Biomedical Engineering Reference
In-Depth Information
12.5.1.1.3 The Enhanced Catalytic Performance of
Nanoparticles and Carbon Nanotube Complexes ....311
12.5.1.1.4 Carbon Nanotube-Based Nanoelectrode Arrays ......313
12.5.1.2 Carbon Nanotubes as Field-Effect Transistors in
Nanosensor Construction ................................................................315
12.5.1.3 Carbon Nanotube-Based Scanning Probe Microscopy
Probe Tips for Imaging Biological Compounds and
Biological Sensitive Measurements ................................................317
12.5.2 The Use of Nanowires in Biological Detection ............................................320
12.6 Conclusion and Future Perspective ............................................................................322
References ....................................................................................................................................324
12.1
Introduction
Rapid advances in nanoscience and nanotechnology have provided a variety of nanoscale
materials with unique optical, electrical, magnetic, or catalytic properties, which have
enabled the fabrication of various functional nanoscale devices such as biosensors [1,2].
Integration of biomaterials (e.g., proteins, peptides, or DNA) with nanostructured materi-
als greatly expands the impact of bioelectronics, particularly in biosensors.
Nanostructures (i.e., structures with at least one dimension in the range of 1-100 nm)
have attracted steadily growing interest due to their unique, fascinating properties and
potential applications complementary to three-dimensional (3D) bulk materials.
Dimensionality plays a critical role in determining the properties of materials due to, for
example, the different ways in which electrons interact in 3D, two-dimensional (2D), one-
dimensional (1D), and zero-dimensional (0D) structures [3]. Compared with 0D nanos-
tructures (so-called quantum dots or nanoparticles) and 2D nanostructures (thin films), 1D
nanostructures (including carbon nanotubes (CNTs) and nanowires (NWs)) are ideal as
model systems for investigating the dependence of electronic transport, optical, and
mechanical properties on size confinement and dimensionality as well as for various
potential applications, including composite materials, electrode materials, field emitters,
nanoelectronics, and nanoscale sensors.
In comparison with nanoparticles (NPs), however, the integration of 1D nanostructures
with biological systems to form functional assemblies has been slow until recently, as it
has been hindered by the difficulties associated with the synthesis and fabrication of
these materials with well-controlled dimensions, morphology, phase purity, and chemi-
cal composition; for example, controlling growth to form semiconducting single-walled
carbon nanotubes (SWCNTs). As better techniques are developed, 1D nanostructures
should find extensive applications in the construction of novel nanoscale devices such as
biosensors, which combine the conductive or semiconductive properties of the nanoma-
terials with the recognition of biomaterials. Owing to the high surface-to-volume ratio of
1D nanostructures, the variation of their electronic conductance to adsorbed surface
species may be sensitive enough for single-molecule detection to become possible.
This chapter is organized as follows: We begin by describing the processing techniques
used to control the nanostructure of CNTs and NWs. We pay particular attention to struc-
ture control and growth mechanisms of these nanomaterials. We then discuss methods by
which CNTs and NWs can be functionalized with appropriate agents for biosensor appli-
cations. This section is followed by a review of interesting new applications of these
materials in electrochemical biosensors, field-effect transistor (FET)-based biosensor, and
nanofabrication of these biosensors.
