FIG. 4.
Click-functionalized macromolecular precursors undergo the Cu-free [3+2] Huisgen cycloaddition to form a 3D ideal network hydrogel through a step-growth polymerization mechanism. Here, two orthogonal click chemistries are used: one for hydrogel formation and another for biochemical patterning within the preformed material. The modular aspect of these reactions allows for independent control of the network structure and chemistry, and facile incorporation of biological molecules. Image reproduced from DeForest et al.70 Color images available online at www.liebertpub.com/teb