Carbon nanotubes based electrochemical sensors and biosensors

Carbon nanotubes are relatively new materials that were discovered in 1991, which have unique electronic properties. Their unique structural features, combined with mechanical, electrical, chemical, magnetic, and optical properties have enabled their use for many important applications. One important application is their use for the fabrication of novel sensors and biosensors with particular focus on electrochemical ones.;To explore their features and enable their processing and manipulation, it is important to explore the different routes for their solubilization. These solubilization routes would enable the preparation of stable solutions and suspensions in acids, polymers, and organic solvents. Solubilization of carbon nanotubes in acids such as sulfuric acid was possible to fabricate a very stable sensor for the detection of NADH. The presence of the nanotubes minimized the level of electrode surface fouling to a large extent. Using Nafion polymer aided in solubilizing the nanotubes by separating the individual nanotubes in a bundle from each other. This suspension was very stable and was used to design a selective glucose biosensor with extended linearity. Using organic solvents such as DMF has proven to be very desirable for nanotubes solubilization due to its relatively high polarity. This carbon nanotubes suspension was used to design a sensor for insulin detection, which showed high degree of electrocatalytic behavior towards this important biological compound.;Another class of carbon nanotubes materials of importance is the polymer-nanotubes composites and biocomposites. The addition of small amounts of nanotubes to the composite mixture would enhance their mechanical and electronic properties to a very large extent. Using Teflon binder, it was possible to fabricate a very sensitive sensor for the detection of glucose and ethanol by employing glucose oxidase and alcohol dehydrogenase respectively within the composite matrix. Mass production of carbon nanotubes disposable sensors was possible by the use of a carbon nanotube composite ink and screen printing technology. The polymer matrix and other additives added to this ink did not impart the electrocatalytic properties of these screen-printed carbon nanotubes disposable electrodes. A new type of biocomposite material was fabricated using a mixture of nanotubes and glucose oxidase in absence of a polymer binder. This new biocomposite was used to fabricate a needle-type glucose biosensor for implantable purposes. (Abstract shortened by UMI.).