The global pandemic due to the latest surge of coronavirus disease 2019 (COVID-19) highlights the shortcomings of the current testing paradigm for viral diagnostics. Here, we report a stepwise protocol for ribonucleic acid (RNA)-extraction-free ‘nano-amplified colorimetric test’ (NACT) for rapid and naked-eye molecular detection of COVID-19. The test employs a unique dual-prong approach that integrates nucleic acid amplification and plasmonic sensing for point-of-care (POC) diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with &lt; 1-hour sample to assay response time. The NACT utilizes plasmonic gold nanoparticles (AuNPs) capped with antisense oligonucleotides (ASOs) as a colorimetric reporter to detect the amplified nucleic acid from the COVID-19 causative virus, SARS-CoV-2. The ASOs are specific for SARS-CoV-2 N-gene which results in the aggregation of the AuNPs in presence of the target RNA segment. This highly specific agglomeration step is seen as a change in their plasmonic response. Furthermore, when tested using 62 clinical samples, the accuracy, sensitivity, and specificity of the test are found to be 98.4%, 96.7%, and 100%, respectively, with a detection limit of 10 copies/μL. The test can easily be adapted to diagnose other viral infections with a simple modification in the ASOs and primer sequences. The colorimetric readout of the test can even be monitored using a handheld optical reader to obtain a quantitative response. Therefore, we anticipate that this protocol will be widely useful for the development of biosensors for the molecular diagnostics of COVID-19 and other infectious pathogens.

RNA-extraction-free nano-amplified colorimetric test for clinical diagnosis of COVID-19

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.