Page 514 - Book Hosokawa Nanoparticle Technology Handbook

APPLICATIONS 17 ADDRESSING OF NANOPARTICLES BY USING DNA MOLECULES

Adenine (A) and Thymine (T)
Specific hydrogen bonds are formed between
Guanine (G) and Cytosine (C)

5′-terminus
O -
O P O - H
O H N N H O CH 3′-terminus
C C C 1 H OH
CH 2 C C
O C H
N C A N H N T
Adenine C C N
N O
O H H O Thymine CH 2
Phospho- -
O P O O
diester bond H P
O O H N O - O
H N H H
CH 2 C C C C C O
O
N C G N H N C C H
N C C N
O H Guanine N H O O CH 2
O P O - Cytosine O
H
O O - P O

3′-terminus
5’-terminus
Figure 17.2
Sequence-specific hybridization of DNA molecules.

of particle boundary because dimensions of nanopar- meniscus movement. DNA in air is stretched because
ticles are extremely small. The possibility was pointed DNA molecules behave to raise length in water phase
out that addressing of nanoparticles creates new opti- due to high hydrophilic property. Yokota et al. [1]
cal and/or electrical devices. Application of DNA stretched DNA molecules using this method followed
hybridization is expected to permit spontaneous by restriction digestion, and succeeded in determina-
addressing of nanoparticles. tion of the restriction map by observing DNA
molecules treated with the restriction enzyme. Flow
1. Stretching of DNA molecules in solution also stretches DNA molecules of which
one terminal is anchored on the substrate surface
Addressing pattern of nanoparticles can be (Fig. 17.4b).
designed by choosing sequences of DNA and Fig. 17.4c illustrates a method based on electric
oligonucleotides as shown in Fig. 17.3. For this pur- field application. Since DNA is negatively charged,
pose, DNA molecules should be artificially DC electric field stretches DNA molecules of
stretched; otherwise DNA shrinks because entropy which one terminal is anchored on the substrate
of DNA molecules increases by bringing DNA ter- surface. However, DC current promotes electrode
minals close together. reaction especially under high ionic condition, and
Several stretching methods have already been pro- therefore stretching by AC electric field has also
posed as shown in Fig. 17.4. Fig. 17.4a illustrates the been developed. The force to stretch DNA by the
molecular combing method, which is based on a AC electric field is lower than that by the DC

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