Figure 1.

Lys(alloc) amino acids alter hydrogel cross-linking. (a) Both peptide sequences contained the MMPsensitive PQ sequence (green box and font). PQ(alloc) contained a Lys(alloc) (red circle and font) spaced from the PQ sequence and C-terminus by glycine residues. Terminal amine groups could be reacted with an acrylate-PEG-SVA to generate the PEG-peptide-PEG diacrylate macromer. (b) PEG−PQ macromers can undergo photopolymerization to form acrylate-based cross-links which impart mechanical stiffness to the hydrogel. However, PEG–PQ(alloc) macromers offer an extra cross-linking site within the peptide sequence, allowing the macromers to terminate at acrylate groups or alloc groups to control the hydrogel mechanics.