[tt] Nanoengineers mine tiny diamonds for drug delivery | Science Blog

Brian Atkins <brian at posthuman.com> on Fri Oct 12 22:47:56 UTC 2007

http://www.scienceblog.com/cms/nanoengineers-mine-tiny-diamonds-drug-delivery-14505.html

Northwestern University researchers have shown that nanodiamonds -- much like 
the carbon structure as that of a sparkling 14 karat diamond but on a much 
smaller scale -- are very effective at delivering chemotherapy drugs to cells 
without the negative effects associated with current drug delivery agents.

Their study, published online by the journal Nano Letters, is the first to 
demonstrate the use of nanodiamonds, a new class of nanomaterials, in 
biomedicine. In addition to delivering cancer drugs, the model could be used for 
other applications, such as fighting tuberculosis or viral infections, say the 
researchers.

Nanodiamonds promise to play a significant role in improving cancer treatment by 
limiting uncontrolled exposure of toxic drugs to the body. The research team 
reports that aggregated clusters of nanodiamonds were shown to be ideal for 
carrying a chemotherapy drug and shielding it from normal cells so as not to 
kill them, releasing the drug slowly only after it reached its cellular target.

Another advantage of the material, confirmed by a series of genetic studies also 
reported in the paper, is that nanodiamonds do not cause cell inflammation once 
the drug has been released and only bare diamonds are left. Materials currently 
used for drug delivery can cause inflammation, a serious complication that can 
predispose a patient to cancer, block the activity of cancer drugs and even 
promote tumor growth.

“There are a lot of materials that can deliver drugs well, but we need to look 
at what happens after drug delivery,” said Dean Ho, assistant professor of 
biomedical engineering and mechanical engineering at Northwestern’s McCormick 
School of Engineering and Applied Science, who led the research. “How do cells 
react to an artificial material left in the body? Nanodiamonds are highly 
ordered structures, which cells like. If they didn’t, cells would become 
inflamed. From a patient’s perspective, this is very important. And that’s why 
clinicians are interested in our work.”

“Novel drug delivery systems, such as the one being developed by Dean and his 
team, hold great promise in cancer therapeutics,” said Steven Rosen, M.D., 
director of the Robert H. Lurie Comprehensive Cancer Center of Northwestern 
University and Genevieve E. Teuton Professor of Medicine at Northwestern’s 
Feinberg School of Medicine. “We anticipate they will allow for more 
sophisticated means of targeting cancer cells while sparing healthy cells from a 
drug’s toxicity.”

To make the material effective, Ho and his colleagues manipulated single 
nanodiamonds, each only two nanometers in diameter, to form aggregated clusters 
of nanodiamonds, ranging from 50 to 100 nanometers in diameter. The drug, loaded 
onto the surface of the individual diamonds, is not active when the nanodiamonds 
are aggregated; it only becomes active when the cluster reaches its target, 
breaks apart and slowly releases the drug. (With a diameter of two to eight 
nanometers, hundreds of thousands of diamonds could fit onto the head of a pin.)

“The nanodiamond cluster provides a powerful release in a localized place -- an 
effective but less toxic delivery method,” said co-author Eric Pierstorff, a 
molecular biologist and post-doctoral fellow in Ho’s research group. Because of 
the large amount of available surface area, the clusters can carry a large 
amount of drug, nearly five times the amount of drug carried by conventional 
materials.

Liposomes and polymersomes, both spherical nanoparticles, currently are used for 
drug delivery. While effective, they are essentially hollow spheres loaded with 
an active drug ready to kill any cells, even healthy cells that are encountered 
as they travel to their target. Liposomes and polymersomes also are very large, 
about 100 times the size of nanodiamonds -- SUVs compared to the nimble 
nanodiamond clusters that can circulate throughout the body and penetrate cell 
membranes more easily.

Unlike many of the emerging nanoparticles, nanodiamonds are soluble in water, 
making them clinically important. “Five years ago while working in Japan, I 
first encountered nanodiamonds and saw it was a very soluble material,” said 
materials scientist Houjin Huang, lead author of the paper and also a 
post-doctoral fellow in Ho’s group. “I thought nanodiamonds might be useful in 
electronics, but I didn’t find any applications. Then I moved to Northwestern to 
join Dean and his team because they are capable of engineering a broad range of 
devices and materials that interface well with biological tissue. Here I’ve 
focused on using nanodiamonds for biomedical applications, where we’ve found 
success.

“Nanodiamonds are very special,” said Huang. “They are extremely stable, and you 
can do a lot of chemistry on the surface, to further functionalize them for 
targeting purposes. In addition to functionality, they also offer safety -- the 
first priority to consider for clinical purposes. It’s very rare to have a 
nanomaterial that offers both.”

“It’s about optimizing the advantages of a material,” said Ho, a member of the 
Lurie Cancer Center. “Our team was the first to forge this area -- applying 
nanodiamonds to drug delivery. We’ve talked to a lot of clinicians and described 
nanodiamonds and what they can do. I ask, ‘Is that useful to you?’ They reply, 
‘Yes, by all means.’”

For their study, Ho and his team used living murine macrophage cells, human 
colorectal carcinoma cells and doxorubicin hydrochloride, a widely used 
chemotherapy drug. The drug was successfully loaded onto the nanodiamond 
clusters, which efficiently ferried the drug inside the cells. Once inside, the 
clusters broke up and slowly released the drug.

In the genetic studies, the researchers exposed cells to the bare nanodiamonds 
(no drug was present) and analyzed three genes associated with inflammation and 
one gene for apoptosis, or cell death, to see how the cells reacted to the 
foreign material. Looking into the circuitry of the cell, they found no toxicity 
or inflammation long term and a lack of cell death. In fact, the cells grew well 
in the presence of the nanodiamond material.

http://www.northwestern.edu

-- 
Brian Atkins
Singularity Institute for Artificial Intelligence
http://www.singinst.org/

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