Metal Nanoparticles as Radiosensitizers for Cancer Radiotherapy in Vivo

Abstract

Metal nanoparticles are capable of enhancing the destructive effect of ionizing radiation on biological tissue, which allows them to be used as radiosensitizers for improving the efficacy of cancer radiotherapy. The most promising nanoparticles are those with a high atomic number (Z>52), since they can serve both as dose-enhancing agents for contrast-enhanced radiotherapy and as contrast media for computed tomography. Due to the high metal content in each particle and the ability to selectively accumulate in tumor tissue, nanoscale agents can deliver more metal atoms to the tumor compared to low-molecular compounds. At present, only two metal nanoparticle agents (NBTXR3 and AGuIX) are undergoing clinical trials as radiosensitizers. However, a wide range of nanoparticles with different composition and structure is being extensively studied in laboratory animals. This review summarizes the results of in vivo studies where nanoparticles containing gold, bismuth or gadolinium were used in combination with external photon irradiation in order to inhibit the growth of model tumors in small laboratory animals.