Biomedical Engineering Reference
In-Depth Information
or oxidation the metal nanoparticle can catalyze, then upon contact
of the nanoparticle and the electrode, a much larger current will
flow (assuming the flux of the species to the nanoparticle is much
higher than the flux of the particle itself to the electrode surface).
This principle was demonstrated by immersing a carbon fiber elec-
trode in an acidic aqueous solution of Pt nanoparticles, and the
reduction of protons and hydrogen peroxide was used as the elec-
trocatalytic reaction to detect single nanoparticle collisions at the
electrode.
170
V. APPLICATIONS IN BIOLOGY AND MEDICINE
Nanoelectrodes are finding increasing use in both fundamental as
well as applied studies of biological systems. In addition to the
performance enhancements discussed above, a benefit of miniatur-
ization with respect to sensors is that it becomes possible to fit
more electrodes onto a given device footprint. Depending on the
applications, this can be harnessed either to provide spatial resolu-
tion or for the realization of massively parallel measurements.
Apart from directly shrinking the dimensions of the working elec-
trode, another approach to nanoelectrochemical systems relies on
functionalizing macro-scale electrodes with nanostructured materi-
als like metal nanoparticles,
125
carbon nanotubes,
171
quantum dots
etc. to interface with biological macromolecules.
172
Besides in-
creased surface areas, these nanostructured bio-interfaces can also
provide access to unique electrical and optical properties of na-
noscale phenomena through confinement effects etc.
125,173
The use
of nanostructured materials represent interesting and important
advancements. Since their application to biology and medicine are
discussed in much more detail in the other chapters of this double
volume, however, we concentrate here on only a few examples
that are linked to the concepts discussed in the earlier Sections of
this Chapter.
The limited selectivity of electrochemical detection is one of
the key bottlenecks to the development and widespread adoption
of (nano)electrochemical technologies in biology and medicine.
Without a means of boosting selectivity, electrochemical detection
remains mostly limited to
in-vitro
measurements with purified
systems or situations where it can be coupled either with separa-
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