Diagnostics for All, a nonprofit startup in Cambridge, MA, has designed a cheap, disposable blood test for liver damage. The device uses a stack of paper the size of a postage stamp for a test of toxicity for drugs to treat HIV and tuberculosis.
Some antiretroviral therapies and many TB drugs are toxic to the liver. Patients on HIV and TB medication in rich countries are typically monitored every month for liver damage and taken off the treatment if liver damage becomes imminent. “In the U.S., [testing] is routine. It’s expected, it’s standard,” says Nira Pollock, a faculty member at Harvard Medical School and infectious diseases expert at Beth Israel Deaconess Medical Center in Boston.
In the developing world, liver function testing is often either suboptimal or nonexistent, she says. “People don’t get monitored because the current tests are expensive, or hard to obtain, or [the results] take far too long.” Patients who are being treated for HIV or tuberculosis succumb to liver failure brought on by the medication.
Diagnostic for All wants to change that. “The testing needs to be decentralized, done by health workers going around [to remote parts of the country], if they’re lucky, on motorcycle,” says Patrick Beattie, product development scientist at DFA. Health-care workers at remote stations would take a photograph of the results using their cell phone and transmit the results to a central hospital for analysis.
The device consists of a few layers of patterned paper, laminated for protection. A droplet of blood from a pricked finger will be placed on a small opening in the lamination. A filter inside will stop the red blood cells, and release the remaining plasma into channels in the paper. Reagents which are sensitive to molecular indicators of liver damage will be picked up along the way, and collect with the plasma on the final layer of paper. A color test will indicate how much of the damage marker is present in the blood sample.
“We’re looking at pennies per device,” says Beattie. Since the raw material for the test is paper, this decreases the cost of production exponentially. Also, it makes use of the properties of paper to cause flow, removing the need for expensive equipment like pumps. The startup is a spin-off from the George Whitesides lab at Harvard University, and holds exclusive license to diagnostic technologies that the lab is tailoring for use in the developing world. The liver function test is the first application of the paper-patterned microfluidics assay that the Whitesides lab developed in 2008.