Chitosan (CS)–polyaniline (PANI) hybrid conducting biopolymer film was obtained on indium–tin-oxide
(ITO) electrode using electrochemical polymerization process. Fourier transform infrared (FT-IR) spectra
of PANI–CS had showed covalent and hydrogen binding between PANI and CS molecules. Electrochemical
impedance spectroscopy (EIS) measurements had showed lowcharge transfer resistance (RCT) of PANI–CS
and PANI. Successive rabbit antibody (IgGs) immobilizationonPANI–CS, CS and PANI matrixes surfacewere
confirmed with FT-IR and EIS measurements. Ochratoxin-A (OTA) interaction with IgGs had increased RCT
values and showed linear response up to 10 ng/mL OTA concentration in electrolyte. Relative change in
RCT was higher in PANI–CS due to higher proportion of carboxylic and hydroxyl functionalities at PANI–CS
matrix surfaces. The absolute sensitivity of PANI, CS, and PANI–CSwere 16±6, 22±9 and 53±8�mL/ng,
respectively derived fromslope of linear response up to 10 ng/mL with 1 ng/mL minimum detection limit
