CRISPR-Cas13a-powered electrochemical biosensor for the detection of the L452R mutation in clinical samples of SARS-CoV-2 variants

Since the end of 2019, a highly contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has deprived numerous lives worldwide, called COVID-19. Up to date, omicron is the latest variant of concern, and BA.5 is replacing the BA.2 variant to become the main subtype rampaging worldwide. These subtypes harbor an L452R mutation, which increases their transmissibility among vaccinated people. Current methods for identifying SARS-CoV-2 variants are mainly based on polymerase chain reaction (PCR) followed by gene sequencing, making time-consuming processes and expensive instrumentation indispensable. In this study, we developed a rapid and ultrasensitive electrochemical biosensor to achieve the goals of high sensitivity, the ability of distinguishing the variants, and the direct detection of RNAs from viruses simultaneously. We used electrodes made of MXene-AuNP (gold nanoparticle) composites for improved sensitivity and the CRISPR/Cas13a system for high specificity in detecting the single-base L452R mutation in RNAs and clinical samples. Our biosensor will be an excellent supplement to the RT-qPCR method enabling the early diagnosis and quick distinguishment of SARS-CoV-2 Omicron BA.5 and BA.2 variants and more potential variants that might arise in the future.

Automated summary

Since the end of 2019, a highly contagious disease called COVID-19, caused by SARS-CoV-2, has claimed numerous lives worldwide. The latest variant of concern is omicron, and BA.5 is becoming the dominant subtype, replacing the BA.2 variant. These subtypes have an L452R mutation, which increases their transmissibility among vaccinated individuals. Current methods for identifying SARS-CoV-2 variants rely on time-consuming and costly PCR-based gene sequencing. In this study, researchers developed a rapid and ultrasensitive electrochemical biosensor using MXene-AuNP electrodes and the CRISPR/Cas13a system to detect the L452R mutation in RNA samples, enabling early diagnosis and distinguishing omicron BA.5 and BA.2 variants.