NEW YORK, Oct. 25 (UPI) -- Exploding carbon nanotubes could serve as bombs that kill tumors, experts told UPI's Nano World.
In the last two years scientists have reported killing cancer using nanotubes and hollow nanoparticles known as nanoshells. Investigators gave cancers injections of nanotubes or nanoshells and then heated them up to 130 to 160 degrees F with high-power lasers.
Now nanotechnologist Balaji Panchapakesan at the University of Delaware and his colleagues report they can heat carbon nanotubes enough to explode using just low-intensity near-infrared lasers.
"They work almost like cluster bombs," Panchapakesan said. "Once they are exposed to light and the resulting heat, they start exploding one after another."
Prior studies had shown nanotubes could explode in air. Panchapakesan and his colleagues found they could explode metallic and semiconductor single-walled nanotubes in liquids as well, such as water or alcohol. Dramatic results were seen in saline solutions, due possibly to electrons the dissolved salt provided the nanotubes that may have enhanced the explosion.
The key was bundling nanotubes together. When a nanotube is by itself, the heat generated by the light is dispersed into the surroundings. In bundles, the heat cannot dissipate as quickly, with heat rising to nearly 1,300 degrees F. This vaporizes the liquid inside the nanotubes, and the result is "an explosion on the nanoscale," Panchapakesan said. The researchers can control the strength of the explosions by controlling the intensity of the lasers.
The researchers tested 1.5-to-4-nanometer-diameter tubes against breast-cancer cells. They blew cells treated with the nanotubes to pieces in less than 60 seconds, while leaving untreated cells intact, showing the explosions are highly localized. This is crucial for therapies that do not harm healthy tissues, explained surgical oncologist Nicholas Petrelli at Christiana Care Health Services in Newark, Del. "This could avoid many of the side effects seen with conventional treatments for cancer, such as nausea, vomiting, diarrhea and effects on bone marrow or platelet levels," he explained.
Recent investigations have shown that nanotubes might prove highly toxic for applications in the body. Panchapakesan said completely destroying the nanotubes could help overcome toxicity problems other nanotube-based treatments face. He and his colleagues will report their findings in the journal NanoBiotechnology.
In the future, Panchapakesan foresees injecting nanotubes into tumors or coating them with biomolecules that guide the nanotubes to their targets. Researchers can then shine lasers on the body and burst only cancer cells.
"This is very much in the preclinical stage of development, and not yet ready for primetime. A lot of issues need to be solved in the lab before it gets moved to the patient setting," Petrelli cautioned.
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Charles Choi covers research and technology for UPI. E-mail: [email protected]
