Fig. 5.

(a) Fluorescence images and corresponding intensities of SQS-LFIA with various blocking buffer treatments (1−, 2−, 3−) for blank sample (−1), medium positive (−2) and strong positive (−3) SARS-CoV-2 antibody samples. Value above each histogram represent the ratio of the response positive signal to blank signal (S/B). (b) Fluorescence images and corresponding intensities of SQS-LFIA for a serum sample of SARS-CoV-2 positive patient with different dilution ratios. (c) Scanning curves of SQS-LFIA strips by the portable optical scanner corresponding to the results of (b). (d) Fluorescence intensities of six different serum samples from SARS-CoV-2 positive patients with different dilutions ratios.