Label-free Sensing of Main Protease Activity of SARS-CoV-2 with an Aerolysin Nanopore.

The main protease (Mpro ), which is highly conserved and plays a critical role in the replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a natural biomarker for SARS-CoV-2. Accurate assessment of the Mpro activity is crucial for the detection of SARS-CoV-2. Herein, we report a nanopore-based sensing strategy that uses an enzyme-catalyzed cleavage reaction of a peptide substrate to measure the Mpro activity. The peptide was specifically cleaved by the Mpro , thereby releasing the output products that, when translocated through aerolysin, quantitatively produced the signature current events. The proposed method exhibited high sensitivity, allowing the detection of Mpro concentrations as low as 1 nM without the use of any signal amplification techniques. This simple, convenient, and label-free nanopore assay may expand the diagnostic tools for viruses.

One-pot and rapid detection of SARS-CoV-2 viral particles in environment using SERS aptasensor based on a locking amplifier.

With the frequent detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in dwellings and wastewater, the risk of transmission of environmental contaminants is of great concern. Fast, simple and sensitive sensors are essential for timely detecting infection and controlling transmission through environment fomites. Herein, we developed a Surface Enhanced Raman Scattering (SERS) aptasensor, which can realize ultrasensitive and rapid assay of SARS-CoV-2 viral particles. In this strategy, we designed a novel locking amplifier which is activated only in the presence of virus by aptamer recognition. The reaction process was carried out though one-pot method at 37 °C, which can save time and resources. In addition, magnetic beads used in reaction system can simplify operation, as well as provide ideas for developing biosensing robots via magnetic field. This SERS aptasensor can detect SARS-CoV-2 virus with a LOD of 260 TU/µL within 40 min in the linear range of 625-10,000 TU/µL. Therefore, this convenience, speediness, sensitivity, and selectivity of detection has great prospects in analyzing SARS-CoV-2 viral particles or other viruses in environment as well as monitoring of environmental virus sources.