Alginate Based Scaffolds for Cartilage Tissue Engineering: A Review

Utilization of Carbon Nanotubes in Manufacturing of 3D Cartilage and Bone Scaffolds

“…Such scaffolds were able to achieve physical characteristics comparable to the native tissues [ 104 , 145 ]. Due to the properties of CNTs, they were also tested for the scaffolds due to the following reasons: (1) their superior mechanical properties, with elastic moduli and tensile strength, far better than the other materials used [ 146 ]; (2) CNT size, shape, surface roughness, and surface area structurally mimics that of collagen fibers, providing a 3D network to support and guide cell proliferation, differentiation, and communication, which is not the case for the polymeric fibers, such as PCL [ 91 , 140 ]; (3) CNTs’ ability to interact with and adsorb extracellular proteins allows enhanced cell interaction and scaffold biocompatibility [ 110 ]; (4) CNTs offer increased cell support, which is important for angiogenesis and vascularization [ 147 ].…”

“…Therefore, synthetic and natural hydrogel-forming polymers turned out to be good candidates, because they possess all of those features [ 85 ]. PVA (polyvinyl alcohol) [ 86 ], PEG (polyethylene-glycol) [ 87 ], PLGA (polylactic-co-glycolic acid) [ 88 ], PLA (polylactic acid) [ 89 ], gelatin [ 90 ], alginate [ 91 , 92 ], collagen [ 93 ] and chitosan [ 94 ] have all been researched as a scaffold material for tissue engineering. These materials have the properties to support cell attachment and proliferation, especially osteocytes and chondrocytes [ 95 ].…”

“…Other research was conducted presenting good biocompatibility, cell proliferation, and extracellular matrix formation, however, Young’s modulus of as-prepared scaffolds are in the range of single to tens of kPa, which is not enough for articular cartilage and bone replacement [ 102 , 103 ]. CNTs, due to their mechanical and biological properties, are a perfect candidate to use as a reinforcing material, instead of plastic fibers like PCL and cellulose fibers [ 91 , 104 , 105 ].…”

“…However, the authors declare that the level of MWCNT-alginate crosslinking is low and it can be increased by introducing more –COOH groups as well as increasing the Ca 2+ ions’ concentration. This would resemble natural complex ECM interconnections more closely, which should result in much better mechanical properties [ 91 ]. Similar findings were published by Lau et al, who analyzed various concentration levels of chitosan and CNTs to compare the porosity in three-dimensional chitosan–CNT scaffolds.…”

In Vitro/In Vivo Evaluation of Sustained Release of Glucagon-Like Peptide-1 (GLP-1) from Nanocomposite Hydrogel to Induce Angiogenesis

“…Carboxylic acid groups are a proper site of amine binding. Therefore, the binding of proteins to alginate in order to enhance cell attachment of this material when it is used as a cell scaffold is favored by forming amide bonds [24,25]. Also, the ability of alginate to form a physical gel due to binding with divalent cations, such as calcium, makes it favorable in tissue engineering applications as an irreversible in situ formation of a gel [26].…”