TABLE 1.

Characteristics of the outlined natural polymers for CTE.

Biomaterials	Characteristics	Advantages	Disadvantages	References
Chitosan	Originating from chitin; Linear natural carbohydrate biopolymer; Free amine groups in its backbone chain; Slower degradation rate	Biodegradability; Biocompatibility; Non-antigenicity; Adsorption capabilities; Antimicrobial activity; Promoting chondrogenesis	Low solubility; Low mechanical strength	Keller et al. (2017), Giuliani (2019), Sultankulov et al. (2019)
Collagen	Important part of natural cartilage organic materials; One of the most abundant proteins in humans and a major component of extracellular matrix	Biocompatibility; Low immunogenicity; Biodegradability; Promoting chondrogenesis; Facilitation of cell ingrowth and remodeling; Easy processing	Low solubility; Low mechanical strength; Rapid biodegradation rate	Lee et al. (2001), Kuroda et al. (2007), Turk et al. (2018), Li L. et al. (2019), Marques et al. (2019)
Silk	Extracted from Bombyx mori cocoon; A biocompatible material found as the core of a structural protein fiber;	Excellent mechanical properties; Biocompatibility Controlled biodegradability; Lower infection risk; Easy processing;	Delayed hypersensitivity; Initiator of immune reactions;	Zhang et al. (2010), Wang et al. (2011), Ma et al. (2018), Bharadwaz and Jayasuriya (2020)
Alginate	Produced from the cell wall of brown algae; Polysaccharide with negative charge; A cell-friendly gelation	Low immunogenicity; Biocompatibility; High abundance resources; Low prices; Regulation of the inflammatory chemokines; Good chondrogenic potential	Low biodegradability; Poor adhesion	Cho et al. (2009), Arlov et al. (2014), Park and Lee (2014), Filardo et al. (2018), Li L. et al. (2019)
Hyaluronic acid	A disaccharide unit; Abundant in the human body, present in the ECM of the skin, cartilage, and lenses	Biocompatibility; High hydrophilicity; Nontoxicity; Elasticity; Anti-inflammatory	Low mechanical properties; Rapid enzymatic degradation	Collins and Birkinshaw (2013), Gupta et al. (2019), Li L. et al. (2019), Zheng et al. (2019)
Gelatin	Obtained from native collagen via hydrolysis; An ideal carrier of proteins, growth factors, and so on	Biocompatibility; Biodegradability; High water-solubility; Cell adhesion	Poor mechanism properties	Larsen et al. (2006), Li F. et al. (2017), Echave et al. (2019)
Platelet-rich fibrin	Derived from platelet-rich plasma; Second-generation platelet concentrate containing abundant growth factors	Greater quantities of growth factors; Outstanding handling and storage traits; Low prices; Easy preparation	Poor mechanism properties	Miron et al. (2017), Wong et al. (2017), Wu et al. (2017), Barbon et al. (2019)
Cellulose	Durable, fibrous, and water-insoluble substance from plant cell walls	Biodegradability; Biocompatibility; Outstanding mechanical properties; Non-toxic Low prices; Natural abundance	Poor mechanism properties	O’Sullivan (1997), Hubbe et al. (2017), Isobe et al. (2018), Tayeb et al. (2018), Dutta et al. (2019)