Biomedical Engineering Reference
In-Depth Information
Fig. 2.4
(
a
) Scheme of hetero-octamer aptamer system to adhere two kinds of cells. (
b
)Flow
cytometry analysis of a mixture of two kinds of cell with hetero-octamer aptamer system with
double labels.
Insets
: the FSC/SSC scattering plot representing the population of adhesive cells
and the whole cell population. (
c
) Fluorescence confocal images showing cell adherence using
hetero-octamer aptamers with DS-DS linkage compared with (
left
) and without (
right
) aptamer
addition (Reproduced from Ref. [
73
] by permission of John Wiley & Sons Ltd.)
2.3.3
DNA Assembly with FNAs for Biosensing
A sensing device basically has to contain at least two components: target recognition
and signal transduction. FNAs possess the advantages of high affinity, high speci-
ficity, broad range of analytes' wide dynamic range, and fast response time to act as
target recognition element in biosensor development. Recently, DNA nanostructures
have been explored as a new type of signal transduction elements which endow
the biosensors with new perspectives and improved performance, such as amplified
signaling, solution-like surface, multiplex detection, and single-molecule resolution.
Signal amplification is always an efficient approach to improve the detec-
tion sensitivity. Target-triggered DNA nanoassembly is one of the simple and
efficient amplification methods in biosensing. Rolling-circle amplification (RCA)
and hybridization chain reaction (HCR) are two most widely used strategies. In
both methods, by connecting the trigger of reactions with the sensing element,
they can generate many repeat units, ssDNA for RCA and dsDNA for HCR.
Therefore, a single recognition event would induce the assembly of numerous DNA
repeating units with signaling molecules for signal amplification. For example, Li's
group [
74
] applied target-allosteric DNAzyme recognition to trigger a cleavage
reaction and generate the primer for RCA reaction. Then after RCA reaction, a
colorimetric reporting mechanism was designed based on a short peptide nucleic
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