Dataset Information

Comparison of photopolymerizable thiol-ene PEG and acrylate-based PEG hydrogels for cartilage development.

ABSTRACT: When designing hydrogels for tissue regeneration, differences in polymerization mechanism and network structure have the potential to impact cellular behavior. Poly(ethylene glycol) hydrogels were formed by free-radical photopolymerization of acrylates (chain-growth) or thiol-norbornenes (step-growth) to investigate the impact of hydrogel system (polymerization mechanism and network structure) on the development of engineered tissue. Bovine chondrocytes were encapsulated in hydrogels and cultured under free swelling or dynamic compressive loading. In the acrylate system immediately after encapsulation chondrocytes exhibited high levels of intracellular ROS concomitant with a reduction in hydrogel compressive modulus and higher variability in cell deformation upon compressive strain; findings that were not observed in the thiol-norbornene system. Long-term the quantity of sulfated glycosaminoglycans and total collagen was greater in the acrylate system, but the quality resembled that of hypertrophic cartilage with positive staining for aggrecan, collagens I, II, and X and collagen catabolism. The thiol-norbornene system led to hyaline-like cartilage production especially under mechanical loading with positive staining for aggrecan and collagen II and minimal staining for collagens I and X and collagen catabolism. Findings from this study confirm that the polymerization mechanism and network structure have long-term effects on the quality of engineered cartilage, especially under mechanical loading.

SUBMITTER: Roberts JJ

PROVIDER: S-EPMC4503261 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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Comparison of photopolymerizable thiol-ene PEG and acrylate-based PEG hydrogels for cartilage development.

Roberts Justine J JJ Bryant Stephanie J SJ

Biomaterials 20130920 38

When designing hydrogels for tissue regeneration, differences in polymerization mechanism and network structure have the potential to impact cellular behavior. Poly(ethylene glycol) hydrogels were formed by free-radical photopolymerization of acrylates (chain-growth) or thiol-norbornenes (step-growth) to investigate the impact of hydrogel system (polymerization mechanism and network structure) on the development of engineered tissue. Bovine chondrocytes were encapsulated in hydrogels and culture ...[more]

PMID: 24060418

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Project description:The mechanical properties of synthetic hydrogels traditionally have been controlled with the concentration, molecular weight, or stoichiometry of the macromolecular building blocks used for hydrogel formation. Recently, the rate of formation has been recognized as an important and effective handle for controlling the mechanical properties of these water-swollen polymer networks, owing to differences in network heterogeneity (e.g., defects) that arise based on the rate of gelation. Building upon this, in this work, we investigate a rate-based approach for controlling mechanical properties of hydrogels both initially and temporally with light. Specifically, synthetic hydrogels are formed with visible light-initiated thiol-ene 'click' chemistry (PEG-8-norbornene, dithiol linker, LAP photoinitiator with LED lamp centered at 455 nm), using irradiation conditions to control the rate of formation and the mechanical properties of the resulting hydrogels. Further, defects within these hydrogels were subsequently exploited for temporal modulation of mechanical properties with a secondary cure using low doses of long wavelength UV light (365 nm). The elasticity of the hydrogel, as measured with Young's and shear moduli, was observed to increase with increasing light intensity and concentration of photoinitiator used for hydrogel formation. In situ measurements of end group conversion during hydrogel formation with magic angle spinning (MAS 1H NMR) correlated with these mechanical properties measurements, suggesting that both dangling end groups and looping contribute to the observed mechanical properties. Dangling end groups provide reactive handles for temporal stiffening of hydrogels with a secondary UV-initiated thiol-ene polymerization, where an increase in Young's modulus by a factor of ~ 2.5x was observed. These studies demonstrate how the rate of photopolymerization can be tuned with irradiation wavelength, intensity, and time to control the properties of synthetic hydrogels, which may prove useful in a variety of applications from coatings to biomaterials for controlled cell culture and regenerative medicine.

Dataset Information

Comparison of photopolymerizable thiol-ene PEG and acrylate-based PEG hydrogels for cartilage development.

Publications

Comparison of photopolymerizable thiol-ene PEG and acrylate-based PEG hydrogels for cartilage development.

Similar Datasets

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