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International Journal of Bioprinting Cellulose-based bio-inks for bone and cartilage TE

Table 2. A summary of nanocellulose based bio-inks for 3D bioprinting applications in bone and cartilage TE
Bio-ink formulation 3D bioprinting 3D bioprinting patterns Bio-ink and scaffold properties Effect on cell-loaded bio-ink Ref.
method
NFC/Alg/poly Extrusion-based 3D-printed grids • Increased ink viscosity • Up to 90% cell activity after [15]
(2-ethyl-2-oxazoline) 3D printing (20 × 20 × 0.4 mm ) • Shear thinning 21 days of cell encapsulation
3
• Quick shear recovery
• Increased mechanical strength
NFC/Alg/polydopa- Extrusion-based A grid structure • Increase of ink viscosity • Enhanced metabolic activities [22]
mine nanoparticles 3D printing (20 mm × 20 mm, • Shear thinning • Higher expression of
6 layers) • Enhanced recovery rate osteogenesis-related genes
• Increased mechanical strength
NCC/CS/HEC/ Extrusion-based Solid cylindrical scaffolds • Increased ink viscosity • Higher expression of osteo- [31]
glycerophosphate 3D printing (8 mm diameter × 2 mm • Increased mechanical strength genic markers
thickness) • Enhanced mineral deposition
• Enhanced ALP activity
Nanocellulose blends Extrusion-based Square grids (40 × 40 × • High-porosity structure • Maintenance of the round [37]
(NCB) 3D printing 1.7 mm , a single layer) • Higher stability and fidelity chondrogenic phenotype
3
• Facilitates chondrocyte • Increased cell viability
adhesion • Enhanced metabolic activities
3
Aqueous counter col- Extrusion-based A grid (5 × 5 × 1 mm ) • Outstanding printability • Enhanced chondrocyte [51]
lision (ACC)-BNC 3D printing • Mechanical stability proliferation
• Structural integrity • Increased deposition of
• High water-binding capacity glycosaminoglycans
BNC/silk fibroin/ Extrusion-based Small grids (10 × 10 × • Increased print resolution • Increased cell viability [52]
gelatin 3D printing 0.4 mm , 2 layers) / large • Enhanced mechanical • Enhanced cell adhesion, pro-
3
grids (20 × 20 × properties liferation, and differentiation
0.6 mm ,15 layers) • Improved pore connectivity
3
printability. Additionally, NFC is similar in size to collagen scaffold gives a high print resolution while maintaining the
fibers, so NFC-based scaffolds have unique advantages in viability of the cells in the ink (avoiding shear damage).
cartilage regeneration . Given that chondrocytes exhibit In addition to having 3D structures with high shape
[12]
high cell viability in Alg inks , their low ink viscosity limits integrity after double crosslinking, the DN-NFC bio-ink-
[13]
their development in 3D bioprinting. Therefore, many printed cartilage constructs loaded with human auricular
researchers have mixed NFC with Alg to compensate for chondrocytes (hACs) also showed up to 90% cell activity
its low zero-shear viscosity for cartilage repair. Markstedt after 21 days of cell encapsulation. Therefore, we are aware
et al. prepared NFC-Alg bio-ink for cartilage TE with that the NFC characteristics are not affected by these
[14]
high print resolution and fidelity, which combines the sophisticated multiple crosslinks.
rheological characteristics of NFC with the crosslinking The sulfated version of Alg has recently received
capabilities of Alg. Despite cell loss on scaffolds filled with increased attention because of its ability to bind a variety
human nasal chondrocytes (hNCs) as a result of shearing of growth factors and promote chondrocyte proliferation
during printing, after 7 day of culture, the cell survival rate and collagen II deposition . Müller et al. added NFC to
[17]
was considerably improved. Trachsel et al. created double alginate sulfate to increase the printability and mechanical
network (DN) polymer hydrogels employing Alg and poly strength of the bio-ink and bioprinted NFC-alginate
(2-ethyl-2-oxazoline) (PEOXA) . DN usually consists sulfate bio-inks loaded with bovine chondrocytes . As
[15]
[18]
of a primary covalent cross-linked network that provides expected, the addition of NFC significantly improved
elasticity and a secondary non-covalent cross-linked the printability of alginate sulfate without affecting its
network that provides ductility; therefore, DN tends to osteogenic properties.
have high strength . PEOXA-Alg hydrogels can sequester
[16]
living cells after enzymatic and ionic crosslinking to form In clinically applicable in vivo investigations, NFC-
DN. In addition, NFC can be added to the DN solution Alg composite hydrogel scaffolds have shown remarkable
to enhance the viscosity and shear-thinning. With the cartilage-promoting characteristics. Apelgren et al.
addition of NFC, the viscosity of the ink increases, while implanted 3D-bioprinted constructs (5 × 5 × 1.2 mm),
the bio-ink displays quick shear recovery characteristics. which was prepared using three sets of NFC-Alg bio-
This rapid shear recovery is also the reason why the NFC inks loaded with hNCs, human bone marrow-derived

Volume 9 Issue 1 (2023)olume 9 Issue 1 (2023)
V 214 https://doi.org/10.18063/ijb.v9i1.637