Fig. 4: Electrochemical detection of viral infection using emulsion-based sensor.
a Schematics of electrochemical enzymatic detection of SARS-CoV-2 RNA, antigen, and host antibody using emulsion-based sensors. b–d Calibration curves for ORF1a gene and nucleocapsid protein of SARS-CoV-2, and IgG antibody using CV with 1 V s−1 scan rate between −0.5 and 0.5 V. LOD was defined using three standard deviations (3σ) of the blank solution. CV were measured on four WEs, out of which three were involved in the reaction with the target species, while one served as a negative control. Data represents as mean values ± SD (n = 3 independent experiments). e–g ROC curves based on the detection results of emulsion-based sensors. AUC was 1, 0.996, and 0.993 for ORF 1a, nucleocapsid protein, and IgG antibody, respectively. Clinical NPS (Positive: 40, Negative: 20) were used to detect ORF1a gene and nucleocapsid protein of SARS-CoV-2, and clinical serum (Positive: 33, Negative: 20) was used to detect the IgG. Each data obtained from three independent electrodes. The experiments were conducted over a total of two rounds. h–j, Waterfall distribution of peak current for clinical samples. Data represents mean values ± SD (n = 3 independent experiments). Cut-off values were determined from the ROC curves: 2.12 (ORF1a gene), 0.857 (Nucleocapsid protein), and 1.3 (IgG antibody) μA. k Correlation between peak current measured from emulsion-based sensors and Ct value measured from RT-qPCR for COVID-19 positive clinical samples. Pearson’s r was −0.67 for antigen testing and 0.42 for antibody testing.
