Surface plasmon resonance sensor unit and its use in biosensor systems

A sensor unit for use in a biosensor system based on surface plasmon resonance technology, comprising:

• a dielectric substrate which is replaceable in said biosensor system and which is coated with a metal film, said film having two or more sensing areas arranged so as to be passed in series or in parallel by a liquid stream,
• each of said sensing areas comprising a layer of an organic polymer or hydrogel over said metal film, containing at least one functional group supporting bi- or polyfunctional molecules capable of specific binding with biomolecules present in said liquid stream which are to be detected, said bi- or polyfunctional molecules comprising ligands that can specifically bind to biomolecules in a sample and a functional structure which can form reversible bonds with said at least one functional group which, through said functional structure, are coupled to said sensing area by a reversible bond, such that said two or more sensing areas can be regenerated for refunctionalization with the same or other bi- or polyfunctional molecules, wherein
• coupling between said bi- or polyfunctional molecules and said biomolecules in said liquid stream is selectively reversible such that the bi- or polyfunctional molecule-functionalized sensing areas can be regenerated, permitting repeated use of the functionalized sensor unit.