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. Author manuscript; available in PMC: 2022 Dec 2.
Published in final edited form as: Prog Polym Sci. 2019 Jul 12;98:101147. doi: 10.1016/j.progpolymsci.2019.101147

Fig. 6.

Fig. 6.

Reversible modulation of biochemical cues. (A) photoreversible patterning of proteins: (a) development of enzymatically cleavable PEG-based hydrogel via SPAAC in the presence of NPPOC-photocaged alkoxyamine functionalities; (b) reaction of protein with CHO-oNB-NHS enabled photo-patternability via on-demand photocleavable oNB moieties; (c) schematic representation of dual-protein patterning; (d) hMSC differentiation on vitronectin-patterned hydrogels showing positive osteocalcein staining on the patterned area only; (e and f) after photo-removal of vitronectin, the confinement of osteocalein staining to the patterned islands. (B) Reversible manipulation of biochemical environments via ligand exchange using allyl sulfide functionalities: (a) PEG hydrogel formation via Cu catalyzed click reaction; (b) cage pattern formed by irradiation with 720 nm two-photon light; (c) bioactive ligand exchange mechanism; (d) hMSC stained with tracker red encapsulated on green rectangular fluorescent RGD-modified hydrogel, in which the fluorescent RGD in the middle part was replaced with non-fluorescent RGD. A: [181], Copyright 2015. Reproduced with permission from Nature publishing group. B: [186], Copyright 2014. Reproduced with permission from John Wiley and Sons Inc.