A team of French researchers has developed a simple and highly sensitive prototype test that can detect SARS-CoV-2 in less than 10 minutes. The device, called CorDial-1, reveals the presence of living virus and therefore can be used to test for active infection.
Unlike many of the other tests currently used in the pandemic, CorDial-1 relies on electrochemistry. “The device is based on the grafting of small antibodies called ‘nanobodies’ on the surface of an electrode to perform electrochemical measurements,” Sabine Szunerits, professor in chemistry at the University of Lille, told Technology Networks.
Nanobodies are tiny fragments of antibodies found in camelids, such as camels, llamas and alpacas. They are small, soluble and very stable, making them efficient biotechnological tools.
In CorDial-1, nanobodies recognizing the envelope or spike protein are immobilized on the surface of an electrode. When a sample is placed on the electrode, SARS-CoV-2 viral particles interact with the nanobodies and induce a change in current. The change in signal correlates with the quantity of viral particles captured by the nanobodies, and with the use of an electrode reader, can be analyzed via a smartphone. “The technology developed in this project is very innovative and gives the device an undeniable competitive advantage,” commented Szunerits.
Electrochemical detection platforms show great potential for viral sensing due to their ease of use, speed and portability. However, certain limitations related to their sensitivity, reproducibility and upscaling have so far restricted their use in the COVID-19 pandemic, explained Szunerits. Choosing the right surface ligand and chemistry is also strongly connected to the success of such diagnostic devices, in addition to robust validation under real and future conditions of use.
The project to develop the CorDial-1 device arose at the start of the COVID-19 pandemic as a close collaboration between partners based at the Universities of Lille and Marseille, the French National Scientific Research Centre (CNRS) and the Lille University Hospital (CHU Lille).
In initial trials, the test was validated on more than 300 samples and demonstrated an exceptional efficiency of 88% positive and 88% negative agreement on clinical samples, as compared to RT-PCR. A patent for the technology was filed in October 2020 and the team is currently working to improve the device further. A three-month trial is planned that will involve completing 1,000 tests per week at CHU Lille and the University of Marseille, “to see how nurses and patients feel about the system, get stockholder feedback, helping us to improve the system before commercialization,” Szunerits told Technology Networks.
In addition to its impressive speed and sensitivity, CorDial-1 also offers the advantage of being easily adaptable, which will help to ensure that the test remains sensitive to SARS-CoV-2 variants. The team has already shown that the technology can be used for Herpes detection and currently has funding from the French National Research Agency to develop tests for influenza.
“We believe this diagnostic concept to be a powerful tool to detect patients’ infection, easily extendable to other viruses and capable to overcome sensing-related mutation effects,” commented Szunerits. The technology’s use is not only limited to viral detection, with other routes to be explored in the future including developing tests to sense blood biomarkers.
Sabine Szunerits was speaking with Anna MacDonald, Science Writer for Technology Networks.