Page 124 - IJB-9-1

International Journal of Bioprinting Fabrication of 3D breast tumor model for drug screening

Table 1. Parameter of 3D bioprinting with different bioinks
Gelatin (wt%) Alginate dECM Thickness Space (mm) Temperature Pressure Speed (mm/s)
(wt%) (wt%) (mm) (°C) (MPa)

4G2S1d 4 2 1 0.2 0.7 10 0.17 5
4G3S1d 4 3 1 0.2 0.7 15 0.15 10
5G3S1d 5 3 1 0.2 1.0 20 0.20 8
6G3S1d 6 3 1 0.2 1.0 20 0.20 8
7G2S1d 7 2 1 0.2 1.0 24 0.24 8

decellularization was evaluated, and it was found that when Due to the addition of high concentration of Matrigel, the
the water droplets contacted the dECM surface at 0 s, 0.5 s, latter showed higher energy storage and loss modulus at
and 1 s, the water contact angles were 81.16 ± 4.09°, 80.35 the same temperature. The structure and properties of
± 2.47°, and 78.05 ± 1.34° (Figure 1F). The water angle collagen fiber are determined by the electrostatic force
decreased with time, indicating that the material showed and hydrophobic interaction between adjacent collagen
strong hydrophobicity. The dECM water contact angle molecules. With the increase of temperature or pH, the
obtained by Li et al. from porcine lung was 82°, which hydrophobic interaction and electrostatic attraction of
[49]
was similar to that of pig liver dECM in this study. In order amino acid side chains in collagen fiber are strengthened,
to enable cells to better exchange nutrients and metabolites so the collagen fiber stiffens and the material changes
with liquid medium, modification was required to make from fluid state to gel state . The storage modulus (G’) of
[51]
dECM more hydrophilic. the three bioinks changed more obvious with the higher
concentration of gelatin from 40 to 10°C, among which
3.2. Printability analysis 7G2S1d increased from 56.2 Pa to 1844.2 Pa, and 6G3S1d
Different concentrations of bioinks were prepared, and 5G3S1d increased from 52.4 Pa and 6.3 Pa to 1321.0 Pa
and in order to evaluate whether the bioinks meet the and 704.0 Pa, respectively. The G’ of the two bioinks with
requirements of 3D printing, these bioinks were pre- 4% gelatin increased the least, which increased from 1.5 Pa
bioprinted. The concentrations of bioinks and printing and 3.1 Pa to 194.4 and 356.7 Pa, respectively, so the G’
conditions were shown in Table 1. With the increase of change is related to the gelatin concentration. The higher
bioink concentration, the required printing temperature the gelatin concentration, the greater the storage modulus
and pressure also had to increase accordingly, otherwise change.
it may lead to disconnection during bioprinting, failing to Figure 2B showed the viscoelasticity of several bioinks,
meet the requirements of scaffolds for tissue engineered which was the comprehensive change of elasticity and
models. In addition, the higher the concentration of gelatin viscosity of materials during the fluidization process.
and sodium alginate in the bioink, the higher the resolution Storage modulus (G’) represented elasticity and loss
of the printed scaffold under suitable conditions; this was modulus (G”) represented viscosity. When the two curves
attributed to the high viscosity of these two materials. intersect, it indicates that the material has undergone
When the gelatin concentration in the bioink was less fluidization or gelation. The energy storage modulus of
than 5%, it was difficult to mold under similar printing the materials in the figure was always higher than the
conditions, and the resolution of scaffold was low and loss modulus because the externally applied energy of the
easy to collapse, which was consistent with the results of fluid was stored and converted into repulsive force during
rheological properties.
the process of the fluid changing from gel state to solid
In addition to pre-bioprinting, rheological properties state . The storage modulus of the material with high
[52]
of bioinks were also tested for further investigation of concentrations could reach more than 10000 Pa and the
printability, and the results were shown in Figure 2. highest could reach 66907 Pa, while the storage modulus
Temperature sensitivity is the property that storage of 4G2S1d was 1036.3 Pa. No intersection point was seen
modulus (G’) of fluid changes with temperature. As between the two curves, indicating that the elasticity of
shown in Figure 2A, the gel points of several bioinks the material was greater than viscosity within the test
were all around 20°C, which was mainly attributed to the range, and no fluidization phenomenon occurred during
temperature sensitivity of gelatin. The change trend was the process. The higher the elasticity of the system was,
the same as the temperature sensitivity of the gelatin/ the more difficult the material was to fluidize, and the less
[50]
sodium alginate/Matrigel bioinks prepared by Mao et al. possible the printed scaffold would deform.

Volume 9 Issue 1 (2023) 116 https://doi.org/10.18063/ijb.v9i1.630