Rapid and sensitive detection of nucleoprotein SARS-CoV-2 virus: SERS vs ELISA

The recent pandemic calls for a rapid and cheap diagnosis of COVID-19 to impede the virus from spreading. The main clinically used techniques for diagnostics of virus diseases are PCR and ELISA, whereas it is well known that optical methods such as FTIR, Raman spectroscopy, and SERS are extremely precise, perspective, and also rapid. Here, we provide a comparative study of SERS and ELISA methods for the detection of SARS-CoV-2 nucleo-proteins revealing and discussing the advantages and disadvantages of both these methods. We show that the standard ELISA method demonstrates the detection limit of about 50-100 pg/ml vs 1 pg/ml demonstrated by SERS with using silver nanoisland substrates. The detection time for ELISA is about 2 h being mainly defined by the requirements of incubation and washing, while SERS measurements take several seconds. We show that the SERS spectra allow distinguishing the features of antigens, antibodies, and even the features showing the bonding between them. We believe that the obtained results and the comparative analysis will be useful for developing cheap and rapid point-of-care diagnostics.