Page 48 - IJB-9-2

International Journal of Bioprinting Biocompatible materials and Multi Jet Fusion

with high interconnectivity for tissue regeneration . a uniform graft. We hypothesized that the screw extrusion
[2]
Polycaprolactone (PCL), which is approved by the United method of 3D printing could produce a structure with
States Food and Drug Administration for internal use in excellent physical and mechanical properties as it would
the human body, is the most widely used 3D printable prevent the deterioration of the thermal properties of the
biomaterial. PCL has not only excellent biocompatibility, polymer and enhance the ejection force. In addition, it is
but also superior mechanical properties and printability [3,4] . expected that the screw method with a constant rotational
force without pressure fluctuations, such as those in the
Gao et al. developed tissue engineered whole-segment
trachea using 3D printing technology. The intact tracheal pneumatic method, would realize the manufacturing of
high-quality products with high uniformity. In this study,
scaffold composed of biodegradable PCL and chondrocyte a screw-type 3D bioprinter was developed and a PCL graft
suspension was implemented, which exhibited good was fabricated using the bioprinter. Physical, mechanical
cartilaginous properties both in vitro and in vivo [5,6] . properties, and in vivo performance of the developed final
Temple et al. attempted to fabricate anatomically shaped product, the PCL graft, were evaluated.
vascularized bone grafts with human adipose-derived stem
cells and 3D-printed PCL scaffolds. They implemented 2. Materials and methods
complex geometry using 3D printing and suggested that
it can be applied to craniomaxillofacial bone defects as 2.1. Development of a screw extrusion 3D bioprinter
essential components of functional bone tissue . Based on the specifications of the 3D bioprinter defined
[7]
as follows, the equipment was designed and then
Although 3D printing structures have been developed manufactured, a system in which the x-axis and y-axis
for the regeneration of various organs as described above, can move independently. A NEMA17 motor was used for
they still have some limitations. One of them is mechanical the x-axis, and a NEMA23 motor was used for the y-axis
properties. The 3D printing structure is manufactured by because the load was larger than that of the x-axis. A
stacking layers, and structural stability varies depending on linear motion guide with low deviation and withstanding
the adhesive force between the layers. Xia et al. explained a large load was used for the driving part. For the use of
that due to the time gap intervals between depositions, the thermoplastic polymer, a 24 V ceramic cartridge heater
the bond strength decreases due to lack of intermixing . capable of heating to a high temperature was used. A 100K
[8]
In addition, since it is difficult to print high-viscosity thermistor was used to measure the temperature. A gt2 belt
biomaterials, there is a limit to the implementation of a was used as the transfer method, which has a high output
graft having high strength [8-10] . speed, and the minimum movement interval is 12.5 µm.
For this reason, various researchers have been studying to Non-cytotoxic stainless steel was used for the barrel and
improve the mechanical properties of 3D-printed structure. screw, which are parts that come in direct contact with
Xia et al. applied a cementitious paste at the interface to the biomaterial.
strengthen the interlayer bonds . Olubamiji et al. reported 2.2. Fabrication of PCL graft
[8]
that they modulate mechanical behavior of 3D-printed The raw material used in this study was PCL (Purasorb PC
cartilage-mimetic PCL scaffolds. They optimized the 12, Purac Bio-chem bv, the Netherlands). It has average
properties suitable for human articular cartilage by molecular weight of 105,000. Porous grafts were fabricated
controlling the molecular weight and pore geometry of by screw extrusion-type 3D bioprinting (Organocube
the material, and explained that their technology has great Mini, Medifab, Republic of Korea) and compared with
potential for cartilage tissue engineering . pneumatic pressure-type 3D bioprinting. The PCL
[11]
In addition, there are studies to improve mechanical grafts (Husteon Mesh, Medifab, Republic of Korea) were
strength by introducing composite materials. Jiao et al. fabricated in various sizes and thicknesses, and the printing
improved the mechanical strength by combining conditions are as follows.
hydroxyapatite (HA) with PCL. They prepared by melt
blending the ceramic and polymer, and then printed Table 1. Printing conditions
with fused deposition modeling method. This graft had Parameters Conditions
higher tensile strength than pure PCL. They appealed
that the bioactive nano-HA/PCL composite scaffolds Temperature 100°C
should have broader application prospects in bone tissue Speed of nozzle movement 10 mm/sec
engineering [12,13] . Distance between the layers 500 µm

We tried to improve the mechanical properties and Width of layers 500 µm
structural stability of the 3D structure and to manufacture Direction of layers 60, 0, -60°

Volume 9 Issue 2 (2023) 40 https://doi.org/10.18063/ijb.v9i2.652