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(2023) Ireland, JakeThesisPluripotent stem cell-derived cardiomyocytes (hPSC–CM) have great importance for predicting safety parameters for pharmaceutical compounds and models of healthy versus disease states of the human heart. In recent years, there has been an insistence that all new pharmaceutical products are tested on in vitro models for potential proarrhythmic effects and the increased demand for improved biomimetic hPSC-CM in pharmaceutical safety assays such as the Comprehensive in vitro Proarrhythmic Assay (CiPA). In addition, hPSC-CM are being utilised in cell therapies to treat and reverse the effects of ischaemic heart disease, offering potential cures for cardiovascular diseases instead of treatments for delaying progressive heart failure. In the first part of this thesis, I will examine how purified extracellular matrix proteins (ECMPs) can influence pluripotent stem cell (PSC) behaviour and how we may use this to precondition cardiac progenitor lineage specifications. I use array-based techniques to investigate how protein combinations affect proliferation, pluripotency, germ layer, and cardiac progenitors. This method allows us to visualise how individual proteins can affect cells' behaviour in a larger array whilst highlighting how specific combinations can precondition pluripotent cells towards a cardiomyocyte lineage. This combinatorial approach led to the identification of several unique matrices that promote differentiation, which will aid efforts at producing therapeutically useful cell types with greater efficiency. In the second part of this thesis, I demonstrate a novel bioreactor that attenuates a magnetic field to dynamically modulate the stiffness of magnetoactive hydrogel to look at how biomimetic dynamic stiffening of a substrate can influence cardiomyocyte lineage specification. We investigate how biomimetic in vivo mechanics may influence cell fate by following the expression profiles of cells in different dynamic environments. Non-invasive electromagnetic signals affect substrate stiffness when combined with magnetic particles and magnetic fibres and how this can help direct cell orientation and accompanying lineage specification Finally, I investigate how variability in cell phenotypes and expression patterns are influenced by biomimetic cues and how these variabilities could be utilised in future safety assessment protocols and cell therapy treatments for cardiovascular disease.
(2023) Lam, NgaThesisThe self-assembly of proteins into intricate high-order structures can be harnessed for the precise positioning of functional molecules in nanotechnology. The organisation of enzymes on protein scaffolds has been previously shown to enhance enzyme catalytic activity. Additionally, the alignment of metal-binding proteins, known as metalloproteins, on filamentous proteins has been exploited to produce electrically conductive nanowires. The focus of this thesis is on the development of improved biosynthetic strategies for the creation of multifunctional nanomaterials by harnessing the self-assembly of filamentous proteins. Central to the engineering in this thesis is prefoldin, which is a molecular chaperone from archaea with the ability to self-assemble into hetero-hexameric complexes and filamentous structures. Prefoldin proteins exhibits high thermal stability and have engineerable interfaces for bioconjugation of functional proteins. Therefore, the research goal of this thesis was to engineer robust and modular protein scaffolds for the precise position of enzymes and alignment of electrically conductive subunits to create biocatalysis and bioelectronic systems. The first aim of the research was to construct a protein scaffold from a hexameric self-assembling protein and immobilise enzymes on the protein scaffold to examine for enhanced sequential catalytic reactions. The second aim explored the capability of prefoldin filaments to align various metalloproteins in proximity over large distances for electron transfer. Distinct metalloproteins were exploited to create nanowires with various electronic properties for applications in bioelectronic devices. The third aim developed a strategy to localise redox enzymes at either end of the metalloprotein nanowires and potentially demonstrate energy transfer along the nanowire between enzymes undergoing redox reactions. The successful achievement of these aims establishes a biostrategy to use a controllable and modular prefoldin protein scaffold for the fabrication of biocatalysis and bioelectronic devices.