Multimeric fusion single-chain variable fragments as potential novel high-capacity ligands

In basic and applied biotechnology, design of affinity ligands has become essential for high-capacity applications such as affinity-based downstream processes for therapeutic molecules. Here, we established a proof-of-concept for the use of multimeric fusion single-chain variable fragment (scFvs) as high-capacity ligands in affinity adsorbents. Mono- and di/tri-scFvs separated by Pro-rich negatively charged linkers were designed, produced, and immobilized to 6% cross-linked agarose beads. Frontal binding experiments with a target protein of 50 kDa resulted in up to 20 mg·mL^-1 and 82% in dynamic binding capacity and utilization yield, respectively, at 100% breakthrough. The utilization of the binding sites was impacted by the ligand format and ligand density, rather than limitation in pore size of adsorbent as previously suggested. Overall, we demonstrated that multimeric fusion scFvs can successfully be developed and used as high-capacity ligands in affinity adsorbents, enabling lean process design and alignment with process specifications.