Table 2.

Summary of available natural and synthetic bio-inks.

Bio-ink Material	Description	Advantages	Disadvantages	References
Alginate	Natural negatively charged polysaccharides from brown algae	Non-immunogenic when implanted in vivo High biocompatibility Capable of transporting oxygen, nutrients, etc.	Lack of cell adhesion Poor printability Unpredictable biodegradability	[14,35,36,37]
Agarose	Polysaccharide obtained from seaweed	High cell viability	Poor support and limited cell growth	[35,38]
Collagen	Structural protein in the extracellular matrix	Easily obtainable from skin and connective tissues of organisms Relatively strong 3D structures	Poor mechanical properties, unless cross-linked Low mechanical strength Unpredictable viscosity and elastic modulus	[39,40]
Nanocellulose	Cellulose that can be derived from biomass, bacteria, and marine sources	Non-cytotoxicity High-aspect-ratio Strong mechanical properties	May not be an accurate model for human cells as we do not produce cellulase to be biodegraded	[41]
PEGDA	Synthetic polymer used for hydrogel fabrication and UV curing	Highly biocompatible Non-toxic and non-immunogenic Capable of photopolymerization High mechanical strength	Material can be brittle and rigid	[42]
Pluronic®	Synthetic polymer-poloxamer	Excellent printability Temperature-responsive gelation	Biocompatibility is not sufficient for long-term cell survival	[43,44]

Note: More information is provided in Table 2 in reference [13].