The interaction of colloidal species is prominently governed by their surface properties. The adsorption of charged proteins at the surface of the Polyaniline nanotubes (PN) results in the electrostatic interactions which can be moulded by controlling the surrounding zeta potential. The zeta potential of PN as a function of pH, charge density and ionic strength was determined and the results are duly explained by 1-pK model and Grahame model as empirical data fits well to these models. Similarly, the surface charge and zeta potential of the 1 NLB antibodies were also determined which later on explained the adsorption of 1 NLB antibodies on PN in aqueous media. The isoelectric point (IEP) of PN showed variation as function of surface coverage by adsorbed 1 NLB antibody mass. These results were utilized to fabricate a label-free impedimetric immunosensor aimed at the detection of hepatitis C (HCV) 1 NLB monoclonal antibodies (anticore mAbs 19D9D6). The bioactive interfacial layer was attained by the immobilization of 1 NLB monoclonal antibodies at the PN which were later on spin coated on ITO substrate for fabricating impedimetric immunosensor. The impedimetric immunosensor shows linear response range of 01 ng mL−1 to 200 ng mL−1 of HCV core antigen concentration with detection limit of 0.02 ng mL−1 (3σ/S). The charge transfer resistance change (Rct) showed an absence of the prominent change depicting the stability of the impedimetric immunosensor whereas the sensitivity of sensor was found to be 12.215 Ω mL ng−1. Display omitted •Polyanilne nanotubes (PN) based label-free impedimetric immunosensor is proposed.•Electrokinetics of PN illuminates the changing chemistry of PN surface due to coverage by adsorbed proteins.•The charge transfer resistance increases with the increase in antigen concentration (Polypeptide 13-40 residue).•Selectivity of 12.215 Ω mL ng-1 was achieved due to the specific nature of 1 NLB interaction with HCV core nucleocapsid polypeptide antigen.