| In this paper, efforts have been devoted to the fabrication of electrochemical sensor and biosensor based on the carbon nanotubes modified electrodes.Consist of two main parts: a new bienzymatic glucose biosensor was proposed for selective and sensitive detection of glucose;selective determination of dopamine free from AA interference based on the carbon nanotube paste electrode.A bienzymatic glucose biosensor was proposed for selective and sensitive detection of glucose. This mediatorless biosensor was made by simultaneous immobilization of glucose oxidase (GOD) and horseradish peroxidase (HRP) in an electropolymerized pyrrole (PPy) film on a single-wall carbon nanotubes (SWNT) coated electrode. The amperometric detection of glucose was assayed by potentiostating the bienzymatic electrode at -0.1 vs. Ag/AgCl to reduce the enzymatically produced H2O2 with minimal interference from the coexisting electroactive compounds. Under the lower operation potential of -0.1 V, the linear response range of the bienzymatic sensor was from 3.00×10?5 to 2.43×10?3M , an extremely lower detection limit of 0.03±0.009mM estimated at a signal to noise ratio of 3. Further research efforts should be devoted to improve the stability of the biosensors.A Carbon nanotubes paste electrodes have been constructed and applied for the simultaneous measurement of various combinations of dopamine (DA) and ascorbic acid (AA). Contrast with the carbon paste electrode, the carbon nanotube paste electrode offers a better potential alternative to selective determination of DA free from AA interference due to the strong electrocatalytic activity. The peak-to-peak separation of their anodic potentials was about 200 mV in 0.067 M (pH 5.40) phosphate buffer solution containing 4×10-4 M DA and 1.2×10-3 M AA .
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