Preparation and properties of novel hydrogel based on chitosan modified by poly(amidoamine) dendrimer

Currently, chitosan (CTS) or chitosan derivatives hydrogels are applied in different fields, such as biological materials, medical materials and hygiene materials. In this study, novel chitosan hydrogels were successfully prepared by chitosan and poly(amidoamine) (PAMAM) dendrimer with glutaraldehyde serving as a cross-linking agent. Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC) were performed to characterize PAMAM. The structure and morphology of hydrogels were characterized by FTIR, thermo gravimetry analysis (TGA), and scanning electron microscopy (SEM). The swelling properties of the hydrogels were investigated in solutions of pH 1.0 and 7.4. The hydrogels showed good swelling capacities and pH-sensitive swelling properties. Besides, the antibacterial activities of the hydrogels against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were tested by optical density. Compared with the pure chitosan hydrogel, their antibacterial activities were significantly improved with the increase in the blending ratio of PAMAM. And with the increase in cross-linking agent and concentration of CTS, the antibacterial activities increased firstly and then slightly decreased. The hydrogel was expected to be a novel antibacterial material.