Improving the Antibacterial Property of Chitosan Hydrogel Wound Dressing with Licorice Polysaccharide

Abstract

A series of hydrogels with different ratios of chitosan and licorice polysaccharide (LP) were prepared by crosslinking to different concentrations of genipin (gp). They were characterized by FTIR (Fourier transform infrared spectroscopy), SEM (Scanning electron microscope), swelling ratio, rheological measurements, degradation with time, cytotoxicity, and antibacterial efficacy. Results show that the hydrogels have porous structures. With an increase in LP content, the swelling rate grows in the early stage of immersion in buffer and drops later. The swelling ratio ranged from 986% to 1677%, and stiffness varied from 777 Pa to 1792 Pa. The addition of LP reduced the mechanical strength and delayed gelation and degradation of the hydrogels. However, the most important discovery was that gp increases the viability of NIH 3T3 cells from 94% to 137%, and LP raises the bacteriostatic efficacy from 51% to 78%. Hydrogels synthesized from 1% genipin, 3% chitosan, and 4% licorice polysaccharide showed the best antibacterial and fibroblast proliferation promoting activities. They exhibited moderate swelling and degradation rates over time, while being more suitable to affect healing of chronic wound infections. These results provide a new strategy to improve the antibacterial effectiveness and cyto-compatibility of chitosan hydrogels with water soluble active LPs from Glycyrrhiza that derive from traditional Chinese medicine.