Table 2.

Biomaterials for 3D printing of the airway and lung.

Types	Advantages	Limitations	Bioinks application of lung and airway	Ref
Natural bioinks
Collagen	• High binding capacity with integrins and domain receptors • Low immunological response	• Weak mechanical properties	Neutralized collagen solution loaded with cells: Ingredients: atelocollagen, acetic acid, reconstitution buffer, nutrient buffer, reconstitution buffer, nutrient buffer. Concentration of collagen: 0.3% w/v.	Kang et al. 85
			In the field of trachea reconstruction, collagen can be used to construct scaffolds. Ingredients: monomeric type I and type II atelocollagen, acetic acid, Tris-buffered saline solution.	Xu et al. 19
Alginate	• Biocompatibility • Low immune response	• Gel strength is weak	Sodium alginate can be used as the middle viscosity layer when manufacturing artificial trachea. Ingredients: calcium chloride solution, alginate hydrogel, 1 × 107 cells/10 mL.	Bae et al. 51
			Alginate can be used to fabricate precise 3D scaffolds for tissue engineering. Ingredients: alginate, CaCl2 solution.	Khoshnood et al. 93
			Scaffold fabrication for cartilage regeneration. Ingredients: sodium alginate, CaCl2, NaCl solution.	Kundu et al. 94
Silk fibroin	• Biocompatibility • Well printability • Well mechanical properties	• Low print resolution • May cause immune responses	Silk fibroin scaffolds are potential for tracheal substitute and epithelial regeneration. Ingredients: Bombyx mori cocoon silk, Na2CO3, LiBr aqueous solutions, n-butanol.	Chen et al. 95
Decellularized extracellular matrix	• Biocompatibility • Simulate the microenvironment in vivo	• Weak Mechanical property • Complex preparation process	Decellularized extracellular matrix can be used in trachea model. Ingredients: tracheal mucosa part, sodium dodecyl sulfate, phosphate-buffered saline, Triton X-100, peracetic acid, ethanol, acetic acid, pepsin, NaOH.	Nam et al. 96
Synthetic biomaterials	• High printability • Easy customization	• Limited cellular interaction capabilities	PSeD/PCL scaffold can be used for bionic cartilage ring construction. Ingredients: PSeD and PCL, tetrahydrofuran.	Xu et al. 97
			Bioprinted tracheal can be fabricated by PCL and human mesenchymal stem cell. Ingredients: PCL, human mesenchymal stem cell.	Ke et al. 98
Compound bioinks	• Can be adjusted according to requirements • Potential for creating complex, functional tissues and organs	• Complex preparation process	The microfluidic lung chip can be constructed by porous polydimethylsiloxane (PDMS) membrane coated with ECM. Ingredients: PDMS, rat tail collagen type I.	Guvendiren and Burdick 99