Page 242 - IJB-10-6

International Journal of Bioprinting DIW of concave hydroxyapatite scaffolds

of reaction, reaching conversion rates of 97.4–99.0%. However, the viscosity of BMF used in this study was
Moreover, the SEM images (Figure 4c) implied that slightly higher than that of the standard human blood with
CDHA is in the form of an entangled network of needle- a normal hematocrit level at 37ºC, i.e., approximately 0.01
shape nanocrystals, as reported in previous works. 37,58,59 Pa·s at a shear rate of 10 s versus 0.003 Pa·s at a shear
−1
Nanocrystal formation was not influenced by the geometry rate of 100 s . Given the good correlation between
−1 61,62
of the 3D-printed scaffolds. Therefore, the excellent the viscosity of the prepared BMF at 25ºC and the human
osteogenic properties found in previous in vivo studies are blood at 37ºC.
expected to be maintained in these scaffolds. 47,59
The pore architecture of the scaffolds printed using
3.3. Blood permeability TPMS patterns resulted in a significant increase in blood
The BMF used for the permeability test exhibited shear- permeability through the longitudinal axis, in comparison
thinning behavior at 25ºC, as determined from rheological with OP. A 5-, 22-, and 65-fold increase was reported for
evaluation (Figure 5a). The viscosity profile was similar to the D, G, and S structures, respectively (Figure 5b). These
other BMFs consisting of xanthan gum and glycerol. 53,60,61 increases would facilitate the transport of nutrients and cells,

Figure 5. Blood permeability results. (a) Viscosity versus the shear rate of the blood mimicking fluid used for blood permeability study; (b) blood
permeability (K) of 3D-printed calcium-deficient hydroxyapatite (CDHA) scaffolds with either a typical orthogonal pattern (OP) or three triply periodic
minimal surface (TPMS)-based structures (gyroid [G], diamond [D], and Schwarz [S]) printed with a nominal porosity of 20%. Abbreviations: n, flow
behaviour index; k, flow consistency parameter.
Volume 10 Issue 6 (2024) 234 doi: 10.36922/ijb.3805