Table 6.

Comparison among fabrication methods in tissue engineering.

Method	Main Characteristic	Resulted Porosity	Cell Viability	Ref.
Freeze casting	Ceramic slurries are used in this method; then, water is evaporated. It produces pores due to formation of ice crystals.	<85%	<90%	[237]
Freeze-drying	It is an easy procedure that can be applied with natural materials such as collagen and fibers. The porosity can be improved by freezing temperature alterations and changing of the concentration of materials.	30%–80%	<90%	[238]
Solvent casting and Particle leaching	It uses casting molds to produce 3D scaffolds by polymer solution. Then, it requires leaching by using organic solvents to simplify the addition of drugs or growth factors to scaffolds.	50%–90%	75%–88%	[239]
Gas foaming	Using high-pressure carbon dioxide for expanding the polymer matrix without applying high temperature or toxic solvents. Changing pressure can also create scaled porous scaffolds.	<90%	N/A	[240]
Phase separation	Changing temperature for polymer and solvent separation results in a solid polymer due to phase separation. Finally, a desirable, homogenous, and interconnected porous scaffold is produced depending on cooling rates.	60%–98%	<98%	[241]
Electrospinning	Nanoscale or microscale fibers are produced by tuning process parameters and chemicals in this method.	80%–95%	<80%	[242,243]
Sol–gel	Colloidal metal oxides are applied traditionally to create tunable porous scaffolds in the sol–gel method with desirable chemistry. Double phasic chitosan scaffolds with a conjunction peptide have demonstrated the capability to recruit stem cells for cartilage repair.	N/A	N/A	[244]
Additive manufacturing	Extrusion methods in biomedical applications are often polymer-based and provide benefits in cost, size, and flexibility against old manufacturing methods. Both polymers and metals can be used in solid free-form sintering, while laser melting is limited to metals.	80%–90%	60%–95%	[245]