Radiofrequency Heating of Gold Nanoparticles: Frequency and Size Study

Traditional cancer therapies such as chemotherapy and radiation are difficult for patients in terms of pain, effectiveness, and cost. To overcome these obstacles, doctors and researchers have been shifting towards hyperthermia applications. Heating of gold nanomaterials using electromagnetic radiation, particularly in the radiofrequency region, is highly desirable as this would be non-invasive and cost-effective. However, there has been a great deal of debate among researchers as to whether gold nanoparticles heat when exposed to radiofrequency (RF) fields and, if they do, this heating is limited to particles less than 10 nm in diameter. In this work, we show that  a variety of sizes of gold nanoparticles (AuNPs), including 20 and 30 nm particles, heat when exposed to megahertz range of RF fields. We experimentally demonstrate that AuNPs exhibit significant heating rates in the frequency range of 10 to 15 MHz. This work demonstrates that heating of gold solutions is not necessarily limited to size or frequency but depends more on the concentration of gold present and the size of the electric field applied. With this insight, we can continue to explore gold nanoparticles as candidates for RF hyperthermia applications.