial support from the BRIGHT institute at Washington University under P50 Pilot Project Program and the National Science Foundation (grant number CBET-1254399). The authors thank Nano Research Facility (NRF), a member of the National Nanotechnology Infrastructure Network (NNIN), for providing access to electron microscopy facilities.

Abstract

Owing to their applications in biodetection and molecular bioimaging, near-infrared (NIR) fluorescent dyes are being extensively investigated. Most of the existing NIR dyes exhibit poor quantum yield, which hinders their translation to preclinical and clinical settings. Plasmonic nanostructures are known to act as tiny antennae for efficiently focusing the electromagnetic field into nanoscale volumes. The fluorescence emission from NIR dyes can be enhanced by more than thousand times by precisely placing them in proximity to gold nanorods. We have employed polyelectrolyte multilayers fabricated using layer-by-layer assembly as dielectric spacers for precisely tuning the distance between gold nanorods and NIR dyes. The aspect ratio of the gold nanorods was tuned to match the longitudinal localized surface plasmon resonance wavelength with the absorption maximum of the NIR dye to maximize the plasmonically enhanced fluorescence. The design criteria derived from this study lays the groundwork for ultrabright fluorescence bullets for in vitro and in vivo molecular bioimaging.

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