Biomedical Engineering Reference
In-Depth Information
interesting biomaterial to create various tissue analogs, including
skin, cartilage, bone, liver, andnerve.
23.3 Chitosan Sponge Scaffolds
The chitosan scaffold for tissue engineering has to have a three-
dimensional, open pore structure, and its pore size must be able to
adjust. Control of scaffold pore size is critical for controlling cellu-
larcolonizationratesandorganizationwithinanengineeredtissue.
2
Poremorphologycanalsobeexpectedtosignificantlyaffectscaffold
degradation kinetics and the mechanical properties of the develop-
ing tissue.
2
Porous chitosan scaffolds are easily prepared by con-
trolledfreezingandlyophilizationofchitosansolutionsandgelsthat
is a thermally induced phase separation (TIPS) process. Madihally
and Kim prepared the porous sponge scaffolds by the TIPS process
andreportedthatmeanporediametersofthescaffoldscouldbecon-
trolled by varying the freezing conditionsin the TIPS process.
2
,
6
Particularly, Lim
et al
. developed chitosan sponge scaffolds hav-
ing interconnective micropores between macropores in the scaffold
architecture by modifying the TIPS process, adding a nonsolvent for
chitosan.
27
This method isdetailed below.
23.3.1
Preparation of Chitosan Sponge Scaffolds
Chitosan sponge scaffolds were prepared by the TIPS and the modi-
fiedTIPSprocess.Chitosan(86%deacetylated)wasdissolvedin1%
aceticacidaqueoussolutiontogive2%(w/v)chitosansolution.Ten
milliliterseachof0%and20%(v/v)n-butanol/1%aceticacidsolu-
tion were dropped into 10 mL of the 2% (w/v) chitosan solution.
The n-butanol was used as a nonsolvent for chitosan in the modi-
fied TIPS process. Final volumes of n-butanol were 0% and 10% in
1% chitosan solution. Each solution was homogenized to obtain the
n-butanol/chitosanmixture.Themixedn-butanol/chitosansolution
was poured onto flat-bottomed molds, then quickly frozen at -70
◦
C
for 24 hours, and lyophilized at -70
◦
C for 24 hours. The porous chi-
tosan sponge scaffolds were washed serially with 100%, 70%, and
50% alcohol for one hour each and then washed with deionized
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