Northwestern University -- Researchers at Northwestern University are using nanodiamonds – miniscule carbon particles – to treat breast and liver cancer. Successful tests in mice have used the nanoparticles as a drug delivery system, releasing cancer treatment drugs over time and making them more effective. “We were able to boost the efficiency 70 times but maintain the safety. It’s the best of both worlds,” said Dean Ho, an associate professor of biomedical engineering at Northwestern University and the leader of the research lab that published these findings Wednesday in Science Translational Medicine.
Nanodiamonds are carbon particles between 2 and 8 nanometers in diameter, more than 10,000 times smaller than a human hair.
And in this case, size matters. The particles are used to deliver drugs to cancerous cells, but they must still be small enough that they can leave the body once the job is done.
On a microscopic scale, these particles are similar to the gemstone that shares their name.“It’s not as flashy as the larger analog of it, but the organized lattice structure, it is diamond-like in structure, it’s just not big,” Ho said.
Northwestern researchers have found that nanodiamonds are particularly useful in delivering drugs, not only because of their size, but because of their shape.
“They’re called truncated octahedrons,” he said. “They’re shaped like a soccer ball but the faces are more angled.” These facets allow drugs to bind very tightly against the surface of the nanodiamond, making an extended release of drugs possible.
“That’s important because drugs that are often used to treat things like cancer are very toxic and any time you can sustain their release, you can hopefully try to reduce the amount of drugs you need to give a patient.”
This method can also reduce the side effects of devastating chemotherapies, he said. “The surface chemistry, coupled with the architecture of the surface, allows for a very sustained interaction with drugs,” Ho said.
Drugs can be either directly bound to the nanodiamonds, or they can be bound temporarily using the electrostatic charge of the particle. Some drugs can find a way to work if they’re not released from the diamond, but for others that need to come off the diamond in order to function, the electrostatic charge can attach them to the diamond and then unbind, he said.
“Nanotechnology in general can enhance delivery, which would improve on the targeting of therapeutic agents,” said Steven Rosen, the director of Robert H. Lurie Comprehensive Cancer Center of Northwestern University in Chicago.
Nanomedicine has been a significant advancement, he said, because it’s less toxic than the drug alone and also has homing qualities. “The nanoparticles are really sort of carrier bins in many instances or unique chemical structures that could target specific molecules. You can link antibodies to the bin that selectively go to a specific tumor site,” Rosen said.
Ho’s team tested the nanodiamond delivery system on liver and breast cancer using a common chemotherapy drug. “The drug we used is doxorubicin. It’s a clinically relevant drug that’s used on patients,” said Ho. “It’s very effective at killing cancer cells but it’s also very effective at killing everything else. We found that if you bind the drugs to the diamond, the efficiency is even enhanced compared to using the drug alone.”
Because the liver metabolizes drugs and also detoxifies the blood, this method works especially well to treat liver cancer. “A lot of this stuff ends up at the liver anyways and it takes some time to get there, but it also takes even a little bit longer to come off the diamond,” said Ho. “So you’re getting this packaged drug going through the blood stream, but then you get the stuff that also comes off over time and a fair amount of that will come off while it’s still in the tumor. It’s the best of both worlds.
One of the questions with nanoparticles is whether the material injected with the drug will cause any side effects, especially when treating the liver, where foreign materials are filtered out of the body. “You don’t want to poison the organ,” said Ho. “And we find that it doesn’t appear to affect liver toxicity even at very high dosages. We also find that it doesn’t seem to cause blood toxicity, systemically. It appears to be a relatively biocompatible system.”
The nanodiamond delivery system has also been found to reduce side effects of chemotherapy. Reduction in white blood cell count is one of the major side effects, he said, that limits the dosage a patient can be prescribed.
“If the white blood cell count, which is essentially your immune system, drops below a certain level you have to stop treatment to avoid superinfections,” said Ho. “One of the things we find is that when you bind the diamond to the drug, from our studies, it doesn’t drop the white blood cell count, yet it still has efficacy to reduce tumor size.”
