DEVELOPMENT OF AN AMPEROMETRIC IMMUNOASSAY BASED ON AN HIGHLY DISPERSED IMMUNOELECTRODE

An amperometric immunoassay technique utilizing a highly dispersed imm unoelectrode was developed. The assay method is based on the 'sandwich ' scheme of immunointeraction. Rabbit IgG has been used as model analy te. Horseradish peroxidase labelled conjugates were employed coupled w ith amperometric detection of iodine reduction. Highly dispersed ULTI carbon serves as an immunosorbent and at the same time as an electrode material. It was found that the dependence of immunoelectrode respons e on the time of incubation during the second stage of 'sandwich'-base d assay was complex. This is probably due to non-equilibrium immuno-ag glomeration of sub-micron sized particles of immunosorbent. The improv ement in the sensitivity of immunoelectrode by increasing the amount o f immunosorbent was demonstrated. The increase in the magnitude of the immunoelectrode response is proportional to the increase of the amoun t of immunosorbent A detection limit of 10 pM has been achieved with a n overall assay time of less than 20 minutes.