Biomedical Engineering Reference
In-Depth Information
6
Chitosan- Based Gels for the Drug Delivery System
Jin Zhao
CoNTENTS
6.1
Introduction ........................................................................................................................ 264
6.2
Chitosan and Chitosan Derivatives for DDS ................................................................. 266
6.2.1
Functional Groups-Modified Chitosan .............................................................. 267
6.2.1.1
N-Alkylated Chitosan ............................................................................ 267
6.2.1.2
Thiolated Chitosan.................................................................................. 267
6.2.2
Polymer-Grafted Chitosan ................................................................................... 269
6.2.2.1
Chitosan-g-Pluronic................................................................................ 269
6.2.2.2
Chitosan-g-PEG ....................................................................................... 270
6.2.2.3
Chitosan-g-Cyclodextrin........................................................................ 270
6.2.3
Graft Copolymer of Chitosan............................................................................... 271
6.3
Chitosan-Based Gel Formation Principles ..................................................................... 273
6.3.1
Physical Cross-Linked Hydrogels ....................................................................... 274
6.3.1.1
Charge Interactions................................................................................. 274
6.3.1.2
Hydrophobic Interactions ...................................................................... 275
6.3.1.3
Hydrogen Bonding ................................................................................. 276
6.3.2
Chemical Cross-Linked Hydrogel....................................................................... 276
6.3.2.1
Schiff Base Formation............................................................................. 277
6.3.2.2
Michael Addition .................................................................................... 277
6.3.2.3
Enzyme-Catalyzed Reaction ................................................................. 278
6.3.2.4
Polymerization......................................................................................... 278
6.4
Geometries of Chitosan Gels and Their Preparation Methods................................... 280
6.4.1
Scaffolds .................................................................................................................. 280
6.4.2
Particles and Spheres............................................................................................. 280
6.4.2.1
Emulsification .......................................................................................... 281
6.4.2.2
Coacervation ............................................................................................ 282
6.4.2.3
Aqueous Cross-Linking Gelation Method .......................................... 283
6.4.2.4
Spray Drying Method............................................................................. 283
6.4.2.5
Sieving Method ....................................................................................... 283
6.4.3
Membranes and Films........................................................................................... 284
6.4.4
Liquids..................................................................................................................... 285
6.5
Drug Loading ..................................................................................................................... 285
6.5.1
Physical Entrapment.............................................................................................. 285
6.5.2
Covalent Incorporation ......................................................................................... 286
6.5.3
Composite Systems ................................................................................................ 286
6.5.4
Hydrophobic Drug Loading into Hydrogels ..................................................... 288
6.6
Drug Release....................................................................................................................... 290
6.6.1
Drug Release Mechanisms ................................................................................... 290
263
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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