Environment–Stimuli Response of Chitosan-Based Hydrogels - Chitosan Based Hydrogels: Functions and Applications - page 253

5 . 6 S u m m a r y
Stimuli-responsive chitosan-based hydrogels have been developed recently. Most
chitosan-based hydrogels have dual- or multi-sensitivity. These responsive properties
endow chitosan-based hydrogels with a wide range of potential biomedical applications,
such as drug delivery systems and tissue engineering.
For tissue engineering, thermosensitive chitosan-based hydrogels could be used as the
injectable hydrogels for cartilage or bone tissue. Artificial muscles could be prepared using
electrosensitive chitosan-based hydrogels. However, low responsive rate and low mechan-
ical strength limit their application. With an understanding of the stimuli-responsive
mechanism, responsive rate controllable chitosan-based hydrogels should be designed by
changing the structure and composition of the chitosan network or by changing the size
of hydrogels. For example, the thermosensitive capacity could modulate the hydrophilic-
hydrophobic balance. Chemical cross-linking is an effective method for improving the
mechanical properties. The choice of the cross-linking agent is very critical due to toxicity
of some cross-linking agents. Moreover, the responsive capacity may decrease or even dis-
appear due to the cross-linking effect. Therefore, it is a great challenge to develop a novel
chitosan-based hydrogel with rapid responsive capacity and excellent mechanical strength.
With respect to drug delivery, chitosan-based hydrogels that can respond to their environ-
ments will provide new and improved methods of delivering molecules for therapeutic
applications. One can select the chitosan-based hydrogels according to the type and prop-
erties of drug. In order to adapt the complexity of life system, the chitosan-based hydrogels
should have gradient stimuli responsiveness.
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