Biology Reference
In-Depth Information
Also, intercalated adriamycin has been used as hybridization
label in a genosensor built by modifying a glassy carbon electrode
(GCE)withmultiwalledcarbonnanotubeswithcarboxylgroupsand
Au-NPs [23]. Differential pulse voltammetry (DPV) was utilized to
monitortheDNAhybridizationevent.Undertheoptimalconditions,
the increase of reduction peak current of adriamycin was linear
with the logarithm of the concentration of the complementary
oligonucleotides from 1.0
×
10
−
12
to 5.0
×
10
−
9
M with a detection
10
−
13
M.
An interesting and relatively new water soluble intercalating
compound, pentaamin ruthenium [3-(2-phenanthren-9-yl-vinyl)-
pyridine] complex [Ru(NH
3
)
5
L] prepared
in situ
, has been also
used to detect the hybridization event. The metal provides with
a redox centre that can be used as the electrochemical indicator,
whilegoldnanoparticlescontributetofacilitatetheelectrontransfer
between the redox indicator and the electrode surface by acting
as tiny conduction centres. Following this detection strategy,
complementarytargetsequencesof
H. pylori
weredetectedoverthe
range 40 to 800 pmol witha detection limitof25
±
2 pmol [13].
Table 4.3 summarizes data reported between 2007 and 2009
for electrochemical genosensors based on dsDNA-intercalated
electrochemical labels.
×
limitof 3.5
4.3.1.4 Detection involving the use of Au-NPs as carriers
Au-NPs can be used as nanocarriers for other NPs or other
electroactive species. As a result, the DNA detection is notably
enhanced compared to the use of single labels. However, this
strategy requires a careful work to avoid irreproducibility in the
biosensors'response [27].
Inthiscontext,Ding
et al.
[50]haverecentlydescribedasensitive
assay for sequence specific DNA detection based on bio-bar code
techniques,andusingelectrochemicaldetectionofCdionsdissolved
from CdS-nanoparticles. Figure 4.8 shows a scheme of the method
used for the amplified sensing of target DNA. Sandwich-type DNA
complexes were fabricated with a thiol-functionalized capture DNA
sequence immobilized on an Au-NP-GCE and hybridized with one
endoftargetDNA.TheotherendoftargetDNAwasrecognizedwith
