Data sheets | SPR Sensor chips

Streptavidin–modified sensor chips

XanTec’s streptavidin-modified (SA) sensor chips are coated with a bioinert (poly)carboxylate matrix pre-functionalized with a recombinant 52 kDa streptavidin tetramer. The immobilized streptavidin captures biotinylated biomolecules—including proteins, peptides, nucleic acids, and other biotin-tagged ligands—efficiently under physiological conditions. Owing to the exceptionally high affinity of streptavidin for biotin (dissociation constant ≈ 10⁻¹⁵ M), SA sensor chips enable highly stable ligand immobilization with negligible dissociation.

A general limitation of streptavidin-based capture surfaces is that the maximum achievable ligand density is typically lower than that obtained by direct covalent immobilization strategies combined with electrostatic preconcentration. This is because the pre-immobilized streptavidin tetramer occupies a significant fraction of the accessible volume within the evanescent field. This should be considered when high ligand densities are required, for example in interaction analyses involving small analytes.

Key features:

Fast assay development: No preconcentration or surface activation required; controlled ligand immobilization under physiological conditions.
Exceptional stability: The strong streptavidin–biotin interaction renders the surface resistant to most common regeneration protocols.
Oriented immobilization: Controlled biotinylation strategies (e.g., AviTag™) ensure high ligand activity and reproducibility.
Broad application range: Suitable for protein interaction studies, nucleic acid hybridization, antibody screening, and other biosensing applications.
Versatile capture capacity: Available on various CMD and HC base coatings to match specific experimental needs.

Schematic illustration of a 3D SA sensor chip. Red dots represent negatively charged carboxyl groups distributed along the green polymer chains. The magnified view shows immobilized streptavidin tetramers (purple) capturing a biotinylated protein ligand (yellow).¹

Product code	SAP	SAD200M	SAD700L	SAHC30M	SAHC200M	SAHC1500M
Base coating	2D, ultra-short CM-dextran (high density)	3D, 200 nm bioinert CM-dextran (medium density)	3D, 700 nm bioinert CM-dextran (low density)	3D, 30 nm bioinert polycarboxylate (medium density)	3D, 200 nm bioinert polycarboxylate (medium density)	3D, 1500 nm bioinert polycarboxylate (medium density)
Capture immobilization capacity [µRIU]³	≈ 600–1,200	≈ 4,000–5,000	≈ 6,000–8,000	≈ 1,200–1,800	≈ 3,500–5,000	≈ 4,500–6,000
Recommended ligands	biotinylated proteins peptides nucleic acids			biotinylated proteins peptides nucleic acids carbohydrates
Recommended analytes	proteins peptides nucleic acids viruses and cells	proteins peptides nucleic acids small molecules (limited)	peptides nucleic acids small molecules	proteins peptides nucleic acids carbohydrates	proteins peptides nucleic acids small molecules (limited) carbohydrates	peptides nucleic acids small molecules small carbohydrates
Intended purpose	kinetics of medium and large analytes especially suitable for weak binders capture of biotinylated secondary antibodies	all-purpose surface kinetics of medium and small analytes alternative to Cytiva SA sensor chips	kinetics of small analytes equilibrium analysis very high capture densities	kinetics of medium and large analytes including carbohydrates capture of biotinylated secondary antibodies	all-purpose surface kinetics of medium and small analytes including carbohydrates high capture densities	kinetics of small analytes including carbohydrates equilibrium analysis very high capture densities

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 SA sensor chip portfolio.

³ Based on capture of 100 µg/mL biotinylated BSA in PBS, with 1 µRIU corresponding approximately to 1 RU.

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Streptavidin–modified sensor chips