Table 3.

Comparison of 3D printing of alginate and silk fibroin

		Alginate	3D Silk printing[119]
Ink composition	Molecule	Polysaccharide	Protein
	Concentration	~4% w/v	~30 wt%
Aqueous bath	Salt ions	Calcium, magnesium…	Sodium, Potassium, Chloride and phosphate
	Cation valent	Divalent	Monovalent
	Salt is a crosslinking agent and structural component	Yes	No
3D Printing	Printing technique	Extrusion-based 3D printing	Extrusion-based 3D printing
	Phase-transition	Ionic bonding	Hydrogen bond
	Dissolving solvent	Chelating reagents	Strong-hydrogen-destroying solvents
Printing capability	Supporting materials for hollow structures	Yes	No
	Mechanic performance	Low	High