Page 195 - Analytical Electrochemistry 2d Ed - Jospeh Wang
P. 195
180 ELECTROCHEMICAL SENSORS
FIGURE 6-8 Composition of an electron-relaying redox polymer used for ``wiring''
enzymes to electrode transducer. (Reproduced with permission from reference 14.)
serves as a basis of amperometric sensors for ethanol (19). Reagentless devices
based on the coimmobilization of ADH and NAD to various carbon or platinum
anodes are employed (e.g., Figure 6-10). NAD is regenerated electrochemically by
oxidation of the NADH, and the resulting anodic current is measured:
NADH ! NAD 2e H
6-11
To circumvent high overvoltage and fouling problems encountered with the direct
oxidation of NADH at conventional electrode (equation 6-11), much work has been
devoted to the development of modi®ed electrodes with catalytic properties for
FIGURE 6-9 Electrical contact of a ¯avoenzyme by its reconstitution with a relay-FAD
semisynthetic cofactor. Fc ferrocene. (Reproduced with permission from reference 2.)
