An electrochemical biosensor for SARS-CoV-2 detection via its papain-like cysteine protease and the protease inhibitor screening

[Display omitted] •SARS-CoV-2 PLpro as a new biomarker is used to diagnose COVID-19.•A novel PLpro-activated peptide-DNA smart nanoprobe is designed for sensitive and specific detection of SARS-CoV-2.•The fabricated biosensor can be used for the detection of SARS-CoV-2 in blood, saliva, and clinical samples.•The biosensor can be used to screen and validate inhibitors of SARS-CoV-2 PLpro. 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. Utilizing this biosensor, the sensitive and specific detection of SARS-CoV-2 PLpro can be conducted in complex real environments including blood and saliva. Five positive and five negative patient throat swab samples have also been tested to verify the practical application capability of the biosensor. Moreover, we have obtained a detection limit of 27.18 fM and a linear detection range from 1 pg mL−1 to 10 μg mL−1 (I = 1.63 + 4.44 lgC). Meanwhile, rapid inhibitor screening against SARS-CoV-2 PLpro can be also obtained. Therefore, this electrochemical biosensor has the great potential for COVID-19 combating and drug development.