Biomedical Engineering Reference
In-Depth Information
6.5.3.2
Friction Between Single Molecule of ssDNA and the Inner Pores
of Carbon Nanotubes (CNT)
Very recently, Noy et al. prepared a dense array of vertically aligned CNT and buried
it in a rigid polymer matrix. By utilizing this special sample, they successfully
detected the friction force between ssDNA and inner pores of CNT (see Fig.
6.22
[
59
]). In DI water, the friction force is 357
˙
171 pN, whereas in NaCl solutions,
the friction force decreases remarkably. This salt effect was explained as follows:
at lower ionic strength, the DNA will be more extended, which is helpful for the
hydrophobic DNA bases to interact with the CNT walls.
6.6
Summary
In the recent two decades, the single-molecule mechanics has been developed into
a remarkable field. DNA is the central molecule of life, which has been involved
in numerous processes in life. The package of DNA in the chromosome and the
duplication and expression of DNA by enzymes and many other processes are
closely related to the mechanical force.
By utilizing the single-molecule experimental methods, a number of important
problems of DNA have been solved. It is anticipated that a revolutionary single-
molecule manipulation platform will emerge, when the single-molecule mechanics
instruments are combined with other techniques, such as single-molecule fluo-
rescence, near-field optics, and confocal Raman spectroscopy. We believe that
further development of single-molecule mechanics will reveal more secrets of DNA
and life.
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