Table 1.
Essential demographic characteristics of participants.
Fig 1.
SARS-CoV-2 IgG standard curve.
Fig 2.
SARS-CoV-2 IgM standard curve.
Table 2.
Lateral flow immunoassays for COVID-19 diagnostic testing.
Fig 3.
The workflow of quantitative spectral LFIA platform.
The optical-based platform applies 10–20 uL of blood from a fingertip or a vein to the test strip, integrating the immunoglobulins and producing results in 5–10 minutes.
Fig 4.
The platform learned LOD (Limit of detection) from the database of 40 COVID-19 negative patients.
Lateral flow immunoassay formed colloidal gold antibody-conjugated IgG/IgM complexes on the colored bands. Then, LOD was determined by α value, which refers to the color reflection value of the antibody-conjugated IgG/IgM complexes by optical scanning. Finally, specimens of 40 COVID-19 negative patients were employed to establish the standard LOD (limit of detection) interval.
Table 3.
The performance of 5 types of lateral flow immunoassays.
Table 4.
COVID-19 IgG/IgM antibody rapid tests.
Fig 5.
The performance of five types of lateral flow immunoassays.
Samples of 12 RT-PCR positive subjects were followed up by days after symptoms onset. Abbreviations: BioMedomics, COVID-19 IgM/IgG Rapid Test (BIOMEDOMICS INC.); ACE Biolabs, COVID-19 IgG / IgM Dual Detection Kit (ACE Biolabs INC.); ASK, COVID-19 Antibody Rapid Teat (TONYAR BIOTECH INC.); TBG, SARS-CoV-2 IgG/IgM Rapid Test Kit (TBG Diagnostics Limited.).
Fig 6.
The α value in different groups of Covid-19 diagnosis.
The quantitative optical-based LFIA platform showed a significant difference of α value in COVID-19 RT-PCR negative and positive patient groups.
Fig 7.
Increase of COVID-19 antibodies distribution by days after symptoms onset.
After converting the α value into the actual antibody concentration unit (ng), a trend could be observed in the Covid-19 RT-PCR positive group that IgM reached the peak value first, and then IgG rose and maintained.