Biology Reference
In-Depth Information
conjugate probe amine-terminated DNA) and poly (ethylene glycol)
units (to limit nonspecific adsorption). After subsequent target
bindingfollowedbyDNA-nanoparticlecapture,thePdnanoparticles
catalyzed the hydrolysis of NaBH
4
and the sorption of many atomic
hydrogens which were used to generate catalytic currents with a
detection limitof 10 aM.
14.3 Nanowires, Nanorods, and Nanofibers
The use of nanowires, nonorods, nanofibers, etc. has also attracted
considerable attention for use in detection of DNA and other bio-
molecules[39].Similartocarbonnanotubes,theseone-dimensional
nanostructurespossesuniqueelectricalpropertiesduetotheirhigh
surface-to-volume ratio and extreme sensitivity of carrier charge
mobility that can be exploited for sensing [1a]. Additionally, the
dimensional scale of these materials is comparable to that of the
biological species being interrogated, providing interesting oppor-
tunities for use as labels or signal transducers for electrochemical
sensing. The extremely small footprint of these nanomaterials may
allow assembly of numerous sensors onto a small area, facilitating
development of devices capable of detecting a hostof analytes.
Synthesis and characterization of nanowires remains a signif-
icant focus area of nanotechnology [40]. Nanowires composed
of metals, semiconductors, conducting polymers, diamond, and
other materials have been reported. Although several methods
exist for producing nanowires, the use of porous templates for
the synthesis of nanowire tubes and -rods is the most commonly
used and has been extensively investigated. In this approach an
inert porous membrane, anodized alumina, for example, is used
as the template for forming well-defined free-standing nanowires
that can be oriented or non-oriented. The nanowires are formed
by electrochemical or electrophoretic deposition of the desired
material(s) into the porous template which can be subsequently
removed or left as a scaffold for the nanowire array. Other methods
for producing nanowires include evaporation/condensation, dis-
solution/condensation, vapor/liquid/solid (vapor deposition), and
substrate ledge or step induced growth.
