Rapid Method to Detect SARS-CoV-2 Spike S1 Antigen

– Faizan Bhat

COVID-19 has posed an enormous global health challenge for the past few years. According to the WHO, more than 550 million cases of COVID-19 have been recorded worldwide so far, and six million people have died. Early diagnosis and treatment of the disease are crucial for its management and containment.

Currently, the most widely used diagnostic techniques such as chest computed tomography (CT) scans and RT-PCR tests are costly and time-consuming. To address this issue, a team led by Sonu Gandhi, Scientist D at the National Institute of Animal Biotechnology (NIAB), Hyderabad and Arindam Ghosh, Professor at the Department of Physics, Indian Institute of Science (IISc) has developed a highly sensitive graphene based immunosensor for rapidly detecting the SARS-CoV-2 Spike S1 antigen.

Schematic representation of anti-spike S1 antibody immobilized on activated graphene field-effect transistor for real time rapid detection of SARS-CoV-2 Spike S1 antigen

The team built the sensor using a chemically modified graphene-based field-effect transistor (FET). To the graphene channel, they attached antibodies that specifically bind to the virus’ spike S1 antigen – the attachment was confirmed using optical spectroscopy and enzyme assays. Real-time change in channel resistance was monitored for detecting the antigen. The lowest concentration that the sensor could detect was ten femtomolar.

A major advantage of FET sensors is their rapid detection and ultra-high sensitivity. The team reduced the fabrication cost by generating the spike S1 antibodies in-house. According to them, in the future, the sensor could also be miniaturised to develop a portable device for the diagnosis of COVID-19.

D Shahdeo, N Chauhan, A Majumdar, A Ghosh, and S Gandhi, Graphene-Based Field-Effect Transistor for Ultrasensitive Immunosensing of SARS-CoV-2 Spike S1 Antigen, ACS Applied Bio Materials, 2022, 5(7):3563-3572.