Biomedical Engineering Reference
In-Depth Information
grafting to chitosan using different methods and their inclusion ability, sorption, and con-
trolled release properties have been studied extensively [215].
2.10.1 grafting of CD onto Chitosan by using eDC
EDC reacts with the carboxyl group of carboxymethylated β-CD to form an active ester
intermediate. The intermediate can react with a primary amine of chitosan to form an
amide linkage. Furusaki et al. [216] described the preparation of a β-CD-grafted chitosan
by coupling carboxymethylated β-CD and a partially deacetylated chitin oligomer using
water-soluble EDC. An insoluble cross-linked chitosan bearing CD moieties was prepared
by a one-step procedure with N-succinylated chitosan and mono-6-amino-mono-6-deoxy-
β-cyclodextrin in the presence of water-soluble EDC under homogeneous conditions
(Figure 2.25) [217]. It was considered that the product obtained in this study was cross-
linked between the carboxyl groups and amino groups on the succinyl chitosan skeleton.
DS by the CD moiety achieved 0.27 with the addition of
N
,
N
-dimethylformamide (DMF)
to the reaction solution.
OH
OH
O
O
O
O
HO
HO
0.96
NHAc
NH
2
0.04
COON
OH OH
NaCNBH
3
,
AcOH/H
2
O/MeOH,
rt, 1 day
HO
O
O
AcHN
CHO
HO
O
O
O
OH
OH
OH
O
O
O
O
O
O
O
Chitosan
HO
HO
HO
NHCOCH
3
NHCO(CH
2
)
2
COOH
NHCO(CH
2
)
2
COOH
NH
2
EDC.
(Mono-6-amino-mono-6-deoxy-CD)
OH
OH
OH
O
O
O
O
O
O
O
HO
HO
HO
NH
NHCOCH
3
NH
NHCO(CH
2
)
2
CO
NHCO(CH
2
)
2
CO
HO
O
OH
Figure 2.25
Preparation of chitosan-graft-β-CD from
N
-succinyl chitosan. (From Aoki, N., Nishikawa, M., and Hattori, K.
2003.
Carbohydr Polym
52: 219-223. With permission.)
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