Detection of IgG Antibodies Against COVID-19 N-Protein by Hybrid Graphene–Nanorod Sensor

The COVID-19 pandemic highlighted the global necessity to develop fast, affordable, and user-friendly diagnostic alternatives. Alongside recognized tests such as ELISA, nanotechnologies have since been explored for direct and indirect diagnosis of SARS-CoV-2, the etiological agent of COVID-19. Accordingly, in this work, we report a method to detect anti-SARS-CoV-2 antibodies based on graphene-based field-effect transistors (GFETs), using a nanostructured platform of graphene with added gold nanorods (GNRs) and a specific viral protein. To detect anti-N-protein IgG antibodies for COVID-19 in human sera, gold nanorods were functionalized with the nucleocapsid (N) protein of SARS-CoV-2, and subsequently deposited onto graphene devices. Our test results demonstrate that the sensor is highly sensitive and can detect antibody concentrations as low as 100 pg/mL. Using the sensor to test human sera that were previously diagnosed with ELISA showed a 90% accuracy rate compared to the ELISA results, with the test completed in under 15 min. Integrating graphene and nanorods eliminates the need for a blocker, simplifying sensor fabrication. This hybrid sensor holds robust potential to serve as a simple and efficient point-of-care platform.