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 (M_crl), mesh size (D_N), 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.

Keywords:

• chitosan hydrogel
• mechanical properties
• tissue engineering
• scaffold

Acknowledgments

The authors wish to thank for the financial support to the DGAPA-UNAM- PAPIIT through project number IB100512-RR180512 and CONACYT through project numbers 114359 and 78798. The authors are also grateful to Damaris Cabrero and Gerardo Cedillo for their technical support.

Notes

1 Time intervals in minutes were: 2.5, 5, 7.5, 10,12.5, 15, 20, 25, 30, 45, 60,120, 180, 240, 320, 1440 and 2880.