Six researchers in the Department of Biomedical Engineering have created a new drug delivery system using silk-based microneedles that can make administering medicine painless.
Using protein in silk — instead of the metal, polymers and silicon wafers that previous microneedle designs used — was a major improvement and provides many benefits, according to Postdoctoral Associate Waseem Raja, one of the co-authors of the paper.
The microneedles are only around 500 microns, approximately a half a millimeter, long according to PhD candidate KonstantinosTsioris, another co-author of the paper.
"They only penetrate the top layer of the skin and don't reach down to the layer where the nerves are," Tsioris said. "If you apply this type of needle, you wouldn't feel any pain as you would with a traditional hypodermic needle."
Raja explained that silk is both biodegradable and biocompatible, which makes the material a better choice for needles than metal.
The microneedles are grouped together in a patch for use. The patch is then applied to the skin like a bandage, according to Department of Biomedical Engineering Chair David Kaplan, a co-author of the paper. He added that theoretically, the patches could be made as large as necessary.
The patches are essentially designed for use by patients, so the patient can put on however many patches he needs and can replace them any time depending on the necessity, giving the patient more control over his needs, according to Kaplan.
The research paper describing the new microneedles, titled "Fabrication of Silk Microneedles for Controlled-Release Drug Delivery", appeared online in Advanced Functional Materials last month.
Other engineers involved in the research were Postdoctoral Associate Eleanor Pritchard, Research Assistant Professor Bruce Panilaitis and Professor of Biomedical Engineering FiorenzoOmenetto.
The speed of the drug's delivery through the silk microneedles can be controlled, according to Kaplan. He noted that the design makes improvements over a standard hypodermic needle's design, because with a hypodermic shot, the patient is given a large concentration of medicine for a short period of time but often needs to go back to the doctor's office for more when the medicine wears off.
"The way we designed the silk microneedles allows us to essentially regulate the release kinetics of the drug, so you can moderate the dose better over a long period of time," Kaplan explained. "In principle, you get a better therapeutic effect."
Raja noted convenience as another advantage.
"You can simply discard the patch when you're done with it, and it doesn't require a power source like some other drug delivery systems require," he said. "This can also be self-administered, so you don't need to go to the doctor's to get a shot."
Kaplan also noted that these silk microneedle patches can be distributed in a wide range of environments.
"You can make the microneedles with the drugs stored in there, and therefore the drugs will be stable," he explained.
Research on these silk microneedles has gone on for a year, according to Raja. Kaplan explained that to create the microneedles, he and the other researchers first made a mold for the needles, similar to making muffins with a muffin tin.
"It's essentially a micro-molding process," Kaplan said. "You literally fill the mold with the silk solution, which is water and protein, and then you let it harden and cure it. Once it's cured, you can then peel off the hardened silk from the mold, and you have the reverse imprint, which is then the microneedles."
The study is ongoing, so Raja thinks it might be a while, possibly several years, until the commercial patches are created and released onto the market.
"What we were doing here was preliminary type research," Tsioris explained. "If we want to make a functioning device out of this, we definitely need more research for it to be completely functional."
