Data sheets | SPR Sensor chips

Protein A–modified sensor chips

XanTec’s PAP, PAD, and PAHC sensor chips are coated with a bioinert polycarboxylate matrix, pre-functionalized with recombinant 47 kDa Protein A. This non-glycosylated Protein A variant includes five IgG-binding domains providing high-affinity binding to the Fc region of all human IgG1, IgG2, IgG4 subclasses. Additionally, it exhibits strong affinity for mouse IgG2a, IgG2b, and IgG3, as well as total IgG from cow, goat, sheep, rabbit, and other mammals. Due to the slightly hydrophobic character of the Protein A, some nonspecific binding may occur; 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 Protein A sensor chips are ready-to-use, eliminating the need for time-intensive assay optimization and streamlining workflows. With five distinct Protein A-modified versions available for SPR applications, each is tailored to specific analytical needs:

Key features:

Fast assay development: No preconcentration or surface activation required. Controlled and reversible ligand immobilization is performed under physiological conditions, reducing preparation time and ensuring reproducibility.
Simple regeneration: Chip surfaces regenerated using glycine·HCl pH 1.5–2.5.
High stability: XanTec’s Protein A sensor chips help minimize assay costs and maximize reusability.
Oriented immobilization: High ligand activity is maintained via directed immobilization through the Fc region.

Schematic illustration of a 3D PA sensor chip. Red dots represent negatively charged carboxyl groups distributed along the green polymer chains. The decaying red gradient represents the evanescent field. The magnified view shows Protein A (orange) binding to the Fc region of an antibody (blue).¹

Product code²	PAP	PAD200L	PAHC30M	PAHC200M
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 human IgG1, IgG2, and IgG4 subclasses, strong affinity for mouse IgG2a, IgG2b, and IgG3, and total IgG from cow, goat, sheep, and rabbit
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 analysis of medium- to large-sized analytes	capture immobilization of Fc fusion proteins and antibodies for analysis of small- to medium-sized analytes antibody quantification in bioprocessing applications	capture immobilization of Fc fusion proteins and antibodies for analysis of medium- to large-sized analytes including carbohydrates	capture immobilization of Fc fusion proteins and antibodies for analysis of small- to medium-sized analytes including carbohydrates antibody quantification in bioprocessing applications

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 PA sensor chip portfolio.

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

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Protein A–modified sensor chips