Biomedical Engineering Reference
In-Depth Information
H
2
O
Hydrophilic
Segment
T
Hydrophobic
Segment
Figure 7.5.
Schematic image of
in situ
gel formation via hydrophobic
interactions.
situ
-forming hydrogel scaffolds for autologous bone and articu-
lar cartilage tissue engineering using mesenchymal stem cells and
chondrocytes.
54
,
56
-
58
7.3.3
Other Polymers as
in situ
-Forming
Hydrogel Scaffolds
One example is poly(organophosphazenes) as
in situ
-forming
hydrogel scaffold. Poly(organophosphazenes) grafted with mPEG as
hydrophilic and amino acid esters as hydrophobic segments were
reportedasanewclassofbiodegradableand
in situ
-forminghydro-
gels in 1999.
59
The polymers' showing their use as hepatocytes
carriers holds promise to maintain good viability and liver-specific
activity.
60
Poly(N-isopropylacrylamide) (PNiPAAm) and its copolymers
havealsobeenpopularinanattempttoyieldhydrogelswiththermal
responsivenessandimprovedproperties.PNiPAAmexhibitsasharp
phase transition in an aqueous solution at body temperature.
61
,
62
Recent developments on PNiPAAm-based hydrogels include their
use for cell encapsulation and delivery.
63
PNiPAAm as an
in situ
-
forming hydrogel scaffold in combination with chondrogenic dif-
ferentiation factors and growth factors (transforming growth factor
β
3) holds promise for orthopedic tissue engineering applications.
64
However, the limited issue of PNiPAAm that has to be addressed
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