Imunocapture Magnetic Beads Enhanced and Ultrasensitive CRISPR-Cas13a-Assisted Electrochemical Biosensor for Rapid Detection of SARS-CoV-2

The rapid and ongoing spread of the coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emphasizes the urgent need for an easy and sensitive virus detection method. Here, we describe an immunocapture magnetic bead-enhanced electrochemical biosensor for ultrasensitive SARS-CoV-2 detection based on clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) proteins, collectively known as CRISPR-Cas13a technology. At the core of the detection process, low-cast and immobilization-free commercial screen-printed carbon electrodes are used to measure the electrochemical signal, while streptavidin-coated immunocapture magnetic beads are used to reduce the background noise signal and enhance detection ability by separating the excessive report RNA, and a combination of isothermal amplification methods in the CRISPR-Cas13a system is used for nucleic acid detection. The results showed that the sensitivity of the biosensor increased by two orders of magnitude when the magnetic beads were used. The proposed biosensor required approximately 1 h of overall processing time and demonstrated an ultrasensitive ability to detect SARS-CoV-2, which could be as low as 1.66 aM. Furthermore, owing to the programmability of the CRISPR-Cas13a system, the biosensor can be flexibly applied to other viruses, providing a new approach for powerful clinical diagnostics.

Automated summary

This study presents an immunocapture magnetic bead-enhanced electrochemical biosensor for ultrasensitive SARS-CoV-2 detection based on CRISPR-Cas13a technology. The biosensor uses low-cost and immobilization-free carbon electrodes for electrochemical signal measurement, streptavidin-coated immunocapture magnetic beads to reduce background noise and enhance detection ability, and isothermal amplification methods in the CRISPR-Cas13a system for nucleic acid detection. The biosensor showed a two orders of magnitude increase in sensitivity with the use of magnetic beads. It can detect SARS-CoV-2 with an ultrasensitive ability as low as 1.66 aM and can be flexibly applied to other viruses.