Biology Reference
In-Depth Information
broad range of disciplines. The Human Genome Project (HGP) [1]
has stimulated the development of analytical methods that yield
genetic information quickly and reliably. Examples of this develop-
ment are the DNA chips [2-4], lab-on-chips based on microfluidic
techniques [5, 6], and self-assembled molecular electronic circuits
[7]. The development of new methodologies possessing the conve-
nience of solid-phase reaction, along with the advantages of rapid
response, sensitivity, and ease of multiplexing, is now a challenge in
thedevelopmentofnewbioanalyticaldiagnostictools.Electrochem-
ical DNA biosensors can meet these demands, offering consider-
ablepromiseforobtainingsequence-specificinformationinafaster,
simpler, and cheaper manner compared to traditional hybridization
assays. Such devices possess great potential for applications, rang-
ingfromdecentralizedclinicaltesting,toenvironmentalmonitoring,
food safety, and forensicinvestigations.
The development of new transducing materials for DNA analy-
sis is a key issue in the current research efforts of electrochemical-
based DNA analytical devices. While DNA immobilization and
detection of the hybridization event are important features, the
choiceof asuitableelectrochemical substrate isalso ofgreat impor-
tance in determining the overall performance of the analytical
electrochemical-based device, especially regarding the immobiliza-
tion e
ciency of DNA.
Carbonaceous materials
such as carbon paste [8], glassy carbon
[9], and pyrolitic graphite [10] are the most popular choices of elec-
trodes used in biosensing devices. However, the use of platinum
[11], gold [12], indium-tin oxide [13], solid copper amalgam [14],
mercury [15], and other
continuous conducting metal substrates
has
been reported [16].
Conducting polymers
—such as polypyrrole and
polyaniline—[17] and
conducting composites
—based on the com-
bination of non-conducting polymers with conductive fillers—[18]
have also been continuously studied during the past few decades.
Finally, nanostructured materials such as carbon nanotubes (CNT)
[19] and metal nanoparticles (NPs) [20] have also been reported as
a base material or fillers for conducting composites or as surface-
modifiers of many types of electrochemical transducers in order
to improve their electrochemical properties. Other nanostructured
materials including gold NPs have been intensively investigated as
