Gold Nanoparticles for Imaging and Cancer Therapy

Abstract

Gold nanoparticles have properties useful in biomedical imaging and cancer therapy. This biocompatible metal has been used for centuries in medicine. In the last 20 years, the rapid developments in nanotechnology have revealed several applications of nanosized gold, which are now being evaluated for clinical procedures. For instance, gold nanoparticles can be used to develop sensors due to their optical properties; they also make possible the development of new hyperthermia and drug delivery treatments. However, gold nanoparticles could find more immediate and direct applications in medical physics procedures, such as X-ray imaging and radiotherapy. First, this chapter provides an overview of the different synthesis routes for the production of biomedical gold nanoparticles. Then, an overview of the physical principles of photon–matter interactions, that are fundamental to the concept of X-ray attenuation in biological tissues, is presented. The properties of gold nanoparticles as contrast agents for X-ray and computed tomography (CT) imaging are reviewed, along with the principles of the radiosensitization effect useful in medical physics and oncology. The main mechanisms leading to dose enhancement, to cell damage and to cell death, are described in the light of the specific interactions taking place between ionizing photons and high-Z materials such as gold (Au) when these are distributed in biological tissues such as tumours. Finally, the performance of gold nanoparticles as CT contrast agents and radiosensitizers in oncology is discussed, in the perspective of their consideration for clinical applications.