Nanoscale dosimetric consequences around bismuth, gold, gadolinium, hafnium, and iridium nanoparticles irradiated by low energy photons

Abstract

In the current study, nanoscale physical dose distributions around five potential nanoparticles were compared. Five potential nanoparticles including bismuth, gold, gadolinium, hafnium, and iridium nanoparticles in the form of a sphere with a diameter of 50 nm were simulated in a water medium. The MCNPX (2.7.0) Monte Carlo code with updated libraries was used for calculations of electron dose deposition and electron flux in water from 25 nm up to 4000 nm with a step of 25 nm. Also, secondary electron spectra after irradiation of nanoparticles with mono-energetic photons with energies of 30, 60, 100 keV were derived. The nano-scale distance-dose curves showed a very steep gradient with distance from nanoparticle surface up to 60 nm and after this point, a gradual decrease was seen. The dose deposition characteristics in the nano-scale were dependent on the type of nanoparticle as well as photon energy. Our results concluded that for each photon energy in the energy range of 30-100 keV, a suitable nanoparticle can be selected to boost the effect of energy deposition by low energy photon beams used in brachytherapy.

Monometallic and alloy nanoparticles: a review of biomedical applications

“…Ir. In medicine, iridium systems have been used as photo agents 59 and biosensors. 60 An advantage of Ir NPs is its easy synthesis without surfactants or other solubilising ligands, which usually increase the amount of impurities in the final product.…”

Nanoscopic biodosimetry using plasmid DNA in radiotherapy with metallic nanoparticles

“…Here, the EF is defined as the ratio of the DNA damages in the presence and lack of NPs, and DEF refers to the ratio of the delivered dose in the presence and absence of NPs. There has been considerable work on the radiosensitizing efficacy of NPs, including mathematical, 24 , 25 in silico, 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 and in various biological systems including molecular solutions, 5 , 36 , 37 , 38 cell‐based models 39 , 40 , 41 , 42 , 43 , 44 and in vivo. 45 , 46 Ionizing radiation causes a variety of direct and indirect damage to DNA, including isolated (single‐strand break (SSB) and single base damages) and clustered/complex lesions (multiple DSBs and/or closely spaced (within 10–20 base pairs) non‐DSB (double strand break) lesions, such as oxidized bases and abasic sites) that affect genome integrity and DNA biochemistry.…”