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Utilising inkjet printing for tissue engineering

Tse, Christopher Chi Wai (2015) Utilising inkjet printing for tissue engineering. PhD thesis, University of Sheffield.

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Abstract

The field of tissue engineering has the potential to improve the quality of life of individuals through combining the knowledge of engineering and life sciences in creating engineered biological substitutes that repair, support and enhance tissue function. Inkjet printing is a versatile tool that can be used for a broad range of applications. Ubiquitous in households, offices and industry, there has been growing interest in the use of inkjet printing for biological applications. Inkjet printing allows the user to deposit nano-picolitre volume of inks of low viscosity with high precision and high repeatability. Within this thesis, inkjet printing was used to explore its applications in the life sciences, with jetting behaviour and scaffold design optimised. The creation of cell-friendly scaffolds was investigated. Gelatin scaffolds, crosslinked with inkjet printed glutaraldehyde were fabricated. Fibroblasts were seeded onto these fabricated scaffolds and shown to proliferate without hindrance, allowing a method to create sub-millimetre cell-friendly fibres for tissue engineering applications. The ability for inkjet printing to create scaffolds to control cell alignment was investigated. Cell orientation can be controlled through inkjet printing paraffin wax to restrict cell proliferation on a substrate. Paraffin wax is not harmful or toxic to cells, and cells were able to grow within the negative spaces between the wax patterns, to create aligned cell culture as cells proliferated. An advantage with the wax scaffolds was that the wax scaffold was readily removable with a scalpel that allowed further analysis of cell behaviour when proliferating into an unrestricted space. A proportion of cells was also detached upon wax removal, proportional to cell density within the wax scaffold and wax channel width. After wax removal, cell cultures quickly lost their ordered appearance within 3 days as they proliferated randomly across the substrate. The creation of in vitro vasculature models through the use of a combination of inkjet-printed wax, PDMS moulding and wax-loss method to create medical phantoms for the study of rheological behaviour was studied. The scalloping behaviour of the printed wax vessel was reduced in the final phantom created, as there would be a thin lining of wax that covers the interior of the PDMS mould after wax removal, making the vessel smoother. Cell printing of neuronally relevant cells were investigated. NG108-15 and porcine Schwann cells (along with fibroblasts to act as a control experiment) were inkjet printed, studying cell viability during and after inkjet printing. It was concluded that cells were not significantly damaged during inkjet printing over a wide range of voltages (50 V-230 V), and no correlation was seen to show an increase in cell death with increasing voltages. Inkjet printed NG108-15 cells showed they produced longer neurites compared to control samples after 7 days. Further to results, it was confirmed that cell printing is limited to a duration of less than 40 minutes due to cell aggregation within the reservoir of the printing system, causing a steady significant decrease in cell numbers during printing.

Item Type: Thesis (PhD)
Keywords: Inkjet Printing, Tissue Engineering, Additive Manufacturing, Schwann Cells, NG108-15, Gelatin, Glutaraldehyde, Reactive Printing
Academic Units: The University of Sheffield > Faculty of Engineering (Sheffield) > Mechanical Engineering (Sheffield)
Identification Number/EthosID: uk.bl.ethos.694444
Depositing User: Mr Christopher Chi Wai Tse
Date Deposited: 05 Oct 2016 12:11
Last Modified: 12 Oct 2018 09:27
URI: http://etheses.whiterose.ac.uk/id/eprint/13950

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