Fabrication and functionalization of hydrogels through "click" chemistry.

Hydrogels are crosslinked polymeric materials that play a vital role in many biomedical areas such as drug delivery, sensor technology, and tissue engineering. Increasing demand of these materials for such advanced applications has necessitated the development of hydrogels with complex chemical compositions such as incorporating small molecules and biomolecules that provide the functional attributes. This Focus Review highlights the tremendous impact of click chemistry on the design, synthesis, and functionalization of hydrogels. The high efficiency and fidelity of the click reactions have enabled rapid and modular synthesis of hydrogels with near-ideal network structures. Efficient incorporation of biomolecular building blocks, such as peptide sequences either during or after the fabrication of hydrogels, have been achieved through various click reactions. Utilization of these efficient reactions has led to the fabrication of many stimuli-responsive or 'smart' hydrogels in recent years.