Molecular Gels for Tissue Engineering - Soft Fibrillar Materials: Fabrication and Applications - page 149

(A) (B)

(a) (b)

3 ′

C

C
C
C
C

5

′

C

C

C

C

C

C

C

C C

C

5 ′

3 ′

(c)

6.0kV 8.5mm x5.00k 8/1/2008 10.09 10.0 μ m

(C)

(a) (b) (c)

0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0

Adding base

0 0 0 0 0 0
Time/min

60 70 80 90

CGGATCCA-3 . (B) FE-SEM image of the
dried DNA hydrogel showing its fine lamel-
lar structure (C) Gel transition triggered by
pH changes (a) 7 nm water-soluble citrate-
modified 13 nm gold nanoparticles (GNPs)
as tracer agent were trapped in DNA hydro-
gel with a layer of MES buffer at pH 5.0. (b)
GNPS were released from the DNA hydrogel
and form a uniformly colored solution upon
the addition of NaOH, which increased the
pH value of the buffer to 8.0. (c) Time trace
of the absorption at 520 nm for the upper
part of the solution before and after addition
of NaOH. (Figure adapted from Ref. [85]
(Copyright 2009) John Wiley & Sons, Inc.)

Figure 4.10 (A) Structure of the pH-
responsive DNA gel. (a) A Y-shaped DNA
nanostructure with three free interlock-
ing domains, also known as the Y unit .
(b) Enlarged image of the circled region
demonstrating the formation of inter-Y-unit
I motif. (c) DNA hydrogel made from the
three-dimensional assemble of Y units. The
sequences of the 3 DNA strands used in
the Y units, coded with different colors ac-
cording to different domains, are: (a) 5 -
CCCCTAACCCCTGGATCCGCATGACATTCG
CCGTAAG-3 ;(b)5 -CCCCTAACCCCCTTACG-
GCGAATGACCGAATCAGCCT-3'; and (c)
5 -CCCCTAACCCCAGGCTGATTCGGTTCATG