TABLE OF CONTENTS Biosensors are devices incorporating a biological sensing element coupled to a variety of transducers such as electrochemical, optical, piezoelectric and colorimetric. The purpose of this is to convert a biological interaction into an easily measurable electrical signal. Research into biosensors has grown enormously over the past few decades. The specific and sometimes reversible interaction of biological components can produce changes in a variety of physical quantities that can be detected by these transduction methods. Such changes are the release or consumption of ions, electrons, changes in optical properties, mass, or the release or consumption of energy in the form of heat. Applications of biosensors have ranged from environmental monitoring to medical applications, for example, in the detection of coumarins and mycotoxins. The ideal characteristics of the biological component are that it is highly selective, stable, should not contaminate the sample being tested and should retain its biological activity when immobilized. The specificity of the biosensor is totally dependent on the properties of the biological component.
Biosensors may be characterized in a variety of ways. One such way is on the basis of the biological component used. In this way, there are two main categories: affinity biosensors and catalytic biosensors. Affinity biosensors are based on specific binding interactions. These use antibodies, cell receptors, nucleic acids and lectins, or their binding counterparts. The catalytic biosensor works on the principle that the analyte becomes altered in some way. All such biosensors are ultimately based on enzyme catalysis, but may employ purified...
