Nanostructured conducting polymer for dopamine detection

In this work, we demonstrate the ability of poly(N-methylpyrrole) to form nanostructures and to detect very low concentrations of dopamine, an important neurotransmitter. Poly(N-methylpyrrole) hollow particles of controlled thickness have been prepared using the layer-by-layer assembly technique and polystyrene core-shell particles as templates, which are subsequently eliminated to yield free-standing hollow microspheres with a layer thickness of 30 nm. The morphology and composition of these structures have been evaluated by scanning electron microscopy, transmission electron microscopy, FTIR, Raman and X-ray photoelectron spectroscopies. Results demonstrate that intact hollow spheres can be obtained controlling the number of polymer deposition cycles. Furthermore, two kind of sensors were constructed by immobilizing poly(N-methylpyrrole)/Au nanocomposites and poly(N-methylpyrrole) nanomembranes on the surface of a glassy carbon electrode. Electrochemical techniques were employed to evaluate the ability of poly(N-methylpyrrole) to absorb/immobilize dopamine molecules. It was found that systems based on this conducting polymer are highly sensitive to the neurotransmitter concentration, presenting a very fast response even when the concentration of the dopamine is very low.