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International Journal of Bioprinting Bioprinted tissue-on-a-chip in drug screening

Figure 4. Diagrams of 3D bioprinting technologies with different mechanisms: (A) inject-based bioprinting, (B) light-assisted bioprinting, (C) extrusion-
based bioprinting. Abbreviations: SLA, stereolithography; DLP, digital light processing.

3.2.3. Extrusion-based bioprinting and substance diffusion, which further influence whether
Most heterogeneous tissue or organ models with inoculated or encapsulated cells in 3D constructs can
relatively larger volumes and vascularized models with survive during cultivation and mature with tissue specificity.
inner circulation structures are printed by extrusion- Nevertheless, focusing on bioink cannot solve the diffusion
based bioprinting. This technique enables the printing problem completely in extrusion-based bioprinting since
of bioinks with a wider range of viscosities compared to simple bioink diffusion contributes to the extremely uneven
inkjet-based bioprinting. Prepared bioinks are usually distribution of matters due to spatial distance.
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extruded as continuous filaments, which influence the Artificial vessels generated with endothelial cells that are
performance of the bioprinted microarchitectures (Figure constructed by conventional extrusion-based bioprinting
4C). Printability, referring to the ability of bioinks to technology are not only disordered and unpredictable, but
maintain the integrity and reproducibility of bioprinted also unable to reflect the effect of blood flow on tissues.
constructs, is mainly evaluated by mechanical properties 3D bioprinting has the potential to fabricate vasculature
relevant to filament collapse, wastage, storage modulus with high biomimicry and even the infused property.
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tests, as well as biological correlations. There is an inverse New strategies based on extrusion-based bioprinting
relationship between mechanical property and biological have been developed, such as coaxial bioprinting and
relevance in 3D constructs agglomerated by bioink. High embedded bioprinting. In coaxial bioprinting, the bioinks
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mechanical properties lead to the obstruction of substance with the crosslinking solution as the core and the alginate
diffusion, which is important for nutrient delivery and drug as the outer shell were printed simultaneously to form
screening. Bioinks with various physical properties showed tubular vessels. In another example, two small adjacent
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different biological correlations by regulating cell adhesion nozzles were embedded into the printing nozzle in coaxial

Volume 10 Issue 3 (2024) 182 doi: 10.36922/ijb.1951