Biomedical Engineering Reference
In-Depth Information
Fig. 13.2
Schematic representation of DNAzyme-based label-free sensor. (
a
)UO
2
2C
induced the
cleavage of DNAzyme complex and released a short ssDNA which adsorbs on AuNP surface.
(
b
) The AuNPs aggregate in the absence of UO
2
2C
but remain dispersed in the presence of UO
2
2C
(Reprinted with the permission from Ref. [
40
]. Copyright 2008 American Chemical Society)
sensors, the label-free sensors had better sensitivity (1 nM detection limit), shorter
operation time, and lower costs [
40
]. DNAzyme-based label-free method has also
been extended to the detection of Pb
2C
[
41
,
42
].
On the basis of high metal-binding specificity of the DNAzymes, the DNAzyme-
AuNP system was mainly developed for the detection of metal ions. In addition to
the DNAzyme-based metal ion sensor, labeled and label-free colorimetric method
for the sensitive and selective detection of Hg
2C
was also reported based on
thymine-Hg
2C
-thymine (T-Hg
2C
-T) coordination chemistry [
43
-
48
]. Since ap-
tamers can bind to a variety of molecules and proteins with high affinity and speci-
ficity, they can also be incorporated into such systems for colorimetric detection of
many other targets based on controlling the assembly and disassembly of AuNPs.
The Lu group developed a general sensor platform based on the structure-switchable
aptamer-encoded disassembly of aggregated AuNPs (Fig.
13.3
)[
49
]. A linker DNA
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