Nanohybrid-Reinforced Gelatin-Ureidopyrimidinone-Based Self-healing Injectable Hydrogels for Tissue Engineering Applications

Abstract

The traditional hydrogels are prone to break due to the applied stress. The deformation of the implanted hydrogels would result in the loss of structural integrity, leading to the failure of hydrogel functionalities and tissue regeneration. Selfhealing hydrogels (AG-UPy), composed of oxidized alginate and ureidopyrimidinonefunctionalized gelatin (G-UPy), were developed to address this challenge. These selfhealing hydrogels possess two independent healing mechanisms, viz., Schiff base formation and UPy dimerization. These hydrogels were compared with oxidized alginate-gelatin (AG) hydrogels. AG-UPy hydrogels showed effective self-healing in a short time (about 2 min) after applying 800% strain, wherein recovery was not achieved with the AG hydrogel. However, the shear-thinning property of UPy made the AG-UPy hydrogel mechanically weaker than the AG hydrogel. To improve the mechanical strength of the AG-UPy hydrogel, we impregnated poly(ethylene glycol)poly(urethane)/cloisite nanohybrid (PEG-PU/C) to prepare the AG-UPy/PEG-PU/C hydrogel. The incorporation of PEG-PU/C resulted in a 20-fold increase in the compression strength compared to that of the AG-UPy hydrogel. The AG-UPy/PEG-PU/C hydrogels also showed rapid self-healing. Incorporating the nanohybrid improved the cell proliferation by 2-and 1.25-fold compared to that of the AG and AG-UPy hydrogels, respectively. Therefore, PEG-PU/C combined with the UPy-functionalized polymer could be used to modulate mechanical strength and self-healing and enhance cell proliferation.

Progress in Gelatin as Biomaterial for Tissue Engineering

“…The addition of nanoclay resulted in a steadier release of the growth factor [16]. These results were in accordance with other studies that demonstrated the great ability of nanoclays to absorb proteins as well as to form tighter hydrogels [49][50][51].…”

“…Nanoclays are silicate-derived multilayers that have been shown to play a key role in the physiology of a wide range of tissues such as bone [48]. Several studies have proved that these nanoparticles are able to complement the already adequate properties of gelatin hydrogels for bone tissue regeneration [16,[49][50][51]. One of the main advantages of nanoclays consists in improving the gelatin's poor mechanical properties.…”

Study on the healing performance of poly(ε‐caprolactone) filled ultraviolet‐curable 3D printed cyclic trimethylolpropane formal acrylate shape memory polymers

“…Self‐healing is defined as the ability of a material to recover or repair the damage 13–16 . It can be classified as the intrinsic and the extrinsic.…”

“…12 Self-healing is defined as the ability of a material to recover or repair the damage. [13][14][15][16] It can be classified as the intrinsic and the extrinsic. In extrinsic self-healing materials, healing agents are dispersed in the matrix and released after being damaged.…”

Hydrogel-based holographic sensors and biosensors: past, present, and future

“…They are ideal candidates for immobilizing enzymes, nucleic acids, proteins or peptides because of their porous structure and soft nature, which can mimic physiological environments and increase the loading capacity [8]. Their applications are found in controlled release, drug delivery, immunomodulation, tissue engineering, or sensing and biosensing [9][10][11][12][13] and the hydrogel-based materials market is forecasted to reach US $31.4 billion by 2027 (https:// www. allie dmark etres earch.…”