Feasibility studies of simultaneous multianalyte amperometric immunoassay based on spatial resolution

A multianalyte immunoassay concept based on the geometric separation of dif ferent analyte-specific antibodies has been demonstrated. The assay and amp erometric detection are done in a cell with two working electrodes controll ed at the same potential, and the amperometric signal at each electrode is monitored. The distance between any two adjacent electrodes in this prototy pe is 2.5 mm, and during the course of amperometric measurement, the produc t formed at one electrode does not reach the other working electrode within 20 min after the addition of enzyme substrate, Thus, the method relies on the spatial resolution between the different antibodies being such that mea surements are taken before cross-interference due to diffusion can occur. I dentical enzyme labels (alkaline phosphatase, ALP) and substrates (p-aminop henyl phosphate, PAPP) are used for all analytes. Alkaline phosphatase-conj ugated rat anti-mouse IgG was immobilized by passive adsorption. Our studie s showed that this concept is feasible and can be applied to the simultaneo us measurement of multiple analytes. (C) 1999 Elsevier Science B.V. All rig hts reserved.