Data sheets | SPR Sensor chips

HLC–modified sensor chips

XanTec’s HLC sensor chips are based on a 3D hydrogel matrix composed of highly flexible, bioinert polycarboxylate chains grafted onto a hydrophilic adhesion promoter on a gold support. Ligands can be covalently attached through their amine, thiol, or aldehyde groups using established coupling chemistries such as EDC/NHS activation, thiol-maleimide coupling, or reductive amination. This versatility enables the immobilization of a wide range of biomolecules, including proteins, antibodies, peptides, nucleic acids, carbohydrates, and small organic compounds.

Compared with native HC coatings, a large fraction of carboxyl groups in the HLC polymer is converted to hydroxyl groups, substantially lowering the surface charge. As a result, HLC sensor chips are even more bioinert than their HC counterparts, and are particularly advantageous in experiments affected by persistent nonspecific binding—an issue often encountered with strongly positively charged biomolecules. The remaining carboxyl groups are typically sufficient to support electrostatic preconcentration and efficient covalent ligand coupling.

Key features:

Reduced surface charge: Significantly lower nonspecific binding than native HC, especially with highly positively charged biomolecules; particularly suited for complex matrices such as cell culture media.
Versatile ligand coupling: Covalent coupling through amine, thiol, or aldehyde groups via standard chemistries (EDC/NHS, maleimide, reductive amination).
Wide immobilization range: From several thousand to ~18,000 μRIU, suitable for analytes from whole cells and viruses to fragments < 300 Da.
Application versatility: Suitable for kinetic, equilibrium, and concentration analyses, as well as diverse screening applications in drug discovery.
High chemical stability: Withstands typical regeneration conditions, maintaining consistent response levels and kinetic behavior after multiple regeneration cycles.
No polysaccharide backbone: Lack of carbohydrate motifs prevents unwanted interactions with lectins or carbohydrate-binding proteins, making HLC sensor chips ideal for analyzing this class of biomolecules.

Schematic illustration of a charge-reduced 3D HLC sensor chip. Red and grey dots represent negatively charged carboxyl groups and charge-neutral hydroxyl groups distributed along the green polymer chains. The decaying red gradient represents the evanescent field.¹

Product code	HLC30M	HLC200M	HLC1500M
Base coating	3D, 30 nm bioinert polycarboxylate (medium density, reduced charge)	3D, 200 nm bioinert polycarboxylate (medium density, reduced charge)	3D, 1500 nm bioinert polycarboxylate (medium density, reduced charge)
Immobilization capacity [µRIU]²	≈ 6,000	≈ 11,000	≈ 18,000
Recommended ligands	proteins peptides nucleic acids carbohydrates
Recommended analytes	proteins peptides nucleic acids viruses and cells carbohydrates	proteins peptides nucleic acids small molecules carbohydrates	peptides nucleic acids small molecules carbohydrates
Intended purpose	kinetics of medium and large analytes especially suitable for weak binders with fast on- and off-rates use with biomolecules with a high tendency for electrostatic interactions with polycarboxylates applications requiring low diffusion limitation compatible with complex buffer compositions	kinetics of small and medium analytes use with biomolecules with a high tendency for electrostatic interactions with polycarboxylates compatible with complex buffer compositions	kinetics of medium and small analytes equilibrium analysis concentration analysis use with biomolecules with a high tendency for electrostatic interactions with polycarboxylates compatible with complex buffer compositions

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.

¹ Preconcentration capacity determined by injecting 100 µg/mL bovine serum albumin (BSA) in 5 mM sodium acetate pH 5.0, with 1 µRIU corresponding approximately to 1 RU. Maximum covalent coupling yields can vary and depend strongly on the properties of the protein to be immobilized. Under optimal conditions, typical coupling efficiencies range from approximately 20–45% of the respective electrostatic preconcentration capacity, with acidic proteins generally exhibiting lower coupling efficiencies.

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HLC–modified sensor chips