(A) Schematic depicting hydrogel formation from
azide-functionalized PEG and DIFO-functionalized peptides crosslinked via SPAAC.
(B) The SPAAC-crosslinked materials gel within minutes and
complete crosslinking in approximately 1 hour. (C) Fibroblast cells
encapsulated within the gels remain viable 24 hours post-crosslinking, as
observed by live/dead assay. Green: live, Red: dead. A-C reproduced with
permission. Copyright 2009, Nature Publishing Group.[25]
(D) Schematic depicting bio-orthogonal crosslinking of engineered
elastin-like proteins via SPAAC or Staudinger ligation. (E) The
SPAAC crosslinked samples complete crosslinking within minutes, while the
Staudinger samples crosslink on the order of 1 hour. Both (F) human
MSCs and (G) murine neural progenitor cells retain their
appropriate phenotypes when cultured within the SPAAC-crosslinked ELP hydrogels,
as observed by immunocytochemistry. Blue: nuclei (DAPI), Red: F-actin
(phalloidin), Green: Nestin. D-G reproduced with permission.[35] Copyright 2016, John Wiley
and Sons.