We report an electrodeposited poly(pyrrole-co-pyrrolepropylic acid) copolymer modified electroactive graphene-carbon nanotubes composite deposited on a glassy carbon electrode to detect the protein antigen(cTnI). The copolymer provides pendant carboxyl groups for the site-specific covalent immobilization of protein antibody, antitroponin I. The hybrid nanocomposite was used as a transducer for biointerfacial impedance sensing for cTnI detection.The results show that the hybrid exhibits a pseudo capacitive behaviour with a maximum phase angle of 49° near 1 Hz,which is due to the inhomogeneous and porous structure of the hybrid composition. The constant phase element of copolymer is 0.61(n = 0.61), whereas, it is 0.88(n = 0.88) for the hybrid composites, indicating a comparatively homogeneous microstructure after biomolecular functionalization. The transducer shows a linear change in charge transfer characteristic(R_(et)) on cTnI immunoreaction for spiked human serum in the concentration range of 1.0 pg mL~(-1)–10.0 ng mL~(-1). The sensitivity of the transducer is 167.8 ± 14.2 Ω cm~2 per decade, and it also exhibits high specificity and good reproducibility. We reported an electrodeposited poly (pyrrole-co-pyrrolepropylic acid) copolymer modified electroactive graphene-carbon nanotubes composite deposited on a glassy carbon electrode to detect the protein antigen (cTnI). The copolymer provides pendant carboxyl groups for the site-specific covalent immobilization of protein antibody, antitroponin I. The hybrid nanocomposite was used as a transducer for biointerfacial impedance sensing for cTnI detection. The results show that the hybrid exhibits a pseudo capacitive behavior with a maximum phase angle of 49 ° near 1 Hz, which is due to the The constant phase element of the copolymer is 0.61 (n = 0.61), while, it is 0.88 (n = 0.88) for the hybrid composites, indicating a comparatively homogeneous microstructure after biomolecular functionalization. The transducer shows a linear change in charge transfer characteristic (R_ (et)) on cTnI immunoreaction for spiked human serum in the concentratio The range of 1.0 pg mL -1 -10.0 ng mL -1 The sensitivity of the transducer is 167.8 ± 14.2 Ω cm ~ 2 per decade, and it also exhibits high specificity and good reproducibility.