Home tests for corona are not as accurate as lab tests. Researchers from the TEindhoven University of Technology (TU/e) together with the University of Utrecht developed a new type of test that is as sensitive and accurate as those in the laboratory. But just as fast and cheap as the kits for home use. The new sensor lights up in a certain color when small amounts of proteins and anti-drug antibodies, as well as COVID-19 spike proteins and antibodies are present in the blood.
“Due to the corona epidemic, there is an increasing demand for medical tests that provide fast and accurate results, are cheap, and ideally can be done by anyone and anywhere,” explains Maarten Merkx of the Institute for Complex Molecular Systems (ICMS). TU/e and research leader of the new study.
The many rapid tests are mainly indicative. For true clarity, a lab test should be done. The disadvantage of these accurate tests is that the results sometimes take one or more days to arrive. That can take too long in some cases.
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Fireflies
Merkx and his research team developed a new test with the accuracy and sensitivity of current laboratory methods and the speed and low cost of existing rapid tests.
The key is bioluminescence, the process organisms like fireflies use to produce light. “If a certain protein or antibody is present in the sample, special proteins – called luciferase enzymes – start to emit light,” Merkx explains. “When the device contains no interesting biomarkers, one type of luciferase enzyme emits green light. A second luciferase enzyme lights up in a different color if biomarkers are found.
To this end, the researchers split the second type of luciferase enzyme into two parts. Each part by itself does nothing. The enzyme only becomes active when the two parts are put together. Each part of the luciferase is chemically linked to a pair of antibodies that recognize different parts of a biomarker.
Biomarker
When a biomarker is present in a test sample, the antibodies bind to the biomarker. That process brings the two parts of the luciferase together, making them glow blue. The more blue light that is visible, the greater the concentration of biomarkers in the sample.
The researchers tested the new detection approach on various biomarkers, including one to detect bacterial and viral infections (C-reactive protein), using 40 patient samples in collaboration with the Rijnstate hospital in Arnhem.
Wide Application
“We believe this testing platform could be used for a wide range of applications, such as rapid screening and testing, for therapeutic antibody-drug monitoring associated with conditions such as rheumatoid arthritis and inflammatory bowel disease, and for the rapid detection of infectious diseases that could be associated with future epidemics or pandemics,” Merkx added.
The article “A plug-and-play platform of ratiometric bioluminescent sensors for homogeneous immunoassays” is published in Nature Communications.
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