2 research outputs found
pH-Ionizable <i>in Situ</i> Gelling Poly(oligo ethylene glycol methacrylate)-Based Hydrogels: The Role of Internal Network Structures in Controlling Macroscopic Properties
The incorporation
of charge within <i>in situ</i> covalently
gelling poly(oligo ethylene glycol methacrylate) (POEGMA) precursor
polymers enables the fabrication of hydrogels that exhibit both pH-responsive
swelling and tunable network structures due to multimechanism cross-linking
interactions. The gelation times, swelling responses, degradation
kinetics, and mechanics of the resulting gels were strongly influenced
by both the type of charge(s) incorporated and pH, with both amphoteric
gels and anionic gels showing clear evidence of dual network formation.
While the amphoteric dual network was anticipated due to charge interactions,
the mechanism of the 5-fold enhancement in mechanical properties observed
with the anionic gel relative to the neutral gel was revealed by isothermal
titration calorimetry and small-angle neutron scattering to relate
to the formation of a zippered chain structure based on dipole–dipole
interactions. Consequently, rational design of the chemistry and the
microscopic network structure results in controllable macroscopic
properties amenable to potential biomedical applications
Injectable and Degradable Poly(Oligoethylene glycol methacrylate) Hydrogels with Tunable Charge Densities as Adhesive Peptide-Free Cell Scaffolds
Injectable,
dual-responsive, and degradable poly(oligo ethylene
glycol methacrylate) (POEGMA) hydrogels are demonstrated to offer
potential for cell delivery. Charged groups were incorporated into
hydrazide and aldehyde-functionalized thermoresponsive POEGMA gel
precursor polymers via the copolymerization of N,<i>N</i>′-dimethylaminoethyl methacrylate (DMAEMA) or acrylic acid
(AA) to create dual-temperature/pH-responsive in situ gelling hydrogels
that can be injected via narrow gauge needles. The incorporation of
charge significantly broadens the swelling, degradation, and rheological
profiles achievable with injectable POEGMA hydrogels without significantly
increasing nonspecific protein adsorption or chronic inflammatory
responses following in vivo subcutaneous injection. However, significantly
different cell responses are observed upon charge incorporation, with
charged gels significantly improving 3T3 mouse fibroblast cell adhesion
in 2D and successfully delivering viable and proliferating ARPE-19
human retinal epithelial cells via an “all-synthetic”
matrix that does not require the incorporation of cell-adhesive peptides