Page 379 - IJB-9-2

International Journal of Bioprinting 3D gel-printed β-TCP/TiO2 porous scaffolds for cancellous bone tissue engineering

freeze dryer at -80°C for 24 h to remove moisture. Finally, 2.4.3. Thermogravimetric analysis
the lyophilized ceramic billets were sintered in a muffle Thermo-grameter analysis (METTLER TOLEDO, USA)
furnace (KSL-1400X-A1, Kejing, China) in the different was carried out to verify the thermostability of β-TCP/TiO
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heating curves for degreasing to obtain the β-TCP/TiO ceramic. For each group of samples, 10 mg ceramic was
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ceramic sample. Hereafter, sintered ceramic samples with 1 loaded into the crucible and heated at 20°C–800°C with a
wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt% of TiO were labeled heating rate was 10°C/min under a nitrogen atmosphere.
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as β-TCP/1-TiO ceramic, β-TCP/2-TiO , β-TCP/3-TiO
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ceramic, β-TCP/4-TiO ceramic, and β-TCP/5-TiO 2.4.4. Scanning electron microscopy (SEM)
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ceramic, respectively. microscopic analysis
The morphologies and microstructure of the ceramics
2.3. Fabrication and 3D printing process of β-TCP/ and scaffolds were examined by a field emission scanning
TiO ceramic scaffolds electron microscopy (Phenom pro, Netherlands) with
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The ceramic slurry containing different weight ratios a voltage of 10 kV. Before observation, the surface of the
of β-TCP, TiO , gelatin, and PVA was aspirated into a specimens was sprayed with a thin gold-plated layer.
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syringe and added to the biological 3D printer (B Series, 2.5. Mechanical properties
Guangzhou Maipu Regenerative Medical Technology Co., The mechanical properties of ceramic and scaffolds
Ltd, China). The nozzle model used in this experiment was were carried out using a universal testing machine
22G (inner diameter was 400 μm) and the layer thickness of (SANSCMT4503, YinFei Electronic Technology Co., Ltd,
3D printing was set to 0.4 mm. Other print parameters are China) at room temperature. For each ceramic or scaffold
as follows: printing speed = 30 mm/s; printing temperature specimen, the samples were prepared into cylindrical
= 50°C; return axis speed = 5 mm/s; return axis length = ceramic sheets with a diameter of 8 mm and a height of 4
2 mm; temperature of ice plate = -5°C; heating temperature mm for compressive strength testing. The surface under the
of the nozzle = 50°C; and discharge speed = 20 mm/s. The pressure was flat and there were no defects on the sample.
printing process was performed according to the pre- The speed of the squeeze head was set at 1 mm/min with 4.8
designed scaffold model (10 × 10 × 10 mm) and the filling kN force. Each group of ceramic plate samples was tested at
rates were set to 20%, 30%, and 40%, respectively. After room temperature with five parallel samples according to
printing, the printed porous scaffolds were immediately the compression test standard GBT 1964-1996.
put into the freeze dryer for freeze-drying at -80°C for 24 h.
Finally, the frozen printed scaffolds were sintered in the 2.6. Porosity of porous ceramic scaffolds
muffle furnace in an optimized heating curve to fabricate The inner porosity of ceramic scaffolds (10 × 10 × 10 mm)
the β-TCP/TiO porous scaffolds. Hereafter, the sample of was also conducted using ethanol as a medium employing
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sintered ceramic scaffolds with 1 wt%, 2 wt%, 3 wt%, 4 wt%, the Archimedean principle. The scaffold of each specimen
and 5 wt% of TiO was labeled as β-TCP/1-TiO scaffold, was measured using a vernier caliper to determine the
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β-TCP/2-TiO scaffold, β-TCP/3-TiO scaffold, β-TCP/4- volume V’. The sample was immersed in ethanol in the
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TiO , scaffold, and β-TCP/5-TiO scaffold, respectively. sealed test tube. After 24 h, the differential of the liquid
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level of alcohol was denoted as h, and the change in the
2.4. Composition analysis of β-TCP/TiO ceramics volume was denoted as V. At last, the r porosity of the
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and scaffolds ceramic scaffold was obtained by the following formula:
2.4.1. X-ray diffraction analysis (XRD)
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X-ray diffraction analysis (XRD) of ceramics was detected P = 1 − V  ×100%, V = π d 2 • h (I)
using an X-ray diffraction analyzer (DX-2700B, Hao Yuan   V  ’  4
instrument co., Ltd, China). The β-TCP/TiO ceramic was Afterward, mean values and standard deviations were
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milled into powder subjected to transmission analysis calculated from five specimens.
by CuK α-radiation with a voltage of 40 kV, a current of
30 mA and a scanning angle range of 20°–80°. 2.7. Biocompatibility evaluation of β-TCP/TiO
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scaffolds
2.4.2. Fourier infrared spectroscopy analysis (FIRS) 2.7.1. Bioactivity on biologic mineralization of β-TCP/
Nicolet 6700 infrared spectrometer (Thermo Fisher, USA) TiO scaffolds
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was used to identify the functional groups of the β-TCP/ The bioactivity of the β-TCP/TiO ceramic scaffolds
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TiO ceramic samples. One to two milligram ceramic was was evaluated by immersing them in a simulated body
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grilled in an agate mortar to powder with dried potassium fluid (SBF) at 37°C for 14 days. After removing from the
bromide. Subsequently, the mixed powder was pressed into given solution, the formation of bone-like apatite and
pieces on the tablet press and tested. the chemical composition of deposits was characterized
Volume 9 Issue 2 (2023) 371 https://doi.org/10.18063/ijb.v9i2.673