478034 Gold Templated Indicator for Ionizing Radiation

Monday, November 14, 2016
Grand Ballroom B (Hilton San Francisco Union Square)
Saumya Gupta, Karthik S. Pushpavanam, Sahil Inamdar and Kaushal Rege, Chemical Engineering, Arizona State University, Tempe, AZ

This research addresses the need for improvement in radiation sensors/dosimeters during radiotherapy. The current sensors involved are polymer gel dosimeters, MOSFETs, and radio-chromic films. Most sensors involved require expensive equipment’s and processing facilities for readout. There is still a need to develop better sensors that can be clinically applied. There are numerous groups around the world trying to conceive a better dosimeter. One of the radiation sensors that was developed recently was based on fluorescence signal emitted from the sensor. To advance the field of radiation sensors, we plan to use visual indication (colorimetric) as a method of detect ionizing radiation.

With an increase in cancer diagnosis in recent years, a treatment that is often prescribed is radiation therapy. When a patient undergoes radiation therapy, a portion of the patient’s body is bombarded with ionizing radiation in hopes that the radiation will stop the growth of the tumor. A small difference in the radiation dosage can be a critical factor in the patient’s battle against cancer. Unfortunately, even the smallest shift in the patient’s body, such as breathing during the treatment process, can shift the tumor, and, therefore, reduce the amount of effective radiation dosage. This indicator would be injected into the tumor and extracted post-procedure to be analyzed. This will reveal the exact amount of incident radiation.

The chemicals that are used in the formula as of now are gold nanoparticles, C16TAB, a surfactant, and nanopure water. The surfactant acts as a barrier between the gold nanoparticles and provides a method to keep them in the solution without thermodynamic precipitation. The Au3+ nanoparticles are diluted into the nanopure water and C16TAB in order to create a homogenous solution. Plasmonic nanoparticles, due to their unique physical and chemical properties, have received considerable attention in the recent past. Nanoparticles based on their formulation exhibit unique colors. This unique ability is the foundation behind our radiation sensors. Currently in literature there are numerous wet and dry methods to prepare nanoparticles one of which is using ionizing radiation.

Ionizing radiation splits water (solvent) into reducing and oxidizing agents. The reducing agents react with the metal ions and reduce them to zerovalent metals. The zero-valent metal, being unstable, aggregates to form larger nanoparticles. The formation of nanoparticles leads to an eventual color change that can be visually detected. In this case, we predict a linear correlation between change in color and the amount of radiation a sample receives.

A gold nanoparticle solution can be used to accurately determine the incident amount of ionizing radiation. We have developed a gold nanoparticle sensor in lab using Hexadecyltrimethylammonium bromide (C16TAB) as the templating molecule. When this solution comes into contact with ionizing radiation there is a visible color change as the gold salt is reduced and templated, creating a dispersion within the fluid.

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