KCS

The COVID-19 pandemic has caused significant social and economic problems worldwide. Currently, RT-PCR, which detects RNA inside a virus, is used as the standard diagnostic method for SARS-CoV-2 but the total diagnostic time, including sample preparation, gene amplification, and detection, requires approximately 3-4 h. Rapid kits for immunodiagnosis using antigen-antibody reactions have also been developed and commercialized to shorten the diagnosis time. However, they have not been adopted as the standard diagnostic method owing to their low LoD and poor accuracy. In particular, false-negatives obtained by commercialized immunodiagnostic kits is a severe problem that can aggravate the spread of SARS-CoV-2. To resolve this problem, we developed a new SERS-based immunodiagnostic assay platform capable of quantifying SARS-CoV-2 lysate with a high sensitivity. In this study, a spike protein DNA aptamer was used as a receptor, and a self-grown Au nano-popcorn surface was used as a SERS detection substrate for the sensible detection of SARS-CoV-2. A quantitative analysis of SARS-CoV-2 lysate was performed by monitoring the change in the SERS peak intensity caused by the new binding between the aptamer DNA released from the Au nano-popcorn surface and the spike protein in the SARS-CoV-2 viron. This technique enables detecting SARS-CoV-2 with a LoD of less than 10 PFU/mL within 15 min. The results of this study demonstrate the possibility of a clinical application that can dramatically improve the detection limit and accuracy of the currently commercialized SARS-CoV-2 immunodiagnostic kit.