Scaffold material is one of the three key factors in tissue engineering. Among the architectures of scaffold material, polymeric hydrogels are increasingly preferred because of their high water content, which is similar to natural extracellular matrix (ECM). Furthermore, injectable hydrogels minimize the invasiveness to the patients during the surgery, thus post-surgery complications can be decreased.

In this work, we fabricated an injectable hydrogel system with multi-phased structure from PEO, Laponite, and chitosan. Micron-sized aggregates were trapped and well distributed within the hydrogels. The injectability is related to the unique shear-thinning behavior of the hydrogels. Addition of chitosan increases the elastic modulus, decreases the strain required to be injected, and reinforces the overall hydrogel network. The elastic modulus of the hydrogels recovered quickly after mimicked injection, because of the physical and reversible nature of the crosslinking. The aggregates increased the adhesiveness of the hydrogels to fibroblast cells.

Films made from the hydrogels were characterized using mechanical tests, in vitro degradation/dissolution tests, and in vitro cell proliferation assay. In vitro cell growth study indicated that the material support cell proliferation. Confocal microscopic images show that fibroblast cells adhere and spread on the film surface.