Vanillin crosslinked 3D porous chitosan hydrogel for biomedicine applications: Preparation and characterization

Crosslinked chitosan (CS) is one of the most useable hydrogels in biomedicine and tissue engineering. Unlike most chitosan crosslinkers that are toxic, such as glutaraldehyde, vanillin is a natural, biocompatible, and antimicrobial alternative. The crosslinking of chitosan and vanillin consists of Schiff base bonds between the amines of chitosan and the aldehydes of vanillin, in addition to hydrogen bonds formed across the network. In most studies, the combination of chitosan and vanillin has been investigated in small sizes (micro/nanoscale and biofilms). In this study, a chitosan-vanillin (CV) hydrogel was studied on a macroscale with a three-dimensional porous structure, and it was compared with chitosan crosslinked with glutaraldehyde (CG) on the same scale. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (FE-SEM) used to identify the bonds formed and examine the morphology of the hydrogels. The gel content, swelling, porosity, mechanical properties, cell viability (on L929 and mesenchymal cells), and antibacterial activity (against Escherichia coli and Staphylococcus aureus) of the samples were investigated. The results showed that the CV had both gel content and high porosity (>90%), with an interconnected porous network of uniform pore size. The CV hydrogel exhibited good antibacterial activity and cell viability. In terms of mechanical properties, CV has weaker mechanical properties compared to CG in the dry state, while the mechanical properties of CV have more improved in the swollen state compared to CG.