Paper-based devices could perform complex, multistep diagnostic tests at a fraction of the cost of traditional medical laboratory analysis
Many research teams are racing to create paper-based devices for medical laboratory tests. Their primary goal is develop a cheap, fast, reliable way to perform diagnostic testing in third world settings, where modern clinical laboratories are few and far between. One development team is working to combine lab-on-a-chip technologies with the low cost of paper-based platforms.
Meanwhile, over the past decade, point-of-care testing (POCT) has revolutionized diagnosis and treatment options for a myriad of conditions. In developing regions or remote areas, low-cost POCT improves accessibility to vital tests for infectious diseases, such as HIV, Malaria, and Ebola, as well as acute medical conditions, such as sepsis.
In the past eight years, Dark Daily has reported many times on the emergence of new POCT devices. From lactic acid screening to the lab-in-a-needle, which is used for detecting liver toxicity, the ability to produce a quick and accurate diagnosis without intensive clinical laboratory testing is growing.
However, one area where many POCT devices face challenges is in surviving extended environmental exposure. This does not pose an issue in major research hospitals or health systems. However, the consequences can be severe when considering the often harsh, resource-limited conditions of developing countries—one area in which POCT stands to offer the greatest value.
Paper Microfluidic Devices; Next Stage in Evolution of POCT
Dark Daily also previously reported on a new handheld Malaria test from researchers at the University of Washington. Using dehydrated reagents, the card-sized test eliminated the need for refrigeration, returning accurate results after exposure to ambient temperatures for up to 60 days. Unfortunately, this approach wasn’t practical for all testing. (See Dark Daily, “Two Different Point-of-Care Test Devices for Malaria Show Why Emerging Technologies Can Be Disruptive to Clinical Pathology Laboratories,” July 5, 2013.)
The current standard for creating rugged, low-cost POCT devices is lateral-flow paper testing. However, many tests only offer testing for a single disease or condition. Many are also limited in their ability to provide information with more than a positive or negative result. However, these limitations might soon change.
In March, Scientific American highlighted an array of new POCT devices combining the potential of many of the “lab-on-a-chip” designs with the durability and low-cost of paper-based testing. Paper microfluidic devices use microscopic printed channels, compartments, and 3-D printing to overcome the limitations of lateral-flow paper tests.
In the article, Ali Yetisen, PhD, of Harvard Medical School, notes, “paper microfluidic devices can do more complex tests that require multiple processing steps.” No longer limited to single tests or binary results, these new methods open the possibility of testing for multiple diseases, assessing accuracy, or increased ability to provide quantified results. All of this is achieved with a single, low-cost device, and without the delays and logistical challenges of laboratory work.
Nucleic Acid Testing without a Medical Laboratory?
Another potential advancement of interest to clinical laboratories is paper-based DNA testing. Paul Yager, PhD, Bioengineer at University of Washington, and George Whitesides, PhD, Chemist at Harvard University, are working on prototypes that use paper-based microfluidic testing and isothermal amplification to replace the polymerase chain reaction (PCR) test used in laboratories.
This would offer an affordable way to copy DNA strands and detect nucleic acids. In the Scientific American article Yager stated, “The aim is to come up with a standard footprint for a paper-based nucleic acid test where you simply change one or two molecules to test for a different disease.” Early devices based on Yager’s and Whitesides’ research have successfully detected antibiotic-resistant MRSA in samples. Research also is underway to adapt the test for the detection of the Zika virus.
Obstacles to the Progression of Paper-Based Microfluidic Testing
According to Bernhard Weigl, flow-based researcher at Intellectual Ventures, a major issue facing these new technologies is scalability. While it might be possible to develop heating technologies—such as the work being completed by Yager and Whitesides—creating a diagnostic test that is reliable in a variety of harsh conditions remains difficult. Particularly when they must be mass produced to create an affordable alternative to established medical laboratory testing methods.
However, Marcus Lovell-Smith, CEO of Diagnostics For All, pointed out the biggest obstacle, noting “These are immensely expensive projects. It’s tens of millions of dollars to get these tests approved.” Ultimately, it’s not technological ability but funding that might decide whether these tools ever make it to market.
The examples presented above demonstrate that multiple research teams are making steady progress toward the goal of creating paper-based diagnostic devices that can do many types of medical laboratory tests in low-resource settings where modern clinical laboratories do not exist or are inaccessible.