`Lab on a Chip` Test Could Detect COVID-19 Immune Response Faster Than Current Antibody Testing

Researchers at the Southern Methodist University (Dallas, TX, USA) who are developing the new test estimate that the “Lab on a Chip” test could detect immune responses to coronavirus in two to three minutes, with just a drop of blood. The materials used to create the test are inexpensive, which should result in low-cost mass production. The chip is two cm in diameter, and the device is simple enough that those without medical training should be able to perform the test.

The test, which is called Multiplexed Assay for the Immune Response to COVID-19 (MAIRC), will look for signs that a person’s immune system has at some point responded to coronavirus being present in their body. Specifically, it will detect human IgG, IgM, and IgA antibodies that are produced when someone is or has been infected with the virus. The test is performed by applying a drop of blood to a microfluidic chip used to analyze tiny amounts of liquid. A filter embedded in the microchip extracts plasma from the blood sample. The chip is then placed into an electronic instrument that uses electric measurements to detect whether specific antibodies are present in the plasma. The same technology can potentially be used to detect other diseases that have known antibody-antigen binding.

The test can be performed anywhere via a smartphone. An additional detection method to measure how much of each type of antibody - IgG, IgM, or IgA - is found in a sample allows doctors to better track a person’s recovery to COVID-19. Because of the extra detection step, it will take two to three minutes for someone using “Lab on a Chip” for COVID detection to get results on their smartphone. In a trial, an earlier version of the device accurately detected IgG antibodies in 60 seconds using a small sample (just one ng/ml) of lab-bought antigens and antibodies. The precision and speed of “Lab on a Chip” are attributable, in part, to several innovations. One of those is the use of alternating current electrothermal (ACET) flows to bring antibodies in the blood plasma closer to sensor surfaces in the chip, so they can be detected.

The next step in the research will be testing the sensitivity and specificity of the device using lab-purchased human plasma samples spiked with lab-purchased antibodies and antibodies. The researchers will then test the device on plasma from actual COVID patients before it would be made available to the public. The researchers estimate the cost of the electronic instrument to read the chip would be about USD 15 to USD 20. The cost of the disposable cartridge, which is where a drop of blood would go, would likely be less than USD 1.

“There are some other techniques to detect antibodies quickly without using expensive laboratory equipment, but they suffer from sensitivity, accuracy, and consistency issues,” said J.-C. Chiao, one of the lead researchers behind the “Lab on a Chip” test. “Our ultimate goal is to create quantifiable, accurate, fast, and inexpensive diagnostic methods based on the detection of human IgG, IgM, and IgA antibodies. This does not currently exist, and it would have a deep and significant impact on the world, given the devastating effect this coronavirus pandemic has had.”

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