Two approaches to electrochemical immunoassay are reported.
The first approach was an indirect method, involving an
electroactive, enzyme-catalysed, substrate to product reaction. Conditions were optimised for the amperometric detection of para-aminophenol, the electroactive product of the alkaline phosphatase catalysed hydrolysis of a new substrate, p-aminophenylphosphate, after separation by HPLC.
The second approach involved the direct electrochemical
detection of an immunoglobulin species, IgG, and the
electrochemical monitoring of the immunological interaction.
In an attempt to characterise the electrochemical response of such proteins, studies were carried out on the adsorptive
stripping voltammetry of the immunoglobulin fragments,
F(ab1 )2 and Fab.
The globular proteins avidin and streptavidin, were then
studied as these were similarly constructed proteins, except
avidin had a disulphide bond, and streptavidin has not. The
interaction of avidin and streptavidin with biotinylated IgG
was also reported as this is an important labelling procedure in immunoassay.