Study Of Non-enzymatic Glucose Electrochemical Sensors Based On Carbon Nanotubes Hybrid Materials

In recent years, non-enzymatic glucose sensor based on nanomaterials, such ustransition metals (oxides), and metal alloys, has become a research hotspot. Amongthese, non-precious metal nanomaterials (Cu, Ni) by virtue of low cost, low toxicityand good electrocatalytic activity to glucose are of particular interest, which makesthem ideal candidates for nonenzymatic glucose sensor. Carbon nanotubes (CNTs)have found substantial applications in electrochemical sensors owing to their highelectrocatalytic properties, high chemical stability, high conductivity, and extremelyhigh mechanical strength. Therefore, CNTs are usually used in conjunction with othercatalytically active, non-precious metals (oxides) to electrochemically detect glucose.The main research contents were shown as follows:(1) Preparation of CuNi/fMWCNTs composites and their electrocatalyticbehavior towards glucose oxidation. MWCNTs were noncovalently functionalizedwith Nafion (fMWCNTs), followed by the immobilization of such fMWCNTs on thesurface of glassy carbon electrode (fMWCNTs/GCE). CuNi nanoparticles were thendeposited on fMWCNTs/GCE using a simple electrochemical method. The structure,morphology, and Cu/Ni molar ratio of the CuNi/fMWCNTs nanocomposites werecharacterized by XRD, SEM, and AAS, respectively. The factors such as depositionpotential, temperature, and time that affected the electrocatalytic activities of theseelectrodes were investigated and optimized. Experimental conditions for the detectionof glucose, such as the scan rate, applied potential were also investigated. Underoptimized conditions, a good linear relationship between oxidation peak and glucoseconcentration was obtained in the range of0.15000μM, with a limit of detect of2.5nM. Moreover, the sensor has been successfully used for the assay of glucose inhuman serum samples with good recovery, ranging from95.6to100.1%.(2) Preparation of NiO/SWCNTs hybrid nanobelts and their electrocatalyticbehavior towards glucose oxidation. NiO/SWCNTs hybrid nanobelts were preparedby the deposition of SWCNTs onto the Ni(SO4)0.3(OH)1.4nanobelt surface, followedby heat treatment at a certain temperature in nitrogen. The morphology and structureof NiO/SWCNTs were characterized by SEM, TEM and XRD. An ultra-sensitiveelectrochemical sensor for the detection of glucose in aqueous solution was fabricatedby modification of glassy carbon electrode (GCE) with NiO/SWCNTs nanobelts. A systematic investigation related to experimental conditions, such as heat treatmenttemperature, NaOH concentration, scan rate, and applied potential has been conducted.Under optimum conditions, the as-fabricated nonenzymatic glucose sensor exhibitsexcellent glucose sensitivity (2980μA cm2mM1), lower detection limit (0.056μM,S/N=3), wider linear range (0.51300μM), and remarkable stability andrepeatability. Moreover, the sensor has been successfully used for the assay of glucosein serum samples with good recovery, ranging from96.4%to102.4%.