Ferrocenes as Electrochemical Sensors

1 Ferrocenes as Electrochemical sensors. The field of sensing molecules of interest in environmental pollution or biomedicine is rapidly growing. As far as electrochemical sensors are concerned their use is based on two different ways to gain information  

As easily conceivable, from a qualitative viewpoint the former exploit the generation of abnormally great currents, whereas the latter are based on the inducement of potential shifts caused by variation of the environment around the redox-active species. 

As far as the use of ferrocene molecules as amperometric sensors is concerned, they have found wide use as redox mediators in the so-called enzymatic electrodes, or biosensors. These are systems able to determine, in a simple and rapid way, the concentration of substances of clinical and physiological interest. The methodology exploits the fact that, in the presence of enzyme-catalysed reactions, the electrode currents are considerably amplified.61 Essentially it is an application of the mechanism of catalytic regeneration of the reagent following a reversible charge transfer , examined in detail in Chapter 2, Section 1.4.2.5  

We will illustrate herein the basis underlying one of the prime applications of this technique the dosage of small concentrations of glucose in the blood. This is of considerable use to people affected by diabetes,61 who have levels of glucose in the blood of the order 1-30 mM. 

One of the best known enzymatic reactions involving glucose is the following oxidation reaction catalysed by glucose oxidase (GOD)  

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