Browsing by Author "Ramsden, J. J."

Now showing 1 - 7 of 7
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    Development of sensitive elements based on photochromic bacteriorhodopsin for fibre optic sensors
    (Cranfield University, 2007-01) Korposh, Serhiy O.; Ramsden, J. J.
    This work focuses on the development of sensitive elements incorporating bacteriorhodopsin thin films for fibre optic sensors. The sensing principle is based on monitoring optical properties of the bacteriorhodopsin thin films during changes of environmental conditions. The photochromic properties of the bR films change in response to the presence of different chemical species and this effect can be employed for the development of sensitive elements for optical sensors. For practical sensing applications, one can monitor changes (in the presence of chemical species) of the spectral and kinetic parameters of bR films incorporated into a matrix. The main topic of this thesis is to study the possibility of using bacteriorhodopsin thin films for the construction of fibre-optic sensors for monitoring ammonia and humidity. The possibility to control sensitivity and selectivity of the sensor to the presence of ammonia and humidity by adding chemicals to the bR film and by employing different materials as a matrix for the creation of bR films is reported. The examples based on ammonia and relative humidity are used to show how using a broad range of different chemical additives bR can be sensitized to a wide spectrum of species, and thus possesses the potential to be a universal film material for optical sensors.
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    Nanotechnology Applied to Stem Cell-Substratum Interactions
    (Cranfield University, 2008-09) Aref, Amirreza; Ramsden, J. J.
    The modulation of biological interaction with artificial surfaces is a vital aspect of biomaterials research. Perhaps the most challenging area is transplantation involving the introduction of stem cells into the body with their ability to differentiate; the response of stem cells to implanted biomaterials (or to the host tissue) provides a uniquely sensitive way to explore biocompatibility. An understanding of how to direct specific substratumcellular responses is critical for the development of future biomaterials (e.g., for prosthesis). Attachment and spreading of a cell to and on a substratum are the first part of the process that leads to the ultimate assimilation of the new cell or prosthesis with the host tissue. Together with conventional microscopy, I have exploited a uniquely powerful noninvasive optical technique (Optical Waveguide Lightmode Spectroscopy, OWLS) to quantify cell attachment and spreading of stem cells to artificial biomaterials, and determine how the cell environment (the substratum),the complex liquid medium bathing the cell, and the presence of congeners, influence attachment and spreading. My results highlight that quantitative characterisation of interfacial interactions, including their kinetics leads to uniquely new insight into cell-protein-material interactions. This knowledge will be doubtless be useful in the development of new generations of biomaterials with improved properties designed for specific applications.
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    On some factors that effect the ‘feel’ of molecules
    (Cranfield University, 2007) McColl, James; Ramsden, J. J.
    There is currently a trend towards the increasing use of nanotechnology in food. Emerging technology has the potential to modify the nutritional value and improve the quality of food products. Nevertheless there are difficulties. Perhaps the most problematic area is molecular sensing and in particular mechanical sensing as modification leads to structurally different molecules. The mucosal layers are the first point of contact in the mechanical sensory process. Mucins are the largest component of the mucosa and these high molecular weight glycoproteins can be found across all animal phyla. Their roles are diverse ranging from a non-specific immune response to lubricators. Mucin is investigated and it is proposed to adsorb in a concentration manner in a quasi-composite layer structure. This structure is related to its functional properties and is conserved over a wide temperature range.
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    Surface engineering for biological recognition
    (Cranfield University, 2010-04) Yeh, Yun-Peng; Ramsden, J. J.; Chien, Hsi-Hsin
    The underlying idea of this thesis is that the surface chemical and morphological nature of bacterial strains uniquely differentiates one from another and hence can be used as the basis for their identification and control. It follows that their interactions with an artificial substratum uniquely characterize them. In principle, potentially it is easier and faster to evaluate the interfacial energy between a bacterium and a substratum than to characterize its genome or determine molecular biomarkers characteristic of the strain, hence validation of this thesis opens the way to rapid screening and diagnosis. Auxiliary to this main idea, an advanced metrology for evaluating the interfacial energies has been developed, exploiting the power of kinetic analysis.
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    Symbiotic nitrogen fixation enhancement due to magnetite nanoparticles
    (Cranfield University, 2011-01) Ghalamboran, M. R.; Ramsden, J. J.
    Population pressure on food production motivates the search for new ways to increase the productivity of arable land, especially land rendered marginal by salinity or aridity. The global thesis motivating this work is that nanotechnology can benefit agriculture. My specific thesis is that that part of nanotechnology concerned with nanoparticle production can benefit soybean yield. I have focused on symbiotic nitrogen fixation, and systematically investigated the effects thereon of magnetite nanoparticles introduced into the rhizosphere.My main finding is that the presence of these nanoparticles increases nodulation -- both the number of nodules and the size of individual nodules. Since the experiments were carried out on plants provided with minimal nutrients, there was no corresponding increase in vegetative growth. Some evidence was obtained for the nanoparticles enhancing the "molecular dialogue" between soybean root and the Bradyrhizobia that become incorporated in the nodules. A secondary finding is that the nanoparticles enhance the growth rate of Bradyrhizobia in culture, which is advantageous for the preparation of inocula. Furthermore, coating soybean seeds with nanoparticles and Bradyrhizobia prior to planting enhances survival of the bacteria, and therefore increases the efficiency of subsequent nodulation.
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    Use of magnetic nanoparticles to enhance biodesulfurization
    (Cranfield University, 2008) Ansari, Farahnaz; Ramsden, J. J.
    Biodesulfurization (BDS) is an alternative to hydrodesulfurization (HDS) as a method to remove sulfur from crude oil. Dibenzothiophene (DBT) was chosen as a model compound for the forms of thiophenic sulfur found in fossil fuels; up to 70% of the sulfur in petroleum is found as DBT and substituted DBTs; these compounds are however particularly recalcitrant to hydrodesulfurization, the current standard industrial method. My thesis deals with enhancing BDS through novel strains and through nanotechnology. Chapter highlights are: Chapter 2. My first aim was to isolate novel aerobic, mesophilic bacteria that can grow in mineral media at neutral pH value with DBT as the sole sulfur source. Different natural sites in Iran were sampled and I enriched, isolated and purified such bacteria. Twenty four isolates were obtained that could utilize sulfur compounds. Five of them were shown to convert DBT into HBP. After preliminary characterization, the five isolates were sent to the Durmishidze Institute of Biotechnology in Tbilisi for help with strain identification. Two isolates (F2 and F4) were identified as Pseudomonas strains, F1 was a Flavobacterium and F3 belonged to the strain of Rhodococcus. The definite identification of isolate F5 was not successful but with high probability it was a known strain. Since no new strains were apparently discovered, I did not work further in this direction. Chapter 3. In a second approach I studied the desulfurization ability of Shewanella putrefaciens strain NCIMB 8768, because in a previous investigation carried out at Cranfield University, it had been found that it reduced sulfur odour in clay. I compared its biodesulfurization activity profile with that of the widely studied Rhodococcus erythropolis strain IGTS8. However, S. putrefaciens was not as good as R. erythropolis. Chapter 4 and 5. I then turned to nanotechnology, which as a revolutionary new technological platform offers hope to solve many problems. There is currently a trend toward the increasing use of nanotechnology in industry because of its potentially revolutionary paths to innovation. I then asked how nanotechnology can contribute to enhancing the presently poor efficiency of biodesulfurization. Perhaps the most problematic difficulty is how to separate the microorganisms at the end of the desulfurization process. To make BDS more amenable, I explored the use of nanotechnology to magnetize biodesulfurizing bacteria. In other words, to render desulfurizing bacteria magnetic, I made them magnetic by decorating their outer surfaces with magnetic nanoparticles, allowing them to be separated using an external magnet. I used the best known desulfurizing bacterial strain, Rhodococcus erythropolis IGTS8. The decoration and magnetic separation worked very well. Unexpectedly, I found that the decorated cells had a 56% higher desulfurization activity compared to the nondecorated cells. I proposed that this is due to permeabilization of the bacterial membrane, facilitating the entry and exit of reactant and product respectively. Supporting evidence for enhanced permeabilization was obtained by Dr Pavel Grigoriev, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino. In Chapter 6, to optimize attachment of the nanoparticles to the surface of the bacteria I created thin magnetic nanofilms from the nanoparticles and measured the attachment of the bacteria using a uniquely powerful noninvasive optical technique (Optical Waveguide Lightmode Spectroscopy, OWLS) to quantify the attachment and determine how the liquid medium and other factors influence the process.
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    Virtual living organism: A rapid prototyping tool to emulate biology
    (Cranfield University, 2011-10) Bándi, Gergely; Ramsden, J. J.
    Rapid prototyping tools exist in many fields of science and engineering, but are rare in biology especially not general tools that can handle the diversity and complexity of the many spatial and temporal scales in nature. In this thesis a general use, cell-based, middle-out biology emulation programming framework (outlining a programming paradigm) is presented, that enables biologists to emulate and use virtual biological systems of previously unimaginable complexity and potentially get results accurate enough to be used in research and ultimately, in clinical practice, such as diagnosis or operations. With this technology, virtual organisms can be created that are viable, fit and can be optimised for any task that arises. The tool, realised with a programming framework created for the C++ language is detailed and demonstrated through several examples of increasing complexity, namely several example organisms and a cancer emulation, showing both viable virtual organisms and usable experimental results.