Fig. 4

Characterization of the fabrication process of the immunosensor. A EIS and B CV curves of bare GCE (a), Au@MoS₂/GCE (b), MPO/Au@MoS₂/GCE (c), BSA/MPO/Au@MoS₂/GCE (d), anti-MPO/BSA/MPO/Au@MoS₂/GCE (e) and anti-Ab/PtCo/CdS@GO/anti-MPO/BSA/MPO/Au@MoS₂/GCE (f) in PBS (0.01 M, pH 7.4) containing 5 mM Fe(CN)₆^3−/4− and 0.1 M KCl. Zʹ = real impedance component (Z_RE); − Zʺ = imaginary impedance component (Z_IM). EIS measurements were carried out with a frequency range of 0.1–100 kHz and amplitude of 50 mV. The CV experiments were scanned from − 0.2 to 0.6 V vs Ag/AgCl reference at a scan rate of 0.1 V s^− 1