Diagnostic biosensor quickly detects SARS-CoV-2 from nasopharyngeal swabs

Currently, most diagnostic tests for COVID-19 rely on a technique called real-time reverse transcription-polymerase chain reaction (RT-PCR), which amplifies SARS-CoV-2 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.

Edmond Changkyun Park, Seung Il Kim and colleagues 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 team based their test on a field-effect transistor — a sheet of graphene with high electronic conductivity. The researchers 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, the team 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 researchers say.

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The authors acknowledge funding from the National Research Council of Science and Technology funded by the Ministry of Science and ICT, Korea and the Korea Health Technology R&D Project through the Korea Health Industry Development Institute funded by the Ministry of Health & Welfare, Korea.

The abstract that accompanies this paper can be viewed here.

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