Biology Reference
In-Depth Information
Figure 14.18.
SEM images of array of MWCNTs at UV-lithography
patterned Ni spots (left) and polished MWCNT array (right). The schematic
mechanism of [Ru(bpy)
3
]
2
+
mediated guanine oxidation.
current associated with [Ru(bpy)
3
]
2
+
oxidation was measured. This
MWCNT-modified nanoelectrode array was also applied for label-
free detection of PCR amplicons [105].
The use of CNTs as carriers of metal tags has been used
to amplify DNA hybridization detection [106]. CdS nanoparticles
were loaded onto acetone-activated CNTs and further function-
alized with streptavidin. The SWCNT-CdS-streptavidin conjugates
reacted with biotinylated DNA probes. Hybridization of these
probes to complementary oligonucleotides anchored on a support
was detected by stripping voltammetric measurements of the
dissolved CdS particles. Approximately 500 particles were loaded
on a single nanotube, effectively lowering the detection limit
by 500-fold when compared to that achieved using a single
nanoparticle label typical of this type of sandwich assay. Another
effective amplification method developed by Wang's group used
CNTs in a dual amplification role in both the recognition and
transduction events [107]. CNTs were used as carriers of alkaline
phosphatase(ALP)enzymetags(9600enzymemolecules/CNT)and
as transducers for accumulation of the product of the enzymatic
reaction,
-naphthol.Theenzyme-functionalizedCNTswerefurther
modified with DNA probes. Magnetic particles were functionalized
α
