Biology Reference
In-Depth Information
graphite powder and used as catalysts for the electrochemical
detection of amikacin antibiotic oxidation, achieving a 40 times
higher current than with a bulk CuO-modified carbon paste
electrode [15]. Cu
2
O hollow spheres (150-220 nm sized spherical
aggregations of small Cu
2
O-NPs) were applied by Zhu
et al.
[44] in
electrochemical DNA sensing using a carbon paste electrode and
MB as the hybridization indicator. They make use of these particles
as enhancers to the ssDNA probe immobilization on the electrode
surface to obtain a sensitive detection of Hepatitis B virus DNA
sequences by differential pulse voltammetry.
More recently, Prussian blue nanoparticles (PB-NPs) were found
tocatalyzetheelectrochemicalreductionofH
2
O
2
whenimmobilized
in the form of layers on ITO electrodes [14]. The application of
PB-NPs as catalytic labels for highly sensitive detection of DNA
hybridization was also reported based on their catalytic effect
toward H
2
O
2
when embedded in polystyrene spheres and loaded
onto a gold-diskelectrode [45].
Iron and iron oxide nanoparticles (Fe and Fe
3
O
4
-NPs)
also present catalytic properties in electroanalysis. Fe-NPs were
described as e
cient and selective catalysts in the electrochemical
detection of H
2
O
2
in the presence of O
2
by facilitating the electron
transfer between adsorbates and the glassy carbon electrode
surface. Fe
3
O
4
-NPs were used to modify a crystalline gold electrode
for the electrochemical detection of dopamine. They showed good
catalytic activity by lowering the dopamine oxidation overpotential,
allowingthedopamineandascorbicacidpeakstobecomeseparated
and resolvable and with even lower detection limits than the Au-NP
system referred above [13].
5.5 Conclusions
The induced catalysis by NPs is showing special interest in the DNA
biosensing technology. The application of NPs as catalysts in DNA
detection systems is related to the decrease of overpotentials of
the involved redox species including also the catalyzed reduction
of other metallic ions used in labeling-based hybridization sensing.
Although the most exploited materials in catalysis are the metals
