Fig 3. DARPin dimers exhibit superior toxin-neutralization potency relative to the constituent monomers.

IMAC-purified DARPin dimers or monomers were added to Vero cells (1.5 × 10³ cells/well) together with TcdB (5 pg/mL). Cell viability was quantified 72 hours later by CellTiterGlo assay and normalized to naïve Vero cells. Error bars represent the standard deviation of at least 2 independent experiments performed in duplicate. Conc, concentration; DARPin, designed ankyrin repeat protein; IMAC, Immobilized metal affinity chromatography; TcdB, C. difficile toxin B.