Novel poly(3-methylthiophene)/Pd, Pt nanoparticle sensor: Synthesis, characterization and its application to the simultaneous analysis of dopamine and ascorbic acid in biological fluids

A promising modified electrode was fabricated by distributing Pt or Pd nanoparticles into conductive polymer matrix of poly(3-methylthiophene) (PMT). Electrochemical investigation of the resulting films was achieved using cyclic voltammetry and differential pulse voltammetry. Several factors affecting the electrocatalytic activity of the hybrid material were studied. Some are related to the polymer such as film thickness, method of its formation and dedoping the polymer film before loading metal particles, other factors are related to the metal particles such as type of metal deposited, method of its deposition, its amount and deposition voltage. EDX analysis was employed to confirm the loading of metal particles to the polymer film. The results suggest that the hybrid film modified electrode combining the advantages of PMT and metal nanoparticles exhibits dramatic electrocatalytic effect on the oxidation of dopamine (DA) and results in a marked enhancement of the current response. The proposed method was applied to the simultaneous determination of ascorbic acid (AA) and dopamine (DA) in physiological pH 7.4 PBS. It was observed that in the presence of AA at millimolar level (0.1 mM), the Pd nanoparticle-modified PMT electrode can sense the increase of DA at micromolar concentration (0.05–1 μM) which is typical of the physiological conditions. The interference study shows that the modified electrode exhibits excellent selectivity in the presence of AA and uric acid (UA) and glucose. It has been shown that this modified electrode can be used as a sensor with high reproducibility, sensitivity, and stability. The method was applied to urine and healthy human blood serum samples and excellent results were obtained.