Page 623 - Book Hosokawa Nanoparticle Technology Handbook

41 SURFACE MODIFICATION OF INORGANIC NANOPARTICLES BY ORGANIC FUNCTIONAL GROUPS APPLICATIONS
3. Hybridization of inorganic nanoparticles with nanoparticles as shown in Fig. 41.4 [4]. In addition to
biomolecules this work, we are trying to hybridize inorganic
nanoparticles with enzymes and antibodies to realize
The synthesis of surface-modified inorganic nanopar- various inorganic-bimolecular complexes.
ticles enables the use of inorganic nanoparticles in In this chapter, we discussed the surface modifica-
various medical applications. The surface-modified tion of inorganic nanoparticles by organic functional
nanoparticles can bind with biomolecules as well as groups. Recent development in the preparative meth-
inorganic materials. The hybridized nanoparticles ods of inorganic nanoparticles has opened the way to
have both inorganic properties and biological speci- the application of the nanoparticles. The organic mod-
ficity. In this section, we discuss the alignment of ification of the inorganic nanoparticles is the most
metal nanoparticles on a ladder structure of deoxyri- suitable method to modify the surface properties
bonucleic acid (DNA) through hybridization between including dispersion and hybridization of the
nanoparticles and DNA single strands. Recently, Mao nanoparticles. We believe that the control of the sur-
et al. [3] succeeded to build up 10 nm rhombic face properties of the nanoparticles widens the range
lattices from 6 or 8 DNA single strands with designed of application.
sequences. They used the nature of DNA single
strands to form Holliday junction that appears during
the exchange of genetic information (Fig. 41.3). They
also succeeded in combining the lattices together to
form lattice and ladder structures of DNA. Based on (a) (b)
this method, we tried to hybridize metal nanoparticles ~19 nm
with the DNA lattice structure to align the metal
nanoparticles. We designed the sequences of DNA
single strands to prepare the similar structure as Mao
et al. [3]. The designed sequence prepares a DNA lad-
der structure that allows a guest DNA single strand to
attach on both side of the DNA ladder. We also ~31 nm
designed a DNA single strand that can hybridize with
the DNA ladder on one end and with a gold Figure 41.3
nanoparticle with the other end. By mixing gold (a) Eight DNA single strands compose the rhombic
nanoparticles, the designed single strand and the structure as proposed by Seeman et al. (b) The rhombic
DNA ladder structure, we succeeded in aligning gold structures attach together to from a planar structure.

(a) DNA single strand (b)

Au nanoparticle

DNA single strand

100 nm

Figure 41.4
(a) Designed arrangement of Au nanoparticles using the DNA ladder structure, (b) transmission electron micrograph of
prepared gold structures.

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