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Han X, et al.

Figure 7. the new version of the vascular system
they are needed the most. The pore diameters were consisted of three monomers plus a photoinitiator. The
engineered to maximise the diffusion rate (yielding a formulations are BPA-ethoxylated-diacrylate, lauryl
lower pore diameter bound for pore radii range), support acrylate and isobornylacrylate (BLI) shown in Figure 9.
angiogenesis, enable steady blood circulation inside the Three types of photo-initiator were tested to select the
vessels and maintain their manufacturability via AM most appropriate one that has the lowest cytotoxicity.
®
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system (yielding an upper pore diameter boundary). The They are Irgacure 184, Irgacure 2959 and Irgacure
conical pores were selected with larger outer diameter 369. BLI samples with three photoinitiators were
pore diameter and smaller inner diameter. This type of investigated by the two methods WST-1assay (three
pore leads to a reduction of the pore diameter without replicates of each kind of a material; characteristic of
the formation of membranes. The design of the conical the sample: diameter: 14 mm, height: 1–2 mm, weight:
pore is shown in Figure 8. 200 mg) and live/dead assay (characteristic of the
sample: diameter: 14 mm, height: 2–3 mm, weight:
3. Material and Methods 300 mg). All samples were disinfected in 70 % ethanol
for 30 min (meanwhile the samples swelled), washed
3.1 Photocurable resin and photoinitiator two times for 30 min with PBS and equilibrated in cell
culture medium. For both methods the mouse fibroblast
The material selected in this work needs to have cell line (3T3) was used, cultured in DMEM with
appropriate viscosity and polymerisation characteristics glutamine (Biochrome AG, Berlin, Germany) containing
to allow it be printed successfully. Additionally, it also 10% fetal calf serum, 50 U/mL penicillin, and 50 µg/mL
needs to have vessel-like properties, such as appropriate streptomycin under 5% CO atmosphere at 37 °C.
2
elasticity, biocompatibility and surface readiness for For live/dead assay the cells were seeded at
2
bio-coatability. The material chosen for this study 25,000 cells/cm , and after 1, 4 and 14 days, the cells

Figure 8. the design of the conical pore on the vascular vessel wall.

International Journal of Bioprinting (2018)–Volume 4, Issue 2 7