Improved mechanical properties of Chitosan/PVA hydrogel – A detailed Rheological study

Hydrogels are competently investigated for the substantial emerging fields of tissue engineering, drug delivery, and bone regeneration, thanks to their water-holding capacity, elastic nature, and mechanical strength. The optimization of the mechanical strength of the hydrogel for biomedical applications by tuning the polymer concentration and cross-linking density has been great demand in recent years. The preparation of stable and mechanically strengthened hydrogels that can mimic the biological tissues are of great challenge. In this study, we prepared the chitosan/PVA hydrogel by varying the concentration of chitosan from 0.5 to 2.5 (%w/v):1 (%w/v) using very less amount of 0.1% glutaraldehyde which is non-toxic in that minimal concentration. The hydrogel system is formed by strong covalent bonds due to the imine and acetal bonds between chitosan and PVA via aldehyde groups of glutaraldehyde. The viscoelastic studies showed that the prepared chitosan/PVA hydrogels exhibit stable gel-like structure with shear thinning behaviour. The viscoelastic nature and mechanical strength of the hydrogels are enhanced with an increase in the chitosan concentration. Further, our results suggest that chitosan/PVA gels with the concentration of 1:1, 1.5:1 and 2:1 (%w/v) have yield stress around 1.1 kPa makes them most suitable for tissue engineering, and the yield stress of 0.5:1 (%w/v) indicates that it could be applied in the injectable drug delivery system. The complex modulus of 1.5:1, 2:1, and 2.5 (%w/v) of chitosan/PVA hydrogels reveals its usage in tissue engineering as it matches the shear modulus of nuclear pulposus. The prepared hydrogels are highly stable and possess superior mechanical strength, could be employed for injectable drug delivery and tissue engineering system.