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. Reference: “Rapid Detection of COVID-19 Causative Virus (SARS-CoV-2) in Human Nasopharyngeal Swab Specimens Using Field-Effect Transistor-Based Biosensor” by Giwan Seo, Geonhee Lee, Mi Jeong Kim, Seung-Hwa Baek, Minsuk Choi, Keun Bon Ku, Chang-Seop Lee, Sangmi Jun, Daeui Park, Hong Gi Kim, Seong-Jun Kim, Jeong-O Lee, Bum Tae Kim, Edmond Changkyun Park and Seung Il Kim, 15 April 2020, ACS Nano.DOI: 10.1021/acsnano.0c02823 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.
