Pt nanoparticles-chemical vapor deposited graphene composite based immunosensor for the detection of human cardiac troponin I

We report a sensitive and stable electrochemical impedance immunosensor prepared with functionalized Pt nanoparticles decorated graphene monolayer deposited on a glassy carbon electrode (GCE). Graphene monolayer was grown on a copper foil by chemical vapor deposition (CVD) method using acetylene as a precursor source and transferred it on GCE and electrochemically oxidized to electroactive graphene (EG). 3-Mercaptopropionic acid (MPA) functionalized Pt-nanoparticles, Pt (MPA), were attached to electroactive graphene (EG) using a molecular bilinker 1-pyrenemethylamine (PMA). Pt (MPA) NP offers free terminal carboxyl group for the site specific covalent biomolecular immobilization of troponin antibody, anti-cTnI, through carbodiimide coupling reaction to form an anti-cTnI-Pt(MPA)-PMA/EG/GCE bioelectrode. The bioelectrode was characterized by transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The bioelectrode exhibited a linear electrochemical impedance response to cTnI over the concentration range of 0.01–10 ng mL−1 in phosphate buffer saline (pH 7.4) with a sensitivity of 80 Ω cm2 per decade and a limit of detection of 4.2 pg mL−1 cTnI.

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