UBC Theses and Dissertations
High-efficiency biofabrication of cell-laden gelatin methacryloyl hydrogels Mohamed, Mohamed Gamaleldin Abdelkhalek
Biofabrication is the automated manufacturing technology of biologically functional, organized cell-material constructs through bioassembly or 3D bioprinting. Microfluidic and bioprinting principles have served as powerful tools for fabricating cell-laden 3D gels for various biological applications, the most important of which is bottom-up tissue engineering. However, the inherently limited throughput of micro-scale devices coupled with the low cost-effectiveness of producing biomaterials has rendered these methodologies unsuitable for practical application. It is also necessary that the biomaterial used for these applications be biocompatible, display adequate mechanical properties, and be manufactured through a reliable manufacturing technology. Due to its printability and biocompatibility, GelMA hydrogel has attracted considerable interest as a scaffolding material for tissue engineering. Nevertheless, the detoxification, purification, dehydration, and sterilization steps for synthesizing GelMA hydrogels are expensive, time-consuming, and serve as a significant reason for its low and irreproducible yields. This research aims to tackle these hurdles in efficiency. First, this work integrated all the required steps of fabricating monodisperse cell-laden microgels onto one chip. The elimination of the off-chip droplet handling requirement enables a high-throughput process. The stability of the operation resulted in a reasonable cell distribution among the microgels over various cell seeding concentrations. Furthermore, cells showed a high viability of around 85% over 5 days in culture. Second, we devised a rapid approach for GelMA detoxification in an aprotic solvent medium with moderate polarity by employing the ion-pairing and desolvation concepts. The GelMA produced through this method displayed a significantly higher yield in comparison to conventionally synthesized batches while also demonstrating a comparable degree of methacrylation. Moreover, this GelMA displayed high biocompatibility and bioprintability. Third, the dehydration step of GelMA was eliminated by using a toluene-based precipitation approach. The extreme hydrophobicity of toluene protects the protein from hydrolysis and leads to the production of a reproducible yield. Toluene also has the advantages of being volatile and lighter than water, which allows for the direct reconstitution of the extracted known yield of GelMA in the aqueous phase.
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