Development of a Disposable Electrode Modified with Carbonized, Graphene-Loaded Nanofiber for the Detection of Dopamine in Human Serum

A one-step electrode surface modification is proposed in which a disposable, screen-printed carbon electrode is functionalized with carbonized, electrospun polyacrylonitrile (PAN)-loaded graphene (G) nanoparticles to form a composite, CPAN5G-4x. The electrochemical behavior of the CPAN5G-4x electrode was examined by cyclic voltammetry and electrochemical impedance spectroscopy. Scanning electron microscopy and X-ray diffraction were used to characterize the surface morphology and physical properties of the carbonized composite nanofibers before and after modification. The modified electrode was found to be effective for the detection of dopamine (DA) using square-wave voltammetry (SWV) in the presence of interfering substances such as ascorbic acid and uric acid. With the addition of sodium dodecyl sulfate (SDS) to an optimized solution of phosphate-buffered saline (PBS) at a pH of 2, the fabricated electrode exhibited enhanced electrocatalytic activity toward the oxidation of DA relative to PBS without SDS at a pH of 7.4. The SWV current displayed a linear response to DA concentrations ranging from 0.5 to 100 mu M, with a limit of detection of 70 nM (S/N = 53) and a sensitivity of 1.4258 mu A mu M-1 cm(-2). Finally, the CPAN5G-4x electrode was used to determine DA levels in human serum. The modified electrode can potentially be harnessed for further electrochemical biosensor applications. (C) 2014 Wiley Periodicals, Inc.