Electrochemical immunoassay stripping voltammetry

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. ... 

Figure 14.2. Some detection principies used in the double-surface DNA hybridization techniques. (A) Label-free detection of target DNA (tDNA). [B] Labeling of tDNA. Redox labels are covalently attached to the tDNA strand outside the segment or on a secondary DNA stiund recognized by the capture probe. After hybridization and separation, the electroactive tags are determined electrochemically [e.g., hy ex situ adsorptive stripping voltammetry [a]. Alternatively, electrochemical enzyme-linked immunoassay can be used for detection of labeled tDNA at the MB surface (b).

Nangia Y, Bhalla Y, Kumar B, Sun CR (2012) Electrochemical stripping voltammetry of gold ions for development of ultra-sensitive immunoassay for chloisuUurrai. Electrochem Commun 14 51-54... 

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