Page 36 - IJB-6-1

Solvent-based extrusion 3D printing
cells. Ghosh et al. printed tissue scaffolds and
[33]
Reference [36] [13] microvascular networks using the DIW technique;
they fabricated a scaffold with a silk fibroin
HAVIC: Human aortic valve interstitial cells, PLA: Polylactic acid, MSCs: Mesenchymal stem cells, PCL: Polycaprolactone, HA: Hydroxyapatite, CNT: Carbon nanotubes,
solution ink; the extruded filament was deposited
in a methanol-rich reservoir for crystallization. In
Biological outcomes HA improved the bioactivity, there was good cell adhesion and spreading at the scaffold surface in vitro. The compressive modulus Supported cell viability and proliferation and induced osteogenic differentiation of hMSCs in vitro and rapidly integrated with the tissue in vivo. vitro studies suggest that the scaffolds supported
hMSC adhesion and growth as well as higher
chondrogenic differentiation under chondrogenic
conditions. Miranda et al. used the DIW
[34]
technique to produce scaffolds with precise
porous features using concentrated TCP and HA
inks with suitable viscoelastic properties. The 3D
printed ceramic scaffolds have shown promising

their application is limited due to their brittleness.
The incorporation of a polymer material with a
Scaffold characterization methods The compressive modulus of printed scaffolds with different CNT concentrations was evaluated by uniaxial compression testing. of printed scaffolds was evaluated by uniaxial compression testing. results for potential use in bone tissue repair;
ceramic ink is a promising approach to overcome
this limitation. The combination of polymer and
ceramic components can also mimic the organic
and inorganic components of natural bone tissue.
[16]
Printing process parameters No specific mentioned The print speed was 15 cm/s, and extrusion rates were as 275 cm 3 /h Sun et al. developed scaffolds composed of
a gradient array of silk/HA, which supported
the cocultures of hMSCs and human mammary
microvascular endothelial cells (hMMECs). The
histology results indicate that the hMSCs and

Cross- linking mechanisms Solvent evaporation Solvent evaporation hMMECs form intricate networks of extracellular
matrix within the 3D scaffolds.
Some synthetic polymers are not water-soluble
and must be mixed with organic solvents to form
solutions; these polymers can often provide

Ink rheology properties CNT concentration was adjusted to achieve an optimum viscosity between 2.5 and 7 Pa.s. The optimal viscosity of 30–35 Pa·s was reached. PLGA: Poly (lactic-glycolic acid), SBE: Solvent-based extrusion, TE: Tissue engineering, hMSCs: Human mesenchymal stem cells better mechanical strength than natural polymers.
Considering the toxicity of many organic
solvents, cells may not be incorporated within
synthetic polymer-laden inks. Several synthetic
polymers have been used in SBE 3D printing,

Ink materials PCL, HA, and CNT dissolved in dichloromethane PCL, PLGA, and HA particles mixed in dichloromethane. including polycaprolactone (PCL), polylactic acid
(PLA), poly (lactic-glycolic acid) (PLGA), and
their copolymers. Serra et al. used PCL and
[35]
bioactive CaP glass to fabricate 3D scaffolds with
orthogonal and displaced double-layer patterns.
Table 1. (Continued) SBE 3D printing types Pneumatic- driven based 3D printing Pneumatic- driven based 3D printing CaP glass particles exhibited increased roughness
Their results indicate that scaffolds containing

and hydrophilicity. The preliminary cell response
of these materials was studied with MSCs; this
study revealed that CaP glass improved cell
adhesion. Gonçalves et al. fabricated scaffolds
[36]
out of composites containing PCL, nano-HA, and

32 International Journal of Bioprinting (2020)–Volume 6, Issue 1