2. The different types of ligands

The use of a biological compound gives the biosensor a high degree of specificity. The ligands most often used are enzymes and antibodies. But whole cells, cell organelles, nucleic acids, antigens or receptors can also be used. In fact, any biological molecule can be used for the specific analysis of the desired analyte. Bound biological compounds can be divided into two categories: those with catalytic activity, such as enzymes and microorganisms, and those which simply bind the analyte without modification, such as antibodies and receptors. The recognition step can therefore reveal either a dynamic or a static event. Dynamic recognition is mainly used for enzyme-based biosensors, while static recognition is mainly used for biosensors studying the formation of an antibody-antigen complex. Each type of event can produce a change transformed into a signal that can be quantified by the transducer....