MO-FG-303-08: PET-Detectable Bimetallic (Zn@Au) Nanoparticles for Radiotherapy and Molecular Imaging Applications

Authors

  • Cho J,

    1. UT MD Anderson Cancer Center, Houston, TX
    2. Rice University, Houston, TX - Texas
    3. University of Texas MD Anderson Cancer Center, Houston, TX - Texas
    4. Rice University, Houston, TX - Texas
    5. UT MD Anderson Cancer Center, Houston, TX
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  • Wang M,

    1. UT MD Anderson Cancer Center, Houston, TX
    2. Rice University, Houston, TX - Texas
    3. University of Texas MD Anderson Cancer Center, Houston, TX - Texas
    4. Rice University, Houston, TX - Texas
    5. UT MD Anderson Cancer Center, Houston, TX
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  • Gonzalez-Lepera C,

    1. UT MD Anderson Cancer Center, Houston, TX
    2. Rice University, Houston, TX - Texas
    3. University of Texas MD Anderson Cancer Center, Houston, TX - Texas
    4. Rice University, Houston, TX - Texas
    5. UT MD Anderson Cancer Center, Houston, TX
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  • Zubarev E,

    1. UT MD Anderson Cancer Center, Houston, TX
    2. Rice University, Houston, TX - Texas
    3. University of Texas MD Anderson Cancer Center, Houston, TX - Texas
    4. Rice University, Houston, TX - Texas
    5. UT MD Anderson Cancer Center, Houston, TX
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  • Cho S

    1. UT MD Anderson Cancer Center, Houston, TX
    2. Rice University, Houston, TX - Texas
    3. University of Texas MD Anderson Cancer Center, Houston, TX - Texas
    4. Rice University, Houston, TX - Texas
    5. UT MD Anderson Cancer Center, Houston, TX
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Abstract

Purpose:

A technical challenge in clinical translation of GNP-mediated radiotherapy is lack of in-vivo imaging tools for monitoring biodistribution of GNPs. While several modalities (x-ray fluorescence, photoacoustic, etc.) are investigated, we propose a potentially more effective technique based on PET imaging. We developed Zn@Au NPs whose Zn core acts as positron emitters when activated by protons, while the Au shell plays the original role for GNP-mediated radiosensitization.

Methods:

Spherical Zn NPs (∼7nm diameter) were synthesized and then coated with ∼7nm thick Au layer to make Zn@Au NPs (∼20nm diameter). A water slurry containing 29mg of Zn@Au NPs was deposited (<10µm thickness) on a thin cellulose target and subsequently baked to remove the water. The cellulose matrix was placed in an aluminum target holder and irradiated with 14.5MeV protons from a GE PETtrace cyclotron with 4µA for 5min. After irradiation the cellulose matrix with the NPs was placed in a dose calibrator to assay radioactivity. Gamma spectroscopy using a HPGe detector was conducted on a very small fraction (<1mg) of the irradiated NPs.

Results:

We measured 158µCi of activity 32min after end of bombardment (EOB) using 66Ga setting on the dose calibrator (contribution from the cellulose matrix is negligible) which decreased to 2µCi over a 24hrs period. A gamma spectrum started one hour after EOB on the small fraction and acquired for 700sec showed a strong peak at 511keV (∼40,000 counts) with several other peaks (highest peak <1200 counts) of smaller magnitude.

Conclusion:

Strong 511keV gamma emission from proton-activated Zn cores can potentially be utilized to image the biodistribution of Zn@Au NPs using a PET scanner. The developed Zn@Au NPs are expected to retain radiosensitizing capability similar to solid GNPs, while observable through PET imaging for human-sized objects. Moreover, bioconjugated PET-detectable GNPs would allow a new option to perform molecular imaging.

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