Table 1.

Characterizations of the natural polymers used in tissue engineering.

Materials	Structure	Sources	Key Features	Ref
Chitosan	Linear polysaccharide	The shell of crustaceans (crabs, lobsters, shrimps, crayfish, and king crabs) as well as mollusks (e.g., squids), cuticles of insects, and cell walls of fungi	Second most abundant natural polymer, Biocompatible, Biodegradable, Bioadhesive, Biologically renewable, Antimicrobial, Hemostatic nature, Non-antigenic, Antioxidant, pH-sensitive	[27,28,29]
Alginate	Linear polysaccharide	Seaweeds and typically extracted from brown algae	Biocompatible, Biodegradable, Cytocompatible, Non-immunogenic, Mucoadhesive, Source abundance, Low cost, Water-soluble, pH-sensitive, in situ gelation	[30,31,32,33]
Starch	Composed of two kinds of polysaccharides, amylose, and amylopectin	The leaves of all green plants and in the seeds, fruits, stems, roots, and tubers of most plants and also in algae	Biocompatible, Biodegradable, Biorenewable, Low cost, Semicrystalline, High mechanical strength	[34,35,36]
Hyaluronic acid	Linear polysaccharide	A major macromolecular component of the ECM in the most connective tissues	Biocompatible, Biodegradable, Bioresorbable, Limited immunogenicity, Recognized by cell surface receptors, Flexible, Unique viscoelasticity	[37,38,39,40]
Chondroitin sulfate	Unbranched polysaccharide	A major component of ECM	Biocompatible, Biodegradable, Easily available, Immune-enhancing activity, Anti-inflammatory, Antioxidant, Antitumor, Anti-coagulation	[41]
Agarose	Liner polysaccharide	Marine red algae and also found as a support structure of cell wall for marine algae	Biocompatible, Non-immunogenic, Water solubility, pH-sensitive, Electro-responsive activity, Thermoreversible gelation behavior	[42,43]
Bacterial Cellulose	Linear polysaccharide	Microorganisms belonging to the Gluconacetobacter xylinum	Biocompatible, Biodegradable, High water-holding capacity, High mechanical strength, Porous structure, High crystallinity	[44,45,46,47,48]
Dextran	Branched polysaccharide	Lactic-acid bacteria	Biocompatible, Low cost, Easy to modify, Stable under mild acidic/basic conditions, Slowly degraded	[49,50,51]
Carrageenans	Linear polysaccharide	Marine red algae	Viscoelastic and gelling properties, Anti-inflammatory, Antitumor	[52]
Gellan gum	Linear polysaccharide	Sphingomonas elodea or Pseudomonas elodea bacteria	Minimal cytotoxicity, Ability to form hard and translucent gels which are stable at low pH, Thermally reversible gel in the presence of metallic ions	[53,54,55]
Xanthan gum	Branched polysaccharide	Xanthomonas bacteria	Biocompatible, Non-toxicity, Biodegradable, Stabile under a broad spectrum of pH, Shear-thinning	[56]
Heparin	Linear polysaccharide	Mucosal tissues such as the porcine intestine or bovine lungs	Antitumor, Anti-viral, Angiogenesis regulatory activities	[57,58]
Collagen	Fibrous protein	A major ECM component of most connective tissues within the mammalian body	Biocompatible, Biodegradable, Low-immunogenic, Hemostatic, High swelling ability, Low antigenicity, Capacity to facilitate cellular attachment	[59,60,61,62]
Gelatin	Protein	A hydrolysis derivative of collagen	Biocompatible, Biodegradable, Non-immunogenic, Elastic, Lower antigenicity, More accessible functional groups	[63,64,65,66]
Silk fibroin	Protein	Silkworms and spiders	Biocompatible, Biodegradable, Great mechanical properties, Versatile processability	[67,68,69,70,71]
Keratin	Polypeptide	A major component in nail, skin, hair, horns hooves, wool, feathers	Biocompatible, Biodegradable, Possesses cellular interaction sites Low-immunogenic, Intrinsic ability to self-assemble into three-dimensional structures	[72,73,74,75]
Fibrin	Glycoprotein	Fibrinogen	Biocompatible, Biodegradable, Ability of monomers to self-assemble into a gel	[76,77,78,79]
Elastin	Structural protein	A component in the ECMs of connective tissues (e.g., blood vessels, esophagus, skin)	Biocompatible, Biodegradable, Elasticity, Self-assembly, Long-term stability	[80,81]