A fast, efficient COVID-19 biosensor is under development
As the BA.5-omicron variant continues to spread, health experts are increasingly preparing for a future where such COVID-19 variants appear, rise and disappear, similar to seasonal flu. A key component to staying on top of these changes is the ability to rapidly monitor the virus on a “population scale,” an effort that requires precise and ultra-fast testing.
To meet this challenge, researchers from IUPUI’s School of Science are developing a new biosensor with the potential to achieve the speed and efficiency needed for the future of COVID-19 testing.
The work was recently reported in ACS Applied Material Interfaces, a journal of the American Chemical Society. It is headed by Rajesh Sardar, a professor of chemistry and chemical biology at the School of Science, and Adrianna Masterson, a graduate student in Sardar’s lab at the time of the study.
“Everyone is chasing high-throughput testing; this kind of rapid analysis is essential for the future of the fight against COVID-19,” Sardar said. “Our technology in particular has many advantages: it is fast, efficient, accurate and incredibly sensitive.”
In terms of speed, Sardar’s lab’s COVID-19 test can currently analyze samples from 96 people in less than three hours, he said. In terms of efficiency, the system only requires 10 microliters of blood.
In 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 types of samples, such as saliva, Sardar said. But the study was conducted with blood, as it is the most complex bodily fluid and therefore the best indicator of a sensor’s accuracy. All test samples were obtained from the Indiana Biobank, which provided 216 blood samples, including 141 samples from patients with COVID-19 and 75 healthy control samples.
Based on a blinded analysis, IUPUI researchers found that their biosensor’s accuracy was 100 percent and its specificity was 90 percent. In other words, the sensor never reported a false negative and only reported a false positive in 1 in 10 samples. For public safety, Sardar said the absence of false negatives is more important than false positives, because a person with a false negative can unknowingly infect others, while a person with a false positive poses no danger.
In addition, Sardar said the sensor proved to be very accurate in measuring the body’s COVID-19 antibody concentration. This is because it detects not only the spike protein of the virus, but also the proteins produced by the body to protect against the virus: immunoglobin G or IgG.
He also said the ability to measure COVID-19 antibodies is significant, as many COVID-19 antibody tests currently approved under FDA emergency use authorization do not provide specific antibody counts, despite the fact that this number indicates the strength of one’s immunity to infection.
Accurately measuring patients’ immunity levels will be critical to protecting against COVID-19 in the future,” Sardar said. “This can be clearly seen in our current state of affairs, as variants such as omicron – and recently BA.5 – infect even fully vaccinated and boosted individuals.”
To achieve its results, Sardar’s lab’s biosensor uses chemically synthesized gold triangular nanoprisms, which provide a uniquely powerful optical response to even minute amounts of IgG. It also means that the sensor can detect antibodies in the earliest stages of infection.
The work, which started in the early days of the pandemic, builds on the first promising results published in June 2021. Next, Sardar plans to further refine the technology, with the goal of eventually processing 384 samples in less than an hour, or 5,000 samples per day if used in a larger test center.
“This research is about preparing for the future,” said Sardar, who is also a researcher at Indiana University Melvin and the Bren Simon Comprehensive Cancer Center. “The H1N1 flu strain is almost 100 years old. I expect the coronavirus to be with us for a long time to come. Looking ahead, we need to devise ways to quickly and easily measure the infections or risk of infection of many people and efficiently to stay one step ahead.”
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Adrianna N. Masterson et al, Selective detection and ultrasensitive quantification of SARS-CoV-2 IgG antibodies in clinical plasma samples using epitope-modified nanoplasmonic biosensing platforms, ACS applied materials and interfaces (2022). DOI: 10.1021/acsami.2c06599
Quote: A fast, efficient COVID-19 biosensor in development (2022, July 21) retrieved July 22, 2022 from https://phys.org/news/2022-07-fast-efficient-covid-biosensor.html
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