SARS-CoV-2 Virus Detection Via a Polymeric Nanochannel-Based Electrochemical Biosensor

The development of simple, cost-effective, rapid, and quantitative diagnostic tools remains critical to monitor infectious COVID-19 disease. Although numerous diagnostic platforms, including rapid antigen tests, are developed and used, they suffer from limited accuracy, especially when tested with asymptomatic patients. Here, a unique approach to fabricate a nanochannel-based electrochemical biosensor that can detect the entire virion instead of virus fragments, is demonstrated. The sensing platform has uniform nanoscale channels created by the convective assembly of polystyrene (PS) beads on gold electrodes. The PS beads are then functionalized with bioreceptors while the gold surface is endowed with anti-fouling properties. When added to the biosensor, SARS-CoV-2 virus particles block the nanochannels by specific binding to the bioreceptors. The nanochannel blockage hinders the diffusion of a redox probe; and thus, allows quantification of the viral load by measuring the changes in the oxidation current before and after virus incubation. The biosensor shows a low limit of detection of ≈1.0 viral particle mL^-1 with a wide detection range up to 10⁸ particles mL^-1 in cell culture media. Moreover, the biosensor is able to differentiate saliva samples with SARS-CoV-2 from those without, demonstrating the potential of this technology for translation into a point-of-care biosensor product.