Immunoelectrodes

An electrode in which an antibody or an antigen/hapten is incorporated in the sensing element is termed an immunoelectrode . The potential response of the immuno-electrode is based on an immunochemical reaction between the sensing element of the electrode and antibody or antigen/hapten in the sample solution. One example of such an electrode is the polymer membrane electrode shown in Fig. 7. The selective response of this electrode to specific immunoglobulins is based on the interaction between antibody in solution and an antigen-ionophore complex in the membrane ... 

Coating the antigen or antibody directly on appropriately modified metal substrates has yielded electrodes that respond potentiometrically to antigen-antibody reactions An immunoelectrode has been prepared by coating the gate of a... 

CHEMFET with antibody It has been shown that the immunological coupling response of some of these electrodes might be a minor component of the overall response, which would make these sensors difficult to use as immunoelectrodes In general, these electrodes as yet have insufficient sensitivity for most practical immunoassays. 

If the reaction is performed on a sensor it is called immunosensor or immunoelectrode (- biosensor). 

An enzyme immunoelectrode suitable for the assay of human serum albumin and insulin uses an oxygen electrode covered with an antibody-containing nylon net kept in place with an O-ring. From 1 to 25 ng/L of albumin and 5 to 100 ng/L of insulin can be assayed (306). A specific sensor for the tumor antigen a-fetoprotein (AFP) is prepared by immobilizing anti-AFP antibody covalendy on a membrane prepared from cellulose triacetate, 1,8-diamino-4-aminomethyl octane, and GA (307). The sensor is applied to an EIA based on competitive Ab/... 

Pfeifer, U., and Baumann, W. Direct potentiometric immunoelectrodes. 2. An immuno-electrode sensitive to 3-indole acetic acid methylester. Fresenius J. Anal. Chem. 1993, 45, 504-511. 

Enzyme immunoelectrodes involve the spatial coupling of the sensor, the immunocomplex, and the catalytic amplification by indicator enzymes. Like the sensor systems described above, enzyme immunoelectrodes are based on common principles of EIA. The choice of enzymes for EIA is rather restricted and is further diminished when electrodes are to be used for detection. So far only GOD, catalase, and HRP have been combined with oxygen-sensing polarographic sensors. An overview of enzyme immunoelectrodes is given in Table 21. 

Fig. 123. Immunoelectrode with double signal amplification based on coimmobilized liposomes and NAD. SDH = substrate dehydrogenase, C = complement, Pi = lipid. (Redrawn from Durst and Blubaugh, 1986).

Janata J 1975 An immunoelectrode J. Am. Chem. Soc. 97 2914-6 Lubbers D W and Opitz N 1975 Die pCO /p02-Optrode Eine neue pC02-bzw. p02-Messonde zur Messung des pC02 Oder p02 von Gasen und Flussigkeiten Z. Naturf. c 30 532-3... 

Immunoelectrodes for the detection of bacteria Biosensor Design and Application ed P R Mathewson and J W Finley (Washington, DC American Chemical Society) pp 59-72... 

Krishnan R., Ghindilis A. L., Atanasov R, and Wilkins E., Development of an ampero-metric immunoassay based on a highly dispersed immunoelectrode, Anal. Lett., 29, 2615-2631,1996. 

A flow immunoelectrode based on highly dispersed carbon to which Abs are bound has been used for IgG and IgM determination. In this approach, immunoreaction and electrochemical determination took place at the same immunocolumn [131]. 

Figure 9.18 Fabrication of CCE/chitosan/AuNP/a AFBl-AFBl-a AFB1-catechol-Au-Fe O immunoelectrode (Reproduced from [1051, with permission from Elsevier)...

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