2.1 Cross-Linking of Natural Polymers Using Imine-Based
Linkages
Natural polymers such as chitosan, gelatin, fibrinogen, and their derivatives, which
are rich in amine groups, have been widely used to fabricate dynamic polymeric
networks using imine chemistry. Likewise, aldehyde groups can be introduced into
natural polymers such as dextran and pullulan through the oxidation of their pendant
hydroxyl groups. As one of the earliest examples, Wei and coworkers reported
several self-healing hydrogels cross-linked through imine linkages [12–14]. In
most of their work, chitosan was reacted with a poly(ethylene glycol) bearing
benzaldehyde groups at chain ends (DF-PEG) to yield gels with tunable physical
properties for different applications. Using this chemistry, a chitosan-based dynamic
hydrogel with good self-healing ability and quick recovery was synthesized for
encapsulation and controlled release of small bioactive molecules such as lysozyme
Fig. 1 Stimuli-responsive nature of dynamic covalent bonds that are commonly used to obtain selfhealing hydrogels
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R. Kilic and A. Sanyal
Linkages
Natural polymers such as chitosan, gelatin, fibrinogen, and their derivatives, which
are rich in amine groups, have been widely used to fabricate dynamic polymeric
networks using imine chemistry. Likewise, aldehyde groups can be introduced into
natural polymers such as dextran and pullulan through the oxidation of their pendant
hydroxyl groups. As one of the earliest examples, Wei and coworkers reported
several self-healing hydrogels cross-linked through imine linkages [12–14]. In
most of their work, chitosan was reacted with a poly(ethylene glycol) bearing
benzaldehyde groups at chain ends (DF-PEG) to yield gels with tunable physical
properties for different applications. Using this chemistry, a chitosan-based dynamic
hydrogel with good self-healing ability and quick recovery was synthesized for
encapsulation and controlled release of small bioactive molecules such as lysozyme
Fig. 1 Stimuli-responsive nature of dynamic covalent bonds that are commonly used to obtain selfhealing hydrogels
246
R. Kilic and A. Sanyal