Chemical and Biomolecular Engineering - Theses
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ItemEnzyme-responsive nanomaterials for the delivery of antimicrobial peptides( 2023-10)The rate of resistance to antibiotics that are commonly used in the clinic is escalating rapidly, surpassing the introduction of new antimicrobial drugs. To address this problem, alternative strategies are being explored, such as the re-evaluation of antibiotics, that have not yet gained widespread clinical application. Antimicrobial peptides (AMPs) represent one of those antibiotics, offering remarkable antimicrobial efficacy against various pathogens. However, in clinical settings, AMPs are typically considered a last-resort option due to their off-target effects and poor stability in-vivo resulting from their cationic and amphiphilic peptide nature. Therefore, most of current strategies addressing these limitations focus primarily on the control and shielding of the cationic charge and the amphiphilic nature of AMPs. These can potentially be achieved through encapsulation of AMPs inside stimuli-responsive polyelectrolyte complexes (PECs) by combining the cationic drug with anionic polyelectrolytes. Stimuli-responsive polymers can be employed as encapsulation materials in PECs to design systems that activate drug release in response to specific changes encountered during microbial infection, such as variations in pH, enzyme activity, or temperature. The overarching aim of this Thesis was to explore the creation of PECs capable of encapsulating the clinically approved antimicrobial peptide, Polymyxin B and its subsequent enzyme-induced release. In Chapters 2 and 3, the aims were: Firstly, to synthesize anionic and helical polymers incorporating enzyme-degradable peptide side chains (Aim 1.1), followed by evaluation of the degradation properties of these polymers in response to the enzyme released by gram-negative bacterium Pseudomonas aeruginosa (Aim 1.2). In Chapter 4, the first objective (Aim 1.3) was to assemble Polymyxin B and the anionic enzyme-degradable polymers into PECs. The next objective (Aim 1.4 ) involved investigating the P. aeruginosa-induced drug release from these PECs, while Aim 1.5 focused on assessing the antimicrobial activity of the developed PECs against P. aeruginosa strains. Chapter 1 provides a review of the current developments in the field of the stimuli- responsive delivery of AMPs using polyelectrolyte complexes. Chapters 2 and 3 discuss the synthesis of polymers with poly(methacrylamide) and poly(acetylene) backbones respectively coupled to enzyme-degradable peptide side chains. Of the synthesized materials, two poly(methacrylamide) polymers from Chapter 2 were found to be the most effective in terms of degradation by the enzyme released by P.aeruginosa, while none of the synthesized acetylene-containing peptides from Chapter 3 polymerized. Subsequently, the poly(methacrylamide) polymer with the highest multivalency was used to form PECs with Polymyxin B in Chapter 4. Eight different formulations of PECs were created, with one being the most optimized in terms of encapsulation efficacy and physiological stability. The stability of the particles was further improved by the addition of Tannic Acid, which acted as a protective coating and a cross-linker. The Thesis then evaluated the ability of the PECs to release Polymyxin B under enzymatic degradation. Finally, the preliminary evaluation of the antimicrobial activity of the PECs against various P.aeruginosa strains were presented.
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ItemSynthesis of DNA-inspired polymers with nucleotide-pendant functionalities( 2023-04)Deoxyribonucleic acid (DNA) is the most important hereditary material. This natural polymer possesses an outstanding ability to store and translate genetic information. However, its use in the biosciences has been restricted by the high cost involved in producing long DNA sequences with more than 200 base pairs, and the limited shelf life of these sequences once produced. To tackle the stability and cost related issues, developing DNA-like materials, such as DNA-inspired polymers, is of increasing interest. Furthermore, combining the DNA substituents and synthetic polymers provides special features that are not seen in either material alone. For example, synthetic polymers typically do not display defined structures and functions as DNA. One of the major challenges in generating DNA-inspired materials is the inclusion of the entire DNA building block into the system, namely the nucleotide, consisting of the nucleobase, deoxyribose and phosphate groups. This project aims to combine all three DNA components into a polymeric system. Exploring the synthetic routes and studying the specific interactions and behaviour of the produced system are the major aims of the project. To accomplish these aims, first adenine (A), thymine (T), cytosine (C) and guanine (G) protected nucleotide functionalised propyl methacrylate monomers were synthesised. This was achieved by coupling 2-hydroxy propyl methacrylate (HPMA) to commercially available protected phosphoramidites, 5'-dimethoxytrityl-N-benzoyl-2'- deoxyadenosine, 3'-[(2-cyanoethyl)-(N,N-diisopropyl)]-phosphoramidite (hereafter denoted as dA(Bz)), 5'-dimethoxytrityl-N-benzoyl-2'-deoxycytidine, 3'-[(2-cyanoethyl)-(N,N-diisopropyl)]-phosphoramidite (hereafter denoted as dC(Bz)), 5'-dimethoxytrityl-2'-deoxythymidine, 3'-[(2-cyanoethyl)-(N,N-diisopropyl)]-phosphoramidite (hereafter denoted as dT) and 5'-dimethoxytrityl-N-isobutyryl-2'-deoxyguanosine, 3'-[(2-cyanoethyl)-(N,N-diisopropyl)]-phosphoramidite (hereafter denoted as dG(ib) via phosphite triester linkages. By designing bio-functional monomers, containing protecting groups, side-reactions were minimised and increased solubility in a broad range of solvents was realised for subsequent polymerisation reactions, i.e., free radical polymerisation (FRP) and reversible addition fragmentation (RAFT). This is the first time phosphoramidite-HPMA monomers have been synthesised via a room temperature approach, and isolated for polymerisation reactions. Secondly, the seminal synthesis of A and T phosphoramidite-functionalised propyl methacrylate polymers was realised, using post- and pre-functionalisation methods via RAFT polymerisation. The RAFT method was used to achieve a higher control over the molecular weight of the produced polymers. Using the post-polymerisation functionalisation method (addition of phosphoramidite functionalities to already polymerised HPMA polymer), a RAFT-made poly(HPMA) with a narrow dispersity (1.29) and controlled DP (58), was functionalised with dA(Bz) and dT protected phosphoramidites via phosphite triester linkages. Although the polymer synthesis was successfully performed, the degree of phosphoramidite functionalisation was low, particularly for the A containing polymer (45 %). Pre-polymerisation functionalisation (direct polymerisation of the HPMA nucleotide-based monomers) was then used to investigate if there was any improvement in the degree of phosphoramidite functionalisation along the polymeric backbone. Applying this approach, A and T phosphoramidite-HPMA monomers were directly polymerised using the RAFT technique. The attempts to improve the degree of functionalisation was successful in case of A containing polymer (66%), however, the degree of functionalisation remained approximately the same as the T containing polymers for both methods (57% for post- and 50% for pre-functionalisation processes). These polymers offer some unique features which are currently not seen in literature including relatively high degree of protected nucleotide functionality, ready dispersion in solvents appropriate to a broad range of polymerisation and protection of the amine group on the nucleobases, ideal for RAFT polymerisations. In addition, the RAFT polymers, still with pendant RAFT agent, have future potential as macro-RAFT agents for subsequent block extension through the addition of other monomers for potential sequence control. This is not explored within the scope of this thesis. The final part of the thesis the noncovalent interactions of deprotected A and T nucleotide-functionalised propyl methacrylate polymers in solution was studied. To achieve this, the removal of the phosphoramidite protecting groups was required to achieve free hydroxyl and amino functionalities which could further interact via noncovalent bonding. The resulting polymers were potentially capable of noncovalent interactions with their complementary polymer (A with T). The noncovalent interactions between the A and T deprotected nucleotide-functionalised propyl methacrylate polymers were studied using ultraviolet (UV) and circular dichroism (CD) spectroscopies at various temperatures. These studies revealed that the pi-pi stacking between the complementary A and T nucleobases was the dominant interaction in the polymer mixture. Performing the studies in three different solvents (dichloromethane (DCM), cyclohexane (CY) and isopropanol (IPA)) showed that increasing the solvent dielectric constant promotes the pi-stacking interactions. For the A and T deprotected nucleotide-functionalised propyl methacrylate polymer mixture in IPA, the enhanced pi-stacking led to spherical and worm-like polymeric assembled structures with average diameters of 100 nm (confirmed by transmission electron microscopy (TEM)). The morphology of the particles was controlled by the degree of functionalisation, where the post-functionalised polymers formed worm-like particles and the pre-functionalised polymers formed spherical particles. In summary, this thesis showed the RAFT synthesis of nucleotide functionalised propyl methacrylate polymers, including complementary nucleobases A and T. The inclusion of hydrophobic and hydrophilic groups along the polymeric backbone led to the formation of self-assembled polymeric nanostructures. The specific structure and behaviour of the produced DNA-like materials makes them attractive for a broad range of biomedical applications such as delivery of drugs and genetic materials. Moreover, the inclusion of phosphate linkages into these materials paves the way for the synthesis of polymers with improved helicity levels.
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ItemEngineering of DNA Micro- and Nanoparticles: Towards Vaccine Delivery( 2021)Vaccines are an effective tool for preventing and controlling various diseases by inducing adaptive immunity. Nanomaterials play an important role in vaccine development. Micro- and nanocarriers can be engineered to improve the therapeutic efficacy of vaccines by (i) preventing the degradation and systemic clearance of vaccine antigens and (ii) facilitating the uptake of vaccines in antigen-presenting cells (iii) co-delivering adjuvants and antigens at desired intracellular compartments for optimal immunotherapy. However, it is important to engineer a carrier that is both effective and safe. Micro- and nanoparticles based on DNA have shown great potential for biological applications, owing to the programmable sequences, predictable interactions, versatile modification sites, and high biocompatibility of DNA strands. This thesis aims to develop facile strategies to synthesize DNA particles for vaccine delivery by self-assembly approaches. First, a simple strategy to synthesize DNA microcapsules is reported. The cytosine-phosphate-guanosine oligodeoxynucleotides (CpG) motif is an efficient vaccine adjuvant that can effectively stimulate the immune system to secrete cytokines. By loading and crosslinking Y-shaped DNA building blocks (containing CpG motifs) into sacrificial calcium carbonate templates, monodisperse and spherical DNA capsules were obtained. These DNA microcapsules were internalized into cells efficiently, accumulated in endosomes, and induced immune cells to secrete high-level of cytokines. Next, we developed a template-assisted and versatile approach for synthesizing a new set of multifunctional particles through the supramolecular assembly of tannic acid (TA) and DNA molecules. Uniform and stable DNA-TA particles with different morphologies could be easily synthesized by using different types of DNA strands. Intriguingly, different DNA sequences can be encoded into this DNA-TA particle for applications in immunotherapy or gene delivery. The incorporation of CpG motifs and ovalbumin into the particles allows the intracellular antigen/adjuvant co-delivery to amplify cytokines production in macrophages, through synergistic effects. In addition, green fluorescent protein (GFP)-expressing plasmid DNA could be transfected by using the DNA-TA particles in HEK293T cells. Finally, nanometer-sized particles were engineered by exploiting the one-pot supramolecular assembly of TA, DNA, and PEG for intracellular delivery of CpG motifs. TA-DNA-PEG nanoparticles with different sizes could be fabricated by adding different molecular weight PEG chains. TA-DNA nanoparticles with tunable size were also synthesized by varying the molar ratio of TA and DNA. The obtained nanoparticles can enhance the cellular uptake of CpG oligonucleotides and consequently the production of cytokines in macrophages. Overall, the engineered DNA-based particles have potential for co-delivering nucleic acids and protein antigens in immune cells to enhance the immunological response against infectious diseases and cancer.
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ItemPolyphenol-inspired engineering of multifunctional films and particles( 2016)Polyphenols, these plant-derived natural products, were traditionally referred to as “vegetable tannins”, due to their original use in the industrial process of “tanning” to convert animal hide into leather. From the 19th century onwards, “real chemistry” got involved in the study of polyphenols, and in the following 100 years, the study of polyphenols has drawn great interest in broad areas of research, including food science, pharmaceutical research, biology, and the original leather manufacturing. However, most of the research on polyphenols is limited to traditional fields, or focuses on the properties of polyphenols in solution. This thesis focuses on exploring the unique physicochemical and biological properties of polyphenols to serve as an important source of inspiration in the search for new and improved materials. A library of functional metal-phenolic network (MPN) nanostructured films and capsules was prepared from the coordination between a phenolic ligand and a range of metal ions. The functional properties of the MPN materials were tailored for advanced drug delivery, positron emission tomography (PET), magnetic resonance imaging (MRI), fluorescence, and catalysis. Furthermore, the engineering of MPN materials into nanoporous replica particles was used as a novel ultrasound imaging probe and therapeutic to detect and decrease endogenous reactive oxidative species, H2O2, in biological systems. By exchanging the previously used multivalent coordination chemistry with dynamic boronate covalent chemistry, biologically relevant, dual-responsive boronate-phenolic network (BPN) capsules that combine the pH responsiveness of MPN with the cis-diol responsiveness of boronate complexes were synthesized. Polyphenol-inspired particle functionalization was later discovered to facilitate an interfacial molecular interaction-induced self-assembly process. This allowed for the generation of a highly versatile and effective methodology to prepare a large variety of superstructures assembled from a wide range of building blocks. This method displayed significant versatilities of sizes, shapes, microstructures, and compositions as building blocks. The generic nature of this method led to a large family of modularly assembled superstructures including core-satellite, hollow, and hierarchically organized supraparticles. Colloidal-probe atomic force microscopy and molecular dynamics simulations provided detailed insight into the role of this polyphenol-based particle functionalization and how this functionalization facilitated superstructure construction.
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ItemSupramolecular polymers as building blocks for the formation of particles( 2014)Over the last two decades, there has been a growing interest in the development of supramolecular polymers, linear macromolecules whose monomeric components are held together by non-covalent interactions. Such supramolecular assemblies are commonly found in nature and are crucial for the function of living tissues and cells. The recent development of synthetic supramolecular polymers has shown promise for enhancing the properties of polymeric materials. Indeed, studies have shown that such materials have significant benefits when compared to conventional, covalently bound, polymers. These benefits are due to the ability of supramolecular assemblies to respond to stimulus, and to dynamically rearrange their structure in a manner unachievable using conventional, covalently bound polymers. Resemblances between the dynamics of synthetic supramolecular polymers and naturally occurring supramolecular polymers are suggestive of their potential for biomedical applications. In this trend, the most promising supramolecular polymer, cyclodextrin (CD) based polyrotaxanes (PRXs), is now emerging as a potential tool to synthetically form dynamic interfaces for applications in the biomedical field. The recent popularity of these polymers in this field is not only due to their inherent, non-covalent properties but also to the low cost, high engineerability and low toxicity of the components they are made of. In this work, CD-based PRXs have been used as building blocks to form particles that were designed for developments in drug delivery. Specifically, the properties specific to PRXs have been exploited to design particles with degradation or stimuli-based response. The unique characteristics of PRXs were found to translate into similarly unique characteristics of the assembled particles. Different approaches have been studied and their advantages and limitations are highlighted. Initial investigations were aimed at designing particles fitting the requirements in properties and specific characteristics highlighted by recent in vivo and in vitro studies. In this direction, we demonstrated controlled degradation of self-assembled PRX-based structures through stimuli triggered disassembly. Such control was also shown for PRX particles dynamically formed using a templated approach, for which disassembly through judicious selection of specific building blocks is highlighted. The use of the templated approach was shown to be more straightforward and versatile in its applications, laying out a framework to form and engineer particles using PRXs as a building block. Lastly, by using CD’s molecular mobility in the PRX as an additional handle for tuning; a “one block” polymer, able to reversibly segregate into multi-blocks leading to the formation of nanoparticles, was developed. This approach is particularly interesting as many responsive polymeric materials have their response due to a stretched-to-coiled transition of individual chain while we show here a transition between a mono-block like architecture to a multi-block like architecture. The preliminary results highlight the potential of PRXs as building blocks for applications in drug delivery systems.
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ItemNanoengineered switchable, multi-responsive carriers for biomedical applications( 2014)Recent progress in material science and nanotechnology has enabled the design of next-generation drug delivery carriers. The implementation of such delivery systems has the potential to significantly enhance the current treatment outcomes, owing to their ability to achieve targeted bio-distribution and enhanced drug payloads. To develop the next generation of drug carriers, it is critical to incorporate a stimuli-responsive trigger into the material design. This allows for the development of “smart” carriers, which can load and release therapeutics in a specific targeted site on demand. Poly(2-diisopropylaminoethyl methacrylate) (PDPA) is a stimuli-responsive polymer that undergoes reversible hydrophobic-hydrophilic phase transition at biological-relevant pH variations. The incorporation of PDPA in the drug delivery systems opens a new route toward advanced drug delivery applications. This thesis focuses on developing several bottom-up approaches to assemble PDPA-based stimuli-responsive delivery systems from a material science perspective. By utilizing Layer-by-Layer (LbL) and self-assembly techniques, switchable, multifunctional systems that responded to various cellular conditions were synthesized. Charge-shifting PDPA capsules were synthesized via LbL assembly and cross-linked using a redox-responsive cross-linker. Dual stimuli-responsive cargo release profiles by pH and redox change were assessed in simulated intracellular conditions. Intracellular degradation kinetics of these capsules was investigated. The tuning of degradation kinetics was achieved by varying the degree of cross-linking density in the capsules, as confirmed by radio scintillation counting. Novel cross-linker free PDPA capsules were later developed. It was found that these capsules could improve the loading ability of drugs as small as 500 Da, and rapidly deconstruct and release cargo upon cellular uptake. Moreover, utilizing self-assembly techniques, multifunctional nanoparticles were synthesized from blending PDPA with an anti-cancer drug and a cell penetrating peptide. By varying the loading ratio in the nanoparticles, tunable cytotoxicity up to 30-fold was achieved. The reported PDPA-based responsive carriers are expected to provide fundamental insights towards the rational deign and synthesis of advanced delivery systems.
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ItemSoft polymeric nanoparticles as additives for CO2 separation membranes( 2014)The use of polymeric membranes for gas separation has experienced a major expansion in the past few decades with current applications which include the separation of CO2 from flue gas. Various approaches have been explored to fabricate membranes with superior separation performance that can exceed the current upper performance limit. These include the incorporation of hard inorganic nanoparticles into polymers to form mixed-matrix membranes (MMMs). The performance of MMMs can be further enhanced if they can be fabricated into asymmetric morphology. The fabrication of asymmetric membranes, in the form of a thin film composite (TFC) membrane, is more commercially viable due to the increased flux and reduced consumption of expensive nanoparticles. TFC membranes are typically composed of a porous support coated with a highly permeable gutter layer, which is in turn coated with a thin active layer. However, the development of effective asymmetric MMMs has been limited. This is due to the difficulty in fabricating nanoparticles in a size that does not exceed the thickness of the active layer and in avoiding defects in the resulting composite structure. The fabrication of next generation mixed-matrix gas separation membranes is also hampered by the need to ensure a defect-free polymer/inorganic particle interface. A similar approach can be applied to the addition of soft polymeric nanoparticles into a selective polymer matrix. In this case, the problem of defects occurring between the particle and the matrix can be avoided through the engineering of particles that are compatible with the polymer matrix. Hence, this thesis aims to synthesize novel soft polymeric nanoparticles with well-defined architectures and utilize these as additives to be incorporated into the thin active layer of TFC membranes. The requirements for these nanoparticles include (a) a soft and CO2 permeable core and (b) a corona which is compatible with the polymer matrix. The best candidate nanoparticles are then blended with a selective polymer matrix to form the active layer of TFC membranes, which are tested for their CO2 separation from N2. The size of the soft polymeric nanoparticles are significantly smaller than the thickness of the active layer and overcome the problem of blending larger inorganic nanoparticles to form asymmetric MMMs. The first soft polymeric nanoparticles studied were based on triblock copolymers containing polyimide (PI) and poly(dimethylsiloxane) (PDMS). Well-defined difunctional PI was initially prepared via step-growth polymerization. Subsequently, PI was functionalized and chain extended with different molar ratios of PDMS-monomethacrylate (PDMS-MA) via atom transfer radical polymerization (ATRP) to form a series of triblock copolymers. Self-assembly of triblock copolymers in a selective solvent for PI, followed by cross-linking via hydrogen abstraction, resulted in the formation of well-defined nanoparticles with a soft PDMS core. The second soft polymeric nanoparticles developed in this study was based on diblock copolymers containing poly(ethylene glycol) (PEG) and PDMS. Commercially available PEG was utilized as a substitute for the PI block due to the difficulty in synthesizing well-defined polymers via step-growth polymerization. Three different molecular weights of monomethyl ether PEG were initially functionalized to form macroinitiators suitable for ATRP. These macroinitiators were then chain extended with PDMS-MA and photoactive anthracene moeities in different molar ratios to afford a series of photoresponsive diblock copolymers. Self-assembly of diblock copolymers in a selective solvent for PEG, followed by photocross-linking via [4+4] photodimerization of anthracene moeities, resulted in the formation of another well-defined soft polymeric nanoparticles with various structures that range from spherical micelles to large compound micelles. The preparation of soft polymeric nanoparticles through the self-assembly of block copolymers is generally carried out in low concentration to avoid aggregation of nanoparticles. This hinders the preparation of nanoparticles on a larger scale. The third soft polymeric nanoparticles explored in this thesis were based on PEG and PEG-b-PDMS grafted star polymers that were synthesized via the ‘core-first’ approach. This method allows the preparation of nanoparticles in high yields as the crude reaction mixture only requires separation from unreacted monomers. Various grafted star polymers with different PEG and PDMS molar ratios were synthesized in high yields and high conversions utilizing a four-arm ATRP initiator. These grafted star polymers were then utilized as additives for existing gas separation membranes. TFC membranes were prepared from commercially available selective poly(amide-b-ether) (Pebax® 2533) that was blended with a series of PEG and PEG-b-PDMS grafted star polymers. These blends formed a thin film on microporous polyacrylonitrile substrates which have been pre-coated with a PDMS gutter layer. Their ability to selectively separate CO2 from N2 was studied at 35°C and an upstream pressure of 3.4 bar. The addition of soft polymeric nanoparticles into the thin active layer of TFC membranes resulted in greatly improved flux as these particles are able to form localized, high flux, soft domains within a selective polymer matrix. These results create an interesting route to further develop and utilize soft polymeric nanoparticles as additives in membranes for gas separation processes.
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ItemEngineering functional amyloid fibrils for biomaterial applications( 2012)The natural ability of biological molecules to self-assemble provides a useful route for the production of nanomaterials with desirable properties. Amyloid fibrils are a class of self-assembling proteins that are defined by their common core structure, which is rich in β-sheet structure. Fibrils are typically ~10 nm in width and have an elongated morphology with a length ~1 µm. These fibrils are historically associated with disease but they are also the functional state of some proteins in nature and can be produced in a controlled way from non-disease proteins. The fibril core structure imparts excellent physical properties such as a flexibility similar to silk and strength similar to steel, which recommend fibrils for applications in materials science. There is growing interest in the production of fibrils with useful properties, although a number of challenges remain before these materials can be applied. This thesis employed the TTR105-115 peptide, also known as TTR1, to drive the assembly of functional peptides into amyloid fibrils. The TTR1 sequence was selected for two reasons. Firstly, this peptide has a high propensity to self-assemble into highly ordered fibrous structures, where the peptides are arranged in a cross-β core structure. The TTR1 peptide also has a proven ability to drive the assembly of functional groups, so that they are displayed away from the fibril core at the C-terminal end of the TTR105-115 based peptide. The influence of these groups on the properties of assembled fibrils was investigated and the role functional groups on the kinetics of fibril assembly were determined. The TTR1-cycloRGDfK peptide was also designed with the aim of producing a fibril that would display specific properties. The peptide incorporated the functional cyclic RGDfK pentapeptide ligand, which has a high affinity and specificity towards the mammalian cell surface αVβ3 integrin receptor. Fibrils assembled from the TTR1-cycloRGDfK peptide were shown to promote the attachment and spreading of adherent mammalian cells when fibrils were presented as a surface coated layer. These findings demonstrated that the selection of functional sequences is paramount to the properties of fibrils based on the TTR1 peptide. The kinetics of functional fibril assembly were characterised using an established set of TTR1-based peptides: TTR1, TTR1-RGD, TTR1-RAD and the novel TTR1-GGK peptide. The functional ligands that are excluded from the fibril core were found to influence both the lag time and elongation rate of fibril formation. The study of TTR1-GGK assembly was further extended to include a wide range of solution conditions including conditions of varying ionic strength, solution pH or solutions containing different salt ions. The addition of salt promoted fibril. The extent of this effect was dependent on the degree of charge shielding, ion selectivity and the Hofmeister effect. The structure of the mature fibril was largely unaltered when fibrils were assembled in the presence of salt ions, indicating that salts may be used to tune fibril formation. Overall, these measurements demonstrated that non-fibril core residues alter the propensity for fibril formation, even with differences of a single amino acid. The impact of non-fibril core groups on assembly should therefore be considered when designing sequences for the production of functional fibrils. Functional amyloid fibrils were also tested for their biocompatibility using cell viability assays and membrane integrity assays. Mature fibrils assembled from the peptides TTR1, TTR1-RGD and TTR1-RAD were the primary focus since these aggregates are the targets for applications in materials science. The overarching conclusions from this work are firstly that the TTR1 peptide is a robust system that can promote the assembly of functional fibrils and secondly that non-fibril core residues greatly influence select properties of assembled fibrils, while other core structural features of fibrils remain intact. Non-core residues determined the extent and specificity of fibril binding to the cell membrane. Layers of TTR1-cycloRGDfK fibrils promoted the attachment and spreading of cells, demonstrating that fibrils can be engineered to have a positive effect on cell processes. A greater understanding of fibril biocompatibility is needed, however, before functional fibrils may be applied to biotechnology applications where cell interactions may be involved.