Studies on the Exposure of Gadolinium Containing Nanoparticles with Monochromatic X-rays Drive Advances in Radiation Therapy

• Main Authors: Fuyuhiko Tamanoi, Kotaro Matsumoto, Tan Le Hoang Doan, Ayumi Shiro, Hiroyuki Saitoh
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: Nanomaterials
• Subjects: monochromatic X-ray; mesoporous silica nanoparticles; high-Z elements; tumor spheroids
• Online Access: https://www.mdpi.com/2079-4991/10/7/1341

While conventional radiation therapy uses white X-rays that consist of a mixture of X-ray waves with various energy levels, a monochromatic X-ray (monoenergetic X-ray) has a single energy level. Irradiation of high-Z elements such as gold, silver or gadolinium with a synchrotron-generated monochromatic X-rays with the energy at or higher than their K-edge energy causes a photoelectric effect that includes release of the Auger electrons that induce DNA damage—leading to cell killing. Delivery of high-Z elements into cancer cells and tumor mass can be facilitated by the use of nanoparticles. Various types of nanoparticles containing high-Z elements have been developed. A recent addition to this growing list of nanoparticles is mesoporous silica-based nanoparticles (MSNs) containing gadolinium (Gd–MSN). The ability of Gd–MSN to inhibit tumor growth was demonstrated by evaluating effects of irradiating tumor spheroids with a precisely tuned monochromatic X-ray.