Microstructured chitosan/poly(γ-glutamic acid) polyelectrolyte complex hydrogels by computer-aided wet-spinning for biomedical three-dimensional scaffolds

The application of additive manufacturing principles to hydrogel processing represents a powerful route to develop porous three-dimensional constructs with a variety of potential biomedical applications, such as scaffolds for tissue engineering and three-dimensional in vitro tissue models. The aim of this study was to develop novel porous hydrogels based on a microstructured polyelectrolyte complex between chitosan and poly(γ-glutamic acid) by applying a computer-aided wet-spinning technique. The developed fabrication process was used to build up three-dimensional porous hydrogels by collecting microstructured layers made of chitosan/poly(γ-glutamic acid) on top of the other. Microstructured polyelectrolyte complex hydrogels were characterized and compared to chitosan/poly(γ-glutamic acid) porous hydrogels with similar composition prepared by conventional freeze-drying technique. Fourier transform infrared analysis confirmed the formation of an electrostatic interaction between the two processed polymers in all the developed chitosan/poly(γ-glutamic acid) hydrogels. The composition of the porous constructs as well as the employed processing techniques had a significant influence on the resulting swelling, thermal, and mechanical properties. In particular, the combination of the ionic interaction between chitosan/poly(γ-glutamic acid) and the defined internal microarchitecture of microstructured polyelectrolyte complex hydrogels provided a significant improvement of the compressive mechanical properties. Preliminary in vitro biological investigations revealed that microstructured polyelectrolyte complex hydrogels were suitable for the adhesion and proliferation of Balb/3T3 clone A31 mouse embryo fibroblasts. The encouraging results in terms of cytocompatibility and stability of the microstructure in aqueous solutions due to the ionic crosslinking suggest the investigation of the developed microstructured polyelectrolyte complex hydrogels as suitable scaffolds for three-dimensional cells' culture.