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. 2021 Dec 7;118(50):e2112942118. doi: 10.1073/pnas.2112942118

Fig. 4.

Fig. 4.

Multivalency enhances aptamer binding and viral neutralization efficiency. (A) Histogram shows fluorescence intensity originating from binding events of RBD-PB6 aptamers on trimeric spike. (B) Scheme of multimerized versions of RBD-PB6-Ta aptamer joined by poly(A) linkers. Picomolar affinities for the multimerized aptamers were recorded by BLI for (C) biotinylated trimer, (D) dimer, and (E) monomer RBD-PB6-Ta immobilized on the sensor surface at different concentrations of spike trimer ranging from 150 nM in 1/3 serial dilutions for the monomer and 16 nM in 1/3 serial dilutions for trimer and dimer. (F) FIDA binding experiments show superior affinity of trimeric and dimeric aptamers for spike protein. (G) Competition assays show enhanced binding inhibition of ACE2:spike interaction with the dimer and trimer of RBD-PB6-Ta. (H) Neutralization plaque assay with SARS-CoV-2 virus on ACE2- and TMPRSS2-expressing VeroE6 cells.