Table 1.
An overview of commonly used natural, synthetic, and ECM-derived polymers in tissue engineering, along with frequently used fabrication methods, target tissues, and advantages/disadvantages.
| Polymer | Strength/Elastic Modulus | Fabrication Method | Target Tissue |
Advantage(s) | Disadvantage(s) | Notes: |
|---|---|---|---|---|---|---|
| Natural Polymers | ||||||
| Alginate | Hydrogel: <1 kPa to 1000 kPa [166] | Electrospinning; Hydrogels; Cryogels [167,168] | Bone; Cartilage; Ligament [167] | Biocompatible; Encapsulate cells [167,169,170,171,172]. | Lacks mechanical strength; Nondegradable unless ionically crosslinked; Slow degradation [166,167,169,171]. | Alginate gels are typically nanoporous (pore size ~5 nm), allowing for rapid diffusion of small molecules through the gel; Potential for drug delivery [167,173]. |
| Chitosan | Fibers: 3500 +/− 780 kPa Scaffold: 70 +/− 10 kPa [174] |
Hydrogel; Cryogel [150,175] | Bone; Cartilage; Ligament; Nerves [169,174] | Antimicrobial properties; Biocompatible; Chemically modifiable [169,176,177,178]. | Limited cell adhesion; Low mechanical strength [169,176,177,178]. | Has been reported to promote bone formation [179]. |
| Collagen I fiber | 100–2900 MPa [180] | 3D-printing; Electrospinning [181] | Bone; Cartilage; Ligament; Skin; Tendon [181] | Biocompatible; Major component of native ACL [169]. | Lacks mechanical strength; Immunogenic [169]. | The addition of hyaluronic acid can prolong degradation and serve as a delivery system for chondrocytes in cartilage tissue engineering [182,183]. |
| Gelatin | Scaffold: 10–100 kPa [184,185] | 3D-printing; Electrospinning; Hydrogels; Cryogels [150,186,187] | Bone; Cardiac; Ligament; Muscle; Skin; Tendon [188] | Biocompatible; Biodegradable; Cost-effective; Cell compatibility; Low toxicity [189]. |
No thermal stability; Poor mechanical properties; Short degradation rate [189]. | Gelatin is derived from collagen and can be used as a cost-effective substitute [188]. |
| Silk | 5–12 GPa for Bombyx Mori with sericin, 15–17 GPa without sericin [190] | Electrospinning; Hydrogel; Cryogel [191,192,193] | Bone; Cartilage; Ligament; Skin [169,174,194] | Good tensile strength [37,169]. | Limited cell adhesion; Sericin coating is immunogenic [37,169]. | Two main constituents: fibroins and sericin. Sericin, absent in spider silk, acts as a glue for the fibroin fibers and elicits an immune response. These constituents contain (varying) amounts of alanine, glycine, and serine [195]. |
| Synthetic Materials | ||||||
| Poly(caprolactone) (PCL) | 0.4 GPa; 3.2 MPa [169,180,196] | 3D-printing; Electrospinning; Gas Foaming [197,198,199] | Bone; Ligament; Soft and Hard Tissues [169,200,201,202] |
Common FDA-approved suture material; Easily manufactured [169]. | Biologically inert; Slow degradation rate (years) [14,169]. | Elongation at break 80%, Tg = −60 C, Tm = 60 C [196]. |
| Poly(diaxonane) (PDX) | 100,000,000 N/m2 = 0.1 GPa, 2–46 MPa [180,203] | Electrospinning [180] | Bone; Cartilage; Ligament [180] | Common FDA-approved suture material; Easily manufactured; Shape memory [169]. | Rapid loss of mechanical strength [169]. | PDX/50% Hydroxyapatite scaffolds allow for excellent scaffold mineralization for bone tissue engineering [204]. |
| Polyethylene terephthalate (PET) | 1.57–5.2 GPa [205] | 3D-printing; Electrospinning [206,207] |
Bone; Ligament; Tendon [208,209,210] |
Biocompatible; Biodegradable; High tensile strength; Stiffness [194,210]. | High crystallinity makes it difficult to print [210]. | Frequently made into meshes containing allografts/autografts, or meshes for hernia repair [211,212]. |
| Poly(glycolic acid) (PGA) | 7.0–10 GPa [213] | Electrospinning; Gas Foaming [214,215] | Cartilage; Skin [216,217] | Common FDA-approved suture material; Easily manufactured [169]. | Rapid degradation and loss of mechanical strength; Biologically inert; Acidic degradation byproduct [169]. | Frequently used in combination with other materials as coatings (ex. hyaluronic acid) [218,219]. |
| Poly(glycerol sebacate) (PGS) | 0.04–1.2 MPa [213,220] | 3D-printing; Electrospinning [198,213] |
Soft Tissue [201,213] | Biocompatible; Biodegradable; Cost effective; Flexible [213]. | Differences between in vivo and in vitro degradation [221]. | Fast degradation (6 mo in vitro) [213]. |
| Poly(3-hydroxybutyrate) (PHB) | 3 GPa [222] | Electrospinning; Salt Leaching; Solvent Casting [223] | Bone; Cartilage; Skin; Tendon; Nerves [194,223,224] | Biocompatible; Piezoelectric [223]. | Brittleness; Hydrophobicity; Low degradation rate [223]. | Often combined with 3 hydroxyvaleric acid (HV) to increase degradation rate and reduce crystallinity; elongation at break 2%; Tg = 1–2 C, Tm = 170 [194,196]. |
| Poly(3-hydroxybutyrate-co-3-hydroxy valerate) (PHBV) | Tensile modulus = 1100 MPa [196] | Electrospinning [225] | Cardiac; Cartilage; Liver; Nerve [225] | Biocompatible; Biodegradable; Low toxicity; Piezoelectric; Thermoplasticity [226,227]. | Hydrophobic; Low mechanical strength; Often requires additives to promote cell adhesion; Poor mechanical properties [226]. | Elongation at break 17%; Tg = 2 C; Tm = 145 C; Tensile strength = 20 MPa [196,225,228]. |
| Poly(lactic-co-glycolic acid) (PLGA) | 40.4–134.5 MPa [213] | Electrospinning [197] | Ligament; Vascular [169,197] | Degradation rate can be tailored by changing the ratio of PLA:PGA [14,169]. | Acidic degradation byproducts; Biologically inert; Reduce cell adhesion; Non-hydrophobic [14,169]. | Degradation rate of 32% weight loss observed at 5 weeks in vitro [213]. |
| Poly(L-lactic acid) (PLLA) | 1–4 GPa [213] | 3D-printing; Electrospinning [229] | Ligament; Neural; Hard and Soft Tissues [169,230] | Easily manufactured; Improved cell adhesion; Slow degradation rate [169]. | Acidic degradation byproduct; Biologically inert [169]. | Viscoelastic properties can be improved by using braid-twist method [169]. |
| Polyvinyl alcohol (PVA) | 48 +/− 3 GPa [231] | Electrospinning; Cryogels [232,233] | Bone; Skin [234,235] | Biocompatible; Good mechanical properties; Non-toxic [169,231]. | Low thermal stability [169,231]. | Young’s modulus and compressive strength increases with PVA concentration [236]. |
| ECM-Derived Polymers | ||||||
| Chondroitin sulfate | Hydrogel: 1.2–11.3 kPa [237,238] | Electrospinning; Hydrogel [237,239] | Bone; Cartilage; Neural; Skin [240] | Biocompatible; Biodegradable; Readily available; Water soluble [240]. | Differences in material quality; Fast degradation; Low thermal resistance; Tunability Weak mechanical properties [240]. | Source: Joint, Nasal, and Tracheal cartilage. Support osteogenesis and suppress bone resorption [241,242,243,244]. |
| Elastin | Bovine ligament: 1 MPa [245] | Electrospinning [246] | Ligament; Skin [247,248] | Provides elasticity, resiliency, cell adhesion and growth; Artificial forms are available [247]. | Difficult to purify; May stimulate an immune response [249,250]. | Source: Aorta. Used in scaffolding for cell generation therapy; Elasticity provides the necessary mechanical cues for maintaining and expanding hematopoietic stem cells [249,250]. |
| Fibronectin | Fibers: 1–15 MPa [251] |
Electrospinning; Hydrogel [249,252] | Bone; Dental Tissue [253] | Promotes cell adhesion, migration, spreading, and proliferation; Wound healing [247,253]. | Decreased cell viability; Insufficient cell-anchorage cues [252]. | Source: Plasma; Promote cell adhesion and control cellular function via peptide domains. Angiogenic differentiation [249,254,255,256,257]. |
| Heparin/Heparan Sulfate-Derived | Hydrogel: 2.3 kPa [258] | Hydrogel [258] | Bone; Cartilage; Neural; Vascular [258,259,260,261] | Anticoagulant; Anti-inflammatory [127,259,262,263]. | Human umbilical vein endothelial cells (HUVEC) metabolic activity is sensitive to heparin (negatively impacted at 10 and 1000 μg/mL) [261]. | Excellent matrix for in vitro culture of articular chondrocytes; Facilitate interactions at cell surface receptors [258,264]. |
| Hyaluronic acid | Hydrogel: 200 kPa [265] | Bioprinting; Electrospinning; Hydrogel; Cryogel; Salt Leaching [266,267] | Bone; Cartilage; Skin [268,269,270,271] | Chemically modified (crosslinked) to improve viscoelastic properties [268]. | Poor biomechanical properties (viscoelasticity and half-life); Pure hydroxyapatite (HA) gel does not permit adhesion [268,272]. | Source: Rooster comb, Umbilical cords, Vitreous humor. The HA-based hydrogel can maintain morphology of chondrocytes [266,267,273,274]. |
| Laminin | Fiber: (blended with PCL) 21.83 kPa | Electrospinning [275] | Nervous System; Skeletal Muscle; Vascular [276] | Biomaterial enrichment; Cell adhesion, differentiation, migration, and wound healing [247]. | Difficult to synthesize long peptides and mimic structure [277]. | Source: Heart, Placenta. Provide basement membrane-like scaffold. Participate in biological process (angiogenesis and neural differentiation) [249,275,278,279]. |