Biochemical and immunochemical characterization of the antigen–antibody reaction on a non-toxic biomimetic interface immobilized red blood cells of crucian carp and gold nanoparticles

A special protein assay system based on a highly hydrophilic, non-toxic and conductive biominetic interface has been demonstrated. To fabricate such assay system, red blood cells of crucian carp (RBC) was initially grown on a glassy carbon electrode surface (GCE) deposited nano-sized gold particles (GPs), a second gold nanoparticle layer (NG) was then absorbed on the RBC surface, and finally mammary cancer 15-3 antibody (anti-CA15-3) was attached on the functional RBC surface. A competitive immunoassay format was employed to detect CA15-3 with horseradish peroxidase (HRP)-labeled CA15-3 as tracer and hydrogen peroxide as enzyme substrate. When the immunosensor was incubated into a mixture solution containing HRP-labeled CA15-3 and CA15-3 sample for 1 h at 37 °C, the amperometric response decreased with the increment of CA15-3 sample concentration. AFM images of the modified layer revealed a uniform distribution of protein and nanogold. In situ QCM and electrochemical measurements demonstrated that the wanted antibody–antigen reactions should occur with high specificity and selectivity. The specific immunoassay system can be developed further to yield sophisticated structures for other proteins.