Biomedical Engineering Reference
In-Depth Information
Fig. 3.1 Targeting human
a
-thrombin with a DNA aptamer and exemplified biosensors
employing aptamer-target interactions. (a) Crystal structure of the complex of thrombin-binding
aptamer (TBA) and its target thrombin (PDB: 1HAP). TBA is a 15 bases DNA oligonucleotide
(GGTTGGTGTGGTTGG) that folds into a G-quartet structure upon binding with thrombin.
(b) TBA-based biosensors for the detection of thrombin (
left
) electrochemical approach [
124
]
and (
right
) Molecular beacon fluorescence technique [
41
]
folding process is therefore extremely important. This brings us to question, what is
the folding duration; what are the intermediate folding states, and do they exist in
discrete step or continuously; what is the reversibility and stability; and what are the
coordinating steps made by cations during G-quartet formation?
There are many significant processes involved in aptamer-target interactions that
need to be elucidated. For instance, what are the potential contributions of associa-
tion and dissociation to aptamers' high affinities? A fuller understanding of the
aptamer-target interaction could provide meaningful insight into the subtleties of
diverse nucleic acid-protein interactions in living cells. More significantly, it should
benefit to molecular recognition-based rational design and its applications such as
biosensor construction (Fig.
3.1b
).
3.1.3 Single Molecule Detection and Nanopore
Nanopore is an emerging single molecule detection technique in which the indi-
vidual binding events of target molecules to a site within the lumen of a nanometer-
scaled pore can be electrically “visualized” through discrete changes in ion
Search WWH ::
Custom Search