A rapid magnetic serological test for COVID-19

Abstract

The COVID-19 pandemic has hit and drastically changed the world during the last months. The severe consequences reveal the necessity of new tools and procedures to reduce the impact of future emergencies. Lateral flow immunoassays (LFA), better known as “rapid tests”, have been used to detect the infection. Now, when vaccination is the goal, they can be used to detect the body's immune response. Both immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies are produced against protein S, one of COVID-19 antigens. IgM is produced in the early stages of the infection whereas IgG takes longer but is more durable and could be the key to lasting immunity (Figure 1A-B).In this work, we propose a magnetic rapid serological test to detect and quantify the COVID-19 IgM and IgG antibodies in the blood (Figure 1C). Two different LFA have been designed to separate the antibodies against the RBD (a fragment of protein S). We tagged anti-human IgM and anti-human IgG with magnetic nanoclusters based on ferrite nanoparticles to make them detectable. These will produce a signal in the inductive sensor, specially designed to read LFA out [1][2]. The mapping technique uses an impedance analyzer synchronized with a micropositioner. The microstructural properties of the magnetic nanoparticles have been investigated by XRD, TEM, and AFM techniques while the magnetic properties have been assessed through NMR measurements and SQUID magnetometry.The detection and quantification of IgG and IgM are promising not only to identify exposed individuals but to generate quick data for rapid decision making.The authors would like to thank IEEE Magnetics Society for funding.  Figure 1. A) SARS-COVID-2 structure and amplification of protein S. B) Serology response: IgM and IgG production. C) Schematic LFA with its components. D) Schematic configuration of the tests designed to quantify the IgM (left) and IgG (right). Created with BioRender.com.  Figure 2. Inductive measurement setup to accurately quantify the IgG and IgM.