A groundbreaking development in air monitoring technology has resulted in the creation of a real-time device capable of detecting any variant of the SARS-CoV-2 virus within a room in approximately five minutes. The researchers at Washington University in St. Louis, US, successfully combined recent advancements in aerosol sampling technology with an ultrasensitive biosensing technique to create this cost-effective proof-of-concept device.
The applications of this device are vast and can be utilized in hospitals, healthcare facilities, schools, and public places to detect SARS-CoV-2 and potentially monitor other respiratory virus aerosols such as influenza and respiratory syncytial virus (RSV). The researchers highlight the exceptional sensitivity of their monitor, which they claim is the most sensitive detector available. Their findings have been published in the journal Nature Communications.
The air purifier can help detect live virus in almost real-time
John Cirrito, a professor of neurology at Washington University, stressed the importance of real-time information about room safety, stating, “There is nothing at the moment that tells us how safe a room is. 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.”
The researchers adapted a previously developed micro-immunoelectrode (MIE) biosensor, originally designed to detect amyloid beta as a biomarker for Alzheimer‘s disease, for detecting SARS-CoV-2. They replaced the antibody recognizing amyloid beta with a nanobody derived from llamas, which targets the spike protein of the SARS-CoV-2 virus. David Brody, a former faculty member at Washington University, contributed to the development of the nanobody in his lab at the National Institutes of Health (NIH).
The nanobody possesses several advantages—it is small, easily reproducible and modifiable, and cost-effective to produce. Carla Yuede, an associate professor at Washington University, explained, “The nanobody-based electrochemical approach is faster at detecting the virus because it doesn’t need a reagent or a lot of processing steps. 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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The biosensor was integrated into an air sampler that operates using wet cyclone technology. The sampler generates a surface vortex by combining high-velocity air with fluid, effectively trapping virus aerosols. An automated pump collects the fluid and sends it to the biosensor for seamless virus detection using electrochemistry.
Rajan Chakrabarty, a professor at Washington University, highlighted the challenge of detecting airborne aerosols due to their highly diluted nature, likening it to finding a needle in a haystack. However, the wet cyclone sampler addresses this issue by sampling a larger volume of air within a 5-minute collection period, resulting in higher virus recovery compared to commercially available samplers.
The team validated the monitor’s performance by testing it in the apartments of two COVID-positive patients. Air samples from the bedrooms, along with control air samples from a virus-free room, were subjected to real-time PCR analysis. The monitor successfully detected RNA of the virus in the bedroom air samples while yielding negative results for the control samples. Additionally, laboratory experiments aerosolizing SARS-CoV-2 in a room-sized chamber demonstrated that the wet cyclone and biosensor could detect varying levels of airborne virus concentrations after only a few minutes of sampling.
