Electrochemical ochratoxin a immunosensors based on polyaniline nanocomposites templated with amine- and sulphate-functionalised polystyrene latex beads

Abstract

Polyaniline nanocomposites doped with poly(vinylsulphonate) (PV-SO3) and nanostructured polystyrene (PSNP) latex beads functionalized with amine (PSNP-NH2) and sulphate ((PSNP-OSO3) were prepared and characterised for use as nitrite electro-catalytic chemosensors and ochratoxin A immunosensors. The resultant polyaniline electrocatalytic chemosensors (PANI, PANI|PSNP-NH2 or PANI|PSNP-OSO3 −) were characterized by cyclic voltammetry (CV), ultraviolet-visible (UV-Vis) spectroscopy and scanning electron microscopy (SEM). Brown-Anson analysis of the multi-scan rate CV responses of the various PANI films gave surface concentrations in the order of 10−8 mol/cm. UV-vis spectra of the PANI films dissolved in dimethyl sulphoxide showed typical strong absorbance maxima at 480 and 740 nm associated with benzenoid p-p* transition and quinoid excitons of polyaniline, respectively. The SEM images of the PANI nanocomposite films showed cauliflower-like structures that were <100 nm in diameter. When applied as electrochemical nitrite sensors, sensitivity values of 60, 40 and 30 μA/mM with corresponding limits of detection of 7.4, 9.2 and 38.2 μM NO2 −, were obtained for electrodes, PANI|PSNP-NH2, PANI and PANI|PSNP-SO3 −; respectively. Immobilisation of ochratoxin A antibody onto PANI|PSNP-NH2, PANI and PANI|PSNPSO3 - resulted in the fabrication of immunosensors.