Ultrasensitive electrochemical immunosensor based on Pt nanoparticle-graphene composite.

We report a protein antibody, Ab-CRP, functionalized Pt nanoparticle-decorated chemical vapor deposition (CVD)-grown graphene on glassy carbon electrode, as a bioelectrode, for the quantitative analysis of human C-reactive protein (CRP). Chemical vapor deposition was used to grow a polycrystalline graphene film on copper and was mounted over a glassy carbon electrode after copper etching through π-π stacking. Ab-CRP was covalently immobilized on mercaptopropionic acid (MPA)-capped Pt nanoparticles that were covalently anchored over the graphene to form a bioelectrode. The bioelectrode was characterized by scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). A detail EIS study was conducted on the bioelectrode towards the quantitative detection of the target Ag-CRP in phosphate-buffered saline (PBS). The optimal electrical equivalent circuit that matches the impedance response of the bioelectrode was studied to delineate the biocompatibility, sensitivity, and selectivity of the bioelectrode. The bioelectrode exhibited a linear response of CRP detection in the range of 10 ng mL(-1) to 10 μg mL(-1) with a sensitivity of 92.86 Ωcm(2) per decade CRP in pH 7.4 PBS.