ON NEW TRENDS IN NANOMEDICINE: OXIDATIVE STRESS, GOLD NANOPARTICLES AND ULTRASOUND

35 years ago, a non-invasive method of cancer treatment was born and began to develop, using ultrasound to affect tumor tissue: sonodynamic therapy. Compared with other methods, its advantage is the deep penetration of ultrasound into biological tissue, which allows treating tumors in deep-lying organs in the patient's body. The active principle of the method is reactive oxygen species generated in the tissue under the influence of ultrasound: superoxide radical O2–, hydroxyl radical OH and hydrogen peroxide H2O2. Reactive oxygen species attack tumor cells, causing apoptosis. Sonosensitizers, special chemical structures with good biocompatibility and activated by ultrasound, are used to convert acoustic energy into chemical energy of reactive oxygen species and are delivered to the tumor in a targeted manner. Various organic and inorganic materials have been used as sonosensitizers. Three years ago, scientists from the University of Malaya first proposed and successfully tested sonosensitizers in the form of gold nanoparticles smaller than 5 nm in size. According to our hypothesis, such gold nanoparticles are sources of spontaneous emission of terahertz photons capable of generating reactive oxygen species in cells, causing oxidative stress and cell death. Then, when introducing such sonosensitizers into the practice of sonodynamic therapy, the latter, in addition to the “ultrasonic component”, will also contain a “background component”, the effect of which on cancerous tissue should also be taken into account. This article was written to emphasize this, as well as to provide a minimal overview of sonodynamic therapy itself.