Polypyrrole Hollow Nanotubes Loaded with Au and Fe3O4 Nanoparticles for Simultaneous Determination of Ascorbic Acid, Dopamine, and Uric Acid

An ultrasensitive electrochemical biosensor was fabricated for electroanalytical determination of ascorbic acid(AA), dopamine(DA) and uric acid(UA) individually and simultaneously based on polypyrrole hollow nanotubes loaded with Au and Fe 3 O 4 nanoparticles(NPs) uniformly(PPy@Au-Fe 3 O 4 ). The PPy@Au-Fe 3 O 4 nanotubes were synthesized in one-pot using MoO 3 nanorods as templates and the polymerization of Py, the formation of Au and Fe 3 O 4 NPs and the removel of MoO 3 templates took place stimultaneously. Electrochemical studies reveal that PPy@Au-Fe 3 O 4 modified glassy carbon electrode(GCE) possesses excellent electrocatalytic activities toward the oxidation of AA, DA and UA. Their oxidation peak currents increase linearly in the concentration ranges of 1–2000 µmol/L for AA, 0.01–25 and 25–300 µmol/L for DA and 0.1–300 µmol/L for UA. Their detection limit values( S/N =3) were calculated as 0.45, 0.0049, and 0.051 µmol/L for AA, DA and UA in the individual detection. By changing the concentrations simultaneously, the calibration curves showed linearity to 1000, 200, and 200 µmol/L with detection limit of 0.39, 0.0060, and 0.060 µmol/L for AA, DA, and UA, respectively. Finally, the obtained biosensor was successfully applied to the detection of AA, DA, and UA with satisfactory results on actual samples.