Characteristics of ethylenediamine tetra-acetic acid treatment on iron(III)-induced modified catechol chitosan hydrogels under different pH conditions

Modified catechol chitosan was synthesized to examine the intricate connections between Fe(III) and catechol under different pH conditions. The conjugation of the catechol moieties, which determines the structure of the hydrogel, was evaluated by nuclear magnetic resonance spectroscopy and ultraviolet‒visible spectroscopy. The gel formation was well maintained by the dual cross-linking networks of the electrostatic interactions between catechol chitosan solution (CCS) and Fe 3+ along with the covalent catechol-coupling-based coordinate bonds. Three pH conditions of 3, 5, and 7 were applied for ethylenediamine tetra-acetic acid (EDTA) treatment as a triggering factor in modifying the uniform hydrogel structure. The hydrogels demonstrated enhanced mechanical strength and cohesiveness at a pH of 5, and rheology analysis was used to determine the storage and loss moduli. Several analysis and characterization techniques were utilized to describe the cross-linking components and confirm the physical properties of the chitosan backbone polymer chain in the modified iron-induced hydrogel frameworks before and after EDTA treatment.