Chitosan/polyaniline hybrid conducting biopolymer base impedimetric immunosensor to detect Ochratoxin-A

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 low charge transfer resistance (RCT) of PANI–CS and PANI. Successive rabbit antibody (IgGs) immobilization on PANI–CS, CS and PANI matrixes surface were 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–CS were 16 ± 6, 22 ± 9 and 53 ± 8 Ω mL/ng, respectively derived from slope of linear response up to 10 ng/mL with 1 ng/mL minimum detection limit.