Ultra-precise label-free nanosensor based on integrated graphene with Au nanostars toward direct detection of IgG antibodies of SARS-CoV-2 in blood.

Rapid distribution of airborne contagious pathogenic viruses such as SRAS-CoV-2 and their severely adverse impacts on different aspects of the human society, along with significant weaknesses of traditional diagnostic platforms, raised the global requirement for the design/fabrication of precise, sensitive, and rapid nanosystems capable of specific detection of viral illnesses with almost negligible false-negative results. To address this indispensable requirement, we have developed an ultra-precise fast diagnostic platform capable of detecting the trace of monoclonal IgG antibody against S1 protein of SARS-CoV-2 within infected patients' blood specimens with COVID-19 in about 1 min. The as-developed electrochemical-based nanosensor consists of a highly activated graphene-based platform in conjunction with Au nanostars, which can detect SARS-CoV-2 antibodies with a fantastic detection limit (DL) and sensitivity of 0.18 × 10-19%V/V and 2.14 µA.%V/V.cm-2, respectively, in human blood plasma specimens even upon the presence of a high amount of interfering compound/antibodies. The nanosensor also exhibited remarkable sensitivity/specificity compared with the gold standard (i.e., ELISA assay), which furtherly confirmed its superb performance.