(733h) A Facile Colorimetric Sensor of Ionizing Radiation Using Polypeptide Mediated Nanoparticle Formation

Widespread use of ionizing radiation, including X-rays and gamma rays, in food technology, imaging and cancer therapy necessitates precise control over dose, which in turn motivates the development of sensors that can detect various energy levels. A variety of dosimeters, including one-dimensional ion-chambers have been explored for different applications that require ionizing radiation. However, most available sensors suffer from drawbacks including portability and conformability. A potential solution to this problem lies in the development of liquid-phase dosimeters and sensors. We have developed a polypeptide-based sensor which changes color upon irradiation with ionizing radiation. In this approach, exposure to ionizing radiation results in radiolysis of water, resulting in the formaiton of free radicals. These, in concert of polypeptides, result in reduction of colorless metal (e.g. gold) salts to colored plasmonic nanoparticle dispersions. Polypeptides are hypothesized to act as both, templating as well as stabilizing agents in nanoparticle formation. The effect of radiation dose as well as kinetics of nanoparticle formation were investigated. The nanoparticles formed were extensively characterized using TEM, DLS and elemental analysis studies. Our studies on polypeptide-templated plasmonic metal nanoparticle formation indicate the possibility of developing a new class of dosimeters which can be used to detect ionizing radiation using a straightforward colorimetric method.