Chitosan hydrogels in 3D printing for biomedical applications

[Display omitted] •A review of current 3D printing techniques for biomedical applications.•An overview of hydrogel criteria as inks for various 3D printing techniques.•Physical and chemical approaches for preparation of chitosan-based hydrogels as 3D printable inks.•A summary of recent advances of chitosan-based hydrogels in 3D printing for various biomedical applications. Tissue engineering and regenerative medicine have entered a new stage of development by the recent progress in biology, material sciences, and particularly an emerging additive manufacturing technique, three-dimensional (3D) printing. 3D printing is an advanced biofabrication technique which can generate patient-specific scaffolds with highly complex geometries while hosting cells and bioactive agents to accelerate tissue regeneration. Chitosan hydrogels themselves have been widely used for various biomedical applications due to its abundant availability, structural features and favorable biological properties; however, the 3D printing of chitosan-based hydrogels is still under early exploration. Therefore, 3D printing technologies represent a new avenue to explore the potential application of chitosan as an ink for 3D printing, or as a coating on other 3D printed scaffolds. The combination of chitosan-based hydrogels and 3D printing holds much promise in the development of next generation biomedical implants.