New Biosensor Detects COVID-19 Virus in Air

A team of researchers from Switzerland has succeeded in developing a novel sensor for detecting the new coronavirus that could be used to measure the concentration of the virus in the environment, such as in places where there are many people or in hospital ventilation systems.

The researchers from Empa (Zürich, Switzerland) and ETH Zurich (Zürich, Switzerland) usually work on measuring, analyzing and reducing airborne pollutants such as aerosols and artificially produced nanoparticles. However, the COVID-19 challenge being faced by the whole world made the team shift its focus to developing a sensor that can quickly and reliably detect SARS-CoV-2 - the new coronavirus. Even before the COVID-19 began to spread, the team was researching sensors that could detect bacteria and viruses in the air and in early January, it came up with the idea of using this basis to further develop the sensor in such a way that it could reliably identify a specific virus was born. The sensor would not necessarily replace the established laboratory tests, but could be used as an alternative method for clinical diagnosis, and more prominently to measure the virus concentration in the air in real time, such as in busy places like train stations or hospitals.

As opposed to the molecular method called reverse transcription polymerase chain reaction, or RT-PCR for short, used in labs to detect viruses in respiratory infections, the researchers have developed an alternative test method in the form of an optical biosensor. The sensor combines two different effects to detect the virus safely and reliably: an optical and a thermal one. The sensor is based on tiny structures of gold, so-called gold nanoislands, on a glass substrate. Artificially produced DNA receptors that match specific RNA sequences of the SARS-CoV-2 are grafted onto the nanoislands. The receptors on the sensor are the complementary sequences to the virus' unique RNA sequences, which can reliably identify the virus.

To demonstrate how reliably the new sensor detects the current COVID-19 virus, the researchers tested it with a very closely related virus: SARS-CoV which broke out in 2003 and triggered the SARS pandemic. The validation was successful although a number of developmental steps are still needed to enable the sensor to measure the coronavirus concentration in the air.

“Tests showed that the sensor can clearly distinguish between the very similar RNA sequences of the two viruses,” said Jing Wang, one of the researchers. “This still needs development work. But once the sensor is ready, the principle could be applied to other viruses and help to detect and stop epidemics at an early stage.”

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ETH Zurich