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Friday, October 3, 2008

Nanodiamond drug device could transform cancer treatment

Nanodiamond-embedded devices could be used to deliver a broad range of therapeutics for the treatment of cancer and inflammation and for regenerative medicine. The extremely thin and flexible devices also can be customized to any shape and thickness.

A Northwestern University research team has developed a promising nanomaterial-based biomedical device that could be used to deliver chemotherapy drugs locally to sites where cancerous tumors have been surgically removed.

The flexible microfilm device, which resembles a piece of plastic wrap and can be customized easily into different shapes, has the potential to transform conventional treatment strategies and reduce patients' unnecessary exposure to toxic drugs. The device takes advantage of nanodiamonds, an emergent technology, for sustained drug release.

In their study, Ho and his colleagues embedded millions of tiny drug-carrying nanodiamonds in the FDA-approved polymer parylene. Currently used as a coating for implants, the biostable parylene is a flexible and versatile material resembling plastic wrap. A substantial amount of drug can be loaded onto clusters of nanodiamonds, which have a high surface area. The nanodiamonds then are put between extremely thin films of parylene, resulting in a device that is minimally invasive.

To test the device's drug release performance, the researchers used Doxorubicin, a chemotherapeutic used to treat many types of cancer. They found the drug slowly and consistently released from the embedded nanodiamond clusters for one month, with more Doxorubicin in reserve, indicating a more prolonged release (several months and longer) was possible. The device also avoided the "burst" or massive initial release of the drug, a common disadvantage with conventional therapy.

In control experiments, where the drug was present but without the nanodiamonds, virtually all of the drug was released within one day. By adding the drug-laden nanodiamonds to the device, drug release was instantly lengthened to the months-long timescale.

In addition to their large surface area, nanodiamonds have many other advantages that can be utilized in drug delivery. They can be functionalized with nearly any type of therapeutic. They can be suspended easily in water, which is important for biomedical applications. The nanodiamonds, each being four to six nanometers in diameter, are minimally invasive to cells, biocompatible and do not cause inflammation, a serious complication. And they are very scalable and can be produced in large quantities.

The architecture of the device is amenable to housing small molecule, protein, antibody or RNA- or DNA-based therapeutics. This gives the technology the potential to impact a range of treatment strategies where implanted, long-term drug release is needed.