Amperometric immunosensor developed for sensitive detection of SARS-CoV-2 spike S1 protein in combined with portable device

In this present study, an amperometric immunosensor was developed based on disposable screen-printed carbon electrode (SPCE) for specific and sensitive detection of SARS-CoV-2 S1 protein. Anti-SARS-CoV-2 S1 monoclonal antibody was firstly immobilized onto the electrode surface. Then, the sandwich complex was formed by addition of S1 protein, secondary antibody and HRP-IgG, respectively. Chronoamperometry measurements were done in the presence of TMB mediator and the detection of SARS-CoV-2 S1 protein was performed by using 10 mu L sample. The limit of detection (LOD) was found to be 0.19 ng/mL (equals to 24.7 amol in 10 mu L sample) in the linear range of 0.5-10 ng/mL obtained in buffer medium. The applicability of this assay was investigated in the linear range of 0.5-3 ng/mL S1 protein in artificial saliva medium with the LOD as 0.13 ng/mL (equals to 16.9 amol in 10 mu L sample). The selectivity study was examined in the presence of Hemagglutinin antigen (HA) in both mediums; buffer and artificial saliva while resulting with the successful discrimination between S1 protein and HA. The one of ultimate goals of our study is to present the possible implementation of this assay to point of care (POC) analysis. Under this aim, this assay was performed in combination with a portable device that is the commercial electrochemical analyzer. Amperometric detection of S1 protein in the range of 0.5-5 ng/mL was also successfully performed in artificial saliva medium with a resulting LOD as 0.15 ng/mL (equals to 19.5 amol in 10 mu L sample). In addition, a selectivity study was similarly carried out by portable device.