Gold Nanocages at forefront of modern cancer treatment

| Staff Reporter

The push of a button launches a missile, which hones in on its final destination and, KA-BOOM, obliterates its target.

While this image may remind you of modern warfare at the macroscopic scale, scientists have also applied this principle to combat cancer at the molecular level with gold nanocages attacking tumor cells.

The nanocages were recently synthesized and evaluated by Professor of Biomedical Engineering Younan Xia, Professor of Radiology Michael Welch and their colleagues, as described in an article published in the Small journal this past March.

Similar to how real missiles destroy their targets via heat, these novel gold nanocages can absorb a certain wavelength of light and convert it into energy with high efficiency.

“Although you might think that gold is a weird thing to be injecting into people, actually people have been using gold colloid to treat arthritis for almost a hundred years,” Welch said.

By heating up, these nanoparticles can kill the tumor cells around them through a process called local tumor hyperthermia.

To evaluate the therapeutic effect of these irradiated gold nanocages on tumor cells, researchers injected the nanoparticles into animals, irradiated them, and monitored the cellular metabolism using 18F-fluorodeoxyglucose positron emission tomography (18F- FDG PET).

In addition to evaluating cellular metabolism, researchers also analyzed the anatomy of the cells after radiation via histology.

Overall, these studies revealed that the cellular metabolism decreased and that the tumor cells showed irreversible damage, both supporting the treatment to be effective.

Gold may be particularly advantageous for medicinal purposes because it is inert, preventing it from being cleared from the body, according to Welch.

The revelation comes as a breakthrough in this area.

“Hyperthermia is an area that people have investigated for many years, and people have tended to do it simply by using ultrasound irradiation of the tumor,” Welch said. “By putting particles in and heating tumors, it is much easier to kill tumor cells.”

These promising results have attracted much attention and financial support in the scientific community, including a five-year grant from the National Institutes of Health awarded in mid-February to fund further investigations.

Using the grant, researchers plan to continue improving the gold nanocages by enhancing their tumor-targeting ability.

“What we want to do with the grant is to compare nanoparticles that just passively diffuse into tumors with particles that are targeted with specific targeting agents,” Welch said.

Researchers plan to attach small molecules, such as antibodies, that can specifically recognize tumor cells onto the gold nanocages to synthesize “guided” molecular missiles.

The design aims to increase the tumor uptake of the nanoparticles, which would increase therapeutic effects and decrease side effects.

Although much progress has been made to improve the nanoparticles, there are still many challenges ahead.

“The challenge is to be able to put the targeting molecule on the nanoparticle and keep the nanoparticle in the circulation and stop the nanoparticle from being cleared by the liver,” Welch said.

Despite the challenges presented, Welch continues to be optimistic about the future promises of these gold nanocages.

To learn more about these cancer-fighting gold nanocages, please refer to the article “Gold Nanocages as Photothermal Transducers for Cancer Treatment” in the Small journal.