Nanowire implants offer remote-controlled drug delivery

Richard Borgens, director of Purdue University's Center for Paralysis Research, helps paralyzed dogs like Kady walk again with the help of treatments like polyethylene glycol (PEG) injections. In a recent study, more than half of the paralyzed dogs that received injections of the polymer within 72 hours of traumatic spinal injury were standing or walking again within weeks. (Credit: North Texan Magazine)

Richard Borgens, director of Purdue University’s Center for Paralysis Research (Credit: North Texan Magazine)

06/23/2015 |

A team of researchers led by Richard Borgens, Mari Hulman George Professor of Applied Neuroscience in Purdue Veterinary Medicine’s Department of Basic Medical Sciences, and director of Purdue’s Center for Paralysis Research (CPR), has created a new implantable drug-delivery system using nanowires that can be wirelessly controlled. The nanowires respond to an electromagnetic field generated by a separate device, which can be used to control the release of a preloaded drug.

Borgens says the system eliminates tubes and wires required by other implantable devices that can lead to infection and other complications. “This tool allows us to apply drugs as needed directly to the site of injury, which could have broad medical applications,” Borgens explains. “The technology is in the early stages of testing, but it is our hope that this could one day be used to deliver drugs directly to spinal cord injuries, ulcerations, deep bone injuries or tumors, and avoid the terrible side effects of systemic treatment with steroids or chemotherapy.” A paper detailing the results of laboratory testing is to be published in the Journal of Controlled Release.

The nanowires are made of polypyrrole, a conductive polymer material that responds to electromagnetic fields. Wen Gao, a postdoctoral researcher in the Center for Paralysis Research who worked on the project with Borgens, grew the nanowires vertically over a thin gold base, like tiny fibers making up a piece of shag carpet hundreds of times smaller than a human cell. The nanowires can be loaded with a drug and, when the correct electromagnetic field is applied, the nanowires release small amounts of the payload.

The process can be started and stopped at will, like flipping a switch, by using the corresponding electromagnetic field stimulating device, Borgens says. “This method allows a very, very small dose of a drug to effectively serve as a big dose right where you need it. By the time the drug diffuses from the site out into the rest of the body it is in amounts that are undetectable in the usual tests to monitor the concentration of drugs in the bloodstream.”

Other team members involved in the research include the CPR’s John Cirillo, who designed and constructed the electromagnetic field stimulating system; Youngnam Cho, a former CPR faculty member; and Jianming Li, a research assistant professor at the center.

– Elizabeth K. Gardner
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