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

Abstract

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 ( R CT) 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 R CT values and showed linear response up to 10 ng/mL OTA concentration in electrolyte. Relative change in R CT 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.