Biomedical Engineering Reference
In-Depth Information
subsequent polymerization within the defect site using a light source such
as UV radiation. Figure 6 demonstrates such an arthroscopic immobiliza-
tion of PEGDA hydrogel in a human cadaveric knee where the defect was
made on the medial tibial condyle. Here, liquid bi-functional PEGDA solu-
tion along with the photoinitiator (Irgacure D2959) is injected into the defect
site using a syringe and an optical fiber with a low-intensity UV light is used
for polymerizing the reactants. The advantage of photogelation over other
crosslinking techniques is the spatial and temporal control, as well as the fast
curing rate obtained under physiological conditions at room temperature,
which makes photogelation especially attractive for tissue engineering [101].
Photopolymerization has been used to encapsulate various cell types such as
pancreatic islets [269], smooth muscle cells [270], osteoblasts [271], chondro-
cytes [24], MSCs [22], and ES (Hwang et al. 2005, personal communication).
Fig. 6 a Photograph showing the in situ photopolymerization of a hydrogel in a defect site
and; b defects in the femoropatellar groove of a bovine knee are filled with the hydrogel
after 5 mins of photopolymerization
Fig. 7 Scheme for creating bilayer hydrogels for stratified tissues using photopolymerization
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