Speaker
Description
"Introduction
Most of the efforts in creating vascular structures using 3D printing have been concentrated on extrusion type of printing. However, mimicking vascular structures such as arterioles (100 µm diameter) is difficult due to the limitations in resolution that extrusion printing has. Inkjet 3D printing is a droplet-based type of printing that has resolution of 30 µm which can achieve printing features similar to arterioles. This project aims to fabricate vascularised bioactive scaffold using inkjet 3D printing, and biocompatible materials which consist of diacrylated PTMC-polyethylene glycol (PEG)-PTMC/gelMA/Polyethylene glycol diacrylated (PEGDA) as scaffolds matrix and water-soluble (WS) ink as sacrificial ink for vascular channel formation.
As an ink, gelatin methacrylate (gelMA) maintains excellent biocompatibility, solubility, and easy acquirement which is suitable for biomedical application1. Poly-trimethylene carbonate (PTMC) which has adjustable mechanical properties and non-acidic degradation produtcs2 can be used as a blend to improve mechanical stability. PTMC was modified into amphiphilic tri-block copolymer which is soluble in water so that the toxic organic solvent can be avoided.
Methodology
GelMA was synthesized in-house via precipitation method. The tri-block copolymer was synthesized following Ruiz et al3. Ink formulation was explored to find the optimum printability and crosslink ability using lithium phenyl-2,4,6-trimethyl-benzoyl phosphinate (LAP) as photoinitiator. For scaffold fabrication, Dimatix inkjet printer equipped with Samba cartridge was used. The samba cartridge consists of 12 nozzles with 2.4 pL drop volume allowing the high-resolution printing. The obtained scaffolds were then characterised by swelling test, mechanical test, and cells culture test using iMSC and HUVECs to analyse the bone tissue formation.
Results
The synthesized tri-block copolymer was a viscous liquid at room temperature and soluble in water. The 1H NMR results showed PEG, TMC, and acryloyl group signals without any remained monomer. Therefore, the synthesis process and purification process of diacrylated tri-block copolymer was successfully done. It was then used for ink formulation containing gelMA, triblock copolymer, and PEGDA with ultra-pure water as a solvent. Different concentration of each material was explored and analysed by liquid handler to find the optimum composition that is 1.5 wt.% gelMA, 10 wt.% copolymer, and 20 wt.% PEGDA700. The size of WS ink droplet is 48 ± 4 µm which offers small channel formation. After water immersion, the WS ink was completely removed and remained the vascular channel with the size of 109.00 ± 2.45 µm. The obtained gelMA/copolymer/PEGDA700 scaffold has better mechanical and adhesion properties compared to PEGDA700 scaffolds which allow better cells attachment.
Conclusions
GelMA, amphiphilic triblock copolymer, and the hybrid materials of those polymers which dissolved in water were successfully prepared. It could minimize the use of an organic solvent which toxic to the cells and then enhance the biocompatibility. The vascularised scaffold was successfully fabricated using the ink formulation and the characterization showed that obtained scaffold has better properties for cells compared to PEGDA700 scaffolds.
References
1. Nichol, J.W. et al., Biomat., 31, 5536-5544 (2010)
2. Fukushima, K., Biomat. Sci., 4, 9-24 (2016)
3. Ruiz-Cantu, L. et al., ACS Applied Materials and Interfaces, (2021)"
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