Plasmonic Digital PCR Chip with Gold Nanorod/MXene Films for Rapid Multiplex Detection of Airborne Viruses

Because of the relatively low concentrations of viruses in indoor air, even during an epidemic, reliable and sensitive virus detection is essential to prevent airborne virus transmission. In this study, a method is introduced for the plasmonic digital polymerase chain reaction (PCR) detection of air-sampled viruses (influenza A, influenza B, HCoV-OC43, and HCoV-229E) in which plasmonic thermocycling is performed based on the light-driven photothermal heating of plasmonic nanostructures. Digital PCR allows for the absolute quantification of nucleic acids with high precision and accuracy. An electrostatic air sampler is used to collect aerosolized viruses in a liquid solution. The air-sampled solution is then injected into a microfluidic channel integrated into a gold nanorod/MXene film. Even for virus concentrations as low as 8.3 × 10³ RNA copies per m³ in air, the gold nanorod/MXene film-based plasmonic digital PCR chip successfully detects viruses over 240 s of plasmonic thermocycling with a virus detection limit of detection of one RNA copy µL^-1 liquid. Moreover, the PCR chip enables the multiplex detection of four types of viruses. This approach enables fast and accurate onsite pathogen identification while greatly minimizing the time needed for airborne virus monitoring.