Syndicate content

Diagnostic Biosensor Detects SARS-CoV-2 (COVID-19) from Nasopharyngeal Swabs in Less Than Minute

According to many experts, early diagnosis and management are critical for slowing the spread of SARS-CoV-2, the new coronavirus that causes COVID-19. Therefore, the race is on to develop diagnostic tests for the virus that are faster, easier and more accurate than existing ones. Now, researchers, reporting online on April 15, 2020 in ACS Nano, have developed a field-effect transistor-based biosensor that detects SARS-CoV-2 in nasopharyngeal swabs from patients with COVID-19, in less than one minute. The open-access article is titled “Rapid Detection of COVID-19 Causative Virus (SARS-CoV-2) in Human Nasopharyngeal Swab Specimens Using Field-Effect Transistor-Based Biosensor,” Currently, most diagnostic tests for COVID-19 rely on a technique called real-time reverse transcription-polymerase chain reaction (RT-PCR), which amplifies DNA that has been produced by reverse transcription from 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, PhD, and Seung Il Kim, PhD, both at the Korea Basic Science Institute in the Republic of Korea, 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 its 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 to 4 times less sensitive than RT-PCR, but different materials could be explored to improve the signal-to-noise ratio, the researchers say.

[Press release] [ACS Nano article]

IMAGE

A new test quickly detects SARS-CoV-2 (spheres) through binding to antibodies (Y-shapes) on a field-effect transistor. (Credit: Adapted from ACS Nano 2020, DOI: 10.1021/acsnano.0c02823).