Chitosan-terephthaldehyde hydrogels – Effect of concentration of cross-linker on structural, swelling, thermal and antimicrobial properties

Chitosan properties can be finely tuned for various bio-applications by cross-linking with suitable cross-linkers
and the extent of its cross-linking. The effect of concentration of cross-linker on the biopolymer would exhibit
different physiochemical properties, surface charges, thermal stability, morphology and their swelling behavior.
In this study, chitosan has been cross-linked with varying concentration of hydrophilic terephthaldehyde (TAL)
as cross-linker and characterized using FT-IR, XRD and thermogravimetric analysis (TGA). The effect of concen�tration of the cross-linker on the morphology, surface charge, pH dependent swelling was studied. The formation
of imine bond between chitosan and TAL was confirmed by using FT-IR. The XRD analysis shows increase in
crystallinity upon increasing the cross-linker concentration of TAL in comparison with the pure chitosan. The
thermal stability of the hydrogels was also studied. With increase in the concentration of TAL, the hydrogels
show a polyphasic structure and the surface charge become more positive. The TAL cross-linked chitosan exhib�ited both highest and lowest in swelling at the physiological pH with varying concentration of the cross-linker. The chitosan-terephthaldehyde hydrogels exhibits good antimicrobial response towards gram negative bacteria. The
results indicate chitosan-terephthaldehyde hydrogels (CST) to have potential applications in various biomedical
applications at physiological pH