Parameters governing gold nanoparticle X-ray radiosensitization of DNA in solution

Radiosensitization by gold nanoparticles (GNP) is a promising approach for improving radiotherapy. We report herein the results of an investigation of three key-parameters governing such radiosensitization in DNA, namely, DNA:GNP molar ratio, GNP diameter and incident X-ray energy. We performed irradiations with a clinical orthovoltage source and tested concentration ratios up to 1:1, five sizes of GNP from 8 to 92 nm and six effective X-ray energies from 14.8 to 70 keV. The most efficient parameters are found to be large-sized GNP, high molar concentration and 50-keV photons, which could potentially result in a dose enhancement factor of 6. The relevance of such parameters as regards the development of future therapeutic applications is discussed. To the best of our knowledge, this study constitutes the first report of systematic data on radiosensitization by GNP.