Advanced materials for recognition and capture of whole cells and microorganisms

Selective cell recognition and capture has recently attracted significant interest due to its potential importance for clinical, diagnostic, environmental, and security applications. Current methods for cell isolation from complex samples are largely dependent on cell size and density, with limited application scope as many of the target cells do not exhibit appreciable differences in this respect. The most recent and forthcoming developments in the area of selective recognition and capture of whole cells, based on natural receptors, as well as synthetic materials utilising physical and chemical properties of the target cell or microorganism, are highlighted. Particular focus is given to the development of cell complementary surfaces using the cells themselves as templating agents, by means of molecular imprinting, and their combination with sensing platforms for rapid cell detection in complex media. The benefits and challenges of each approach are discussed and a perspective of the future of this research area is given.

Progress in x-ray spectroscopies for the study of advanced materials

This thesis work is focused on the use of selected core-level x-ray spectroscopies to study semiconductor materials of great technological interest and on the development of a new implementation of appearance potential spectroscopy. Core-level spectroscopies can be exploited to study these materials with a local approach since they are sensitive to the electronic structure localized on a chemical species present in the sample examined. This approach, in fact, provides important micro-structural information that is difficult to obtain with techniques sensitive to the average properties of materials. In this thesis work we present a novel approach to the study of semiconductors with core-level spectroscopies based on an original analysis procedure that leads to an insightful understanding of the correlation between the local micro-structure and the spectral features observed. In particular, we studied the micro-structure of Hydrogen induced defects in nitride semiconductors, since the analysed materials show substantial variations of optical and electronic properties as a consequence of H incorporation. Finally, we present a novel implementation of soft x-ray appearance potential spectroscopy, a core-level spectroscopy that uses electrons as a source of excitation and has the great advantage of being an in-house technique. The original set-up illustrated was designed to reach a high signal-to-noise ratio for the acquisition of good quality spectra that can then be analyzed in the framework of the real space full multiple scattering theory. This technique has never been coupled with this analysis approach and therefore our work unite a novel implementation with an original data analysis method, enlarging the field of application of this technique.

High Intensity Lasers Application to Advanced Materials Processing: Laser Peening and Related Processes

High Intensity Lasers Application to Advanced Materials Processing: Laser Peening and Related

Investigating polymer-peptide conjugates and electrospinning for the production of advanced materials

This thesis describes the production of advanced materials comprising a wide array of polymer-based building blocks. These materials include bio-hybrid polymer-peptide conjugates, based on phenylalanine and poly(ethylene oxide), and polymers with intrinsic microporosity (PIMs). Polymer-peptides conjugates were previously synthesised using click chemistry. Due to the inherent disadvantages of the reported synthesis, a new, simpler, inexpensive protocol was sought. Three synthetic methods based on amidation chemistry were investigated for both oligopeptide and polymerpeptide coupling. The resulting conjugates produced were then assessed by various analytical techniques, and the new synthesis was compared with the established protocol. An investigation was also carried out focussing on polymer-peptide coupling via ester chemistry, involving deprotection of the carboxyl terminus of the peptide. Polymer-peptide conjugates were also assessed for their propensity to self-assemble into thixotropic gels in an array of solvent mixtures. Determination of the rules governing this particular self-assembly (gelation) was required. Initial work suggested that at least four phenylalanine peptide units were necessary for self-assembly, due to favourable hydrogen bond interactions. Quantitative analysis was carried out using three analytical techniques (namely rheology, FTIR, and confocal microscopy) to probe the microstructure of the material and provided further information on the conditions for self-assembly. Several polymers were electrospun in order to produce nanofibres. These included novel materials such as PIMs and the aforementioned bio-hybrid conjugates. An investigation of the parameters governing successful fibre production was carried out for PIMs, polymer-peptide conjugates, and for nanoparticle cages coupled to a polymer scaffold. SEM analysis was carried out on all material produced during these electrospinning experiments.

Advanced mechanics of materials with microstructure

The study of advanced materials aimed at improving human life has been performed since time immemorial. Such studies have created everlasting and greatly revered monuments and have helped revolutionize transportation by ushering the age of lighter–than–air flying machines. Hence a study of the mechanical behavior of advanced materials can pave way for their use for mankind’s benefit. In this school of thought, the aim of this dissertation is to broadly perform two investigations. First, an efficient modeling approach is established to predict the elastic response of cellular materials with distributions of cell geometries. Cellular materials find important applications in structural engineering. The approach does not require complex and time-consuming computational techniques usually associated with modeling such materials. Unlike most current analytical techniques, the modeling approach directly accounts for the cellular material microstructure. The approach combines micropolar elasticity theory and elastic mixture theory to predict the elastic response of cellular materials. The modeling approach is applied to the two dimensional balsa wood material. Predicted properties are in good agreement with experimentally determined properties, which emphasizes the model’s potential to predict the elastic response of other cellular solids, such as open cell and closed cell foams. The second topic concerns intraneural ganglion cysts which are a set of medical conditions that result in denervation of the muscles innervated by the cystic nerve leading to pain and loss of function. Current treatment approaches only temporarily alleviate pain and denervation which, however, does not prevent cyst recurrence. Hence, a mechanistic understanding of the pathogenesis of intraneural ganglion cysts can help clinicians understand them better and therefore devise more effective treatment options. In this study, an analysis methodology using finite element analysis is established to investigate the pathogenesis of intraneural ganglion cysts. Using this methodology, the propagation of these cysts is analyzed in their most common site of occurrence in the human body i.e. the common peroneal nerve. Results obtained using finite element analysis show good correlation with clinical imaging patterns thereby validating the promise of the method to study cyst pathogenesis.

Frontiers in Materials Science and Technology

This special issue aims to provide up-to-date knowledge and the latest scientific concepts and technological developments in the processing, characterization, testing, mechanics, modeling and applications of a broad range of advanced materials. The many contributors, from Denmark, Germany, UK, Iran, Saudi Arabia, Malaysia, Japan, the People’s Republic of China, Singapore, Taiwan, USA, New Zealand and Australia, present a wide range of topics including: nanomaterials, thin films and coatings, metals and alloys, composite materials, materials processing and characterization, biomaterials and biomechanics, and computational materials science and simulation. The work will therefore be of great interest to a broad spectrum of researchers and technologists.