image: Rajesh Sardar, center, talks with Omolade Olofintuyi, left, a Howard University graduate student who conducted research on an advanced biosensor for COVID-19 in his lab this summer through a program funded by NSF. see more
Credit: Photo by Chris Meyer, Indiana University
As the omicron BA.5 variant continues to spread, health experts are increasingly preparing for a future in which these variants of COVID-19 emerge, increase and recede in a fashion similar to seasonal flu. An important part of keeping up with these changes will be the ability to rapidly monitor the virus at a “population scale,” an effort that will require accurate and ultra-rapid testing.
To help meet this challenge, researchers in the IUPUI School of Science are developing a new biosensor with the potential to achieve the speed and efficiency required for the future of COVID-19 testing.
The work was recently reported in Applied Material Interfaces, a journal of the American Chemical Society. It is led by Rajesh Sardar, professor of chemistry and chemical biology in 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 tests; this kind of high-speed analysis is essential for the future of the fight against COVID-19,” Sardar said. “There are many advantages to our technology in particular: it is fast, efficient, accurate and sensitive without precedent.”
In terms of speed, Sardar’s lab’s COVID-19 test can analyze samples from 96 people in less than three hours, he said. In terms of efficiency, the system requires only 10 microliters of blood.
By comparison, a typical blood panel order from a primary care physician collects 10 milliliters of blood, more than 1,000 times more.
The sensor also works with other types of samples, such as saliva, Sardar said. But the study was done using blood, as it is the most complex body 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 samples from healthy controls.
Based on a blind analysis, the IUPUI researchers found that the accuracy rate of their biosensor was 100 percent and its specificity rate was 90 percent. In other words, the sensor never reported a false negative and only reported a false positive in 1 out of 10 samples. For public safety purposes, 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 is not a danger
In addition, Sardar said the sensor was found to be very accurate in measuring the concentration of COVID-19 antibodies in the body. This is because it detects not only the spike protein of the virus, but also proteins created by the body to protect itself from the virus: immunoglobulin G, or IgG.
He also said the ability to measure COVID-19 antibodies is important because many COVI9-19 antibody tests currently approved under FDA emergency use authorization do not provide specific antibody counts, despite this number indicates the strength of a person’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, as variants such as omicron and, more recently, BA.5, are infecting even fully vaccinated and boosted individuals.”
To achieve its results, the biosensor in Sardar’s lab uses chemically synthesized triangular gold nanoprisms, which provide a unique and powerful optical response to even minute amounts of IgG. It also means that the sensor can detect antibodies in the early stages of infection.
The work, which began in the early days of the pandemic, builds on promising initial results published in June 2021. Next, Sardar aims to further refine the technology, aiming to be able to process 384 samples in less than one 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 the Indiana University Melvin and Bren Simon Comprehensive Cancer Center. “The H1N1 strain of flu is almost 100 years old. I expect the coronavirus will be with us for a long time as well. Going forward, we need to find ways to measure infections or risks of infection in many people quickly and simple. and efficiently to stay one step ahead of the virus.”
This work was supported in part by the NIH National Center for Advancing Translational Science, through a grant from the Indiana CTSI.
magazine
ACS applied materials and interfaces
Title of the article
Selective detection and ultrasensitive quantification of SARS-CoV-2 IgG antibodies in clinical plasma samples using epitope-modified nanoplasmonic biosensing platforms
Publication date of the article
31-May-2022
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