Biomedical Engineering Reference
In-Depth Information
Fig. 13.4
Dipstick tests based on aptamer/AuNPs lateral flow device. (
a
) Schematic representation
of adenosine-induced disassembly of aptamer-linked AuNP aggregates. Biotin is denoted as black
stars. (
b
) DNA sequences and linkages in AuNP aggregates. Lateral flow devices loaded with the
biotin-labeled AuNP aggregates (on the conjugation pad) before use (
c
)andinanegative(
d
)ora
positive (
e
) test (Reproduced from Ref. [
62
] by permission of John Wiley & Sons Ltd)
and electron-transfer processes and almost perfect quenching of the fluorescence
[
67
,
68
]. Based on this quenching property, AuNPs have been successfully used
to construct fluorophore/quencher-based biosensors. As an example, AuNPs have
been used in molecular beacons for fluorescent detection of DNA, which showed
100-fold greater sensitivity compared to organic quenchers [
69
].
Based on combining AuNPs as the fluorescence quencher and structure-switch
aptamer as the probe, Zhao and coworkers reported a turn-on fluorescence thrombin
biosensor [
70
]. After the complementary dye-labeled ssDNA hybridizes with
aptamer-functionalized AuNPs, the fluorescence of the dye is quenched. Upon
recognition of thrombin by the aptamers, the fluorescent DNA strand was released
and the fluorescence was recovered. Taking advantage of a similar principle,
aptamer-modified gold nanoparticles were also employed to develop “turn-on”
fluorescent sensors for sensitive detection of breast cancer markers [
71
].
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