Identification of GPVI Affimers and their effect on GPVI-ligand interactions and platelet aggregation. Screening of GPVI-binding Affimers raised against GPVI monomer (A) and GPVI dimer (B) by phage ELISA. Fc domain (gray) was tested as a control. No protein was added in Blank (yellow). A total of 31 unique Affimers that bind to immobilized GPVI monomer (blue) and GPVI dimer (green) with the highest affinity were identified from 48 clones. These clones are numbered as M1 to M24 and D1 to D24 for Affimers screened against GPVI monomer and dimer, respectively. The effect of Affimers M17, D22, and the dimer-specific Affimer (D18) on GPVI dimer interaction with immobilized CRP-XL (C) and collagen (D) were characterized by competitive ELISA and expressed as % inhibition as compared to buffer control. Affimer scaffold was also used as a control. The effect of Affimers M17, D22 and D18 on CRP-XL (E) and collagen (F)–induced platelet aggregation was studied by aggregation assays. Data were normalized using the scaffold control (100% aggregation) as reference. Data are presented as mean ± standard deviation (SD); n ≥ 3.