Page 46 - IJB-10-4

International Journal of Bioprinting 3D bioprinting in otorhinolaryngology

construct restores its characteristics and cell activity. and downstream effects were evaluated based on the
106
The artificial structure generated by 3D bioprinting should different dispensing head speeds and temperature.
114
also be non-toxic to tissue cells with sufficient strength to In summary, an ideal bioink should be in a
support the defective tissue for a specific period before liquid state before bioprinting and uniformly distributed
gradually degrading and allowing the regenerated cells to in the cell suspension. Crosslinking should also occur
restore function via anastomosis. This section reviews the immediately after bioprinting to form a stable shape. In
printability, biodegradability, and mechanical properties addition, some factors, including mechanical properties,
of bioinks. cell survival rate, bioprinting temperature, bioink
4.1. Printability viscosity, and heat preservation time, are related to bioink
115
Otorhinolaryngology-related experiments and clinical printability. Future research should focus on achieving
applications often involve the production of tissues high printability without compromising other bioprinting
with different shapes and fine structures. Printability properties to improve the overall bioprinting quality and
determines the application of printed products, but it can obtain ideal bioprinting products.
be affected by many factors, such as printer parameters 4.2. Biodegradability
and bioink properties. 107,108 The successful construction of The implanted bioinks in the body are gradually
a bioprinter requires a certain degree of bioink printability, absorbed or dissolved into the surrounding tissues.
which is affected by droplet size, bioprinting speed, and Small biomolecules generated by absorption can regulate
moving distance. Therefore, the selection of an appropriate the microenvironment, induce cell proliferation and
bioprinting strategy is crucial to bioprinting. With the differentiation, and adapt to tissue growth. Compared
109
need to build constructs with a high degree of precision, with other disciplines, the anatomical structures in the
high print fidelity and resolution are required, making head and neck region have more precise environmental
it necessary to optimize high-resolution bioprinting requirements. Consequently, bioinks should have
parameters. For example, bioink viscosity can be regulated good biodegradability and not induce inflammation.
to improve the bioprinting resolution and avoid print Simultaneously, during the degradation process, the
nozzle clogging. In a laser-induced forward transfer biological stress of the materials can be transferred to
(LIFT) study, it was suggested that better print quality is new tissues, thereby stimulating tissue regeneration
associated with jet-impingement printing with a single while avoiding stress shielding and the risk of secondary
breakup. As the bioprinting distance increases, the surgery. Therefore, biodegradability should be optimized
bioprinting category may change from a single breakup in consideration of the duration of cell proliferation,
to multiple breakups with secondary droplet formation. differentiation, and tissue and organ repair.
Researchers have also observed that a high concentration
of cell ink often results in a higher viscosity, which is In recent years, numerous experiments have focused
associated with an extremely high cell survival rate. The on the challenges of tissue and organ repair and the
high-viscosity solution also produces a durable printed implementation of 3D bioprinting to circumvent these
structure, but the process requires a higher pressure flow, issues. However, head and neck tissue structures are
thereby limiting the size of the gauge and the minimum complex with different structures and functions (e.g.,
achievable print size. Different printer bioink viscosities soft tissues, bones, and cartilage). To optimize the
110
have different requirements, such as low-viscosity bioink biodegradation rate for a target tissue, researchers can
for inkjet printers. For a solution with a viscosity of 10 regulate several parameters, such as the type of material,
mPa·s, an extrusion printer requires at least 30–36 × 10 crosslinking conditions, and environmental factors.
116
7
mPa·s while a laser-assisted printer requires 1–300 mPa·s Silk contains two protein components: cellulose and
for optimal printing. 33,111-113 Therefore, there is a trade-off sericin. According to previous studies, silk-based scaffolds
between the precise control of a variety of parameters and reported higher mechanical strength than other natural
printability. Secondly, bioprinting processes often involve biodegradable polymer scaffolds, and the degradation rate
117
living cell bioink compositions, and in such cases, cell of silk-based scaffolds could be adjusted accordingly.
vitality also affects printability. Lee et al. proposed a 3D Additionally, the products of silk decomposition (e.g.,
bioprinting system consisting of a clean air workstation, glycine and alanine) can also be used as raw material for
118
humidifier, and Peltier system to improve the printability the synthesis of new proteins. Bradner et al. designed a
of hydrogels and increase cell viability. Researchers have bioabsorbable and drug-eluting silk-based ear tube device
also successfully fabricated ear-shaped, large-volume, for middle ear drainage in the treatment of otitis media
cell-printed constructs (LCCs) by bioprinting porcine ear effusion. At present, other ear tubes made of absorbable
chondrocytes. Furthermore, the line width of the hydrogel materials are limited by their rapid absorption and

Volume 10 Issue 4 (2024) 38 doi: 10.36922/ijb.3006