Covid-19: Czech scientists develop reusable biosensor for rapid testing

Photo: Eva Kézrová, Czech Radio

Czech scientists have developed a new method for detecting Covid-19 using a biosensor that delivers test results in just minutes. The prototype has proven as accurate as nasal swab tests, which take half a day or longer to process. In addition to being much faster, researchers say, the biosensor also determines how much of the virus is present – a key measure of the likely stage and severity of infection.

Photo: Eva Kézrová, Czech Radio

Of the Covid-19 tests that are currently officially available to Czech doctors, only the polymerise chain reaction (PCR) test, which works with nasal swabs, is considered reliably accurate. But PCR tests detect the virus by cleaving and multiplying an RNA sample, a multistage process which can take even a full day.

Hana Lísalová is head of the research team at the Optical and Biophysical Systems department at the Academy of Sciences that has developed the biosensor prototype. Apart from being faster that PCR tests, she told Czech Radio, the biosensor also goes beyond simply detecting the presence of an antigen.

“We have confirmed the functionality of the biochip and the entire system. And we went a step further by conducting blind and comparative studies with PCR tests. All the biosensor and PCR test results corresponded, both the negative and positive ones.

Photo: Eva Kézrová, Czech Radio

“But our biosensor can also determine the concentration of viral antigens. That is a big advantage. Existing tests only show if these antigens are present or not. … We are now in negotiations with industry partners and will hope to bring the biosensor to market as soon as possible.”

Existing rapid Covid-19 tests, which collect saliva samples, can yield results within a matter of minutes – but often at the expense of reliability. Another problem is that it much harder to confirm a positive infection in asymptomatic patients.

The Motol University Hospital in Prague last week began conducting a widescale comparative study of 600 people using standard PCR tests that detect antigens and two others that detect the body’s immune response, or antibodies in an effort to bridge that gap, says microbiologist Pavel Dřevínek.

Photo: Daniel Špaček,Neuron Collective

“The first group comprises patients with clinical symptoms of Covid-19. We do not expect to see a big difference in testing accuracy there. But the second group comprises asymptomatic patients who have been exposed to the virus. With this group, for us the big question is which rapid tests are as accurate as PCR.”

In both respects, the biosensor that Hana Lísalová’s team has developed excels. What’s more, it can detect Covid-19 not only in bodily fluids but also, for example, in samples collected from surfaces and even wastewater. A further advantage is that in case of a negative test result, the biochip can be reused.

While the basic method was developed already years ago to rapidly detect pathogens in food, such as salmonella, the Covid-19 biochip took many months to perfect. Its commercial release is likely still months away.