Rapid antigen tests can swiftly and easily reveal whether or not someone is infected with COVID-19. Antibody-based tests, on the other hand, aren’t extremely sensitive, thus they may miss early infections with low viral loads.
Researchers have now devised a quick test for detecting SARS-CoV-2 that uses molecularly imprinted polymer nanoparticles rather than antibodies, as reported in ACS Sensors.
Compared to antibody-based testing, the new test is more sensitive and works under more severe situations.
The reverse transcription-polymerase chain reaction remains the gold standard test for COVID-19 diagnosis (RT-PCR). Although this test is extremely sensitive and specific, it takes 1-2 days to receive a result, is costly, and necessitates the use of specialised lab equipment and skilled workers.
Rapid antigen tests, on the other hand, are quick (15-30 minutes) and may be done at home without any prior training. They do, however, lack sensitivity, which can lead to false negatives. In addition, the assays rely on antibodies against SARS-CoV-2 for detection, which are sensitive to temperature and pH changes.
Newcastle University’s Marloes Peeters and Jake McClements, MIP Diagnostics’ Francesco Canfarotta, and colleagues intended to develop a low-cost, quick, robust, and highly sensitive COVID-19 test using molecularly imprinted polymer nanoparticles (nanoMIPs) rather than antibodies.
By establishing molecular imprints, or moulds, in the nanoparticles, the researchers were able to create nanoMIPs against a tiny portion, or peptide, of the SARS-CoV-2 spike protein.
The imprinted peptide and, as a result, the complete protein were recognised and bound by these nanoscale binding cavities, which were the right size and shape. They used printed electrodes to attach the nanoparticles that were most tightly bound to the peptide.
They built a 3D-printed prototype device that detects virus binding by monitoring temperature variations after demonstrating that nanoMIPs could bind SARS-CoV-2.
The liquid flowed over the electrode when the researchers introduced samples from seven patient nasopharyngeal swabs to the device, and the researchers noted a shift in temperature for samples that had previously tested positive for COVID-19 by RT-PCR.
The test took only 15 minutes to complete, and preliminary results showed that it could detect SARS-CoV-2 at a 6,000-fold lower level than a commercial quick antigen test.
The nanoMIPs, unlike antibodies, could withstand high temperatures and acidic pH, potentially extending the test’s shelf life in hot regions and making it helpful for monitoring SARS-CoV-2 in wastewater and saliva samples.
The researchers note that in order to verify that the test has a lower false negative rate than existing fast antigen assays, it must be evaluated on a larger number of patient samples.
To read our blog on “In minutes, a new testing kit can detect any COVID-19 variant,” click here
