A team of researchers in the Republic of Korea has successfully fabricated a promising transistor-based biosensor that detects SARS-CoV-2, a novel coronavirus that causes the COVID-19 disease, in nasopharyngeal swabs in less than one minute.
Currently, most diagnostic tests for SARS-CoV-2 rely on a technique called real-time reverse transcription-polymerase chain reaction (RT-PCR), which amplifies the virus RNA from patient swabs so that tiny amounts of the virus can be detected.
However, the method takes at least 3 hours, including a step to prepare the viral RNA for analysis.
The research team led by Dr. Edmond Changkyun Park and Dr. Seung Il Kim from Korea Basic Science Institute, Korea Research Institute of Chemical Technology and the University of Science & Technology wanted to develop a faster diagnostic test that could analyze patient samples directly from a tube of buffer containing the swabs, without any sample preparation steps.
The scientists based their test on a field-effect transistor, a sheet of graphene with high electronic conductivity.
They attached antibodies against the SARS-CoV-2 spike protein to the graphene.
When they added either purified spike protein or cultured SARS-CoV-2 virus to the sensor, binding to the antibody caused a change in the electrical current.
Next, they tested the technique on nasopharyngeal swabs collected from patients with COVID-19 or healthy controls.
Without any sample preparation, the sensor could discriminate between samples from sick and healthy patients.
“The new test was about 2-4 times less sensitive than RT-PCR, but different materials could be explored to improve the signal-to-noise ratio,” the authors said.
The team’s biosensor is described in a paper in the journal ACS Nano.
Giwan Seo et al. Rapid Detection of COVID-19 Causative Virus (SARS-CoV-2) in Human Nasopharyngeal Swab Specimens Using Field-Effect Transistor-Based Biosensor. ACS Nano, published online April 15, 2020; doi: 10.1021/acsnano.0c02823