The conspicuous progress in using monoclonal antibodies (mAb) as immunotherapeutic agents, for cancer therapy, medical diagnostics, and imaging has made mAbs a billion-dollar industry. Current commercially available isolation and purification methods for mAbs production such as affinity chromatography using Protein A resins (PrA) present reusability, stability, and cost issues. We have synthesized polymeric-IgG receptors (P-IgG) as an alternative for Protein A (PrA) resins, which are 57-fold cheaper than typical commercial PrA resins. The synthetic P-IgG were reusable for &gt;15 cycles as opposed to PrA resins with 5-6 reuses. P-IgG synthesized on 200 nm iron-core silica-shell magnetic-silica nanoparticles (SNPs), offer binding sites complementary to the size and shape of the Fc region on a monoclonal antibody. A strong PrA binder; mouse IgG2a was used as the template protein to anchor its Fc stem down via imine linkages to the SNPs’ surface. Carbohydrate moieties on IgG2a Fc stem were oxidized to dialdehydes by periodate and then reacted with aminated SNPs to form imine bonds. Silane monomers with hydrophobic, hydrophilic, and H-bonding functional groups are introduced, and the template is removed, leaving specific stem IgG binding site moieties that are specific to the IgG2a Fc stem. By introducing multiple silane monomers onto SNPs with diverse functional groups, the P-IgG mimics the PrA activity profile of high specificity and selectivity. Binding constants, binding capacities, stability, reusability, particle size variations, surface charge changes, and surface morphological characteristics of P-IgG were compared to commercially available Protein A resins. LC/MS-MS proteomic studies were performed to evaluate IgG isolation efficiency from human serum.

Polymeric-IgG receptors on core-shell magnetic silica nanoparticles for antibody isolation

ACS Spring 2022

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