Abstract
The mechanical milieu of the extracellular matrix (ECM) plays a key role in modulating the cellular responses. The native ECM exhibits viscoelasticity with stress relaxation behavior. Here, we reported the preparation of degradation-mediated stress relaxing semi-interpenetrating (semi-IPN) polymeric networks of hydroxyethyl cellulose in the crosslinked gelatin-polyethylene glycol (PEG) architecture, leveraging a newly developed synthesis protocol which successively includes one-pot gelation under physiological conditions, freeze-drying and a post-curing process. Fourier transform infrared (FTIR) confirmed the formation of the semi-IPN blend mixture. A surface morphology analysis revealed an open pore porous structure with a compact skin on the surface. The hydrogel showed a high water-absorption ability (720.00 ± 32.0%) indicating the ability of retaining a hydrophilic nature even after covalent crosslinking with functionalized PEG. Detailed mechanical properties such as tensile, compressive, cyclic compression and stress relaxation tests were conducted at different intervals over 28 days of hydrolytic degradation. Overall, the collective mechanical properties of the hydrogel resembled the mechanics of cartilage tissue. The rate of stress relaxation gradually increased with an increasing swelling ratio. Hydrolytic degradation led to a marked increase in the percentage dissipation energy and stress relaxation response, indicating the degradation-dependent viscoelasticity of the hydrogel. Strikingly, the hydrogel maintained the structural stability even after degrading two-thirds of its initial mass after a month-long hydrolytic degradation. This study demonstrates that this semi-IPN G-PEG-HEC hydrogel possesses bright prospects as a potential scaffolding material in tissue engineering.
Highlights
Developing a simple synthesis protocol to design biomaterial capturing a compositional, structural, mechanical and biological resemblance to natural tissue is still a major challenge in the field of tissue engineering [1,2]
We report here on the preparation of highly porous and structurally stable semi-IPN G-polyethylene glycol (PEG)-Hydroxyethyl cellulose (HEC) hydrogel using poly(ethylene glycol)diglycidyl ether (PEGDGE) as a crosslinking agent following gelation, freeze-drying and the post-curing process
Grafting predominates the cross-linking during this reaction probably due to the low amount of lysine groups present in the gelatin chains which resulted in insufficient cross-linking and quickly soluble products
Summary
Developing a simple synthesis protocol to design biomaterial capturing a compositional, structural, mechanical and biological resemblance to natural tissue is still a major challenge in the field of tissue engineering [1,2]. Types of tissues and their structural and mechanical complexities make the biomaterial designs more challenging [2] This is true for regenerating articular cartilage using scaffold-based tissue engineering. The composition of cartilage—water (70–80%), collagen (50–75%) and glycosaminoglycans (15–30%)—provides it viscoelastic, compressive, tensile and frictional properties that are essential for its smooth function within the biomechanically arduous joint environment [6]. This necessitates an in-depth study on mechanical properties (long-term static plus dynamic properties) of the scaffolding materials intended to be used for in vitro cartilage tissue regeneration using stem cells
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