Scientists from the Department of Nuclear Medicine and Tracer Kinetics at Osaka University developed a novel system for targeted cancer radiation therapy that uses gold nanoparticles labeled with astatine-211. Owing to the limited range and half-life of the radiation, along with the localization of the nanoparticles, healthy cells are considerably less likely to be harmed. This work may lead to effective cancer treatments without the side effects of current techniques.

Now, a team of scientists led by Osaka University has used gold nanoparticle “nanoseeds” containing a  to ensure that radiation was localized only to cancer cells. Astatine-211 is an unstable isotope of the element astatine that contains one extra neutron. This causes it to undergo radioactive decay while emitting . Because of their large size, rapidly moving alpha particles can cause fatal double-strand breaks in the DNA of cancer cells while remaining close to the radiation source. In addition, because the half-life of astatine-211 is so short, about 7 hours, it will become inactive long before the  can leak into healthy tissues. This allows large therapeutic doses to be administered without causing severe side effects. “We have developed a new safe and powerful cancer treatment using gold nanoparticles with astatine-211, which emits alpha rays that strongly damage target DNA but have a very short range inside the body,” first author Hiroki Kato explains.

Targeting cancer at the nanoscale
Figure 2: Gold nanoparticles (red) become internalized by cells and accumulate around the nucleus (blue). Credit: Hiroki Kato et al.

Using rat or mouse models, the nanoparticles were injected directly into tumors. The team found that the nanoparticles entered the cancer cells but did not spread to other organs during a time period equivalent to six radioactive half-lives. At the same time, the nanoparticles were highly toxic to the  cells. “We have demonstrated that tumor growth can be strongly suppressed by injecting this nano drug directly into the tumor,” senior author Koichi Fukase says. Because gold nanoparticles can be easily fabricated, and astatine-211 may be produced in cyclotrons without the need for , this new therapy can be made widely available in hospitals.

Read the Article


Light-controlled reactions at the nanoscale

Controlling strong electromagnetic fields on nanoparticles is the key to triggering targeted molecular reactions on their surfaces. Such control over strong fields is achieved via laser light. Although laser-induced formation and breaking of molecular [...]