The Role of Aldehyde-Functionalized Crosslinkers on the Property of Chitosan Hydrogels

Chitosan has been utilized as a popular biopolymer to fabricate hydrogels for biomedical applications. However, chitosan hydrogels are generally too brittle to mimic the deformability of the extracellular matrix in many tissues and organs. In particular, the role of the varied crosslinkers in determining the elasticity of chitosan hydrogels is lack of discussion. Here, three aldehyde-functionalized crosslinkers (i.e., aldehyde-modified poly(xylitol sebacate)-co-poly(ethylene glycol) (APP), glutaraldehyde (GA), and polydextran aldehyde (PDA)) are used to react with quaternized chitosan (QCS) through imine bonds to form hydrogels. The microstructures, mechanical performances, and cytocompatibility of the three hydrogels are systematically investigated. The APP/QCS hydrogels presented the best compressive and stretch properties among the three hydrogels. The mechanical property and antibacterial activity of APP/QCS hydrogels can be further modulated using varied QCS amounts, where more QCS contributed higher stiffness and stretchability as well as better bacterial inhibition to the APP/QCS hydrogels. Taken together, it is demonstrated that the inherent elastomeric characteristic of APP crosslinker provides the desirable elasticity and stretchability to QCS hydrogels compared to the other aldehyde-functionalized crosslinkers of GA and PDA. This strategy of using multivalent elastomeric crosslinkers to fabricate deformable chitosan hydrogels can expand the use of chitosan hydrogels in tissue engineering applications.