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

Figure 6. Development of 3D bioscaffolds with macroporous and interconnect microporous morphology from bicomponent ink containing NFC and
CMC via the combination of DIW 3D printing, freeze-drying and DHT techniques.

after DHT. Therefore, this technique may inspire pore size 3.4. HEC
adjustment and mechanical property improvement of Owing to its excellent shear-thinning behavior and
cellulose-based scaffolds. outstanding rheological properties , along with its
[93]
biocompatibility, HEC is often used as an additive in
3.3 Hydroxypropyl methylcellulose bioengineered inks to meet the bioprinting requirements.
Hydroxypropyl methylcellulose (HPMC) is also a Li et al. added HEC to several bio-inks with different
cellulose ether derivative; however, it is available in crosslinks to evaluate its effects on the fidelity, degradation,
different substitution types with limits on methoxy and rheology of bio-inks . The results show that HEC
[94]
[87]
and hydroxypropoxy groups . These groups provide can improve the fidelity of these bio-inks without affecting
various characteristics, including flexibility, hydration, their crosslinks. In addition, HEC improves the LCST of
gelation temperature, and LCST behavior. Moreover, in the gel, enabling 3D bioprinting at near body temperature.
medical engineering, HPMC is mainly used as a material HEC increases the swelling rate to ensure a water-rich
for encapsulating drugs or as an ink tackifier in TE environment in the scaffold for increased cell activity and
[88]
scaffolds . Götz et al. prepared degradable bone implants nutrient delivery. Therefore, HEC can be used to modify
[89]
using extrusion-based 3D printing with HPMC and bio-inks in several ways. Maturavongsadit et al. prepared
[89]
calcium magnesium phosphate polymers . The addition cell-laden nanocellulose/CS-based bio-inks for 3D
of HPMC increased the viscosity and shear-thinning bioprinting . The authors added HEC as a gelling agent
[31]
behavior of the ink. Ni et al. integrated SF and HPMC for to the CS-NCC bio-ink to improve its gelation kinetics.
printing a bone marrow MSCs-laden DN hydrogel for The glyoxal groups in HEC interact with the amine group
cartilage tissue repair . The β-sheet structure between of CS via covalent crosslinking through the Schiff’s base
[90]
SF molecules is formed via low-power ultrasonication of reaction . With the addition of HEC, the gelation time of
[95]
SF and acts as the rigid first network, whereas the HPMC- this hydrogel was significantly reduced without affecting the
methacrylate anhydride (MAn) crosslink acts as the biocompatibility of the 3D-bioprinted bone tissue scaffold.
soft second network. HPMC modified with MA forms a
tight bond between SF and HPMC-MAn because of the 4. Conclusion and outlook
exposure of more hydrogen bonds that interact with the
β-sheet. Simultaneously, the presence of HPMC has a In this review, we focus on the applications of nanocellulose
[91]
synergistic effect on the gelation of SF . This DN hydrogel and cellulose derivatives in 3D bioprinting for bone and
combines the advantages of the two different hydrogels cartilage TE. As it meets the basic requirements of bio-inks and
and has good mechanical properties . Moreover, loaded is easily modified, nanocellulose has been widely used in 3D
[92]
bone marrow MSCs have high activity and proliferative printing. T-NFC modified by TEMPO oxidation has a good
tendencies. At the same time, high expression of cartilage- nucleation effect on hydroxyapatite and is suitable for bone
related genes, such as high mobility group-box gene9 (Sox TE, while the anionic carboxylic acid group in T-NFC can
9) and collagen type II (Col II), was detected. form ionic crosslinks with cations to enhance the mechanical

Volume 9 Issue 1 (2023)olume 9 Issue 1 (2023)
V 223 https://doi.org/10.18063/ijb.v9i1.637