PVA-gelatin hydrogels formed using combined theta-gel and cryo-gel fabrication techniques

Abstract

Poly(vinyl alcohol) (PVA) is a synthetic, biocompatible polymer that has been widely studied for use in bioengineered tissue scaffolds due to its relatively high strength, creep resistance, water retention, and porous structure. However, PVA hydrogels traditionally exhibit low percent elongation and energy dissipation. PVA material and mechanical properties can be fine-tuned by controlling the physical, non-covalent crosslinks during hydrogel formation through various techniques; PVA scaffolds were modified with gelatin, a natural collagen derivative also capable of forming reversible hydrogen bonds. Blending in gelatin and poly(ethylene glycol) (PEG) with PVA prior to solidification formed a highly organized hydrogel with improved toughness and dynamic elasticity. Theta-gels were formed from the solidification of warm solutions and the phase separation of high molecular weight gelatin and PVA from a low molecular PEG porogen upon cooling. While PVA-gelatin hydrogels can be synthesized in this manner, the hydrogels exhibited low toughness with increased elasticity. Thus, theta-gels were additionally processed using cryo-gel fabrication techniques, which involved freezing theta-gels, lyophilizing and rehydrating. The result was a stronger, more resilient material. We hypothesized that the increased formation of physical hydrogen bonds between the PVA and gelatin allowed for the combination of a stiffer material with energy dissipation characteristics. Rheological data suggested significant changes in the storage moduli of the new PVA-gelatin theta-cryo-gels. Elastic modulus, strain to failure, hysteresis and resilience were studied through uniaxial tension and dynamic mechanical analysis in compression. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Conflicts of interest There are no conflicts to declare.

MWCNTs reinforced conductive, self‐healing polyvinyl alcohol/carboxymethyl chitosan/oxidized sodium alginate hydrogel as the strain sensor

“…As shown in Figure 3(a,b), with the increase of the amount of OMWCNTs, the breaking strength of the hydrogel showed a trend of increasing first and then decreasing. The composite hydrogel containing 5% OMWCNTs had the highest breaking strength (>0.8 MPa) which was higher than that of other composite hydrogels reported in literature 38,39 . This was because that the introduction of OMWCNTs made the entanglement between macromolecular chains tighter.…”

“…The composite hydrogel containing 5% OMWCNTs had the highest breaking strength (>0.8 MPa) which was higher than that of other composite hydrogels reported in literature. 38,39 This was because that the introduction of OMWCNTs made the entanglement between macromolecular chains tighter. Meanwhile, part of the tensile stress was transferred to the OMWCNTs dispersed in the hydrogel during the stretching process, resulting in the improvement of the tensile strength of the composite hydrogel.…”

Rational Design of Smart Hydrogels for Biomedical Applications

“…Thus, scientists are focusing on developing novel feature of PVA by mixing with other polymers, cross-linking, or grafting ( Kamoun et al, 2017 ). In order to obtain superior PVA mechanical properties, various approaches have been attempted to fabricate hydrogels by regulating the physical, non-covalent cross-links, such as blending with gelatin, chitosan, and PEG ( Charron et al, 2019 ). For example, Golafshan et al (2017) design a new PVA–alginate hydrogel, which could supply with damp surroundings and be beneficial for accelerating wound healing.…”

Methotrexate-Loaded Gelatin and Polyvinyl Alcohol (Gel/PVA) Hydrogel as a pH-Sensitive Matrix

“…The mechanical properties of PVA can be adjusted via several methods, most of them rely upon thermal transition where crystallization of a PVA solution occurs through non-covalent intermolecular bonds to develop into a cross-linked polymer network structure. The formation of hydrogen bonds between Gel and PVA had been hypothesized to contribute toward the high resilience of hydrogel on the site of action because of the supramolecular network [ 32 , 33 ]. In the present research work, the MTX-loaded Gel/PVA hybrid hydrogel was formulated first with different polymers to cross-link the ratios to provide protection for the drug, specifically at a lower pH (stomach).…”