Extended Data Fig. 4: 0g-Vertical Flow Immunoassay (VFI) analytical performance and quality control metrics.

a, 0g-VFI intensity for C-reactive protein (CRP) and immunoglobulin M (IgM) spots are a function of CRP and IgM concentration on multiplex membranes. CRP and IgM samples were assayed from three independent 0g-VFI (n = 3) and each CRP and IgM data point presented is the mean ± SEM of the triplicate. For each CRP and IgM plot, a four-parameter logistic model was used to generate the fitted curve and the limit of detection (LOD), represented as a dotted line, was determined using the following formula: \({\rm{L}}{\rm{O}}{\rm{D}}={\bar{x}}_{{\rm{negC}}}+3{{\sigma }}_{{\rm{negC}}}\), where LOD is equal to the mean of the negative control (negC) + 3 standard deviations (σ) of the negative control. b, Intra- and inter-assay coefficients of variation (CV) across CRP and IgM assays are presented; CVs were calculated by CV (%) = (Standard Deviation/Mean) x 100. For the inter-assay CV, each point represents the CV of the control spots obtained from three independent identical replicates of 7 CRP and IgM 0g-VFI membranes (n = 14). For the intra-assay CV, each point represents the CV of the three control spots obtained within the same membranes from 43 independent CRP and IgM 0g-VFI. c, Representative intensity distribution across 0g-VFI membranes. The plot shows three IgM spots from three independent 0g-VFI membranes (R1, R2, and R3) exposed to an IgM concentration of 1 μg/mL; the average of the three IgM spots is presented in black.