Impact of gold nanoparticles size and location on the dose-enhancement factor in the model of liquid crystal DNA dispersion

Gold nanoparticles (GNPs) are known for their ability to enhance the biological effect of ionizing radiation. The GNP localization relative to critical cellular targets, especially to nuclear DNA, in this application is decisive. Recent research has shown that the spatial distribution of GNPs in the particles of DNA liquid-crystalline dispersion modeling the density of chromatin packaging in vivo is determined by GNPs` size. In this paper, the absorbed dose of photon radiation with energy from 20 to 600 keV and dose enhancement factors (DEF) for two models of GNPs distribution relative to the particle of DNA liquid-crystalline dispersion were calculated by Monte Carlo method in the Geant4 code. GNPs` concentration were 1%, 2% and 4% of the DNA mass. The highest DEF from 13.2 to 1.1, depending on the photon energy, was obtained for the model №1. For Model №2, DEF depended little on the GNPs` size. The DEF values in model №1 were from 1.1 to 7.6 times more than in model №2 depending on photon energy. These results indicate the importance of the GNPs spatial distribution for the enhancement of absorbed dose in critical targets, especially in cell nucleus.