Au nanoparticle–polyaniline nanocomposite layers obtained through layer-by-layer adsorption for the simultaneous determination of dopamine and uric acid

The layer-by-layer adsorption technique was used to prepare polyaniline (PANI)–gold nanoparticles (AuNP) multilayered structures with different AuNP/PANI ratios. By means of microgravimetric measurements it was found that the amount of the adsorbed species depends on the duration of the AuNP adsorption step. At fixed adsorption step durations the amount of both (PANI and AuNP) materials increases linearly with the number of adsorption steps.Two types of PANI–AuNP multilayered nanocomposites with different AuNP/PANI ratio were studied as electrocatalytic materials for dopamine and uric acid oxidation. The sensitivity of PANI–AuNP for dopamine oxidation was found to depend on type of the nanocomposite whereas for uric acid oxidation the sensitivity remained unaffected by the type of the nanocomposite structure. This result is discussed in terms of the different limitations for both oxidation reactions. By means of differential pulse voltammetry experiments linear concentration dependences of the anodic peak currents were observed for both dopamine and uric acid in the concentration ranges 7–148 μmol dm−3 and 29–720 μmol dm−3, respectively. In the presence of both analytes no interference effects were detected.