Dual lateral flow optical/chemiluminescence immunosensors for the rapid detection of salivary and serum IgA in patients with COVID-19 disease

To accurately diagnose COVID-19 infection and its time-dependent progression, the rapid, sensitive, noninvasive determination of immunoglobulins A specific to SARS-CoV-2 (IgA) in saliva serum is needed complement tests that detect G M. We have developed a dual optical/chemiluminescence format lateral flow immunoassay (LFIA) immunosensor for IgA saliva. recombinant nucleocapsid antigen specifically captures antibodies patient specimens. labelled anti-human reveals bound fraction. colorimetric chemiluminescence detection enables affordable ultrasensitive SARS-CoV-2. Specifically, simple smartphone-camera-based device measures colour signal provided by nanogold-labelled IgA. For transduction, we used contact imaging portable based on cooled CCD, measured light resulting from reaction HRP-labelled with H2O2/luminol/enhancers substrate. total 25 9 samples infected and/or recovered individuals were analysed LFIA, which was sensitive reproducible enough semi-quantification subjects strong serological response early stage infection. Switching CL detection, same exhibited higher capability, revealing presence salivary individuals. patients included study (n = 4), level correlated time elapsed diagnosis severity disease. This IgA-LFIA could be useful noninvasively monitoring immune responses investigating diagnostic/prognostic utility context large-scale screening assess efficacy vaccines.