Figure 2.

Interpenetrating networks can be independently degraded in a stepwise manner. (a) IPNs are first treated with 4S9 to remove the thiol-ene network, and then fully degraded by treatment with 2A9 to yield fully soluble macromolecular building blocks. (b) Peptide recognition sequences for 2A9 and 4S9 included in hydrogel crosslinkers and degradation reaction post sortase treatment. (c) Schematic depicting individual labeling of each network with distinct fluorophores, and the monomeric component released upon each sortase treatment, tracked by increases in supernatant fluorescence. (d) Fluorophore release studies. At time = 0 min, 18 mM GGG, the respective sortase, and 1 mM CaCl₂ were added to the solution the IPN hydrogels were in. Hydrogel degradation was tracked by monitoring supernatant fluorescence, with values normalized to those obtained from 100% degraded gels 12 hours post reaction. N = 5 gels per treatment. (e) AFM measurements of IPN gels pre- and post-4S9 treatment. IPN pre 4S9 treatment: 4648 ± 750 Pa; IPN post 4S9 treatment: 908 ± 550 Pa. Unpaired t-test, **p = 0.0024.