The gold standard for the diagnosis of SARS-CoV-2, the causative agent of COVID-19, is real-time polymerase chain reaction (PCR), which is labor-intensive, expensive, and not widely available in resource-poor settings. Therefore, it is imperative to develop novel, accurate, affordable, and easily accessible assays/sensors to diagnose and isolate COVID-19 cases. To address this unmet need, we utilized the catalytic potential of peroxidase-like DNAzyme and developed a simple visual detection assay for SARS-CoV-2 RNA using a conventional thermal cycler by the PCR-induced generation of DNAzyme sensor. The performance of RT-PCR DNAzyme-based sensor was comparable to that of real-time PCR. The pilot scale validation of RT-PCR DNAzyme-based sensor has shown ~100% sensitivity and specificity in clinical specimens (nasopharyngeal swab, n = 34), with a good correlation (Spearman r = 0.799) with the Ct-value of fluorescence probe-based real-time PCR. These findings clearly indicate the potential of this inexpensive, sensitive, and specific molecular diagnostic test to extend our testing capabilities for the detection of SARS-CoV-2 to curtail COVID-19 transmission.
An ink-jet printed dual-CD ratiometric fluorescent paper-based sensor for the visual detection of Cu2+
