Data sheets | SPR Sensor chips

HCX sensor chips (NHS–preactivated)

XanTec’s HCX sensor chips are based on a 3D hydrogel matrix composed of flexible polycarboxylate chains grafted onto a hydrophilic adhesion promoter on a gold support. The carboxylate groups are partially pre-activated with NHS esters, providing medium to high activation level and enabling high immobilization capacities. This pre-activation significantly simplifies and accelerates ligand coupling, making HCX chips a powerful tool for streamlined workflows. They are particularly advantageous for spot immobilization in imaging SPR systems.

Although a certain fraction of a spotted ligand will immobilize when drying spots, electrostatic preconcentration substantially increases immobilization yields. A preconcentration scouting step is therefore recommended prior to coupling. However, small molecules freely diffuse into the hydrogel and do not require preconcentration for efficient immobilization.

Key features:

Save time: Pre-activated sensor chips allow direct and convenient ligand immobilization, saving time and effort.
Reliable results: Avoid variability of reagent quality and instead achieve consistent, reproducible immobilization every time.
Flexibility: From moderate-capacity chips for protein-protein interaction studies to ultra-high-capacity formats for fragment screening, HCX covers the entire spectrum of ligand density requirements.

Schematic illustration of a pre-activated 3D HCX sensor chip. Yellow donut symbols and red dots represent amine-reactive NHS esters and negatively charged carboxyl groups distributed along the green polymer chains. The decaying red gradient represents the evanescent field.¹

Product code²	HCPX	HCX30M	HCX200M
Base coating	2D, ultra-short bioinert polycarboxylate (high density) NHS pre-activated	3D, 30 nm bioinert polycarboxylate (medium density) NHS pre-activated	3D, 200 nm bioinert polycarboxylate (medium density) NHS pre-activated
Covalent immobilization capacity [µRIU]³	≈ 2,500	≈ 9,000	≈ 15,000
Recommended ligands⁴	proteins peptides nucleic acids (spot immobilization)	proteins peptides nucleic acids (spot immobilization)	proteins peptides nucleic acids (spot immobilization)
Recommended analytes	proteins peptides nucleic acids viruses and cells carbohydrates	proteins peptides nucleic acids viruses and cells small molecules (limited) carbohydrates	peptides small molecules nucleic acids (low-molecular-weight) carbohydrates (low-molecular-weight)
Intended purpose	spot immobilization in imaging SPR systems kinetics of medium and large analytes including carbohydrates especially suitable for weak binders with fast on- and off-rates immobilization of secondary antibodies and capture proteins.	spot immobilization in imaging SPR systems kinetics of medium and large analytes including carbohydrates especially suitable for weak binders with fast on- and off-rates immobilization of secondary antibodies and capture proteins	spot immobilization in imaging SPR systems kinetics of small analytes equilibrium analysis especially suitable for situations requiring higher capture densities immobilization of secondary antibodies and capture proteins

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 This overview represents a selection of the full HCX sensor chip portfolio.

³ Covalent immobilization capacity was 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.

⁴ Ligands require an NHS-reactive amine.

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HCX sensor chips (NHS–preactivated)