Dose enhancement factor caused by gold nanoparticles: influence of the dosimetric sensitivity and radiation dose assessed by electron spin resonance dosimetry

Abstract

Gold nanoparticles have been extensively used to increase the sensitivity of radiation dosimeters. In this work, nanocomposites of alanine (Ala), 2-methylalanine (2MA), asparagine (Asn) and monosodium glutamate (MSG) containing gold nanoparticles were prepared. The influence of the mass percentage of gold (0.1% up to 3%), absorbed dose (2 Gy–10 kGy) and the intrinsic sensitivity of these materials on the dose enhancement factor (DEF) were investigated. The prepared nanocomposites were characterized by UV–vis absorption spectroscopy and dynamic light scattering technique. Electron spin resonance spectroscopy was employed to assess the dosimetric response. The results revealed that the gold nanoparticles aggregated in the nanocomposites of MSG and Asn but not in the Ala and 2MA samples. Higher DEFs were observed for materials with lower intrinsic sensitivities (Asn and MSG) and for lower doses of radiation, suggesting that the dosimetric response of the nanocomposite dosimeters is governed by the probability of radical recombination. The higher the radiation dose, gold mass percentage and/or intrinsic sensitivity of the dosimetric material, the higher the production of radiation-induced free-radicals, enhancing the probability of radical recombination and resulting in lower DEFs. These results bring new insights about the use of gold nanoparticles to the construction of more sensitive radiation dosimeters.