Roberto de la Rica, Health Research Institute of the Balearic Islands
Screening and Management of COVID-19 with Paper-Based Nanoparticle Tests
Written by Jessalyn Low Hui Ying
Current conventional methods for the diagnosis of COVID-19 require a nasopharyngeal swab test. However, this must be done by trained professionals, therefore limiting the number of tests done per day. Furthermore, it is important to detect biomarkers like cytokines that can prognosticate outcomes of COVID-19, so as to achieve better distribution of healthcare resources. In this talk, Roberto de la Rica reports the development of paper-based biosensors that can be used for non-invasive detection of COVID-19 antigens, as well as detection of prognostic biomarkers in blood and respiratory samples from patients.
In this paper-based biosensor, a piece of filter paper is first modified with polystyrene sulfonate (PSS), and then a drop of antibody-decorated gold nanoparticles. The PSS prevents the irreversible interaction of nanoparticles with the paper, which was validated using scanning electron microscopy. The gold nanoparticles from the paper reservoir can then be transferred to another substrate just by pressing against it. For the diagnosis of COVID-19, this receiving substrate can be a face mask. As the nanoparticles are decorated with anti-COVID-19 antibodies, antibody-antigen interactions will occur resulting in a color change should the target antigens be present. The level of antigens is reflected in the intensity of the color which can then be detected through a mobile application. When tested, the biosensor achieved a high specificity of over 0.97 and sensitivity over 0.7 for COVID-19 antigen detection.
This biosensor can also be used to detect the interleukin 6 (IL-6) protein, which is a cytokine that has been shown to be part of the cytokine storm in COVID-19 patients. The biosensor was able to achieve a very low limit of detection of 10-3 pg/mL, and could detect IL-6 levels higher than 17 pg/mL in blood and higher than10 pg/mL in respiratory samples. “The ability of detecting this cytokine in blood and respiratory samples is important in order to evaluate both systemic and local inflammation in COVID-19 which are related but do not have to be necessarily the same,” says de la Rica.