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International Journal of Bioprinting Extrusion-based biomaterial inks

expanded by integrating it with organ-on-a-chip [1,2] and can be engineered by using multi-nozzle extrusion-based
organoids biofabrication . One representative work is that bioprinting [7-9] . Extrusion-based biomaterial inks, including
[3]
Grigoryan et al. fabricated a lung model with established natural derived and synthetic polymers or their blends, have
multivascular networks and functional intravascular a wide range of viscosities, ranging from a minimum of
topologies by bioprinting with biocompatible hydrogels . 30 mPa·s to a maximum of 6 × 10 mPa·s .
[10]
7
[4]
In another report, an engineered heart with cardiac Biomaterial ink plays the role of extracellular matrix
ventricles, a product of co-bioprinting of collagen with (ECM) by providing mechanical support for cells and
cardiomyocytes, showed remarkable performance of regulating their physiological activities. The selection
synchronized contractions and directional action potential of suitable biomaterial ink is an important aspect of
propagation . The core of bioprinting is the bioink, which bioprinting, and it is necessary to comprehensively
[5]
is the combination of living cells and biomaterial inks consider the printing conditions and the functional
stored in a bioprinter cartridge . The bioink determines requirements of the tissue constructs. Once the specific
[6]
the shape and function of printed constructs, which is cell sources and tissues or organ types have been decided,
closely related to the structure and function similarity different aspects of biomaterial ink should be taken into
of biomimetic tissue. The ideal bioinks require good full consideration, such as bioactivity, biodegradability,
bioactivity and printability as well as corresponding printability, mechanical properties, and impact on the
mechanical properties for 3D construction of tissue. performance of bioprinted 3D constructs. There have
According to the working principle of bioprinter, been some reviews on bioinks [11-13] and extrusion-based
traditional bioprinting technologies can be classified into bioprinitng [14-17] ; for example, Panwar et al. reviewed
four types: inkjet bioprinting, laser-assisted bioprinting, bioinks for microextrusion-based bioprinting and focused
digital light processing, and extrusion-based bioprinting. on their printability . Recently, a systematic review
[18]
Among the existing bioprinting modalities, extrusion- introduced the candidate of bioinks for extrusion-based
based bioprinting is one of the most widely used bioprinting bioprinting . The lack of ideal bioinks presents a major
[19]
technology with greatest flexibility to construct large challenge to extrusion-based bioprinting technology.
scale tissues and in situ tissue or organ. The advantages However, there are a few systematic reviews that focused
of extrusion-based bioprinting include low cost, simple on extrusion-based biomaterial inks and their property,
equipment, universality of biomaterials, and living cell- classification, modification, and selection strategy.
friendliness and compatibility, etc. Extrusion-based In this review, we systematically explain the properties
biomaterial inks (Figure 1) are biomaterial inks that can of extrusion-based biomaterials inks, including
be extruded through the printing nozzle, and exhibit biocompatibility, biodegradability, mechanical strength,
continuous filaments form during bioprinting process. printability, solidification formability, molecular
Various biomaterials are compatible with extrusion-based permeability, and bionic bioactivity (Figure 2). Then,
bioprinter, such as biocompatible hydrogels, copolymers, and we detail the advantages and usable ranges of many
cell spheroids, thus multi-material complex 3D constructs

Figure 1. Definition of extrusion-based biomaterial inks. Figure 2. Performance of extrusion-based biomaterial ink.

Volume 9 Issue 2 (2023) 2 https://doi.org/10.18063/ijb.v9i2.649