Effect of the Method for Immobilizing Receptor Layer on the Analytical Characteristics of a Label-Free Electrochemical Immunosensor for the Determination of Measles Antibodies

The effect of the method of immobilization of receptor layer on the analytical characteristics of label-free electrochemical immunosensors for determining antibodies to the measles virus is estimated. The receptor layer bearing the measles antigen was immobilized by dropping a model suspension on the surface of a glassy-carbon electrode, followed by drying in air and covalent crosslinking by electrografting of p-nitrophenyldiazonium chloride using glutaraldehyde as a crosslinking agent. The dependences of the peak current of the mediator system on the concentration of measles antibodies in model suspensions are linear and described by the equations I = -(28 +/- 1)c(at) - (30 +/- 4) and I = -(19 +/- 2)c(at) - (15 +/- 5) for the covalent immobilization and drop deposition of the receptor layer, respectively. Immobilization of the bioreceptor by covalent crosslinking does not lead to a significant improvement in the sensitivity of the determination; however, it expands the linear concentration range tenfold and decreases the total duration of the immunoassay procedure to 20 min with respect to the immunosensor with a drop-immobilized antigen.