Figure 3.

Detection of SARS-CoV-2 RBD S glycoprotein using CoV2-RBD-1C aptamer-based direct ELONA. (A) SARS-CoV-2 RBD S glycoprotein in a buffer solution (N = 3). Nuclease-free water was used for the background control, while S glycoprotein coated with no aptamer served as the negative control. The regression equation for difference in absorbance value and S glycoprotein concentration (5 - 5,000 ng/ml) in sodium carbonate buffer was y = 0.0001929x + 0.2185 with R² = 0.98, where x is the concentration of the S glycoprotein in ng/ml, and y is the absorbance value (OD₄₅₀). (B) SARS-CoV-2 RBD S glycoprotein spiked in a 0.1% human nasal fluid (N = 6). Diluted human nasal fluid was used as the background control, while S glycoprotein in a 0.1% human nasal fluid coated with no aptamer served as the negative control. Absorbance was obtained by subtracting the background control from all other wells. The regression equation for OD₄₅₀ difference versus S glycoprotein concentration (0 - 5,000 ng/ml) in 0.1% human nasal fluid was y = 0.2389x – 0.4017 with R² = 0.99. All results are presented in ± SEMs.