BIACORE 3000 is a system for real-time biomolecular interaction analysis (BIA) using surface plasmon resonance (SPR) technology. SPR is an optical measuring technique that measures the mass concentration changes of molecules in close proximity to a specially- prepared surface. This allows determination of the on-rate and off-rate kinetic constants (ka and kd) for an interaction, as well as the equilibrium affinity (KD). One partner is immobilised on a surface and a solution of the other molecule is passed over that surface. The Biacore can be used to study the interactions of proteins, protein conjugates, nucleic acids, lipid micelles, low molecular weight ligands and even larger particles such as viruses and whole cells.