Detection of SARS-CoV-2 S protein based on FRET between carbon quantum dots and gold nanoparticles

The COVID-19 pandemic caused by SARS-CoV-2 virus brings nasty crisis for public health in the world. Until now, the virus has caused multiple infections in many people. Detecting antigen to SARS-CoV-2 is a powerful method for the diagnosis of COVID-19 and is helpful for controlling and stopping the pandemic. Herein, a rapid and quantitative detection method of SARS-CoV-2 spike(S) protein was built based on the fluorescence resonance energy transfer (FRET) phenomenon without complicated steps. In the process of detecting, the carbon quantum dots (CQDs) and gold nanoparticles (AuNPs) act as donor and acceptor. By modifying the SARS-CoV-2 antibodies on the surface of CQDs and AuNPs, we achieved S protein specific detection using the distance-based FRET phenomenon. Through the electric charge regulation, the limit of detection (LOD) is 0.05 ng/mL, the linear range is 0.1-100 ng/mL, and the detection process only takes 12 min. The proposed method exhibits several advantages such as be available for variants (B.1.1.529 and B.1.617.2) and be suitable for human serum, which is of significance for detecting viral in time and prevention the viral transmission.