The thesis presents an investigation of the nano-patterning of hydrogenated amorphous carbon (a-C:H) surfaces to control protein adsorption. The relevant literature is first reviewed, noting the link between protein adsorption and mis-folding and its relevance to bio-compatibility and nano-toxicity. It then identifies how nano-topography influences protein adsorption, the debates and conflicts in the literature regarding this effect and the issues associated with controlling nanotopography independently of local surface composition. The first experimental chapter deals with the preparation and analysis of a-C:H patterns made by focused ion beam (FIB) milling and atomic force microscopy (AFM) nanoindentation. These methods resulted in nano-patterns with 2 nm height amplitude and 60 nm spacing, hence of size commensurate with that of proteins. The challenges associated with the production of such patterns are discussed, particularly the analysis and simulation of the implanted gallium profile in the FIB patterns. Advanced AFM techniques were used to investigate the possible compositional nature of the patterns. The Interleave/Lift method detected an onset of long range interactions between a protein coated tip and the patterned surfaces at a 38 nm tip-surface distance for both patterning methods. A hill/valley compositional contrast was also noted, stronger in the case of the FIB pattern. Short range adhesive tip/surface forces were mapped with the digital pulse force method (DPFM). Again, this showed stronger compositional contrast for the FIB pattern. These effects were interpreted as arising from the electrostatic interactions between the negatively charged protein coated tip and the patterned surfaces. Using SRIM modelling and the measured contrast values, a negative charge per adsorbed protein of 1.3-3e was estimated. The second half of the thesis investigates protein adsorption on a-C:H for four different protein/solvent systems; bovine serum albumin (BSA) and bovine plasma fibrinogen (BPF) in de-ionized (DI) water or phosphate buffer saline (PBS) solutions. Fourier transform infrared (FTIR) analysis revealed that there is a significant change in the secondary structure of the proteins once they adsorbed onto a-C:H, corresponding to an increase of the 0 -sheet component, often associated with exposure of the buried hydrophobic groups. This is also consistent with the large surface footprint of the adsorbed proteins, measured by AFM microscopy. Adsorption on FIB-patterned surfaces reveals changed adsorption behaviours, with significant increases in adsorbed foot-prints for all systems expect for the BSA-DI system where this footprint decreases slightly. Finally, adsorption experiments were carried out on patterns made by the FIB and AFM techniques. This comparison indicates that, for the FIB pattern, BSA adsorbs preferentially in the valleys whereas, for the AFM pattern, it resides on the hills. This effect, consistent with the previous analysis, was attributed to the buried charges in the valleys of the FIB pattern. Overall, the work presented in this thesis showed that nano-patterned a-C:H model surfaces are useful to study and control protein adsorption, suggesting that, in the case studied here, nano-topography modifies qualitatively the adsorption process. In addition, the methods developed here can be extended to other patterning techniques and protein systems to study independently the influence of topography and composition on protein adsorption.

No description available.

We describe theoretically the optical properties of ultra-thin Lii-V semiconductor quantum wells and graphene. Specifically, we introduce a new mechanism for the interaction of electrons and optical phonons in III-V semiconductor quantum wells which is mediated via the spin-orbit coupling. We then describe the manifestation of this interaction in the fine structure of the cyclotron resonance near the frequency of the optical phonons in GaAs/AlGaAs heterostructures when the magnetic field is applied perpendicularly to the plane of the two-dimensional electrons. We find that the cyclotron resonance can mix with the transverse optical phonon and that the size of the crossing with this phonon is dependent on the total spin-polarisation of the electron gas.

The work described in this thesis concerns carbon nanotube reinforced glass/ceramic nanocomposites. The aim of the research project was to achieve uniform carbon nanotube dispersions in glassy matrices and subsequently measure the physical properties of the materials.

This thesis is concerned with ultrafast photophysics and excitation energy transfer in biomimetic and bio-sensing molecular nanomaterials, which have been investigated using timeresolved photoluminescence spectroscopy. Artificially-synthesised fully 7r-conjugated nanorings with 6-24 units of porphyrins incorporated have demonstrated remarkable full delocalisation of the absorbing excited state across the entire ring on an ultrafast timescale. The largest ring of 24 porphyrin units with a diameter of,...., 10 urn is the largest man-made molecular nanaring at present. The constraint that the lowest electronic transition is forbidden due to their high molecular symmetries is released by static and dynamic distortions in the solution. T hese findings provide promising opportunities for using these man-made light-harvesting materials that match the efficiency of their natural counterparts in technological applications. Self-assembled organic fluorescent nanoparticles (NPs) formed of amphiphilic monomers with targeting ligands exhibit potential to be used in bio-sensing applications. Homotransfer and heterotransfer of excitation energy in nanoparticles have been investigated, where mannose covalently linked on Ampl-B monomers provide binding sites for Concanavalin A which is attached with energy acceptors. Increasing the molar ratios of Ampl-B-mannose and Amp3-B can increase the binding sites and forming directional energetic cascades towards the NP surface, respectively. However, the amount of these two monomers must be optimised in order to reach the highest donor-acceptor energy transfer rate in the system. The works in this thesis have explored the fundamental optical properties of new Of ganic nanomaterials, which provide opportunities for biological relevant and light-harvesting applications.

The aim of this PhD project was to produce cyclodextrin based polymeric nanocapsules.

Few-layer transition metal chloride graphene intercalation compounds have becJI fabricated by the mechanical exfoliation of graphite intercalation compounds (GTCs) containing CoC12 , NiCh, CuCl2 , MnCh and FeC13 . The number of graphene layers and the distribution of the intercalate in the few-layer graphene intercalation compounds (FLGICs) have been characterised using the optical contrast of the FLGICs against the Si02 substrate and the G-peak of the Raman spectrum. FLGICs containing CL single intercalate layer surrounded by two graphene layers have been fabricated and characterised, which are an ideal system to study 2D magnetic phase transitions.

The central themes of this thesis are the design aspects and function of versatile molecular assemblies that mimic the behaviour of biological compartments, such as the cell. Synthetic biomimetic compartments are designed by utilising specific molecular interactions, which direct self-assembly. Coacervates, formed by spontaneous liquid-liquid phase separation upon ionic assembly of polyelectrolytes, have been described as a novel phase of soft matter. For the first time, nucleotide small molecules (the building block of nucleic acids) have been employed in the formation of coacervate droplets through facile mixing with the polycation, poly(diallyldimethylammonium) chloride (PDDA). Coacervate formation has been shown to be dependent upon the strength of the ionic interaction between the polyvalent anion and polycation. Moreover, this novel nucleotide-based coacervate is highly stable, existing in the form of microscopic droplet dispersions in aqueous solution that are capable of sequestering chemical species, such as organic dyes, porphyrins, biopolymer-coated inorganic nanoparticles and proteins. Supramolecular assembly of porphyrin molecules and enhanced enzyme activity within the coacervate droplets has been demonstrated, highlighting the function of such a material as a biomimetic compartment. Building upon initial work, the high molecular weight polymer PDDA has been replaced with lower molecular weight poly(L-lysine) (PLys) in order to produce coacervate microdroplets using biologically-relevant components. Such nucleotide- peptide coacervate droplets are of particular interest in the search for plausible routes towards a model protocell. A wide range of nucleotide molecules (including di- and mono-phosphate species) and the redox cofactor flavin adenine dinucleotide (FAD) have been employed as coacervate building blocks. Using 24 or 3 kDa PLys coacervate droplets were formed with the characteristic stability and uptake properties previously observed. Nanoparticle or enzyme mediated catalysis within the droplets was achieved and intra-droplet porphyrin aggregation demonstrated. Finally, self-assembled nanostructures were formed using a biomimetic peptide sequence covalently tethered to a phospholipid tail. Discrete, micellar aggregates were identified, characterised and shown to preferentially solubilise hydrophobic molecules and, through ionic preorganization, could be encapsulated within a nanoscopic biomineral shell.

SINCE its invention in 1986, the atomic force microscope (AFM) has revolutionised the field of nanotechnology and nanoscience. It is a tool that has enabled research into areas of medicine, advanced materials, biology, chemistry and physics. However due to its low frame rate it is a tool that has been limited to imaging small areas using a time lapse technique. It has only been in recent years that the frame rate of the device has been increased in a tool known as high-speed AFM (HSAFM). This increased frame rate allows, for the first time, biological processes to be viewed in real time or macro sized areas to be imaged with nanoscale resolution. The research presented here concentrates on a specific type of high-speed AFM developed at the University of Bristol called contact mode HSAFM. This thesis explains how the microscope is able to function, and presents a leap in image quality due to an increased understanding of the dynamics of the system. The future of the device is also discussed. III

Ni-Cu/Cu multilayered nanowires were grown in different polymer based track-etched membranes using pulsed potentiostatic electrodeposition. The nanowires were imaged using transmission electron microscopy and a regular repeat structure was observed confirming the presence of multilayered growth. X-ray fluorescence showed that there was approximately 13 % co-deposition of Cu within the Ni-Cu layer as expected from a single electrolyte deposition technique.