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Zhang, et al.
A B

C

Figure 1. Fabrication of bioconstruct through the composite forming technology by combining extrusion printing with dynamic crosslinking.
(A) Complex hierarchical construct made by the integrated system combining melt extrusion and singularization printing (from ref.
[22]
licensed under Creative Commons Attribution 3.0 license). (B) Meniscus printing based on the extrusion of bioink containing polylactic
acid (PLA) fibers, human adipose-derived stem cells, and alginate, and crosslinking by CaCl (Reprinted with permission from Narayanan
2
LK, Huebner P, Fisher MB, et al., 2016, 3D-Bioprinting of Polylactic Acid (PLA) Nanofiber–Alginate Hydrogel Bioink Containing hASCs.
ACS Biomater. Sci. Eng., 2(10):1732–1742 . Copyright © 2016 American Chemical Society). (C) Vascular structure formed by stacking
[27]
pre-crosslinking alginate patterns and subsequently enhanced by adding Ba (from ref. licensed under Creative Commons Attribution
2+
[28]
3.0 license).
the glioma model prepared by this method could mimic 2.2. Combination of electrohydrodynamics and
the glioma microenvironment and had enhanced drug extrusion printing
resistance .
[30]
In summary, the integration of dynamic crosslinking Electrohydrodynamics refers to the dynamics of
means is an important driving force for the development electrically charged fluid, which constitute the basis of
of extrusion printing technology; especially, the electrospinning, material jetting, and electrostatic direct
combination of coaxial extrusion printing and materials writing. The process of electrospinning, electrospray,
with ionic crosslinking properties gives great advantages or electrostatic direct writing is achieved similarly by
in the construction of vessel-like structures. Compared applying a voltage between the nozzle and the receiving
with the existing two-dimensional lamellar microchannel plate. However, due to different material properties, the
manufacturing technology, this method has obvious resultant forces formed on the charged fluid surface are
advantages and potentials in the integration forming different, resulting in different shapes of material after
process with living cells. Besides, the vessel-like constructs they leave the nozzle.
made by this method can better mimic the tubular structure Compared with other methods, electrospinning
and is more convenient for 3D bioprinting. In addition, is more widely used to fabricate tissue engineering
the aforementioned dynamic crosslinking technology scaffolds because the structure made by electrospinning
usually achieves various degrees of crosslinking in the resembles ECM. However, the electrospinning structure
whole extrusion printing process through online control of does not have enough mechanical properties and cannot
process parameters or dynamic adjustment of the external form a 3D structure with a certain thickness; therefore,
physical field. Hence, this kind of method accords with many researchers start to combine electrospinning
the characteristics of the above-mentioned 3D composite with extrusion printing. Besides, some of the research
bioprinting. results pointed out that electrostatic direct writing can

International Journal of Bioprinting (2021)–Volume 7, Issue 1 9