<strong>Activity Assay- ELISA</strong>. The Binding Activity of SARS-CoV-2 Spike RBD Nanobody with SARS-CoV-2-S1-RBD. Activity: Measured by its binding ability in a functional ELISA. Immobilized SARS-CoV-2-S1-RBD (<a href='https://www.cusabio.com/Recombinant-Protein/Recombinant-Human-Novel-Coronavirus-Spike-glycoprotein-S---partial-12928552.html'>CSB-YP3324GMY1</a>) at 2 μg/ml can bind SARS-CoV-2 Spike RBD Nanobody, the EC<sub>50</sub> is 0.8674 ng/ml.