Biomedical Engineering Reference
In-Depth Information
tetranucleotide probe sequences can be built based on the 4
4
com-
binations of nucleotide bases. Each spot contains multiple copies
of the particular tetramer sequence. When the array is treated with
labeled, partially digested sample DNA, hybridization may occur
at several probe sequence sites. In this case, we assume that hy-
bridization occurred in six different sites. After identifying the base
sequences of these spots, the sequences of the sample DNA can be
reconstructed by sorting the detected sequences.
Constructing arrays with longer oligonucleotides enables the
analysis of longer strands of sample DNA. With massively con-
structed DNA arrays, it is expected that simple, straightforward,
and yet reliable methods of SBH should eventually be feasible.
The SBH method was introduced at a very early stage of genome
research. Quite recently, an innovative method of SBH has been
reported which can further improve the traditional SBH based on
the shotgun principle.
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4.
Microelectronics Array for an Electrochemistry Approach
As outlined in the foregoing section, DNA arrays help biochemists
to achieve their goals by providing the opportunities of examining
every gene simultaneously. Because of its benefits such as low
expense, high throughput and miniaturization, this technology is
firmly established as one of the most powerful tools ever devel-
oped and is valuable in various research areas including clinical
research, diagnostics, toxicology studies, drug development and
personalized medicine. At the same time, there are problems for
DNA microarrays due to the architecture and intended operation,
e.g., probe saturation in the capturing spots, washing artifacts and
spot-to-spot variations. Such experimental uncertainties limit the
scope of applications to only a semi-quantitative platform. In addi-
tion, the current DNA arrays have not been designed for real-time
analysis but for before-after operations. In this regard, Hassibi et al.
have developed a real-time DNA array system by tuning fluoro-
phore labels involving fluorescence energy transfer upon hybridi-
zation.
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They reported that the sensing performance was improved
by measuring the fluorescence in the presence of excess amounts
of target DNA in the solution phase. Moreover, the hybridization
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