An investigation on the differences between physical and chemical cross-linkedPVA/chitosan hydrogels as potential materials for wound healing

Hydrogels play an important role in fabricating modern wound dressings, a fact which has led to the focus of researchers in this field. The morphological structure, physical and mechanical properties are dominant characteristics of a wound dressing, immensely affected by the fabrication process parameters. Physical methods (namely freezing-thawing) and chemical methods (utilizing chemical cross-linkers) are the primary routes to prepare hydrogels, nevertheless, the difference between the properties of wound dressings prepared using these methods constituted of poly(vinyl alcohol)PVA/chitosan are not reported yet; accordingly, differences between physical and chemical cross-linked PVA/chitosan hydrogels were investigated in this research. Besides, other important features of a dressing for wound healing, such as antibacterial and biocompatibility properties, swelling ratio, as well as water vapor permeability were studied. Results showed that a porous structure was only obtainable using the physical method, whereas the chemical method gave rise to a dense structure, and accordingly, vapor permeability and swelling ratio were less than that of the physical one. Particularly, in wound dressings that were formed by the physical method, the tensile strength and modulus were more than that of formed by the chemical cross-linking agent. The analysis also exhibited that hydrogels were able to protect wounds against microorganisms and the mechanical efficiency was high enough in dry and wet states; moreover, good biocompatibility of these dressings and providing a cool and moist environment to help the healing adjacent to the wound were obtained from both chemical and physical methods

Keywords:

PVA , Chitosan , Hydrogels , Freeze-thaw method , Wound dressing