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Proton Activation of Gold Nanoparticles (GNPs) and Quantum Dots (QDs) for Gamma (SPECT/PET) and Optical (luminescence) Imaging Applications

J Cho

J Cho1*, R Mangaiyarkarasi2 , S Bastani3 , C Kingsley4 , O Mawlawi5 , C Gonzalez-Lepera6 , (1) Oklahoma State University, Stillwater, OK, (2) Oklahoma State University, Stillwater, OK, (3) Oklahoma State University, Stillwater, OK, (4) UT MD Anderson Cancer Center, Houston, TX, (5) MD Anderson Cancer Ctr., Houston, TX, (6) UT MD Anderson Cancer Center, Houston, TX


TH-AB-FS4-6 (Thursday, August 3, 2017) 7:30 AM - 9:30 AM Room: Four Seasons 4

Purpose: Despite the extensive use of gold nanoparticles (GNPs) and quantum dots (QDs), the in vivo imaging capabilities that they offer are limited. GNPs and QDs can be radio-labeled or radionuclide-doped for PET and SPECT imaging, however, there are risks for radionuclide dissociation. We were motivated to create inherently radioactive GNPs and inherently radioactive and self-illuminating QDs for PET/SPECT/optical imaging applications.

Methods: Approximately 40 mg of GNPs (AuroVistTM 1.9 nm) were dissolved and deposited to dry on a 0.13 mm thick aluminum disk and then was covered with a 30 μm thick aluminum disk (both 12 mm diameter). Similarly, 33 mg of QDs (CdSe/ZnS, NN-Labs, Inc.) were prepared. Each sample (GNPs or QDs) in the aluminum disks was placed in the COMECER target holder and was bombarded with protons (14.3MeV energy on GNPs or QDs) with a 10 μA beam for 10 minutes. Each bombarded sample was then placed in a dose calibrator to assay radioactivity and a small fraction of each sample was placed in a HPGe detector for gamma spectroscopy. 3 hours after proton bombardment, QDs were placed in IVIS for luminescence imaging.

Results: Gamma spectroscopy for proton bombarded GNPs showed gamma peaks (134keV and others) from decaying 197Hg (T½=23.8 hr) from 197Au(p,n)197Hg interactions. Similarly, proton bombarded CdSe/ZnS QDs showed gamma peaks (171, 245, and 511 keV) from decaying 111In (T½=2.8 days) and 76Br (T½=16.2 hr) from 111Cd(p,n)111In, and 76Se(p,n)76Br interactions. Luminescence imaging displayed strong Cherenkov luminescence and some evidence of QD self-activation in terms of self-luminescence.

Conclusion: 134 keV gamma emissions from proton-activated GNPs may be ideal for high resolution SPECT imaging. 171, 245, and 511 keV gamma emissions from the proton activated QD can be utilized for SPECT and PET imaging. Cherenkov and UV luminescence from proton activated QDs may self-excite QD for QD luminescence.

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