Beyond Conventional Protein A: Mild Elution and Aggregate Control for Complex Antibody Purification

Jul 16,2026

bestchrom

Bispecific antibodies and other complex biologics can present purification challenges that conventional Protein A processes were not designed to address. Their structural complexity may increase sensitivity to low-pH exposure and susceptibility to aggregation, fragmentation, and other product-related impurities. Meanwhile, conventional Protein A resins often provide limited separation between monomers and aggregates, increasing the burden on downstream polishing operations.

This joint white paper from Bestchrom Biosciences and Altruist Biologics evaluates two engineered Protein A resins—Novo-A Diamond and Extrem A Diamond—using an industrially relevant bispecific antibody. Their elution behavior, aggregate separation capability, operating flexibility, and manufacturing applicability were compared with those of a conventional Protein A resin.

Both engineered resins enabled substantially milder elution, with peak elution pH values of 5.00 for Novo-A Diamond and 4.87 for Extrem A Diamond, compared with 4.29 for the conventional resin. They also generated distinct aggregate-enriched tailing regions, creating clearer separation between monomer-rich and aggregate-rich fractions. Under the initial comparison conditions, aggregate reduction reached 66.93%, while monomer purity in the pooled eluate reached 95.53%.

Further optimization with 50 mM NaCl or CaCl₂ enhanced chromatographic resolution and broadened the operating window, supporting more flexible pool-cut strategies and more robust process development and scale-up. Both resins also demonstrated strong alkaline stability during repeated 0.5 M NaOH cleaning cycles, supporting their potential use in multi-cycle manufacturing.

Together, these findings show how next-generation Protein A platforms can move capture beyond recovery—combining mild-pH elution, early-stage aggregate control, and manufacturing-relevant robustness to improve product quality and reduce downstream purification burden for complex antibody processes.

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