Abstract
In this research study, we developed a voltammetric electrochemical sensor probe with a copolymer Nafion (Sulfonated Tetrafluoroethylene-based Fluoro-polymer) decorated with hydrothermally prepared sandwich-type CuO/ZnO nanospikes (NSs) onto a glassy carbon electrode (GCE) for reliable thiourea (TU) detection. The detailed characterizations in terms of structural morphology, binding energy, elemental compositions, grain size and crystallinity for synthesized NSs were performed by field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis, respectively. The differential pulse voltammetric (DPV) analysis for TU showed good linearity at current-versus-TU concentration on the calibration plot in the 0.15~1.20 mM range, which is defined as a dynamic detection range (LDR) of TU in a phosphate buffer solution. Considering the slope of LDR over the GCE-coated NSs surface area (0.0316 cm2), the TU sensor sensitivity (0.4122 µA µM−1 cm−2) was obtained. Besides this, the low limit (LOD) for TU detection was calculated and found to be 23.03 ± 1.15 µM. The fabricated Nafion/CuO/ZnO NSs/GCE sensor probe was created as a reliable sensor based on reproducibility, interference effect, stability and response time. Real bio-samples were investigated and the results confirm the anticipated reliability of the TU sensor probe. Thus, this is a noble way to develop enzyme-free electrochemical sensors that could be an alternative approach for the detection of chemicals in the field of enzyme-free biosensor development technology.
Highlights
Within the technological revolution, thiourea (TU) is a compound containing carbon, hydrogen, sulfur and nitrogen widely applied for human and veterinary medicines formulation, agrochemicals production, rubber vulcanization, metal electro-deposition, cleaning agents and food additives [1,2,3]
A magnified image of field emission scanning electron microscopy (FESEM) for CuO/ZnO NSs is presented in Figure 1e, where a spike-like structure is found in the image
Sandwich-type CuO/ZnO NSs were prepared by the hydrothermal method in an alkaline phase
Summary
Thiourea (TU) is a compound containing carbon, hydrogen, sulfur and nitrogen widely applied for human and veterinary medicines formulation, agrochemicals production, rubber vulcanization, metal electro-deposition, cleaning agents and food additives [1,2,3]. Among the electrochemical detection methods of trace biochemical, cyclic voltammetry (CV), impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) are potential tools for researchers to develop sensor probes based on semiconductor metal oxides as sensing elements [21,22]. This study was performed to develop a selective thiourea (TU) sensor based on CuO/ZnO NSs as a sensing substrate deposited on a GCE, where a Nafion copolymer was used as binding glue between CuO/ZnO NSs and a GCE. A commercial GCE (0.0316 cm2) was modified by the deposition of a thin layer of CuO/ZnO NSs and the resultant modified GCE was utilized as the sensing electrode known as the working electrode of the TU sensor For this purpose, the synthesized CuO/ZnO NSs (5.0 μg) were made slurry in ethanol (1.0 mL) and subsequently used to form an NS layer to coat the GCE’s flat part.
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