Electrochemical nitrite nanosensor developed with amine- and sulphate-functionalised polystyrene latex beads self-assembled on polyaniline

Aniline doped with polyvinyl sulphonate (PV-SO3−) was electropolymerised on screen printed carbon (SPCE) and glassy carbon (GCE) electrodes. Then nano-structured polystyrene (PSNP) latex beads functionalised with amine (PSNP-NH2) and sulphate (PSNP-OSO3−) were self-assembled on the modified SPCE and GCE. The resultant polyaniline nanocomposites (PANI|PSNP-NH2 or PANI|PSNP-OSO3−) were characterised by cyclic voltammetry (CV), 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 of the order of 10−8 mol cm−2. UV–vis spectra of the PANI films dissolved in dimethyl sulphoxide showed typical strong absorbance maxima at 480 and 740 nm associated with benzenoid π–π* transition and quinoid excitons of polyaniline, respectively. The SEM images of the PANI nanocomposite films showed cauliflower-like structures that are <100 nm in diameter. When applied as electrochemical nitrite sensor, sensitivity values of 60, 40 and 30 μA/mM were obtained for electrode systems containing PANI|PSNP-NH2, PANI and PANI|PSNP-SO3−, respectively. The corresponding limits of detection of the sensors were 7.4, 9.2 and 38.2 μM NO2−.