Biosensors as Functional Analogs of Chemoreceptors

Biosensors are based on the direct spatial coupling of an immobilized biologically active compound with a signal transducer and an electronic amplifier (Fig. 2). They use biological systems at different levels of integration to specifically recognize the substance to be determined (Table 1). The first step of this interaction is the specific complex formation of the immobilized biologically active substance, R, with the analyte, S. 

1 In the literature the two basic types of biosensors are also called binding sensors and catalytic sensors. 

On the other hand, the molecular recognition by enzymes, which are also applied in the form of organelles, microorganisms and tissue slices, is accompanied by chemical conversion of the analyte to the respective products. Therefore this type of sensor is termed a metabolism sensor2. The initial state is usually reached when the analyte conversion is complete. With metabolism sensors, under certain conditions cosubstrates, effectors, and enzyme activities can be measured via substrate determination. Amperometric and potentiometric electrodes and thermistors are the preferred transducers, but in some cases optoelectronic sensors have also been used. With biomimetic sensors physical signals such as sound, stress, or light are measured through their ability to 

In biosensors the following sequence of processes takes place  

A similar sequence of events occurs in biological chemoreceptors under the action of very complex biomolecules and membranes. 

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