Chemistry Reference
In-Depth Information
d
n
1
r
3
n
g
|
7
Figure 6.19
Chemical
structures
of Adamantane-peptide
precursors
6.31
(Ada-GFFYK
n
-ss-K
(4-n)
-CONH
2
, n
ΒΌ
0-3).
may hinder the biocompatibility of the engineered tissue. One strategy to ad-
dress this is with biodegradable gels that can switch to a sol state with the
appropriate triggers.
Yang and coworkers have developed an adamantane-peptide-based self-
assembling 6.31 molecular gel (Figure 6.19) that can be switched easily to a sol
state upon complexation with methyl-b-cyclodextrin (M-b-CD).
67
The hydro-
gel is capable of gelation through disulfide bond cleavage by glutathione and
was shown to effectively foster the growth of mouse fibroblast 3T3 cells. The
hydrogel promoted cell adhesion and 3T3 cells were cultured on top of the gels
for 3 days. The cells were then collected postculture using M-b-CD.
The b-CD derivative forms a tight complex with the adamantane (Ada)
portion of the molecule and disrupts the hydrophobic interactions of
the supramolecular structure, resulting in the dramatic increase in solubility of
the gelator. The strong interaction between M-b-CD and Ada results in the
breakdown of the hydrogel structure and induces a sol transition of the gelator,
which can then facilitate the postculture recovery of 3T3 cells using centri-
fugation. These mild conditions for gelation and recovery improve the bio-
compatibility for cell encapsulation and suggest prospective applications for
postculture cell analysis. This system highlights the potential of fabricating 3D
gel scaffolds with postculture cell recovery for regenerative medicine and tissue
engineering, allowing for ex vivo engineering of viable cells in recoverable
hydrogel scaffolds for tissue transplantations. These scaffolds should be bio-
degradable to maximise their ability to foster the replacement of tissues.
68
An elegant example in the application of molecular gels for tissue engineering
(regenerative endodontics) was reported by Galler and coworkers.
69
They hy-
pothesised that the incorporation of dental pulp-derived stem cells in an
enzyme-cleavable molecular gel 6.32 (Figure 6.20), with the addition of growth
factors, would serve as a better alternative filling to the inert fillings currently
used in root canal treatment. The idea in transplanting cells within a molecular
gel (besides imparting easy delivery during dental surgery) is to support them
structurally whilst they proliferate and differentiate, regenerating the lost tissue.
With an enzyme-cleavable gel, the cells would ideally spread throughout the gel
scaffold and degrade it, remodelling it over time, mimicking in vivo systems.
Their molecular gel toolkit is based on customisable ''multidomain peptides''
3
.
