McCormick Magazine

Tiny diamonds, big impact

Dean Ho’s gem of a drug-delivery system hides as it heal

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dean hoDiamonds and cloaks are the treasures and tools of jewel thieves, not professors. But when researchers use them on a much smaller scale, diamonds can help deliver drugs inside the human body, and cloaks in the form of polymer films can help shield the medicine from the body’s immune system and healthy cells.

Dean Ho, assistant professor of biomedical engineering and mechanical engineering at McCormick, has used these tools on a nanometer scale — or one billionth of a meter — to deliver chemotherapy to patients and to localize and disguise drugs from the immune system.

Nanodiamonds have a carbon structure similar to that of the diamonds we see in jewelry — but with a diameter of two to eight nanometers, hundreds of thousands of these nanodiamonds could fit onto the head of a pin. Ho and his research team aggregated clusters of 50 to 100 nanodiamonds and then loaded the chemotherapy drug on the surface. The drug remains inactive until the cluster reaches its target, when the cluster breaks apart and slowly releases the drug.

Researchers say that the clusters are ideal for carrying chemotherapy because they shield the drug from normal cells and prevent problems that plague current drug-delivery systems — such as inflammation, which can block the drug’s effectiveness and even promote tumor growth.

After the research was published it received nationwide media attention, including mentions in more than 100 outlets, such as CNN and United Press International.

In another study, Ho, along with researchers from Northwestern and UCLA, coated tiny chips with layers of the nanoscale polymer films, about four nanometers per layer, to build a sort of matrix or platform to hold and slowly release the anti-inflammatory drug Dexamethasone. The films act like an invisibility cloak, hiding the chips from the body’s defenses.

The coated chips were implanted in one group of mice and compared with a second group without implants and a third with uncoated implants to assess immune response. Researchers found that the coated implants suppressed the expression of cytokines, proteins released by the cells of the immune system to initiate a response to a foreign invader. By contrast, the uncoated implants generated an inflammatory response from the surrounding tissue, which ultimately would have led to the body’s rejection of the implant and the breakdown of its functionality. Tissue from the mice without implants and the mice with the coated implants was virtually identical, proving that the nano-cloaked implants were effectively shielded from the mice’s defense system.

“For chemotherapy, this system could enhance treatment efficacy while preventing uncontrolled delivery and the resultant patient side effects,” Ho says.

“Furthermore, as implantable devices continue to find widespread application in cardiovascular medicine, neural disorders, and diabetes, the nano-cloaking capabilities can serve as a widely applicable approach to extend the lifetime of these devices. This would eliminate unnecessary surgeries and enhance the efficiency of patient care.”

Ho recently received the Wallace H. Coulter Foundation Early Career Award for Translational Research. The award allows Ho to explore the application of devices that combine nanodiamond clusters and nanoscale polymer films to treat complications (e.g., inflammation and scarring) associated with open heart surgery.

“Nanotechnology is changing the face of drug treatment strategies,” Ho says. “We’re hoping our research will inspire new applications for nanomedicine that stand at the forefront of biology and engineering.”

—Emily Ayshford