Antibodies for immunosensors - A review

Immunosensors (ISs) are miniaturized measuring devices, which selectively detect their targets by means of antibodies (Abs) and provide concentration-dependent signals. Ab binding leads to a variation in optical properties, electric charge, mass, or heat, which can be detected directly or indirectly by a variety of transducers. The quality of ISs primarily depends upon the selectivity and affinity of the Abs used in the receptor unit. Since sensitivity is directly related to the affinity of the ligand binding, reversibility excludes high sensitivity. Consequently, detection units for single-use and quasi-continuous measuring devices are presently preferred. An important future development is seen in the field of multianalyte sensors. The most attractive application is based on Abs with sufficiently different cross-reactivities. The response pattern provides information on the presence and concentration of structurally similar analytes, as they are found for instance in pesticide groups such as the s-triazines. It is obvious that this development will be significantly accelerated by applying recombinant techniques for Ab production. The next step is directed toward the generation of recombinant Ab libraries, which will provide a huge repertoire, generated at the DNA level, for new Ab types.