Evaluation of gold nanoparticles radio sensitization effect in radiation therapy of cancer

In recent years, the use of gold nanoparticles (GNPs) in radiation therapy has been studied by experimentation and Monte Carlo simulation repeatedly. Although the idea of increasing doses has been raised by high-atomic elements since decades ago, but due to the adaptation of gold nanoparticles with the biological system, scientists have incited more about the various uses of these materials in radiation therapy. The results of all studies in this field are consistent with the increase in tumor-derived doses with gold nanoparticles in radiotherapy. But the results of the interaction of radiation energy are still controversial with the size of gold nanoparticles. In other words, in the Monte Carlo simulations the gold nanoparticles with a size of about 10 to 100 nm, and in biological studies, the nanoparticles with a dimension of 1.9 nm were used. On the other hand, some studies of energy dependence have been developed in dose enhancement, and in some other studies the effect of the size of gold nanoparticles has been investigated on photon energy. However, in some respects, the results of radiation therapy using by gold nanoparticles does not appear to be definitive, although the photoelectric effect in low energies is considered to be the dominant phenomenon. The main idea behind the GNP dose enhancement in some studies is not able to explain the results especially in recent investigation on cell lines and animal models radiation therapy using GNPs. With the rapid development of nanotechnology in the biomedical field, GNPs have been widely used in the diagnosis and treatment for disease. Numerous pre-clinical studies in vitro and in vivo have proved the potential value of metal-based GNPs as radio sensitizers in cancer treatment. Various studies have indicated that radio sensitizing ability could be influenced by nanomaterial size, concentration, surface coating, and the radiation energy. Hence, gold nanostructures provide a versatile platform to integrate many therapeutic options leading to effective combinational therapy in the fight against cancer. In this review article, the recent progress in the development of gold-based NPs towards improved therapeutics will be discussed. A multifunctional platform based on gold nanostructures with targeting ligands, therapeutic molecules, and imaging contrast agents, holds an array of promising directions for cancer research.