Civil Engineering Reference
In-Depth Information
properties can be tailored by varying the above parameters, conforming to the diverse
mechanical properties of native blood vessels. h is study demonstrated a mechanistic
understanding of fundamental information of the molecular interactions for utiliz-
ing CNCs in O-CNCs-i brin nanocomposites, which can further help to improve the
mechanical properties of CNCs-based nanocomposites for small-diameter replacement
vascular grat applications [234]. Jia
et al.
investigated the potential use of CNCs in the
electrospun scaf olds for vascular tissue engineering applications. h e cellulose ace-
tate and cellulose scaf olds had CNCs prepared by electrospinning and deacetylation.
h e produced scaf olds showed higher cell viability with vascular smooth muscle cells
(VSMC) as compared to those with only CNCs and no i ller and increases with CNCs
content [235] .
15.9.3
Hydrogels
Kohnke
et al.
prepared CNCs/xylan-based hydrogels by using the freeze-casting pro-
cess and the crosslinking ef ect was induced in hydrogels by -OH groups of CNCs
and -CHO groups (introduction of dialdehyde groups in xylan by periodate oxidation)
of xylan. h is proposed crosslinking interaction was coni rmed by cross-polarization
magic angle spinning (CP/MAS) and nuclear magnetic resonance (NMR) spectros-
copy. Morphological study of hydrogels was characterized by scanning electron micros-
copy (SEM) and mechanical property was tested in terms of compressive strength. h e
compressive strength of dry freeze-cast foams decreased with increment of degree of
oxidation of xylan, probably due to the changes in rigidity of polymer chain of xylan
upon oxidation, which opens the xylan pyranos ring [236]. h e freeze-cast xylan-CNCs
foams are shown in Figure 15.16.
Ya n g
et al.
prepared rigid "rod-like" CNCs and aldehyde-functionalized CNCs
(CHO-CNCs) reinforced carboxymethylcellulose (CMC) and dextran-based inject-
able hydrogels. All CNCs-reinforced hydrogels maintained their original shape when
immersed in purii ed water or 10 mM PBS solution for more than 60 days. h e CHO-
CNCs-reinforced hydrogels were more elastic, dimensionally stable, and capable of
facilitating higher loading of nanocrystals compared to unmodii ed CNCs, without
sacrii cing mechanical performance. For hydrogels and their individual components,
Figure 15.16
(a) Freeze-cast xylan foams containing (let ) reference xylan and (right) oxidized xylan,
immersed in water. (b) Freeze-cast xylan-CNCs foams containing (let ) reference xylan and (right)
oxidized xylan, immersed in water. (c) A xylan-CNCs composite hydrogel containing about 96% (w/w)
water [236] .
