Evaluation of an in situ forming composite hydrogel based on gelatin–sodium alginate–polyethylene oxide for biomedical applications: effect of incorporated Sophora japonica on hydrogel performance

Abstract

Hydrogels are ideal candidates for biomedical applications such as wound healing, tissue engineering, and bone regeneration due to their porosity and similarity to the extracellular matrix of humans. A gelatin/sodium alginate (SA) hydrogel with the inclusion of polyethylene oxide (PEO) was utilized to achieve enhanced mechanical strength. Hydrogels were prepared at different ratios of polymer solutions to select the hydrogel that exhibited an optimal gelation time. Sophora japonica, a plant leaf extract (SJLE) rich in flavonoids and isoflavonoids, was added to the hydrogel to enhance tissue repair. The developed hydrogels were extensively characterized for their morphology, porosity, and swelling rates. The gelatin/(SA + PEO) hydrogel prepared at a ratio of (4 : 1) displayed suitable gelation time and swelling rate which were further improved by incorporating the plant extract. FTIR studies displayed successful integration of the plant extract within the matrix of the hydrogel. SEM results demonstrated increased porosity and pore area distribution in the matrix of the hydrogel incorporating 20% and 30% plant extract which is essential for cell transportation of nutrients and cell attachment. The hydrogels demonstrated significant antimicrobial activity in vitro with superior activity observed for TA-15 formulation (12.5% gelatin, 2.5% SA, 3% PEO, and 30% SJLE) against two Gram-positive bacteria, Staphylococcus aureus and Bacillus cereus (i.e., biofilm inhibition rates of 93.58 ± 10.81 and 92.06 ± 3.49%, respectively). Moreover, in vitro evaluation of the hydrogels revealed low cytotoxicity and high biocompatibility. Hence, the gelatin/(SA + PEO) hydrogel loaded with the Sophora japonica plant extract could be exploited as a promising biocompatible antimicrobial biomaterial for biomedical applications including bone tissue engineering.