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Subject: search.filters.subject.340307 Structure and dynamics of materials

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    Laser ablation – film capture – electrospray ionization – mass spectrometry LA-FC-ESI-MS : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University, Albany, New Zealand
    (Massey University, 2023) Mao, Zhirui
    Laser ablation mass spectrometry (LA-MS) is an analytical method widely used in various fields. This study investigates a modified version of LA-MS that involves using a moving liquid film to capture and transfer the laser ablated material into a mass spectrometer. The use of a moving film to capture the ablated material and convey it to the electrospray ionization (ESI) source of a mass spectrometer allows for real time analysis, and the use of a focused laser spot across a translating sample allows for spatial resolution to be achieved. The addition of ionization enhancers, such as formic acid, or metal chelating agents to the liquid film allows additional flexibility when coupled with soft ionization afforded by an ESI source. This method allows for samples to be ablated in an open system under ambient atmospheric conditions. To demonstrate the versatility of this novel technique: solid graphite; caffeine powder and droplets; wood; and school shark vertebrae were all studied using this new method.
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    Development of luminescent lanthanide-based supramolecular and interlocked architectures : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University, (Albany), New Zealand
    (Massey University, 2022) Sansom, Gabriela
    The chemistry of mechanically interlocked molecules (MIMs), copper(I)-catalyzed azide-alkyne cycloaddition (click) reactions and lanthanide ions each individually are promising targets for the development of advanced luminescent materials, such as responsive molecular sensors and molecular switches. Herein, the synthesis of a family of dipicolinic acid (DPA) ligands, one containing a propargyl group (L₁) and three containing bulky groups (i.e. a 1,8-naphthalimide (L₂), a tert-butylbenzyl (L₃) and a 9-anthracene (L₄) group) appended to their 4-pyridyl position through CuAAC click chemistry are presented. These groups were chosen based on their ability to sensitize Ln³⁺ emission as well as their potential to act as stopper groups for small macrocycles for the development of quasi-[4]-rotaxanes. L₁ – L₃ formed highly luminescent complexes with Eu³⁺ and Tb³⁺. A CuAAC reaction was successfully carried out on a tris-alkyne appended DPA lanthanide complex, [La(L₁)₃]³ˉ, however synthetic difficulties were faced whilst carrying out the ATCuAAC derivative for the synthesis of quasi-[4]-rotaxanes. Due to this, slightly different DPA chelating systems were investigated such that they inherited both chelating and stoppering abilities. Thus, a series of methyl-protected DPA rotaxane ligands R₂ – R₄ were synthesized and R₃ was proven through photophysical titrations to form Ln³⁺ self-assemblies. UV/Vis titrations supported the formation of 2:1 R₃:Ln³⁺ species whereas fluorescence titrations supported the formation of 3:1 R₃:Ln³⁺ species (i.e. quasi-[4]-rotaxanes), thus further studies are ongoing to confirm this binding ratio. Lastly, preliminary findings regarding the synthesis of amide-protected DPA rotaxane ligands are also presented. The research herein integrates three highly valuable fields of chemistry and provides foundational results for the development of a range of advanced luminescent materials, such as Ln³⁺-containing interlocked molecules.
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    Modular functionalization of engineered polyhydroxyalkanoate scaffolds : a thesis presented in partial fulfilment of the requirements for degree Doctor of Philosophy in Microbiology at Massey University, New Zealand
    (Massey University, 2019) Wong, Jin Xiang
    Microbial polyhydroxyalkanoates (PHAs) are spherical polyesters that are naturally synthesized in vivo by a variety of microorganisms as carbon and energy reserves under imbalanced nutrition environments. Notably, PHA particles can be functionalized by the genetic modification of surface-exposed PHA-associated proteins, e.g. PHA synthase (PhaC), and this approach has led to multiple successful proof-of-concept demonstrations for bio-technology applications. However, current recombinant methods to functionalize PHAs require a certain biological complexity, such as simultaneous polyester and protein synthesis within a single cell. The less defined nature of this technology means limited control over particle morphology and surface functionalization. Seeking to overcome these limitations, the work presented in this thesis is to introduce the concept of modularity to the PHA particle technology, by merging the PHA particle technology with Tag/Catcher protein ligation systems. The Catcher domain can rapidly form a covalent bond with its pairing short peptide tag in a site-specific manner, without the need of additional reagents nor enzymes at broad ligation conditions. The SpyTag/SpyCatcher pair was merged recombinantly with PHA particle technology, where the resulting SpyCatcher-coated PHA particles were able to immobilize various SpyTagged proteins in vitro in a tunable manner and remained functional. This thesis further demonstrates several functionalization processes to streamline this modular strategy by assessing the possibility of whether non-purified SpyTagged proteins could ligate with the PHA particles in complex environments. The results demonstrated that SpyCatcher-coated PHA particles could be functionalized adequately using two of the proposed methods. To further expand the design space of this generic modular platform towards programmable multi-functionalization, various bimodular PHA particles utilizing alternative Tag/Catcher pairs (e.g. SdyTag/SdyCatcher and SnoopTag/Snoop-Catcher pairs) were designed and studied. One of the constructs resulted in the simultaneous multi-functionalization of plain PHA particles in one-step with two differently tagged proteins in in vivo and ex vivo reaction conditions. This work presents the modular design of PHA scaffolds and several streamlined manufacturing processes to the production of task-specific designer PHAs. Introducing the concept of modularity to the PHA particle technology enabled better control of particle uniformity, reproducibility, and immobilized protein density while remaining functional. These concepts should be broadly applicable to the design and manufacture of advanced functional materials for industrial applications.