University of Washington, Seattle (08.26.2013)
The standard tuberculin skin test (TST) is done by inserting a needle at a specific angle and depth in the arm to deposit a small amount of solution under the skin. Engineers from the University of Washington and researchers from Seattle’s Infectious Disease Research Institute designed a patch with minute biodegradable needles that pierce the skin and deliver the TB test.
When the researchers tested the patch on guinea pigs, they found skin reactions were similar to those with the standard TST. Marco Rolandi, senior author, considered the microneedle patch test to be simpler and more reliable than the traditional TST, particularly for children who might be afraid of needles or developing countries with limited medical help. He compared using the patch to applying a bandage. Other advantages included: little room for error, as the microneedle length determined depth of delivery rather than needle angle; less painful; and more successful, as the solution would not be given too deep or too shallow into the skin for the test to fail.
The researchers made the microneedles from chitin, a biodegradable material. Each microneedle is 750 micrometers long, or approximately one-fortieth of an inch. Each needle tip is coated with purified protein derivative, which is used in TB testing. The researchers will continue developing the microneedle TB test and plan to test it on humans next. They also plan to develop additional diagnostic tests using microneedles.
The full report, “Chitin Microneedles for an Easy-to-Use Tuberculosis Skin Test,” was published online in the journal Advanced Healthcare Materials (2013; doi: 10.1002/adhm.201300185).