New COVID-19 Test is Fast, Efficient, Accurate and Unprecedentedly Sensitive

The COVID-19 test developed by researchers from the School of Science at IUPUI (Indianapolis, IN, USA) can currently analyze samples from 96 individuals in under three hours. In terms of efficiency, the system requires only 10 microliters of blood. By comparison, a typical blood panel order by a primary-care physician collects 10 milliliters of blood - over 1,000 times more. The sensor also works with other sample types, such as saliva, although the study was conducted using blood since it is the most complex bodily fluid and therefore, the best indicator of a sensor's accuracy.

For the study, the researchers tested 216 blood samples: 141 samples from patients with COVID-19 and 75 healthy control samples. Based upon a blind analysis, the researchers found their biosensor's accuracy rate was 100% and its specificity rate was 90%. In other words, the sensor never reported a false negative and only reported a false positive in 1 out of 10 samples. For the purposes of public safety, the absence of false negatives is more important than false positives, because a person with a false negative may unknowingly infect others, whereas a person with a false positive is not a danger.

Additionally, the sensor was found to be highly accurate at measuring the body's COVID-19 antibody concentration. This is because it detects not only the virus's spike protein but also the proteins created by the body to protect against the virus - immunoglobin G, or IgG. The ability to measure COVID-19 antibodies is significant because many COVI9-19 antibody tests currently approved under the FDA's emergency use authorization do not provide specific antibody counts, despite the fact that this number indicates the strength of a person's immunity to infection. To achieve its results, the biosensor uses chemically synthesized gold triangular nanoprisms, which provide a uniquely powerful optical response to even minuscule amounts of IgG. It also means the sensor can detect antibodies in the earliest stages of infection.

"Everyone is chasing high-throughput testing; this type of high-speed analysis is essential to the future of the fight against COVID-19," said Rajesh Sardar, a professor of chemistry and chemical biology in the School of Science, who led the development. "There are many advantages to our technology in particular: It's fast, efficient, accurate and unprecedentedly sensitive."

"Accurately measuring patients' immunity levels will be critical to protecting against COVID-19 going forward," added Sardar. "This research is about preparing for the future."

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