Figure 7.

Poly(ethylene glycol) (PEG) synthetic polymer overview. A) Types of PEG chains and example functional groups that can be conjugated to the ends of PEG chains; B) Bioactive modification of PEG for maintenance of viability and function (via cell attachment of anchorage-dependent cells) using cell adhesive peptides derived from adhesive protein domains and enzyme-degradable peptide sequences that permit cell or host-mediated remodeling of the hydrogel network. Cell adhesive peptides (orange circles with linkers) can be incorporated into the hydrogel network by post-grafting cell-adhesive moieties to a polymerized hydrogel network or by co-polymerization with acrylated- or thiolated-peptides using Michael-type reactions or acrylate-acrylate or thiol-acrylate photopolymerization. Enzyme-sensitive peptide sequences (yellow ovals) can also be conjugated to acrylated-PEG effectively inserting a degradable moiety between two PEG monoarcylate chains or thiolated enzyme-degradable peptides can be incorporated at crosslink junctions using multi-arm PEG during photopolymerization.