Biomedical Engineering Reference
In-Depth Information
TAble 2.4
Approaches for PEGylating Chitosan: Grafting of a Preformed Polymer onto Chitosan
Chitosan (RNH
2
)
Reactants and Reaction Condition
Chitosan-g-PEG
MPEGCOOH, WSC, BtOH
6-
O
-triphenyl methylation
MPEGCOOH, WSC, BtOH
O
MPEG
NHR
O
O
O
O
MPEGO
N
OH
MPEGO
H
NHR
O
O
O
O
O
O
O
HO
O
R
′
R
′
PEGO
N
H
PEGO
NHR
H
H
NH
2
PEG + R′(NCO)
2
MPEGCHO, NaBH
3
CN
MPEG
NHR
MPEG-CH(OEt)
2
(1)H
+
, (2)NaBH
3
CN
MPEG
NHR
n
Note:
The chitosan-g-PEG graft copolymer is often referred to as “PEGylated chitosan.” MPEG: methoxy-terminated
PEG, PNP:
p
-nitrophenyl, WSC: water-soluble carbodiimide, and BtOH: hydroxybenzotriazole.
1) MPEGI
Chitosan-3-O, 6-O-TMPEG
2) NH
2
NH
2
.H
2
O
Chitosan
2-NH
2
, 3-OH, 6-OH
1) MPEGT
Chitosan-3-O, 6-O-TMPEG
2) NH
2
NH
2
.H
2
O
Phthaloylation
N
Chitosan
CI
CI
3-OH,6-OH
N
N
1) MPEGI
Chitosan
Chitosan-6-O-TMPEG
CI
2) NH
2
NH
2
.H
2
O
6-OT, 3-OH
1) Phthaloylation
2) 6-O-Triphenylmethylation
3) 3-O-Acetylation
4) CI
2
CHCOOH
MPEGAm
TEMPO
BAIB
Chitosan-CHO
Chitosan-6-NH-MPEG
1) MPEGI
Chitosan-6-O-TMPEG
2) NH
2
NH
2
.H
2
O
Chitosan
6-OH
1) MPEGT
Chitosan-6-O-TMPEG
2) NH
2
NH
2
.H
2
O
Figure 2.37
Approaches for regioselective PEGylating chitosan: grafting of a preformed polymer onto chitosan. The chito-
san-g-PEG graft copolymer is often referred to as “PEGylated chitosan.” In chitosan, only free groups are
denoted; TEMPO radical: 2,2,6,6-tetramethylpiperidin-1-oxyl; BAIB: [bis(acetoxy) iodo]benzene; MPEGAm:
MPEGamine; MPEGI: MPEG iodide; MPEGT: MPEG dichlortriazine.
Search WWH ::
Custom Search