Date of Award

2020

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Physics

Department

Physics

First Advisor

Michael P. Antosh

Abstract

Radiation therapy is a common technique to kill cancer cells. The purpose of this experiment is the enhancement of radiation effect on the treatment of tumors. The main difficulty of radiation therapy is that it can damage cancerous cells as well as healthy cells. Gold nanoparticles can enhance effects of the radiation treatment on tumors due to the interaction of radiation with gold nanoparticles to produce extra electrons through the Auger effect. This causes reduced side effects on healthy cells though using less radiation dose and maximizes radiation damage on cancer cells through the extra electrons produced by the gold nanoparticles. Gold nanoparticles can enhance the radiation dose using in vitro and in vivo experiments. Using in vitro studies, size is an important variable.

Copper-Cysteamine (Cu-Cy) nanoparticle is a promising new nanoparticle that can produce singlet oxygen irradiated by X-rays and is appropriate for cancer treatment. Copper-Cysteamine (Cu-Cy) nanoparticles can be used to enhance radiation effectiveness in mice.

My Ph. D research investigates the following topics:

  • The effect of gold nanoparticles size and radiation energy on cancer cells survival and uptake in radiation therapy.
  • Review of the effect of size on gold nanoparticles in radiation therapy in cancer cells.
  • The effect of copper-cysteamine nanoparticles size and radiation energy on radiation therapy enhancement.

In a review work I have focused on how the size of gold nanoparticles can affect the amount of radiation enhancement. Based on the literature, the non-targeted gold nanoparticles 50 nm have maximum radiation therapy enhancement. The enhancement of radiation therapy of gold nanoparticles depends on various cell lines, the concentration of gold, sizes of the particles, radiation energy and intracellular localization in vitro and in vivo.

In experimental work I found that the size of gold nanoparticles plays a key factor in radiation enhancement. Gold nanoparticles size can enhance radio-sensitization effects by how they interact with radiation and cancer cells. We examined an in vitro experiment on JC mouse breast cancer cells using gold nanoparticles sizes 5, 15, 30, 50 and 100 nm with X-rays. The cells were treated with the same mass of gold nanoparticles (0.05 μg) for each size, with different energies (100, 250, and 350 kVp). The results showed that all sizes of gold nanoparticles decreased cell survival. The cancer cells of 50 nm gold nanoparticles (p= 0.0001) were significantly less than 5 nm gold nanoparticles (p= 0.0013).

Gold nanoparticles are versatile materials for biomedical applications because they are relatively inert, stable, and easily synthesized. Gold nanoparticles are treated into the tumors and irradiated with X-rays. This is due to gold nanoparticles releasing an extra electron by the Auger effect. The Auger electron has low energy and is deposited within the tumor to kill the cancer cells.

Copper-Cysteamine (Cu-Cy) nanoparticles can efficiently destroy cancer cells by X-rays through production of a singlet oxygen molecule. The Cu-Cy nanoparticle increases the effectiveness of radiation therapy for cancer patients. The cell survival of the melanoma cancer cells was tested as a function of Cu-Cy nanoparticle size. The hyaluronic acid conjugated with larger size of Cu-Cy (200 nm) decreased cell survival compared to the smaller size (40 nm) of Cu-Cy at 90 kVp with a dose of 2 grays. The results showed that all sizes of Cu-Cy nanoparticles decreased cell survival in cancer cell.

Available for download on Wednesday, July 06, 2022

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