Washington University researchers (from left) John Cirrito, Rajan Chakrabarty, Joseph Puthussery and Carla Yuede stand with the SARS-CoV-2 wet cyclone aerosol sampler they developed. [Photo by Shubham Sharma/Washington University]
The proof-of-concept device is possible thanks to recent advances in aerosol sampling technology and an ultrasensitive biosensing technique, said researchers at the McKelvey School of Engineering and the School of Medicine.
“There is nothing at the moment that tells us how safe a room is,” neurology professor John Cirrito said in a news release. “If you are in a room with 100 people, you don’t want to find out five days later whether you could be sick or not. The idea with this device is that you can know essentially in real time, or every 5 minutes, if there is a live virus.”
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Cirrito and Carla Yuede, associate professor of psychiatry, previously developed a micro-immunoelectrode (MIE) biosensor to detect a biomarker for Alzheimer’s disease. With the help of study co-author Dr. David Brody, they modified the biosensor to instead use a nanobody from llamas that recognizes the SARS-CoV-2 virus spike protein.
“The nanobody-based electrochemical approach is faster at detecting the virus because it doesn’t need a reagent or a lot of processing steps,” Yuede said. “SARS-CoV-2 binds to the nanobodies on the surface, and we can induce oxidation of tyrosines on the surface of the virus using a technique called square wave voltammetry to get a measurement of the amount of virus in the sample.”
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Wet cyclone air sampling to detect the COVID-19 virus
An illustration of the SARS-CoV-2 virus monitor’s wet cyclone air sampler and biosensor. [Image courtesy of Joseph Puthussery/Washington University]
Wet cyclone air sampling technology proved the answer. The wet cyclone sampler pulls air in at high velocities and mixes with fluid lining the walls to trap the virus aerosols. Then a pump sends the fluid to the biosensor for electrochemistry analysis.
“The challenge with airborne aerosol detectors is that the level of virus in the indoor air is so diluted that it even pushes toward the limit of detection of polymerase chain reaction (PCR) and is like finding a needle in a haystack,” Chakrabarty said. “The high virus recovery by the wet cyclone can be attributed to its extremely high flow rate, which allows it to sample a larger volume of air over a 5-minute sample collection compared with commercially available samplers.”
The device — about 1 ft. wide and 10 in. tall with a flow rate of approximately 1,000 liters per minute — lights up when it detects any variant of the SARS-CoV-2 virus.
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Covid-19 detection device testing and next steps
The researchers successfully tested their device in laboratory experiments and the apartments of two people with COVID-19. They’re now working to commercialize the technology, which could be used to prevent the spread of COVID-19 in schools, healthcare facilities, workplaces and other shared spaces.
“We are starting with SARS-COV-2, but there are plans to also measure influenza, RSV, rhinovirus and other top pathogens that routinely infect people,” Cirrito said. “In a hospital setting, the monitor could be used to measure for staph or strep, which cause all kinds of complications for patients. This could really have a major impact on people’s health.”
More information is available from Washington University and in the research team’s article in Nature Communications.
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