Table 1.

Current efforts toward 3D composite bioprinting

Combined processes		Main characteristics	References
Phase transition through temperature gradient	Extrusion printing	Improve the mechanical properties and biocompatibility of the printed construction at the same time	[21,22]
Ionic crosslinking	Extrusion printing	Provide more fabrication flexibility by controlling ion diffusion and material extrusion speed; perform cell printing under room temperature; effectively construct vessels like microchannels	[27-30]
Electrohydrodynamics	Extrusion printing	Fabricate scaffolds with good mechanical properties and large scales, and the structure can mimic natural extracellular matrix on the micro-nano scale; effectively prepare the scaffolds with a multiscale pore structure	[37,38,43-45]
Cell printing	Hybrid additive/ subtractive manufacturing	Construct vascularized bio constructs with certain mechanical strength and complex microstructure	[62-64]
Physical field control	Extrusion printing	Improve printing flexibility, especially with environmentally responsive intelligent materials; regulate materials and cells in the printing process	[65-69]