Au@TiO2 Nanocomposites Synthesized by X-ray Radiolysis as Potential Radiosensitizers

Author

Maria C. Molina Higgins, PhD StudentFollow

DOI

https://doi.org/10.25772/B4VB-7Z70

Defense Date

2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Mechanical and Nuclear Engineering

First Advisor

Dr. Jessika Rojas

Abstract

Radiosensitization is a novel targeted therapy strategy where chemical compounds are being explored to enhance the sensitivity of the tissue to the effects of ionizing radiation. Among the different radiosensitizers alternatives, nanomaterials have shown promising results by enhancing tumor injury through the production of free radicals and reactive oxygen species (ROS). In this work, Gold-supported titania (Au@TiO₂) nanocomposites were synthesized through an innovative strategy using X-ray irradiation, and their potential as radiosensitizers was investigated. Radiosensitization of Au@TiO₂ nanocomposites was assessed by monitoring the decomposition of Methylene Blue (MB) under X-ray irradiation in the presence of the nanomaterial. Radiosensitization of Au@TiO₂ was thoroughly investigated as a function of parameters such as Au loading, TiO₂ particle size, nanomaterial concentration, different irradiation voltages, and dose rates. Results showed that the presence of Au@TiO₂ increases significantly the absorbed dose, thus enhancing MB decomposition. The mechanism behind Au@TiO₂ radiosensitization relies on their interaction with X-rays. TiO₂ produces reactive ROS whereas Au leads to the generation of photoelectrons and Auger electrons upon exposure to X-rays. These species lead to an enhanced degradation rate of the dye, a feature that could translate to cancerous cells damage with minimal side effects. The radiosensitization effect of Au@TiO₂ nanocomposites was also tested in biological settings using Microcystis Aeruginosa cells. The results showed an increase in cell damage when irradiated in the presence of Au@TiO₂ nanocomposites. Au@TiO₂ nanocomposites were fabricated using X-ray radiolytic synthesis, a method that diverges from conventional fabrication processes and leads to negligible by-product formation, an important feature for medical and catalytic applications. In this work, Au nanoparticles are supported on TiO₂ with a mean particle size of either 6.5 nm or 21.6 nm, using different ligands such as NaOH or urea, and under different absorbed doses to determine the effects of these parameters on the nanomaterials’ characteristics. Overall, Au@TiO₂ synthesized by X-rays showed remarkable promise as radiosensitizers, a concept relevant to a number of medical, biological and environmental applications.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

5-7-2019