ABSTRACT
The development of versatile and sensitive biotools to quantify specific SARS-CoV-2 immunoglobulins in SARS-CoV-2 infected and non-infected individuals, built on the surface of magnetic microbeads functionalized with nucleocapsid (N) and in-house expressed recombinant spike (S) proteins is reported. Amperometric interrogation of captured N- and S-specific circulating total or individual immunoglobulin (Ig) isotypes (IgG, IgM, and IgA), subsequently labelled with HRP-conjugated secondary antibodies, was performed at disposable single or multiplexed (8×) screen-printed electrodes using the HQ/HRP/H2 O2 system. The obtained results using N and in-house expressed S ectodomains of five SARS-CoV-2 variants of concern (including the latest Delta and Omicron) allow identification of vulnerable populations from those with natural or acquired immunity, monitoring of infection, evaluation of vaccine efficiency, and even identification of the variant responsible for the infection.