Chitosan-based inks for 3D printing and bioprinting

The advent of 3D-printing/additive manufacturing in biomedical engineering field has introduced great potential for the preparation of 3D structures that can mimic native tissues. This technology has accelerated the progress in numerous areas of regenerative medicine, especially led to a big wave of biomimetic functional scaffold developments for tissue engineering demands. In recent years, the introduction of smart bio-inks has created growing efforts to facilitate the preparation of complex and homogeneous living-cell-containing 3D constructs. In the past decade, a considerable body of literature has been created on identifying an ideal bioinspired-ink with excellent printability, cell viability, bioactivity, and mechanical properties. This state-of-the-art review article briefly outlines 3D-printing/bioprinting techniques applied for chitosan-based bio-inks, their resources, crosslinking methods, characteristics, reasons for their superiority over other bio-inks, and challenges of commercialization; this is followed by a comprehensive description of the full potential and the key indicators of success in terms of 3D bio-printing of such bio-inks as platforms for tissue regeneration, advanced biosensors, drug delivery, and wastewater treatment. Next, the restrictions and challenges of chitosan bio-inks are highlighted. In this work, we also discussed about developing a coherent research strategy based on combination of microfluidics-based lab-on-a-chip (organ-on-a-chip) platforms with 3D-bioprinting which enables designing of self-healing scaffolds. And finally, the potential of smart inks based on chitosan for 4D bioprinting of more detailed and practical engineered tissues and artificial organs is reviewed.