Microfabricated photocrosslinkable polyelectrolyte-complex of chitosan and methacrylated gellan gum.

Chitosan (CHT) based polyelectrolyte complexes (PECs) have been receiving great attention for tissue engineering approaches. These hydrogels are held together by ionic forces and can be disrupted by changes in physiological conditions. In this study, we present a new class of CHT-based PEC hydrogels amenable to stabilization by chemical crosslinking. The photocrosslinkable anionic methacrylated gellan gum (MeGG) was complexed with cationic CHT and exposed to light, forming a PEC hydrogel. The chemical characterization of the photocrosslinkable PEC hydrogel by Fourier transform infrared spectroscopy (FTIR) revealed absorption peaks specific to the raw polymers. A significantly higher swelling ratio was observed for the PEC hydrogel with higher CHT content. The molecular interactions between both polysaccharides were evaluated chemically and microscopically, indicating the diffusion of CHT to the interior of the hydrogel. We hypothesized that the addition of MeGG to CHT solution first leads to a membrane formation around MeGG. Then, migration of CHT inside the MeGG hydrogel occurs to balance the electrostatic charges. The photocrosslinkable feature of MeGG further allowed the formation of cell-laden microscale hydrogel units with different shapes and sizes. Overall, this system is potentially useful for a variety of applications including the replication of microscale features of tissues for modular tissue engineering.