ABSTRACT
Carbon nanotubes (CNTs) have attracted considerable attention because of the unique combination of their one-dimensional (1D) molecular symmetries and physicochemical properties.1 Among the many potential applications,1,2 CNTs have become promising functional materials for the development of advanced biosensors. It has been demonstrated that CNTs promote electron transfer with various redox-active proteins, ranging from glucose oxidase3,4 with a deeply embedded redox center to cytochrome c5,6 and horseradish peroxidase7,8 with surface redox centers. For using CNTs in biosensing applications, however, it is essential to immobilize biomolecules on the CNT structure without diminishing their bioactivity. Therefore, various intriguing approaches have been devised for functioning CNTs with various biomolecules,9−15 such as deoxyribonucleic acid (DNA), proteins, and enzymes, either on their sidewalls or at the end caps.16−20
Although the CNT bioconjugates provide functional materials for the development of advanced biosensors, device design and fabrication also play an important role in regulating the biosensing performance. For many electrochemical biosensing applications, randomly entangled CNTs have been coated onto conventional electrodes.17,21−24 The use of vertically aligned CNTs,25 coupled with well-dened chemical functionalization, may offer additional advantages for facilitating the development of advanced biosensors with a high sensitivity and good selectivity.20,26−28
In this chapter, we present an overview of the CNT functionalization and electrode fabrication for biosensing applications by spotlighting certain selected examples from the research and development carried out in our own and some other research groups. As the main aim of this chapter is to demonstrate important concepts and rational methods for the development of CNT biosensors with no intention for a comprehensive literature survey of the subject, there will be no doubt that the examples to be presented in this chapter do not cover the entire range reported in literature.
