Biology Reference
In-Depth Information
Figure 4.15.
Schematic display of the experimental procedure for the
determination of mutated papillary thyroid carcinoma DNA-based on the
use of enlarged Au-NPs and SWSV [81] (reprinted with permission of
Elsevier).
protocols for the development of a model thrombin aptasensor
[82]. The sensing platform is illustrated in Fig. 4.16. It consisted
of a gold electrode-aptamer/thrombin/aptamer-functionalized Au-
NP (Apt-Au-NP) sandwich design, where the detection sensitivity
was improved due to the development of three-level cascaded
impedimetric signal amplification steps. A thiolated thrombin-
aptamer was self-assembled on a gold electrode and used to
capture the analyte thrombin in sample solution, obtaining the
Au/TBA/MCH/thrombin electrode. The Apt-Au-NPs were subse-
quently bound to this electrode forming the sandwich system
mentioned above and achieving the first-level signal amplification
of the electron-transfer resistance. Then, the Apt-Au-NPs bound
to the modified electrode were used as the seeds for their
catalytic enlargement thus obtaining the second/third level signal
amplification. Due to the steric-hindrance between the enlarged
Apt-Au-NPs blocking the electron-transfer of the redox probe, the
electron-transfer resistance of the Au/TBA/MCH/thrombin/Apt-
Au-NPs electrode increased, realizing the second-level signal
amplification. In addition, the negatively charged SDS used as
stabilizer capped the enlarged Apt-Au-NPs with negative charge,
which repels the negatively charged redox probe, [Fe(CN)
6
]
3
−
/
4
−
,
