▎ 摘　　要

This article describes a bioelectrode for the determination of human cardiac troponin-I (cTnI). A glassy carbon electrode was coated with a hybrid film of graphene and multiwalled carbon nanotube (G-MWCNT) and modified with platinum nanoparticles (Pt NPs) that were capped with mercaptopropionic acid. The PtNPs were anchored on the G-MWCNT hybrid film via the cross-linker 1-pyrenemethylamine and subsequently functionalized with antibody against troponin (anti-cTnI). The bioelectrode was characterized by transmission electron microscopy, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The performance of the immunoelectrode was investigated by electrochemical impedance spectroscopy, and response was fit to Randle's equivalent circuit model. The charge transfer resistance (R-et) at a.c. frequencies of < 1 Hz is found to be a viable sensing parameter. The dissociation constant of the immunoreaction between surface immobilized anti-cTnI and the analyte cTnI is 0.29 nM (with a Hill coefficient of 0.23), this indicating a negative cooperativity and high binding affinity of cTnI for anti-cTnI on the electrode surface. The EIS response is linear in the 1.0 pg mL(-1) to 10 ng mL(-1) concentration range, and the R-et sensitivity is 145.5 a"broken vertical bar cm(2) per decade.