Metal and chelator complexes—A newly discovered technology to purify immunoglobulins without Chromatography, polymers, membranes, or specific ligands.

We introduce a new concept and a potentially general platform for the purification of immunoglobulins that does not rely on any resins, chromatographic media, membranes, or specific ligands; rather, it makes use of aromatic [metal—chelator] complexes. A hydrophobic chelator is combined with three different metal ions to establish our purification system. We experimented on the purification of IgG, IgM, and IgA, along with an artificial impurity background. Our impurity background contained 2600 proteins, along with 600 membrane proteins. Our system captured the target immunoglobulins quantitatively via [cation—pi] and [pi—pi] interactions and allowed for their recovery at high yields (80% to 88%, by densitometry) and purity (90% to 96%, by SDS-PAGE), while preserving their secondary structure (by circular dichroism, CD, and native PAGE gel electrophoresis) and monomeric state (by dynamic ligand scattering, DLS). The entire process was performed at pH 6-7, thereby avoiding complications that derive from exposure to harsh acidic conditions (e.g., aggregation, partial denaturation). The potential to upscale the technology was evaluated at the laboratory scale. The leaching of the metal—chelator complex to the eluted antibodies was assessed and found to be less than 1%. The recycling of the chelator after the purification process generated a satisfactory yield of 95-97% . The cost-effectiveness and simple integration into the future, industrial-scale downstream processing of therapeutic-grade biopharmaceuticals is discussed.