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Bacterial Killing by Light-Triggered Release of Silver from Biomimetic Metal Nanorods

Authors

  • Kvar C. L. Black,

    1. Biomedical Engineering Department, Northwestern University, Evanston, IL 60208, USA
    2. Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208, USA
    3. Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Evanston, IL 60208, USA
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  • Tadas S. Sileika,

    1. Biomedical Engineering Department, Northwestern University, Evanston, IL 60208, USA
    2. Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208, USA
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  • Ji Yi,

    1. Biomedical Engineering Department, Northwestern University, Evanston, IL 60208, USA
    2. Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208, USA
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  • Ran Zhang,

    1. Materials Science and Engineering Department, Northwestern University, Evanston, IL 60208, USA
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  • José G. Rivera,

    1. Biomedical Engineering Department, Northwestern University, Evanston, IL 60208, USA
    2. Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208, USA
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  • Phillip B. Messersmith

    Corresponding author
    1. Biomedical Engineering Department, Northwestern University, Evanston, IL 60208, USA
    2. Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208, USA
    3. Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Evanston, IL 60208, USA
    4. Materials Science and Engineering Department, Northwestern University, Evanston, IL 60208, USA
    5. Chemical and Biological Engineering Department, Northwestern University, Evanston, IL 60208, USA
    6. Institute for Bionanotechnology in Medicine, Northwestern University, Evanston, IL 60208, USA
    • Biomedical Engineering Department, Northwestern University, Evanston, IL 60208, USA.

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Abstract

Illumination of noble metal nanoparticles at the plasmon resonance causes substantial heat generation, and the transient and highly localized temperature increases that result from this energy conversion can be exploited for photothermal therapy by plasmonically heating gold nanorods (NRs) bound to cell surfaces. Here, plasmonic heating is used for the first time to locally release silver from gold core/silver shell (Au@Ag) NRs targeted to bacterial cell walls. A novel biomimetic method of preparing Au@Ag core–shell NRs is employed, involving deposition of a thin organic polydopamine (PD) primer onto Au NR surfaces, followed by spontaneous electroless silver metallization, and conjugation of antibacterial antibodies and passivating polymers for targeting to gram-negative and gram-positive bacteria. Dramatic cytotoxicity of S. epidermidis and E. coli cells targeted with Au@Ag NRs is observed upon exposure to light as a result of the combined antibacterial effects of plasmonic heating and silver release. The antibacterial effect is much greater than with either plasmonic heating or silver alone, implying a strong therapeutic synergy between cell-targeted plasmonic heating and the associated silver release upon irradiation. The findings suggest a potential antibacterial use of Au@Ag NRs when coupled with light irradiation, which has not been previously described.

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