Table 2.
Summary of protein-based inks for 3D printed tissue scaffolds
| Proteins | Ink composition | Methods | Crosslinking | Auxiliary | Young’s modulus | Tissues | References |
|---|---|---|---|---|---|---|---|
| Collagen | Monolithic (up to 24 mg/ml) | Extrusion | Physical | Supporting bath | 10 kPa; 100 kPa (GLU crosslinking) | Heart | [39] |
| Monolithic (up to 17.5 mg/ml) | Extrusion | Physical | Heating | ~30 kPa | Meniscus | [72] | |
| Monolithic (up to 12 mg/ml) | Extrusion | Physical | pH | NA | cartilage | [70] | |
| Collagen fibrils | Extrusion | Physical | Shear-induced fiber alignment | NA | Corneal | [177] | |
| Composite (Gelatin; hyaluronic acid) | Extrusion; Light | Physical; Covalent | Rheology additives | NA | Liver | [57] | |
| Composite (gold nanorods) | Light | Physical | Near-infrared femtosecond laser | NA | Vessel | [184] | |
| Composite (Pluronic® F-127) | Extrusion | Physical | Rheology additives | 7 kPa | Bone marrow | [71] | |
| Composite (Alginate) | Extrusion | Physical | Rheology additives | NA | Bone; liver | [284] | |
| Gelatin | Gelatin methacrylamide (up to 20 w/v%) | Extrusion; Light | Covalent | Photopolymerization | NA | Liver | [67] |
| Gelatin methacrylamide (10 w/v%) | Extrusion | Covalent | Structural enhancement | ~130 kPa | Cartilage | [285] | |
| Gelatin methacryloyl (up to 20 w/v%; Gellan) | Extrusion | Physical | Rheology additives | ~ 186 kPa | Cartilage | [55] | |
| Gelatin-methacryloyl (10 w/v%; 0.6% Collagen) | Extrusion | Covalent | Photopolymerization | NA | Cartilage | [136] | |
| Gelatin methacrylamide (10 w/v%) | Extrusion; Light | Covalent | Enzymatic reactions; Photopolymerization | NA | Fibroblast | [61] | |
| Silk | Monolithic (up to ~30 wt%) | Extrusion | Physical | Aqueous salt bath | 117 MPa (wet) 2 GPa (dry) | Vessel | [40] |
| Monolithic (up to ~30 wt%) | Extrusion | Physical | Methanol bath | 5.6 GPa | Bone | [83] | |
| Monolithic (16 wt%) | Extrusion | Covalent | Enzymatic reactions | 150 – 320 kPa | Meniscus | [211] | |
| Methacryloyl-modified (up to 30% w/v) | Light | Covalent | Digital micromirror device | 15 kPa (Tensile); 40 kPa (Compressive, 20% strain) | Brain; cartilage | [237] | |
| Monolithic (up to 2 wt%); Composite (Gelatin) | Extrusion; Light | Covalent | Photopolymerization; Rheology additives; Sacrificial templates | ~400 kPa | Cartilage | [239] | |
| Monolithic (Hydrogel) | Extrusion | Physical | Amino acid sequence | 0.21 kPa | Fibroblast | [49] | |
| Composite (PEG) | Extrusion | Physical | Rheology additives | NA | Fibroblast | [225] | |
| Composite (glycerol; Gelatin) | Extrusion | Physical | Rheology additives | 1.4 kPa | Bone | [216] | |
| Composite (GelMA; PEGDMA) | Extrusion; Light | Physical; Covalent | Photopolymerization; Enzymatic reactions | ~40 kPa | Heart | [243] | |
| Composite (Fibrin/Gelatin) | Extrusion | Physical; Covalent | Rheology additives | ~16 kPa | Cartilage | [217] | |
| Composite (Gelatin) | Extrusion | Physical | Rheology additives | ~70 kPa (Compressive, 20% strain) | Cartilage | [218] | |
| Fibrin(ogen) | Monolithic (ca. 1mg/ml) | Extrusion | Physical | Ionic bonding | NA | Skin | [253] |
| Composite (Alginate; Methylcellulose) | Extrusion | Physical | Rheology additives | NA | Bone | [255] | |
| Composite (PCL; PLCL) | Extrusion | Physical | Structural enhancement | 1 MPa | Urethra | [252] | |
| Composite (Hyaluronic acid; Polyvinyl alcohol) | Extrusion | Physical; Covalent | Rheology additives; Enzymatic reactions | NA | Nerve | [254] | |
| Composite (Furfuryl-gelatin) | Extrusion; Light | Covalent | Photopolymerization; Rheology additives; Enzymatic reactions | NA | Heart | [286] | |
| Composite (PEG; alginate) | Extrusion | Physical; Covalent | Ionic bonding; Enzymatic reactions; Photopolymerization | Ca. 0.9 – 3 MPa | Cartilage | [257] | |
| Composite (Gelatin) | Extrusion | Physical; Covalent | Heating; Enzymatic reactions | 1 kPa | Vessel | [251] | |
| Keratin | Monolithic (up to 6% w/v) | Light | Covalent | Photopolymerization | ~15 kPa | Fibroblast | [113] |
| Composite (Lignin; guar gum; glycerol) | Extrusion | Physical | Rheology additives | NA | NA | [268] | |
| Soy | Composite (glycerol; dithiothreitol) | Extrusion | Covalent | Rheology additives | 1 kPa ~4 kPa (EDC crosslinking) | NA | [272] |
| Composite (polyurethane) | Extrusion | Physical; Covalent | Rheology additives | NA | Fibroblast | [270] |
GLU: glutaraldehyde; EDC: 1-ethyl-3-(3 dimethylaminopropyl) carbodiimide; PEGDMA, Poly(ethylene glycol) diacrylate.