American researchers have developed a nanowire-based drug delivery system that can be controlled remotely via an electromagnetic field to improve treatment efficiency.
Unlike existing drug delivery systems, the implantable nanowires don’t need to be connected to any tubes or cables, reducing the risk for the patients of developing infections.
"This tool allows us to apply drugs as needed directly to the site of injury, which could have broad medical applications," said Richard Borgens, professor of applied neuroscience at the Purdue University and leader of the research team.
"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 tumours and avoid the terrible side effects of systemic treatment with steroids or chemotherapy."
The nanowires, made of a conductive polymer material called polypyrrole, respond to an electromagnetic field generated by a remote control device.
The researchers grew the nanowires vertically over a thin gold base smaller than a human cell. This approach gave the device a sort of ‘carpet-like’ structure that can soak in drugs. When the correct electromagnetic field is applied, the nanowires release a small amount of the medication into the patient’s body.
"We think it is a combination of charge effects and the shape change of the polymer that allows it to store and release drugs," said Borgens. "It is a reversible process. Once the electromagnetic field is removed, the polymer snaps back to the initial architecture and retains the remaining drug molecules."
The team tested the drug-delivery system in mice with compression injuries to their spinal cords. The drug administered through the nanowire ‘carpet’ was the corticosteroid dexamethasone. The study measured a molecular marker of inflammation and scar formation in the central nervous system and found that it was reduced after one week of treatment.
"This method allows a very, very small dose of a drug to effectively serve as a big dose right where you need it," Borgens said. "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."
Polypyrrole is an inert and biocompatable material, but the team is working to create a biodegradeable form that would dissolve after the end of the treatment period.
The current device only works when implanted close to the surface, some 3cm deep. The researchers are now trying to increase this depth to be able to delivery drugs into deeper structures of the body.