Fig. 2

Characteristics of pGOLD and titration curve for SARS-CoV-2 antibody detection. a The SEM image (up) of pGOLD substrate before arraying the antigens of SARS-CoV-2, the scale bar is 500 nm; the photograph of a set of pGOLD (down), the scale bar is 2 cm. b Recombinant human IgG and IgM antibodies to Wild-type S1 of SARS-CoV-2 with known concentration were serial diluted from 2 nM to 2 fM in fetal bovine serum (FBS), then assayed on pGOLD and glass substrates. As shown in b, the left slide is the pGOLD substrate, and the right part is glass substrate. On pGOLD, the fluorescent signal was saturated at 2 nM of IgG, with limit of detection down to 20 fM, over two orders of magnitudes lower than on glass substrate. c The titration curves and dynamic range of SARS-CoV-2 specific IgG and IgM antibody detection on pGOLD and glass substrates. The mean fluorescence intensity (MFI) was calculated from five array spots for each concentration. The error bars represented the standard deviation of the MFI over the three replicate measurements