Biology Reference
In-Depth Information
Figure 2.10.
The representation of the aptasensor based on NPs' amplifi-
cation for ATP detection.
which binds to surface-confined DNA via electrostatic interaction
was used forsignalgeneration, interrogated by chronocoulometry.
In presence of the target molecule, ATP, the binding to the
aptamer causes its conformational change leading to the release
of the reporter DNA labeled with Au-NPs. In this way numerous
moleculesof[Ru(NH
3
)
6
]
3
+
arereleasedinsolutiongeneratingasig-
nal amplification. A wide linear range for the detection of ATP was
obtainedbetween 1 nMand 10
μ
M withadetection limit of0.2 nM.
A similar approach was conducted by using quantum dots (QDs)
for signal amplification [51]. In this case the hybrid formed by a
thiol-labeled oligonucleotide and the thrombin aptamer was immo-
bilizedontoagoldelectrode.Whenbindingtothrombintheaptamer
adopts its G-quartet structure and only the single-stranded probe
remained onto the electrode, which is now available for hybridiza-
tion witha QD-labeledcomplementary oligonucleotide(Fig. 2.11).
The CdS-QD were then dissolved and CD
2
+
was detected on a
mercury-film electrode: this technique led to a detection limit of
0.43fMforthrombinwithalinearrangebetween2.3nMand2.3fM.
Other works based on this kind of approach without or with sig-
nalamplificationwererecentlypublishedforthedetectionofadeno-
sine[52, 53] and lysozyme[48].
