Conductive catalytic redox hydrogel composed of aniline and vinyl-ferrocene for ultrasensitive detection of prostate specific antigen

In this work, a conductive catalytic redox hydrogel composed of aniline and vinyl-ferrocene was prepared which showed good conductivity and strong electrochemical redox signal at 0.04   V (vs. Ag/AgCl). The hydrogel was simply generated in situ on the glassy carbon electrode to fabricate an amperometric immunosensor. The redox hydrogel provided a three dimensional porous structure, which improved the specific surface area of modified electrode. Based on the catalytic activity of ferrocene toward the oxidation of ascorbic acid, the electrochemical signal can be amplified. Gold nanoparticles were modified on the redox hydrogel by electrochemical deposition to promote electron transfer, which also can immobilize antibody. Prostate-specific antigen (PSA), a significant indicator of prostate cancer, had been measured as a model tumor marker. Under the optimized conditions, a linear range of the prostate specific antigen concentrations from 0.001 to 200   ng   mL −1 with a detection limit of 0.54   pg   mL −1 ((S/N)   =   3) was obtained. Importantly, the detection of PSA in the human blood serum samples showed satisfactory accuracy with the enzyme linked immunosorbent assay results, which showed the redox hydrogel possessed huge potential for the detection of other tumor markers.