Biomedical Engineering Reference
In-Depth Information
3.5
3
2.5
2
1. 5
1
0.5
0
Bare gold
CRGD-MAP
RGD-MAP-C
Figure 7.8
The effects of the cysteine-modified oligopeptides on the proliferation of mouse embryonic
stem cells. Figure reproduced with permission from: ref. 62, © 2004 Taylor & Francis Group.
with the enzymatic dephosphorylation of 1-naphthly phosphate (1-NP) to 1-naphthol,
which was dephosphorylated by alkaline phosphatase (an ESC markers) into a 1-naphthol
on an undifferentiated mouse ESC. The peak current in the electrochemical responses of
1-NP was decreased as the number of undifferentiated ESCs increased, in contrast, the peak
current did not change with the number of differentiated mouse ESCs.
Cell Chip Composed of a Three-Dimensional Gold Nanoparticle
Encapsulated in Graphene Oxide
Recently, a three-dimensional gold nanoparticle (GNP) encapsulated in graphene oxide
(GO) was reported as a very effective material to determine the differentiation potential of
NSCs based on a spectroelectrochemical tool [63]. The GO-encapsulated GNPs, which were
fabricated as both a substrate and nanoparticle, exhibited excellent performance in enhancing
the intensities of Raman signals from undifferentiated NSCs, especially at the 1656 cm
−1
Raman peak that is assigned to C = C bonds (Figure 7.9). Both the absolute value of the
Raman peak at 1656 cm
−1
and the relative value of the Raman intensity at 1656 cm
−1
(C = C
bond) divided by the Raman intensity at 1470 cm
−1
(C-H bond) from undifferentiated NSCs
was found to be higher in undifferentiated NSCs than in differentiated NSCs (Figure 7.10).
These distinct features were found to be mainly attributed to the fact that undifferentiated
stem cells have a large number of molecules rich in C = C bonds (high degree of C = C satu-
ration), which are more adhesive to the surface of GO than other molecules. These different
adhesion properties between the molecules and the surface of GO were reported as a critical
cue that resulted in the different enhancement of Raman signals, making it possible to dis-
tinguish the undifferentiated and differentiated state of stem cells. Similarly, several stem-
cell markers such as cidofovir (Cido) and methyl 4-hyroxybenzoate (M4H), were also
reported to produce different intensities of Raman signals, which were also mainly attrib-
uted to the differences in numbers of C = C bond in their molecular structures. This prefer-
ential attraction of GO to molecules containing aromatic structures (high numbers of C = C
bonds) was also found to be effective in determining the differentiation state of NSCs using
electrical or electrochemical methods, consistent with the Raman study mentioned above
(Figure 7.11). Since the unsaturated state of the cell membrane is a general characteristic of
undifferentiated stem cells, the technique introduced here is highly promising for applying to
other types of stem cells (embryonic, mesenchymal, and hematopoietic) in order to monitor
their undifferentiated and differentiated states, which can potentially lead to advancement in
the practical use of stem cells as a new regeneration medicine.
