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International Journal of Bioprinting 3D-printed nanocomposites: Synthesis & applications

Table 1. Comparison of the four bioprinting approaches

Specification Inkjet Laser-assisted Light-induced Microextrusion-based Ref
Principle Electrical heating or Applying an energized pulsed UV-initiated curing Extrusion of pre-gel 29-39
piezoelectric actuation laser on target or ribbons and of the liquid photo- solution through a
being deposited over metal responsive materials on needle and build up
substrates. the build stage layer-by-layer
Resolution 85–300 μm > 5 μm > 25 μm 100 μm–10 mm
Gelation Fast; chemical Fast; chemical, photo- Fast; chemical, photo- Medium; chemical
crosslinking. crosslinking crosslinking crosslinking, shear-
thinning, temperature
Dispensing speed Fast (1–10,000 Medium-fast Fast, chemical Slow (10 μm–50 mm/s)
droplets/s) (200–1600 mm/s) crosslinking
Material viscosity 3.5–12 mPa·s 1–300 mPa·s 1–300 mPa·s 30–6 × 10 mPa·s
7
Cell density Low (<10 cells/mL) Medium, 10 cells/mL Medium, 10 cells/mL High, cell spheroids
8
8
6
Cell viability >85% >95% >90% 40–80%
Advantages • Low-cost, simple • High resolution • Low cost • Bioinks with wide
system • High cell viability • High resolution range of viscosity
• High resolution • Good vertical fidelity • Fast bioprinting • High cell density
• Fast printing speed speeds • Simple system
• High cell viability • High cell viability • Multiple composition
• Fair vertical fidelity • Feasibility
Disadvantages • Limited availability • Complex system • Moderately complex • Low to moderate cell
of bioinks with low to • Expensive system viability
medium viscosities • Medium bioprinting • Bioink limited to • Slow bioprinting speed
• Low cell density speed photo-polymerization • Moderate resolution
• Mostly applied to 2D • Medium on cell density crosslinking
• Medium on cell density

movement with a three-axis motion control system coaxial needles were first adopted by Ozbolat et al. in 3D
to build 3D layer objects. In the traditional extrusion- bioprinting to fabricate micro-fluidic channels. 40-42 The
based printing technique, the plastic filament is extruded bioink is injected through the exterior needle, while the
through a high-temperature extruder, and the melted crosslinking agent is extruded through the interior needle,
plastic solidified once extruded and quickly bound to leaving stand-alone perfusable vessels. The commonly
25
the previous layers. Microextrusion bioprinter with used bioink and crosslinking agent for coaxial printing
syringes was created based on the general concept of fused are alginate composite and CaCl solution. 41,43,44 Sacrificial
2
deposition modeling (FDM) printer. This strategy is very bioprinting, a “removable” bioink deposited in a matrix
popular in tissue engineering owing to its advantages via microextrusion bioprinting which was followed by
such as ease of operation, availability of inks with a wide matrix curing and sacrificial ink removal, 45,46 was first
47
range of viscosities, multiple crosslinking methods, and demonstrated by Wu et al. This method could be utilized
high cell loading density. 26-28 To create 3D architectures, for fabricating 3D interconnected wall-less channels. Similar
biomaterials are loaded into the syringe and extruded via a to sacrificial bioprinting, embedded extrusion bioprinting
pneumatical (Figure 1e) or mechanical-driven (Figure 1f) was developed to fabricate heterogeneous complex 3D
system. Inks with a viscosity between 30 mPa·s and 60 tissue with biomaterials in high resolution, 48,49 where the
14
kPa·s can be readily extruded via a pneumatic system, bioinks are extruded into a supporting matrix, composed
51
48
50
whereas high-viscosity bioinks of greater than 60 kPa·s of elastomer, viscous oil, granular gel suspension, or
52
can be better extruded via a mechanically driven system. A self-healing hydrogels, which is removed afterward.
systematic consideration should be given to the pressure, The supporting bath material should, in general,
movement speed, extrusion flow rates, needle size, and behave like Bingham plastic that is rigid at low shear
layer heights in order to ensure an optimal resolution.
forces but flexible when it reaches high shear stresses. 27,49
Inspired by the concept of using a coaxial spinneret Suitable yield stress smooths needle movement and
to fabricate hollow nanofilaments in electrospinning, supports printed constructions. Supporting bath yield

Volume 10 Issue 2 (2024) 83 doi: 10.36922/ijb.1637