The SPRi-Biochip™, the SPRi-Slide™ or the SPRi-XelSlides are the core of the SPRi technology. The SPRi-Biochip consists in a high index glass prism coated with a thin gold layer. The SPRi-Slide (or SPRi-XelSlide) is a high index slide covered with a thin gold layer, which can be combined with a glass prism with the help of a high index matching liquid, and be used in a SPRi experiment as a substitute for the SPRibiochip. These slides are usually used when SPRi is coupled to another technique because Slides are easier to adapt than SPRi-Biochips.
The metal is necessary to enable the effect of surface plasmon resonance. Other metals such as aluminum and silver can be used, but gold gives best results when we work with a liquid medium. In addition, there is no problem of oxidation when using gold and this material is biocompatible.
Bare gold surfaces can be used to immobilize thiolated molecules or to design your own surface chemistry. If the ligand is not thiolated, the SPRi-Biochip surface must be functionalized to allow the immobilization of the ligands. The surface chemistry is chosen according to the nature of the ligands.
Different surface chemistries are available:
The SAM surface chemistries that we developed are ready-to-use. Ligands of interest can be proteins (antibodies, antigens, and peptides), nucleic acids (DNA, RNA), saccharides, polymers, in their native states or conjugated with biotin or GST-tag. The table below summarizes the different SAM surface chemistries available in our catalogue.
CO chemistry is suitable for immobilizing molecules with an amine function (NH2 group). The immobilization principle is based on the high affinity of sulfur atoms (present in Cystamine) on gold, and the reactions between free amine molecules from proteins (or peptides) and aldehyde molecules (present in Glutaraldehyde). In this process, imine links or Schiff’s bases are formed. The link between Cystamine and Glutaraldehyde is also an imine.
A COe chemistry is CO surface chemistry on which an Extravidin layer is deposited. This surface chemistry is suitable for immobilizing biotinylated molecules. Extravidin is linked to Glutaraldehyde by the formation of Schiff’s bases or imine links. Biotinylated ligands are immobilized via the specific interaction between Extravidin and Biotin.
CH surface chemistry is a POE layer which has not been activated yet. It corresponds to the first step of the CS chemistry. This surface chemistry must be activated. This surface chemistry is also offered in 2 densities: CH-HD (High density) and CH-LD (low density).
CSe chemistry is CS surface chemistry on which an Extravidin layer is deposited. This surface chemistry is suitable for biotinylated molecules. Extravidin is linked to activated POE by the formation of amide bonds. Biotinylated ligands are immobilized via the specific interaction between Extravidin and Biotin.
CTg surface chemistry consists of CO surface chemistry on which an anti-GST antibody is immobilized. GST-tagged ligands can be immobilized via the specific interaction between the GST protein and the anti-GST antibody.
Cep surface chemistry is suitable for immobilizing molecules with primary amine groups. When the biomolecule is linked to the surface chemistry a stable covalent ether bond is created.
CS-EDA surface chemistry is suitable for immobilizing molecules with COOH groups. In this configuration the immobilized molecules must be activated to create a stable covalent amide bond.
CIm surface chemistry is suitable for immobilizing molecules with SH groups. In this configuration the coupling function is a maleimide group to create a stable covalent thioether bond.
COa surface chemistry is CO surface chemistry on which the protein A is coated. Protein A is used to detect human or mouse immunoglobulins IgG1 and IgG2 with a high affinity. Protein A interacts with IgM, IgA, IgE and IgG3 with a low affinity. Protein A has no known affinity for human IgG3 and IgD and mouse IgM, IgA and IgE.
We offer 3D surface chemistries based on carboxylmethyl dextran at high, medium and low densities. A 3D surface chemistry is a hydrogel in which ligands can be nested. The thickness of the hydrogel can be chosen (between 200 or 50 nm). The configuration of the experiment is thus closer to “in solution” as in 2D surface chemistries. The link between the hydrogel and the ligand is based on amine coupling.