Immobilization is a procedure to attach ligand on the SPR sensor surface in order to facilitate an interaction measurement. Usually ligands are covalently attached by reactive group but they can be also captured e.g. with streptavidin. Molecular properties such as molecular weight, reactive group (-NH2, -SH, -COOH) and purity affect the choice of appropriate immobilization technique. Aminocoupling is mostly used covalent immobilization technique due to the fact that most macromolecules contain several amine groups.
Typical immobilization protocol using aminocoupling:
Pre-concentration can be done before surface activation to ensure proper immobilization conditions for particular ligand used.
After creating a sensor surface by immobilizing a protein, the analyte interaction can be measured. A typical protocol for the interaction measurement is as follows: