Chitosan-Based Gels for the Drug Delivery System - Chitosan Based Hydrogels: Functions and Applications - page 284

(a) 28 Diclofenac sodium

26

24

22

20

18

16

14

12

Control
+
-

10

8

6

0 5 10 15 20 25

Time (h)

(b)

Propranolol

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20

15

10

Control
+
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5

0

0 5 10 15 20

Time (h)

Figure 6.16
Drug delivery of chitosan/PVA gels with different charges drugs. Control : pure chitosan/PVA hydrogel; +:
hydrogel with positive nanoparticles; −: hydrogel with negative nanoparticles. (From Tang, Y. F. et al. 2010.
Polym Bull 64: 791-804. With permission.)

was achieved successfully. Apart from this, a special structure, cyclodextrin, is of interest
for introducing hydrophobic domains while still maintaining the bulk hydrophilicity and
swelling state of the hydrogel [10]. Cyclodextrin, as mentioned in Section 6.2.2.3, possesses
a hydrophilic exterior and a hydrophobic interior cavity that is capable of binding hydro-
phobic molecules, and therefore provides ideal binding sites for these kinds of drugs. By
grafting cyclodextrin onto chitosan, a chitosan-g-cyclodextrin is prepared [40,116]. A con-
trolled release study suggested that p -nitrophenol entrapped with a chitosan-g-cyclodextrin