Facile fabrication of moldable antibacterial carboxymethyl chitosan supramolecular hydrogels cross-linked by metal ions complexation

Herein, carboxymethyl chitosan (CMCh) supramolecular hydrogels cross-linked by metal ions (Ag⁺, Cu²⁺ and Zn²⁺) are reported. The hydrogels were formed within a few seconds by simple mixing of CMCh solution with metallic salt solutions at an appropriate pH. The prepared hydrogels were characterized by using FT-IR, XRD, SEM and rotational rheometery. FT-IR measurements suggested that the facile complexation of metal ions with carboxylic, amino and hydroxyl groups of CMCh chains promoted the rapid hydrogelation. SEM images revealed a cross-linked structure of hydrogels, while microstructural openings were observed by cross-sectional studies of the freeze-dried hydrogels. Moreover, the hydrogels showed a remarkable moldability to form free standing objects. The antibacterial activities of the hydrogels were also studied against Escherichia coli and Staphylococcus aureus by agar well diffusion method. The results demonstrated an excellent antibacterial activity of the supramolecular hydrogels. Therefore, the developed CMCh supramolecular hydrogels might be used effectively in biomedical field.