3D printed agar/ calcium alginate hydrogels with high shape fidelity and tailorable mechanical properties

3D-Reactive printing of engineered alginate inks

“…For instance, the viscosity profiles as a function of the applied shear rate and shear stress are the main properties interpreted, by means of theoretical models, in terms of useful post printing features such as extrudability, stress distribution and capability to form self-standing fibers 22,24,25 . These techniques were used for a wide range of materials of artificial origin, such as PEG 26 and Pluronic F127 27 , but also of natural origin hydrogels like chitosan 28 , gelatin 29,30 , collagen 31 , alginate, 32 and composites 33,34 . Among the different inks that were proposed for 3D-printing, alginate assumes a position of relevance for different reasons.…”

“…Moreover, these approaches rely on the concept that the composition of the hydrogels should be adapted to fit the needs of the 3D-printing process. This results in the production and characterisation of a range of candidate compositions to be compared and tested in quest of the optimal formulation [34][35][36] . The 3D-printing of alginate solutions consists, typically, in ionic crosslinking the polysaccharidic chains by the presence of divalent cations in solution 32,[37][38][39] .…”

Biofabrication Strategies for Musculoskeletal Disorders: Evolution towards Clinical Applications

“…Synthetic bioinks have thus been used since the beginning of the biofabrication era. Key examples includes the use of Polyethylene glycols (PEGs) [ 63 , 64 , 65 , 66 ], Poly(vinyl alcohol) (PVA) [ 46 , 67 , 68 , 69 ], N-isopropylacrylamide (NIPAAm) [ 70 , 71 ], and polyacrylamide (PAAm) [ 72 , 73 , 74 ]. In this section, recent developments and clinical advantages of these materials are highlighted.…”

“…As seen in Figure 3 B, even structures that have washed away NIPAAm post printing demonstrate reduced viability around the pores where the sacrificial NIPAAm was deposited during printing. Additional examples of synthetic bioinks include PAAm blends that can be used to guide cellular growth with high accuracy and directional input [ 72 , 73 , 74 ]. This is an interesting concept as it allows users to align cellular growth and direct the interaction between neighboring cells, as seen in Figure 3 C. This ability may be of particular interest for musculoskeletal applications as the cellular and matrix orientation is very distinct across different zones within musculoskeletal soft tissues [ 83 , 84 , 85 , 86 ].…”

“…This is an interesting concept as it allows users to align cellular growth and direct the interaction between neighboring cells, as seen in Figure 3 C. This ability may be of particular interest for musculoskeletal applications as the cellular and matrix orientation is very distinct across different zones within musculoskeletal soft tissues [ 83 , 84 , 85 , 86 ]. Furthermore, the mechanical properties of PAAm can be tailored to facilitate soft–hard interfaces required within musculoskeletal regeneration [ 74 ]. This capability is highly important for musculoskeletal systems, which are comprised of three distinct tissue properties and the interfaces between them: (1) hard mineralised tissues, (2) soft muscular tissues, and (3) viscoelastic connective tissues [ 87 ].…”