Microneedle Patch Could Replace Standard TB Skin Test
Researchers see uses for other diagnostic tests (August 26)
Each year, millions of people in the U.S. get a tuberculosis (TB) skin test to see whether they have the infection that still affects one-third of the world’s population. But the standard diagnostic test is difficult to give, because a hypodermic needle must be inserted at a precise angle and depth in the arm to successfully check for TB.
Now, researchers at the University of Washington have created a patch with tiny, biodegradable needles that can penetrate the skin and precisely deliver a TB test. The researchers published their results online in Advanced Healthcare Materials.
“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 Dr. Marco Rolandi. “This test is painless and easier to administer than the traditional skin test with a hypodermic needle.”
The researchers developed microneedles made from chitin that are each 750 micrometers long, or about one-fortieth of an inch. Each needle tip is coated with purified protein derivative, the material used for testing for TB. The researchers found that these microneedles were strong enough to penetrate the skin and deliver the TB test.
They tested the patch on guinea pigs and observed that after the microneedles were inserted using the patch, the skin reaction associated with having a TB infection was the same as when the standard hypodermic needle test was used.
The researchers plan to continue developing the microneedle TB test and to evaluate it next in human subjects. They also hope to develop different diagnostic tests using microneedles, including allergy tests.
Source: University of Washington; August 26, 2013.