Nanowires deliver drugs on target
Submitted by user_64683 on 01 July, 2015.
Published date:
Wednesday, July 1, 2015 - 21:45
SEM image: Polypyrrole nanowires make a new drug delivery system. [Purdue/Borgens]
Researchers have unveiled a stunning SEM image of a nanowire implantable drug delivery system that can be wirelessly controlled to release its payload.
The nanowires respond to electromagnetic fields generated by a remote device, and crucially, the system eliminates the need for tubes and wires that can lead to infection.
"This tool allows us to apply drugs as needed directly to the site of injury," says Professor Richard Borgens from the Weldon School of Biomedical Engineering at Purdue University.
"The technology is in the early stages of testing but it is our hope that it could one day be used to deliver drugs directly to spinal cord injuries, ulcerations, deep bone tumours," he adds.
To fabricate the system, Borgens and colleagues grew electromagnetically-sensitive polypyrrole nanowires onto a thin gold substrate, to form a patch of the nanowires.
They then loaded the patches with the corticosteriod Dexamethasine, deposited it onto spinal cord lesions within mice, and applied an electromagnetic field for two hours, every day, for a week.
A) SEM and B) TEM images of vertically arranged gold embedded polypyrrole nanowires. Individual nanowires sometimes became attached at their apex (arrows) due to the softness of the materials and preparation for SEM. [Wen Gao, Richard Ben Borgens/Journal of Controlled Release]
Bioluminescent imaging, on the living mice, revealed that glial fibrillary acidic protein overexpression - an indicator of neuroinflammation in spinal cord injury - was significantly reduced in the treated animals.
"This method allows a very, very small dose of a drug to effectively serve as a big dose right where you need it," explains Borgens "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, biocompatible material, but the researchers are now working to create a biodegradable form of the system, that would dissolve after treatment.
They are also carrying out research to pinpoint the exact mechanism of the drug release process.
An image of a field of polypyrrole nanowires captured by SEM [Purdue University/Richard Borgens]
"This is a reversible process. Once the electromagnetic field is removed, the polymer snaps back to the initial architecture and retains the remaining drug molecules," adds Borgens
Research is published in the Journal of Controlled Release.
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