Mechanical and structural response of a hybrid hydrogel based on chitosan and poly(vinyl alcohol) cross-linked with epichlorohydrin for potential use in tissue engineering

Abstract

The development and characterization of a hybrid hydrogel based on chitosan (CS) and poly(vinyl alcohol) (PVA) chemically cross-linked with epichlorohydrin (ECH) is presented. The mechanical response of these hydrogels was evaluated by uniaxial tensile tests; in addition, their structural properties such as average molecular weight between cross-link points (Mcrl), mesh size (DN), and volume fraction (v(s)) were determined. This was done using the equivalent polymer network theory in combination with the obtained results from tensile and swelling tests. The films showed Young's modulus values of 11 ± 2 MPa and 9 ± 1 MPa for none irradiated and ultraviolet (UV) irradiated hydrogels, respectively. The cell viability was assessed using Calcein AM and Ethidium homodimer-1 assay and environmental scanning electron microscopy. The 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan thiazolyl blue formazan (MTT Formazan assay) results did not show cytotoxic effects; this was in good agreement with nuclear magnetic resonance and fourier transform infrared spectroscopies; their results did not show traces of ECH. This indicated that after the crosslinking process, there was no free ECH; furthermore, any possibility of ECH release in the construct during cell culture was discarded. The CS-PVA-ECH hybrid hydrogel allowed cell growth and extracellular matrix formation and showed adequate mechanical, structural, and biological properties for potential use in tissue engineering applications.

Influence of natural and synthetic crosslinking reagents on the structural and mechanical properties of chitosan-based hybrid hydrogels

“…It was observed that the mobility and deformation of their polymeric chains were significantly reduced; hence, the network lost water absorption capability. Comparing the swelling behavior 330 between CS/PVA with the CS/PVA/GA and CS/PVA/GEN blends, it was found that the overshooting effect, which was reported for CS and CS/PVA blend by Garnica-Palafox et al (2014), was inhibited because of the chemical crosslinking reagents. considerable effect on the hydrophilicity of these hydrogels (64 ± 1 • and 63 ± 1 • , respectively).…”

“…However, the long-term structural and mechanical stability of the blend is still an issue. To address this issue, chemical crosslink- 30 ing reagents have been used (glutaraldehyde He & Xiong (2012); Hu et al A c c e p t e d M a n u s c r i p t (2013), epichlorohydrin Garnica-Palafox et al (2014) and genipin Khurma et al (2006); Bispo et al (2010)). Recent efforts have demonstrated that the physicochemical properties of CS can be tuned, which has been achieved by combining CS with other polymers or using chemical crosslinkers.…”

“…On the A c c e p t e d M a n u s c r i p t other hand, due to the CS hydrogels structure contains ionic groups (NH + 2 ), an osmotic pressure gradient is generated because of the difference in ion concentration within the gels and the outside PBS solution (Na + , Cl − and K + ). As hydrogels swells the osmotic pressure decreases and eventually the 305 swelling equilibrium is reached (Berger et al (2004); Garnica-Palafox et al (2014)). So, the greater the difference in the ion concentration is, the larger the osmotic pressure becomes, causing a larger equilibrium water uptake of hydrogel sample (Gupta & Shivakumar (2012)).…”

Engineering Muscle Constructs for the Creation of Functional Engineered Musculoskeletal Tissue

“…Future development of synthetic scaffolds should focus on continued development of protein-based electrospun constructs, and implantation of these constructs in VML injury models [46,47,49]. Hybrid micropatterned and electrospun substrates are being adapted to promote the growth and differentiation of MPCs, while studies using modified hydrogels are incorporating structural proteins such as fibrin and chitosan to better replicate the progenitor cell niche in vitro [50,69,70]. Future studies using native protein-based scaffolds should focus on shaping these technologies for use in skeletal muscle VML injury models.…”

Biocompatibility of Human Auricular Chondrocytes Cultured onto a Chitosan/Polyvynil Alcohol/Epichlorohydrin-Based Hydrogel for Tissue Engineering Application

“…Crosslinking with epichlorohydrin (ECH) can be cited as an example of the chitosan chemical modifications carried out in order to prevent its dissolution in acidic solutions. Crosslinking CS-PVA with ECH brings more construction stability through formation of a polymeric tridimensional network increasing its lifespan (Garnica-Palafox et al, 2014). The aim of our study was to evaluate the biocompatibility of human microtic auricular chondrocytes with a CS-PVA-ECH based hydrogel in order to propose this material as a scaffold to support and promote neotissue formation.…”