Peptide-based
supramolecular hydrogels have attracted great attention
due to their good biocompatibility and biodegradability and have become
promising candidates for biomedical applications. The bottom-up self-assembly
endows the peptides with a highly ordered secondary structure, which
has proven to be an effective strategy to improve the mechanical properties
of hydrogels through strong physical interactions and energy dissipation.
Inspired by the excellent mechanical properties of spider-silk, which
can be attributed to the rich β-sheet crystal formation by the
hydrophobic peptide fragment, a hydrophobic peptide (HP) that can
form a β-sheet assembly was designed and introduced into a poly(vinyl
alcohol) (PVA) scaffold to improve mechanical properties of hydrogels
by the cooperative intermolecular physical interactions. Compared
with hydrogels without peptide grafting (P-HP0), the strong β-sheet
self-assembly domain endows the hybrid hydrogels (P-HP20, P-HP29,
and P-HP37) with high strength and toughness. The fracture tensile
strength increased from 0.3 to 2.1 MPa (7 times), the toughness increased
from 0.4 to 21.6 MJ m–3 (54 times), and the compressive
strength increased from 0.33 to 10.43 MPa (31 times) at 75% strain.
Moreover, the hybrid hydrogels are enzymatically degradable due to
the dominant contribution of the β-sheet assembly for network
cross-linking. Combining the good biocompatibility and sustained drug
release of the constructed hydrogels, this hydrophobic β-sheet
peptide represents a promising candidate for the rational design of
hydrogels for biomedical applications.
In this work, three dyes based on fused carbazole–coumarin–ketone structures were designed and synthesized. These dyes were named CCK–Me, CCK–Ph, and CCK–Tol in accordance with their different substituents. Their excellent...
Short peptides that can respond to external stimuli have
been considered
as the preferred building blocks to construct hydrogels for biomedical
applications. In particular, photoresponsive peptides that are capable
of triggering the formation of hydrogels upon light irradiation allow
the properties of hydrogels to be changed remotely by precise and
localized actuation. Here, we used the photochemical reaction of the
2-nitrobenzyl ester group (NB) to develop a facile and versatile strategy
for constructing photoactivated peptide hydrogels. The peptides with
high aggregation propensity were designed as hydrogelators, which
were photocaged by a positively charged dipeptide (KK) to provide
strong charge repulsion and prevent self-assembly in water. Light
irradiation led to the removal of KK and triggered the self-assembly
of peptides and the formation of hydrogel. Light stimulation endows
spatial and temporal control, which enables the formation of hydrogel
with precisely tunable structure and mechanical properties. Cell culture
and behavior study indicated that the optimized photoactivated hydrogel
was suitable for 2D and 3D cell culture, and its photocontrollable
mechanical strength could regulate the spreading of stem cells on
its surface. Therefore, our strategy provides an alternative way to
construct photoactivated peptide hydrogels with wide applications
in biomedical areas.
Regulating
cell–surface interactions plays a key role for
biomaterials and their applications in cell-based therapies. In this
paper, we demonstrated a dual-responsive hydrogel platform to achieve
phototriggered protein immobilization and reduction-induced protein
release. By o-nitrobenzyl photochemistry, including
sequential aldehyde generation upon light irradiation and imine ligation
with amine compounds, adhesive proteins can be effectively immobilized
on the hydrogel with spatial and quantitative control, thus mediating
cell adhesion in designed areas. By reduction chemistry of the disulfide
bond, the patterned proteins can be released from the hydrogel, thus
detaching cells in a noninvasive manner. Finally, the dynamic adsorption–dissociation
of proteins enables the hydrogel to be tactfully used for cell sheet
harvesting in an enzyme-free mode with light-defined shapes. This
work not only provides an efficient strategy for recovery of cells
and cell sheets but also provides insights into cell–material
interactions mediated by proteins.
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