Scientists developing low-cost, saliva-based Covid-19 test inspired by glucose test strips for diabetes

Researchers are developing a rapid, low-cost and mass manufacturable saliva-based biosensor test for Covid-19 inspired by the glucose test strips used to check blood sugar levels in people with diabetes.

According to the research team from the University of Strathclyde in Scotland, the test could eventually be mass manufactured for as little as 20 pence per test. It is designed for rapid in the field use, similar to a lateral flow test, to allow people in community settings to determine their Covid-19 status.

When a person is self-testing, they would put saliva directly onto the test strip where the measurement is run by the instrument and the result produced on a display, avoiding the discomfort associated with nasopharyngeal swabs.

Compared to other diagnostic tests, glucose blood tests can already be manufactured at scale, with test strips and readers CE marked with regulatory approval for use in the management of diabetes. This means the route to producing a Covid-19 test based on the technology can be much quicker.

A paper published in Royal Society of Chemistry journal ‘Chemical Communications' , details how a special chemical treatment is applied to the sensor surface to produce the test, which uses the ACE2 enzyme - the receptor that coronavirus uses to bind on to cells - meaning clinically relevant detection levels of the virus can be achieved.

The team have patented the experimental technology, and using clinical samples provided by NHS Greater Glasgow and Clyde Biorepository, will translate this proof of concept work into a working product.

It is being commercialised in the form of a spin out company called Aureum Diagnostics, supported by Norcliffe Capital, who will develop the test into a CE marked commercial product for real world use. The company is aiming to have a first version of the test for emergency use ready in 12 months and a fully CE marked test on the market in 18-24 months.

Lead investigator, Dr Damion Corrigan from the department of Biomedical Engineering at Strathclyde, said: "The test would provide a scalable route to sensitive, specific, rapid and low-cost testing for Covid-19, but in addition could serve as a low cost tool to rapidly diagnose other respiratory viruses and determine whether someone has Covid-19, flu or rhinovirus. This means it could enable screening of workers, at very low cost, for example in their place of work, identifying and isolating those with the disease and enabling those recovered to go back to work.

"Initially, we will demonstrate this with Covid-19 and then commercialise the test so that we can work on using the underlying patent to produce new sensor technologies for other respiratory viruses and infectious diseases."

The team partnered with Lifescan in Inverness, one of the world's leading manufacturers of diabetes test strips.

Dr Corrigan, added: "Very few other diagnostic technologies can compete in terms of cost and scale. By printing ACE2 onto the sensor, it means the strip is designed to selectively capture the coronavirus and also be mutation proof. The test should remain sensitive to different strains of the virus unlike tests based on polymerase chain reaction (PCR) or antibody tests which only look for a small part of the viral material."

The experimental sensor was initially tested with inactivated virus samples at different concentrations, ranging from low to high, alongside negative samples from a commercially available molecular diagnostics standards kit.

Hospital laboratory tests were then carried out on real patient samples provided by the NHS Greater Glasgow and Clyde Biorepository. The most recent set of experiments showed detection was possible in 15 minutes.

Dr Michael Murphy, Consultant Microbiologist in the Department of Microbiology, at Glasgow Royal Infirmary, NHS Greater Glasgow and Clyde and co-investigator on the study, said: "Covid-19 has shone a massive spotlight on the need for rapid, affordable diagnostic tests produced at scale. There is a vital need to develop similar diagnostic tests for flu and other viral infections to help improve patient care, screen health care workers and reduce the risk of hospital acquired infections."

"At NHS Greater Glasgow and Clyde, we're working to prepare for future pandemics by working on innovative solutions to the challenges of rapid diagnostics," Dr Murphy said.