Data sheets | SPR Sensor chips

Protein AG–modified sensor chips

XanTec’s Protein AG (PAG) sensor chips are coated with a bioinert polycarboxylate matrix pre-functionalized with a recombinant 50.5 kDa Protein AG. This non-glycosylated variant combines four IgG-binding domains from Protein A and two IgG-binding domains from Protein G, providing high-affinity binding to the Fc region of all human IgG subclasses. In addition, it exhibits strong affinity for mouse IgG2a, IgG2b, and IgG3, as well as total IgG from cow, goat, sheep, rabbit, and other mammals.

To ensure highly specific IgG binding, non-essential domains (e.g., cell wall-, cell membrane-, and albumin-binding regions) have been removed from the recombinant Protein AG. Nevertheless, due to its slightly hydrophobic character, some nonspecific binding may occur. The inclusion of blocking agents (e.g., BSA) and/or nonionic detergents (e.g., Tween) in the running buffer is therefore recommended to minimize background signals. XanTec’s PAG sensor chips are ready-to-use, enabling rapid assay setup without time-intensive surface optimization.

Key features:

Fast assay development: No preconcentration or surface activation required; controlled and reversible capture under physiological conditions.
Broad antibody compatibility: Wider subclass and species coverage than Protein A.
Simple regeneration: Regeneration using glycine·HCl pH 1.5.
High stability: Robust capture surfaces support repeated regeneration cycles.
Oriented immobilization: Directed Fc-region binding ensures high ligand activity.

Schematic illustration of a 3D PAG sensor chip. Red dots represent negatively charged carboxyl groups distributed along the green polymer chains. The magnified view shows Protein AG (yellow–orange) binding to the Fc region of an antibody (blue).¹

Product code	PAGP	PAGD200L	PAGHC30M	PAGHC200M
Base coating	2D, ultra-short bioinert CM-dextran (high density)	3D, 200 nm bioinert CM-dextran (low density)	3D, 30 nm bioinert polycarboxylate (medium density)	3D, 200 nm bioinert polycarboxylate (medium density)
Capture immobilization capacity [µRIU]³	≈ 5,000	≈ 12,000	≈ 6,000	≈ 11,000
Ligands	Fc region of all human IgG subclasses; strong affinity for mouse IgG_2a, IgG_2b, IgG₃, and total IgG from cow, goat, sheep, and rabbit
Recommended analytes	proteins peptides nucleic acids	proteins peptides nucleic acids small molecules	proteins peptides nucleic acids carbohydrates	proteins peptides nucleic acids carbohydrates small molecules
Intended purpose	kinetic measurements based on oriented Fc-region immobilization	capture immobilization of Fc fusion proteins and antibodies for medium- to large-sized analytes antibody quantification	capture immobilization of Fc fusion proteins and antibodies for small- to medium-sized analytes antibody quantification	capture immobilization of Fc fusion proteins and antibodies for medium- to large-sized analytes including carbohydrates antibody quantification

¹ All illustrations are schematic representations and are not drawn to scale; dimensions, densities, and spatial relationships do not reflect actual physical or chemical proportions.

² Table includes a selection from XanTec’s full PAG sensor chip portfolio.

³ Maximum immobilization capacities are based on capture from a 100 µg/mL solution of Protein A-purified, pooled rabbit IgG in PBS, with 1 µRIU corresponding approximately to 1 RU.

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Protein AG–modified sensor chips