Poly-Thionine/SWCNT Nanocomposite Coated Electrochemical Sensor for Determination of Vitamin C

Background: The electrochemical sensors convert biological or chemical information, such as analyte concentration or a biomolecular (biochemical receptor) interaction, into electrical signals. In this paper, we describe the development of a poly-thionine/ single-walled carbon nanotube (P-Th/SWCNT) composite for the electrochemical detection of ascorbic acid (vitamin C). Methods: To improve electrochemical performance, we attempted to electro-polymerize the thionine monomers, an essential chemical building block, directly on the surface of singlewalled carbon nanotubes (SWCNT). Results: Field Emission Scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS) results revealed that a complex structure of the P-Th/SWCNT was formed. The presence of carbon (C), oxygen (O), nitrogen (N), and sulfur (S) components was confirmed, which indicated the effective fusion of poly-thionine onto SWCNT. Moreover, the X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy confirmed the composite formation. Utilizing cyclic voltammetry, the composite's electrochemical behavior was examined. Conclusions: Excellent electrocatalytic activity towards the oxidation of ascorbic acid was shown by the P-Th/SWCNT composite. The as-prepared P-Th/SWCNT composite-modified sensor can detect ascorbic acid in food, medical, and pharmaceutical samples.