Locally increased mortality of gamma-irradiated cells in presence of lanthanide-halide nanoparticles

Nathan J. Withers; Natasha N Glazener; John B. Plumley; Brian A. Akins; Antonio C. Rivera; Nathaniel C. Cook; Gennady A. Smolyakov; Graham S. Timmins; Marek Osiński

doi:10.1117/12.877029

15 February 2011 Locally increased mortality of gamma-irradiated cells in presence of lanthanide-halide nanoparticles

Nathan J. Withers, Natasha N Glazener, John B. Plumley, Brian A. Akins, Antonio C. Rivera, Nathaniel C. Cook, Gennady A. Smolyakov, Graham S. Timmins, Marek Osiński

Author Affiliations +

Proceedings Volume 7909, Colloidal Quantum Dots/Nanocrystals for Biomedical Applications VI; 79090L (2011) https://doi.org/10.1117/12.877029
Event: SPIE BiOS, 2011, San Francisco, California, United States

Abstract

Cerium-doped lanthanum fluoride colloidal nanocrystals (NCs) offer a way to improve radiation therapy through the enhanced absorption of high-energy photons. The use of Monte Carlo simulation allows the direct calculation of the macroscopic dose enhancement factor (MDEF), a figure of merit for NC-enhanced radiation therapy. Our simulations of brachytherapy using an Ir-192 source agree with previous work on the subject for gold NCs and show effectiveness of LaF₃:10%Ce NCs to be approximately 50% that of gold. Polyethylene-glycol-capped LaF₃:10%Ce NCs were synthesized, isolated, suspended in phosphate buffered saline (PBS), and characterized with transmission electron microscopy, dynamic light scattering, photoluminescence spectroscopy, and absorption spectroscopy. LaF3:10%Ce NCs were used in radiation dose enhancement experiments that involved an incoming 662 keV gamma flux from dual Cs-137 sources to test the mortality of Saccharomyces cerevisiae. At a small loading of 1.8 mg NC/g of PBS, the experiment did not produce a measurable increased mortality. To understand the results, additional Monte Carlo simulations revealed that the photon energy of 662 keV gamma rays is far from optimal, providing only a 4% increase in dose for a concentration of 18 mg of NCs / g of PBS. Further simulations showed that the optimal photon energy for this technique is 60 keV, tripling the absorbed dose for a concentration of 18 mg of NCs / g of PBS.

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Nathan J. Withers, Natasha N Glazener, John B. Plumley, Brian A. Akins, Antonio C. Rivera, Nathaniel C. Cook, Gennady A. Smolyakov, Graham S. Timmins, and Marek Osiński "Locally increased mortality of gamma-irradiated cells in presence of lanthanide-halide nanoparticles", Proc. SPIE 7909, Colloidal Quantum Dots/Nanocrystals for Biomedical Applications VI, 79090L (15 February 2011); https://doi.org/10.1117/12.877029

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