Biofabrication of 3D cell-encapsulated tubular constructs using dynamic optical projection stereolithography
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It has been widely recognized that one of the critical limitations in biofabrication of functional tissues/organs is lack of vascular networks which provide tissues and organs with oxygen and nutrients. Biofabrication of 3D vascular-like constructs is a reasonable first step towards successful printing of functional tissues and organs. In this thesis, a dynamic optical projection stereolithography system has been implemented to successfully fabricate 3D Y-shaped tubular constructs with living cells encapsulated. The effects of operating conditions on the cure depth of a single layer have been investigated, such as UV intensity, exposure time, and cell density. A phase diagram has been constructed to identify optimal operating conditions. Cell viability immediately after printing has been measured to be around 75%. Post-printing mechanical properties, swelling properties, and microstructures of the gelatin methacrylate hydrogels have been characterized. The resulting fabrication knowledge helps to effectively and efficiently print tissue-engineered vascular networks with complex geometries. The cure depth is one of the most important parameters in photopolymerization, which is dependent of several factors. Having the desired cure depth for a single layer is critical towards ensuring acceptable and satisfactory resolution in the 3D fabricated constructs. This thesis has also investigated the effect of the photoinitiator concentration on the cure depth. Finally, working curves of the GelMA solutions with different concentrations have been constructed. It is concluded that 1) with the increase of the photoinitiator concentration the cure depth decreases; and 2) with the increase of the GelMA concentration, the depth of UV penetration decreases.