Biosensors are devices for the determination of analytes that contains a biological element, such as an enzyme that recognizes a specific kind of interest in the sample. Glucose oxidase (GOx) is an enzyme widely used for the development of biosensors due to their high catalytic activity and good stability.Biosensors for glucose-mediated electron transfer have a physicochemical transducer that acts as an intermediary between the species of interest and the electrode. However, there are several problems associated with mediated electron transfer biosensors, such as stability of the mediators and intermediaries.The glucose biosensors direct electron transfer are those in which there is no mediator, so that the reaction of the enzyme occurs at the electrode surface, allowing a higher amperometric response to the concentration of the species of interest. Many nanostructured materials have been studied in order to use them on electrodes for the immobilization of GOx.Carbon nanotubes (CNTs) are excellent candidates for substrates for enzymes due to their unique structural and electronic properties. The dimensions of the CNTs allow approaching the active site where it is immobilized GOx on CNTs. For the immobilization of GOx on CNTs, different techniques have been studied, of which the main are the direct adsorption of the enzyme on the substrate and the technique of layer-by-layer, in which a polyelectrolyte of opposite charge to the enzyme is immobilized on the substrate before the enzyme, so that there is electrostatic attraction between the enzyme and the electrolyte.The interest in this work is to monitor the electrochemical activity of GOx immobilized on a composite when the carbon felt and carbon nanotubes such as "cup-stacked" (CF/NTCCS). Will be tested by the direct adsorption of GOx and the technique of layer-by-layer with various polymers such as positively charged polyelectrolytes, since GOx has a negative charge at physiological pH. After the electrochemical detection of GOx, the electrodes modified with CNTs will be tested for glucose. This work is interested in finding out what technique of immobilization of GOx on the composite CF/NTCCS allows greater eletrocatalytic current of glucose oxidation, and thus is more promising for the development of glucose biosensors third generation.
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