Microfluidic Tools for DNA Analysis - DNA Nanotechnology: From Structure to Function - page 125

Fig. 7.11 Micro-wells used in DNA sequencing. ( a ) 454 technology (Reprinted with permission
from Macmillan Publishers Ltd: Ref. [ 51 ], copyright 2005); ( b ) repeated loading, removing, and
sealing (Reprinted with permission from Macmillan Publishers Ltd: Ref. [ 52 ], copyright 2011);
( c ) single-molecule sequencing from single polymerase (Reprinted from Ref. [ 53 ] with permission
from AAAS)

7.2.3 Sequencing

Methods described above are sometimes restricted by the throughput, because they
normally could detect only single target. In order to detect multiple targets in
a single device, without resorting to complex instrumentation, researchers could
perform reactions in individual micro-wells. The typical example utilizing this
strategy is DNA sequencing [ 51 - 53 ]. The amplification of nucleic acid can be
performed in a tube, and the amplicons were transferred into the micro-wells in
a chip (Fig. 7.11 a). Xie and coworkers detailed a sequential fluidic injection and
repeated the sealing/unsealing process (Fig. 7.11 b). They triggered the fluorophore
generation in the sealed state and unsealed and washed the array before the cycle
is repeated. Due to the random segmentation and the huge numbers of micro-wells,
the sequence library is equivalent to the whole genome. Besides the above clone-
based methods, single-molecule DNA sequencing was also achieved in specially
fabricated nanostructures [ 54 ] inside which the single polymerase was immobilized
(Fig. 7.11 c) [ 53 ].