A Device for Real-Time Detection of SARS-CoV-2 Aerosols in Built Environments

JOSEPH V. PUTHUSSERY, Dishit Ghumra, Kevin McBrearty, Brookelyn Doherty, Benjamin Sumlin, Amirhossein Sarabandi, Anushka Mandal, Nishit Shetty, Woodrow Gardiner, Jordan Magrecki, David Brody, Thomas Esparza, Traci Bricker, Adrianus Boon, Carla M. Yuede, John Cirrito, Rajan K. Chakrabarty, Washington University in St.Louis

     Abstract Number: 542
     Working Group: Aerosol Science of Infectious Diseases: Lessons and Open Questions on Models, Transmission and Mitigation

Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a strain of coronavirus that cause the coronavirus disease 2019 (COVID-19) pandemic. The virus mainly spreads through respiratory droplets expelled from infected individuals during sneezing, coughing, breathing, and speaking. These virus aerosols can lead to airborne transmission of the disease, as they can linger in the indoor air for several hours. Today, over two years since the start of the pandemic, real-time direct detection of the SARS-CoV-2 virus in the air remains a technological challenge.

Here, we present a proof-of-concept pathogen Air Quality (pAQ) monitor for real-time (5 min time resolution) direct detection of SARS-CoV-2 aerosols. The pAQ monitor comprises a custom-built high flow (~1000 lpm) wet cyclone bioaerosol sampler coupled to a SARS-CoV-2 spike-protein specific llama-derived nanobody based micro-immunoelectrode (MIE) biosensor for real-time detection of SARS-CoV-2 in air. Ambient air is directly sampled using the wet cyclone pre-filled with phosphate-buffered saline (PBS) solution. The virus aerosols enter the wet cyclone through a tangential inlet and get deposited on the inner walls of the cyclone due to the centrifugal forces acting on them. The particle separation efficacy of the wet cyclone determined by computational fluid dynamic modeling showed comparable or better virus sampling performance than commercially available bioaerosol samplers. We tested the MIE biosensor performance using four dominant SARS-CoV-2 virus strains: Washington (WA1), Beta (B.1.351), Delta (B.1.617.2), and Omicron (BA.1) and obtained a limit of detection (LoD) ranging between 6-32 RNA copies/ml. Laboratory testing of the pAQ monitor demonstrated a device virus detection sensitivity of 77-83% and an LoD of 7-35 viral RNA copies/m³ of air for the different SARS-CoV-2 variants.

Current efforts are underway for simultaneously detecting other airborne pathogens using the pAQ monitor via multiplexing of MIE biosensors with different target-specific nanobodies. The widespread use of such technologies will assist public health officials with implementing prompt infection control measures.