The global COVID-19 pandemic is not over, despite significant and stunning advances in vaccine technology. A key challenge in limiting the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been quickly and accurately identifying infected individuals. Now, investigators from Japan have developed a new antibody-based technique for the rapid and reliable detection of SARS-CoV-2 that does not require a blood sample.
The global response to the COVID-19 pandemic has been severely limited by the ineffective identification of SARS-CoV-2-infected individuals, and the high rate of asymptomatic infections (16%–38%) has exacerbated this situation. Thus far, the predominant detection method collects samples by swabbing the nose and throat. However, the application of this method has been limited by its long detection time (4–6 hours), high cost, and requirement for specialized equipment and medical personnel, particularly in resource-limited countries.
An alternative and complementary method for confirming COVID-19 infection involves the detection of SARS-CoV-2-specific antibodies. Testing strips based on gold nanoparticles are currently in widespread use for point-of-care testing in many countries. They produce sensitive and reliable results within just 10–20 minutes, but they require blood samples collected via a finger prick using a lancing device. This can be painful and increases the risk of infection or cross-contamination. Plus, the used kit components present a potential biohazard risk.
Lead author Leilei Bao from the Institute of Industrial Science, The University of Tokyo, explains: “To develop a minimally invasive detection assay that would avoid these drawbacks, we explored the idea of sampling and testing the interstitial fluid (ISF), which is located in the epidermis and dermis layers of human skin. Although the antibody levels in the ISF are approximately15%–25% of those in blood, it was still feasible that anti-SARS-CoV-2 IgM/IgG antibodies could be detected and that ISF could act as a direct substitute for blood sampling.”
After demonstrating that ISF could be suitable for antibody detection, the researchers developed an innovative approach to both sample and test the ISF. “First, we developed biodegradable porous microneedles made of polylactic acid that draws up the ISF from human skin,” explains Beomjoon Kim, senior author. “Then, we constructed a paper-based immunoassay biosensor for the detection of SARS-CoV-2-specific antibodies.” By integrating these two elements, the researchers created a compact patch capable of on-site detection of the antibodies within 3 minutes (result from in vitro tests).
This novel detection device has great potential for the rapid screening of COVID-19 and many other infectious diseases that is safe and acceptable to patients. It holds promise for use in many countries regardless of their wealth, which is a key aim for the global management of infectious diseases.
Reference: “Anti SARS CoV 2 IgM/IgG antibodies detection using a patch sensor containing porous microneedles and a paper based immunoassay” by Leilei Bao, Jongho Park, Boyu Qin and Beomjoon Kim, 1 July 2022, Scientific Reports.