Direct Quantitation of SARS‐CoV‐2 Virus in Urban Ambient Air via a Continuous‐Flow Electrochemical Bioassay

Airborne SARS‐CoV‐2 virus surveillance faces challenges in complicated biomarker enrichment, interferences from various non‐specific matters and extremely low viral load in the urban ambient air, leading to difficulties in detecting SARS‐CoV‐2 bioaerosols. This work reports a highly specific bioanalysis platform, with an exceptionally low limit‐of‐detection (≤1 copy m(−3)) and good analytical accordance with RT‐qPCR, relying on surface‐mediated electrochemical signaling and enzyme‐assisted signal amplification, enabling gene and signal amplification for accurate identification and quantitation of low doses human coronavirus 229E (HCoV‐229E) and SARS‐CoV‐2 viruses in urban ambient air. This work provides a laboratory test using cultivated coronavirus to simulate the airborne spread of SARS‐CoV‐2, and validate that the platform could reliably detect airborne coronavirus and reveal the transmission characteristics. This bioassay conducts the quantitation of real‐world HCoV‐229E and SARS‐CoV‐2 in airborne particulate matters collected from road‐side and residential areas in Bern and Zurich (Switzerland) and Wuhan (China), with resultant concentrations verified by RT‐qPCR.