3D printing for biological applications

Different 3D printing methods with different biomaterials to create structures for cell-cell interactions were discussed. In this research, three different printed structures were printed from three different 3D printing techniques for the studies of cell interactions. Biopolymer of PCL and it nanocomposites have been designed and fabricated using 3D bioprinter for cardiac tissue engineering. Mechanical, thermal and biological characterisation were done for the printed scaffolds with cardiac cells to determine how these properties affects cell growth. Biodegradation was also tested using Pseudomonas lipase to determine the possible use of these printed scaffolds for cardiac tissue engineering. Results showed that cardiac cells grow better on 3D printed scaffold of PCL with 1% CNT as compared to PCL and PCL with 3% CNT. Next, to have a better understanding on how bacteria cells communicate with one another in a liquid culture, PEGDA hydrogel was designed and fabricated using stereolithography system. Quorum sensing (QS) through secreted small molecules is one of the ways in which Pseudomonas aeruginosa cells communicate with one another. So, by spatially designing honey-combed structures, QS molecules can be diffused across the hydrogel for cells to interact. Mechanical, swelling and printability properties of the structures were determined to obtain fully functional structures for cell interactions for 24 hours. Well-defined honey combed structures could be printed with PEGDA with 1% Igra819. These structures will then be seeded with P. aeruginosa for further studies. Finally, two photon polymerisation was used to print and spatial pattern bacteria cells in an encapsulated gelatin matrix. These structures save time as cells can be printed directly. A predatory interaction between E. coli and S. aureus was observed through a microcolony assay. Initial results from the distal and mix marcolony assay showed that this predatory effect was only observed when E. coli and S. aureus were in close proximity of each other. Predatory mechanism was deduced through RNA sequencing and Transposon screening. Due to its high resolution, 2PP was used to spatial pattern E. coli and S. aureus with distance up to 50 microns apart. With more research on 3D printing and biomaterials, the search for the “killer application” in biology might be realised in the near future.Doctor of Philosophy (MAE