2. Different types of ligands

The use of a biological compound gives the biosensor a high degree of specificity. The most frequently used ligands are enzymes and antibodies. But whole cells, cellular organelles, nucleic acids, antigens or even receptors for biologically active molecules (hormones, toxins, growth factors, neurotransmitters...) 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 micro-organisms, 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...