Enzymatic stripping, examples

Levels of a number of metabolites as well as a number of enzymes in body fluids are indicative of disease conditions. Many of the enzymatic reactions mentioned above have been used in solution clinical assays as well as in test strips.446,497-508 512-515 Assays for hydrogen peroxide and the enzyme peroxidase using NADH and a tetrazolium salt have been de-scribed.509,5io Assays of exogenous substances (e.g., drugs or their metabolites) also utilize this chemistry. The determination of alcohol using alcohol dehydrogenase is an example.511 As mentioned above, the assay of enzyme levels can also be achieved using tetrazolium salts.516-520... 

Most devices rely on the use of disposable one-use-only test strips , and a droplet of blood from a needle-prick is drawn, for example, from the thumb, onto the strip by capillary action. The strip represents the recognition element, and the blood sample undergoes an enzymatic chemical reaction followed by another reaction. After the blood is added to the test strip it is inserted into the hand-held device (transducer) and sufficient time allowed for the reactions to occur, most often automatically determined by the device itself. 

The attachment of the ferrocene groups to small molecules has been used in two main classes of biosensor in the first, the conjugate is an enzyme substrate such that a shift in its redox potential occurs following enzymatic modification. An example is ferrocenylethyl phosphate (Figure 9) that facilitates the electrochemical assay of alkaline phosphatase, a common enzyme label for immunoassays. The redox potential of the alcohol product is lower than the phosphate ester and hence by poising the potential, the product can be selectively measured and so the alkaline phosphatase activity measured. The sensitivity of this method was further enhanced by the use of stripping voltammetry to detect the product. ... 

Analytical applications of voltammetry at permanently heated electrodes range from determination of dissolved oxygen till DNA hybridisation analysis and include stripping analysis, enzymatic sensors and electrochemiluminescence. Examples will be given later in Sect. 6.4. 

---