Abstract
Carbon fiber microelectrode (CFME) modified by Nafion and single-walled carbon nanotubes (SWNTs) was studied by voltammetric methods in phosphate buffer saline (PBS) solution at pH 7.4. The Nafion-SWNTs/CFME modified microelectrode exhibited strongly enhanced voltammetric sensitivity and selectivity towards dopamine (DA) determination in the presence of ascorbic acid (AA). Nafion-SWNTs film accelerated the electron transfer reaction of DA, but Nafion film as a negatively charged polymer restrained the electrochemical response of AA. Voltammetric techniques separated the anodic peaks of DA and AA, and the interference from AA was effectively excluded from DA determination. Linear calibration plots were obtained in the DA concentration range of 10 nM - 10 μM and the detection limit of the anodic current was determined to be 5 nM at a signal-to-noise ratio of 3. The study results demonstrate that DA can be determined without any interference from AA at the modified microelectrode, thereby increasing the sensitivity, selectivity, and reproducibility and stability.
Highlights
Dopamine (DA) has long been of interest to neuroscientists and chemists because of its role as a very important neurotransmitter in mammalian central nervous systems and the fact that low levels of DA concentration bring about Parkinson’s disease [1]
There was no voltammetric response at the modified microelectrode in the blank phosphate buffer saline (PBS) solution (Figure 1a)
After modification with a suitable amount of Nafion-SWNTs, a well-defined, peakshaped, redox couple appeared at an anodic peak potential of 0.18 V and a cathodic peak potential of
Summary
Dopamine (DA) has long been of interest to neuroscientists and chemists because of its role as a very important neurotransmitter in mammalian central nervous systems and the fact that low levels of DA concentration bring about Parkinson’s disease [1]. A conventional way to solve this problem is to coat the electrode surface with an anionic film to protect the surface from interference Since their discovery carbon nanotubes (CNTs) have attracted much research interest as novel materials with excellent electrical conductivity, mechanical strength, chemical stability and flexibility properties [2]. They present several forms, including single- (SWNTs), double- (DWNTs), and multiwalled carbon nanotubes (MWNTs). The electrochemical determination of DA was performed without any interference from the AA contained in the solutions, and the modified microelectrode provided clear advantages such as excellent reproducibility and stability, rapid response, and a very low detection limit of 5 nM
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