The interaction between streptavidin and biotin results in a high affinity biomolecular interaction with negligible dissociation of the ligand from the sensor chip surface, making it an ideal choice for highcapacity, reproducible SPR experimentation. The Octet^® SPR SADH sensor chip consists of streptavidin pre-immobilized on a 3D carboxymethylated dextran hydrogel, which allows binding to a variety of chemically or enzymatically biotinylated target ligands. Due to the highly efficient binding between the immobilized streptavidin and the biotin tagged ligand, only low nanomolar concentrations of the ligand are usually required.