New needle patch applied to TB testing

New microneedle patch to revolutionize TB testing

University of Washington engineers have done their patchwork, arriving at a revolutionary new method of tuberculosis skin testing by scrapping the hypodermic needle...literally.

Gone will be the days of inserting hypodermic needles at precisely the right angle and arm depth to determine a patient’s TB status if the chitin microneedle patch — which is comprised of biodegradable needles — pans out.

“With a microneedle test there’s little room for user error, because the depth of delivery is determined by the microneedle length rather than the needle-insertion angle,” said senior author Marco Rolandi, a UW assistant professor of materials science and engineering, in a news release. “This test is painless and easier to administer than the traditional skin test with a hypodermic needle.”

Aided in part by researchers at the Infectious Disease Research Institute in Seattle, Rolandi and the rest of the team tested the patch on guinea pig subjects and discovered that the skin reactions resulting from the patch in TB-positive participants were congruent to those that occurred with properly implemented hypodermic needle tests.  But in contrast to hypodermic tradition, the patch offered a simpler, more accurate alternative that could also ease the worries of needle-shy patients.

“It’s like putting on a bandage,” Rolandi noted. And “as long as the patch is applied on the skin, the test is always delivered to the same depth underneath the skin.”

The microneedles that line the patch are made from silicon, metals, synthetic polymers and the biodegradable component chitin (a material derived from the outer shells of certain insects and crustacean creatures); additionally, each needle is of equal size (750 micrometers long/one-fourth of an inch) and coated with purified protein derivative, which is typically used to test for tuberculosis.

“It’s a great application of this technology and I hope it will become a commercial product,” said paper co-author Darrick Carter, a biochemist and a vice president at the Infectious Disease Research Institute, in a news release.

The researchers hope to begin testing the TB patch on human subjects in the near future; they also aim to utilize the microneedle patch technology for other forms of ailment testing, such as allergy inquiries.

The findings were published in the journal Advanced Healthcare Materials on August 26.