An Electrochemical Biosensor for SARS-CoV-2 Detection Via its Papain-Like Cysteine Protease and the Protease Inhibitor Screening

The persistent coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is still infecting hundreds of thousands of people every day. Enriching the kits for SARS-CoV-2 detection and developing the drugs for patient treatments are still urgently needed for combating the spreading virus, especially after the emergence of various mutants. Herein, an electrochemical biosensor has been fabricated in this work for the detection of SARS-CoV-2 via its papain-like cysteine protease (PLpro) and the screening of protease inhibitor against SARS-CoV-2 by using our designed chimeric peptide-DNA (pDNA) nanoprobes. Briefly, peptide substrates can be specifically cleaved by SARS-CoV-2 PLpro to release DNA fragment (DNA1) from the nanoprobes. Subsequently, the double-stranded DNA (dsDNA) can be formed on the surface of electrode by the hybridization of the released DNA1 and the DNA2 strands previously immobilized on the electrode surface, which can further load methylene blue for signal output and amplification. Utilizing this biosensor, the sensitive and specific detection of SARS-CoV-2 can be conducted in blood, saliva, and clinical samples. Meanwhile, rapid inhibitor screening against PLpro can be also obtained. Therefore, this electrochemical biosensor has the great potential for COVID-19 combating and drug development.