Biosensors for the detection and quantification of human immunoglobulin G (IgG) are critical in the fields of clinical diagnosis and quality control in the biopharmaceutical industry. Surface Plasmon Resonance (SPR) was used to study the binding behavior of human IgG to a hexameric peptide ligand (HWRGWV) and compared to the binding of IgG to Protein A.  In both cases, self-assembled monolayers on gold were used to covalently immobilize the ligands. Immobilization by using peptides that were  Fmoc-protected, acetylated, and non-acetylated were considered. Mixed monolayers with �NH2 and �OH termini were studied for the effect of ligand density on protein binding. An increase in fractional conversion of Fmoc-peptides with increased content of �OH in the mixed monolayers was observed. IgG-Protein A binding and peptide-IgG binding yielded equilibrium dissociation constants of 1.4 x 10-7 M and 1.8 x 10-6 M respectively. The maximum binding capacities, Qm for protein A biosensors and peptide biosensors were determined to be 6.7 mg/m2 and  3.5 mg/m2, respectively. Real-time data were used to determine the kinetic rate constants, ka and kd. IgG binding from buffer solutions and from complex mixtures was investigated. Biosensor regeneration studies were performed to allow multiple binding cycles. This study offers a novel and promising approach to biodetection in effluents from columns and reactors by using stable and inexpensive ligands.

Equilibrium and dynamics of human IgG adsorption to novel peptide affinity ligands using Surface Plasmon Resonance

243rd National Meeting (2012)

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