Tech Briefs Magazine - October 2023 - 36

Health & Biotech
Air Monitor Can Detect COVID-19 Variants in Five Minutes
The proof-of-concept device could also monitor for flu, RSV, and other respiratory viruses.
Washington University in St. Louis, MO
N
ow that the emergency phase of
the COVID-19 pandemic has ended,
scientists are looking at ways to
surveil indoor environments in real
time for viruses. By combining recent
advances in aerosol sampling technology
and an ultrasensitive biosensing
technique, researchers at Washington
University in St. Louis have created a
real-time monitor that can detect any
of the SARS-CoV-2 virus variants in a
room in about five minutes.
Results of their work on the monitor,
which they say is the most sensitive
detector available, were published in
Nature Communications.
" There is nothing at the moment
that tells us how safe a room is, " said
Neurology Professor John Cirrito. " 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 five minutes,
if there is a live virus. "
Cirrito and Carla Yuede, an Associate
Professor of Psychiatry, had previously developed
a micro-immunoelectrode (MIE)
biosensor that detects amyloid beta as a
biomarker for Alzheimer's disease and
wondered if it could be converted into a
detector for SARS-CoV-2. They reached
out to Rajan Chakrabarty, the Harold
D. Jolley Career Development Associate
Professor of Energy, Environmental, and
Chemical Engineering in McKelvey Engineering,
who assembled a team that included
Joseph Puthussery, a postdoctoral
research associate in Chakrabarty's lab
who had expertise in building real-time
instruments to measure the toxicity of air.
To convert the biosensor from detecting
amyloid beta to coronavirus, the researchers
exchanged the antibody that recognizes
amyloid beta for a nanobody from llamas
that recognizes the spike protein from the
SARS-CoV-2 virus. David Brody, MD, PhD,
and an author on the paper, developed the
nanobody in his lab at the National Institutes
of Health (NIH). The nanobody is
small, easy to reproduce and modify and
inexpensive to make, the researchers said.
36
The monitor uses a biosensor made with nanobodies that is integrated into an air sampler that operates
based on the wet cyclone technology. (Image: Joseph Puthussery)
" 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. "
Chakrabarty and Puthussery integrated
the biosensor into an air sampler that operates
based on the wet cyclone technology.
" 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 five-minute sample
collection compared with commercially
available samplers. "
The team's monitor has a flow rate of
about 1,000 liters per minute, making it
one of the highest flow-rate devices available.
It is also compact at about 1 foot
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wide and 10 inches tall and lights up when
a virus is detected.
The team tested the monitor in the
apartments of two COVID-positive patients.
The real-time PCR results of air
samples from the bedrooms were compared
with air samples collected from a
virus-free control room. The devices detected
RNA of the virus in the air samples
from the bedrooms but did not detect any
in the control air samples.
In laboratory experiments that aerosolized
SARS-CoV-2 into a room-sized chamber,
the wet cyclone and biosensor were
able to detect varying levels of airborne
virus concentrations after only a few minutes
of sampling.
" 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. "
The team is working to commercialize
the air quality monitor.
For more information, contact Talia
Ogliore at talia.ogliore@wustl.edu; 314935-2919.
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