Md. Azahar Ali et al have fabricated a new microfluidic chip that can provide rapid COVID-19 antibody tests in a few seconds. The researchers utilised an advanced nanomaterial-based biosensing platform by 3D nanoprinting of three-dimensional electrodes. The electrodes were coated by nanoflakes of reduced-graphene-oxide (rGO) using aerosol jet nanoprinting and immobilising specific viral antigens on the surface of the nanoflakes. The electrodes were integrated within a microfluidic device and used in a standard electrochemical cell. When antibodies were introduced they selectively bound to the antigens present on the electrode surface causing a change in the impedance of the electrical circuit which was detected via impedance spectroscopy. The test could identify two antibodies against structures on the virus, including the spike S1 protein and the receptor-binding domain at a limit-of-detection of 2.8 × 10−15
and 16.9 × 10−15 m, respectively. The sensor could be regenerated by eluting the antibodies from the antigens allowing for successive sensing of test samples. The test could help to measure patient responses to vaccines and determine if they have been previously exposed to SARS-CoV-2 virus and the results could be transmitted to a smartphone.
Source: Advanced Materials| 22 December 2020| https://doi.org/10.1002/adma.202006647