Effect of different crosslinking agents on carboxymethyl chitosan-glycyrrhizic acid hydrogel: Characterization and biological activities comparison.

Hydrogels were widely utilized in biomedical applications, with their mechanical properties and drug release behavior largely dependent on the type and degree of crosslinking. In this study, the effects of anhydrous ferrous chloride (Fe2+), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS), and polyvinyl alcohol/borax (PVA/Borax) on the properties of carboxymethyl chitosan (CMCS) and glycyrrhizic acid (GA) hydrogels were investigated. The GA-CMCS-based hydrogels (GFC, GEDC, GPBC) were prepared and their Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and rheological properties were analyzed. The results showed that GFC excelled in self-healing, swelling, and water retention. Furthermore, hydrogels with varying GA concentrations crosslinked by Fe2+ were tested for antibacterial activity and cellular nitric oxide (NO) levels, and were compared to GEDC and GPBC. Notably, Fe2+-crosslinked hydrogels demonstrated significant antibacterial efficacy, the antibacterial rate of 3 % GFC reached 93 %. When compared to the LPS group, which had an inflammatory NO level of 30.58 ± 0.95 μM, the 3 % GFC group demonstrated a notable reduction to 12.88 ± 1.04 μM. In contrast, GEDC and GPBC showed limited antibacterial and anti-inflammatory properties. In brief, hydrogels' physical, chemical, and biological properties were notably affected by various crosslinking agents. This study provides valuable insights for designing hydrogels tailored to specific application requirements.