Literature Seminar: Combination of Ionizing Radiation and Gold Nanoparticles in Cancer Therapy

April 21, 2017

Md Rezaul Karim Khan, Department of Chemistry, Virginia Commonwealth University

Abstract
Ionizing radiation is ubiquitous; we are constantly being exposed to the natural and artificial radiation. Exposure of high-energy ionizing radiation such as gamma rays or X-rays to living cells can cause cancer, which is a leading cause of death worldwide and responsible for approximately 25 percent of all deaths in the USA and UK.1 Alternatively, this radiation can be used to destroy cancer cells using a procedure termed radiotherapy.  Radiotherapy is a common primary treatment procedure for multiple malignancies, including cancers of the head and neck, breast, lung, and prostate.2  According to American National Cancer Institute around half of all cancer patients go through some type of radiotherapy during the course of their treatment. Depending on the type, size, and location of the cancer; total radiation dose varies in radiotherapy. To protect healthy cells, the total radiation dose is divided into several smaller doses over a period of several days known as fractionated radiotherapy. To achieve quality treatment, the doses are need to be properly measured using radiation sensors such as thermoluminescent detectors and scintillating detectors.  Even though there are different kinds of sensors for radiation measurement, in many cases these dosimeters are not easy to handle and involve costly fabrication processes. Therefore there is a need for a simple visible sensor for fractionated radiotherapy. Nanotechnology combined with ionizing radiation can offer us an improved radiation sensor for better cancer treatment.3 In recent years, gold nanoparticles have attracted much attention of research for cancer treatment because of their simplistic synthesis and surface modification, strongly enhanced and tunable optical properties as well as excellent biocompatibility. A recent paper by Pushpavanam et al., addresses the fabrication of a simple and visible plasmonic nanosensor for radiation dose measurement during radiotherapy.2 Depending on the amount of ionizing radiation, colorless salt solutions of gold ions (Au+) convert to different colors of plasmonic gold nanoparticles. A change in color can help ensure the ease of identifying the radiation dose with the bare eye. Another paper by Wolfe et al., reports about dose enhancement in cancerous cell in radiotherapy using gold nanoparticles.  They show dose increment due to the interactions between ionizing radiation and gold nanoparticles via electron spin resonance dose measurement method in 2-Methyl-Alanine, a biological-equivalent sensitive material.4
References
1. Dreaden, E. C.; Austin, L. A.; Mackey, M. A.; El-Sayed, M. A. Size matters: gold nanoparticles in targeted cancer drug delivery. Therapeutic Delivery 2012, 3, 4, 457-478.
2. Pushpavanam, K., Narayanan, E., Chang, J., Sapareto, S., Rege. K. A Colorimetric Plasmonic Nanosensor for Dosimetry of Therapeutic Levels of Ionizing Radiation. ACS Nano 2015, 9, 12, 11540-11550.
3. Kwatra, D., Venugopal, A., Anant, S. Nanoparticles in radiation therapy: a summary of various approaches to enhance radiosensitization in cancer. Transl. Cancer Res. 2013, 2, 4, 330-342.
4. Wolfe, T., Guidelli, J.E., Gómez, A.J., Baffa, O., Nicolucci, P. oExperimental assessment of gold nanoparticle-mediated dose enhancement in radiation therapy beams using electron spin resonance dosimetry. Phys. Med. Biol. 2015, 60, 4465-4480.