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27th ANNUAL SYMPOSIUM 2002

28-30 August 2003 University College Cork.

Communications

2003

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Microscopical Society of Ireland OFFICERS OF THE SOCIETY President: Alexander Black, Department of Anatomy, National University of Ireland – Galway, Ireland. Immediate Past President: Prof. Martin Steer, Department of Botany, University College Dublin, Belfield, Dublin 4, Ireland. Secretary: Dr. Michael Ball, National Centre for Biomedical Engineering Science, National University of Ireland – Galway, Ireland. Treasurer: Dr. Michael Morris, Department of Chemistry, University College Cork, Ireland. Honorary Public Relations Officer: Dr. Alan G. Ryder, National Centre for Biomedical Engineering Science, National University of Ireland – Galway, Ireland. Committee Members: Dr. Marty Gregg, Department of Pure and Applied Physics, The Queens of University Belfast BT7 1NN, N.Ireland Dr. David Cottell, The Electron Microscopy Laboratory, University College Dublin, Belfield, Dublin 4, Ireland. Local Organising Committee: Venue: University College Cork. Webpage: http://www.nuigalway.ie/msi/

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PRESENTATION ABSTRACTS * presenting author. MEASUREMENT OF BIOLOGICAL INTERACTIONS WITH BIOMATERIALS USING AFM. S.Wall,* C.Peppiatt and M.Ball. National Centre for Biomedical Engineering Science, National University of Ireland-Galway, Ireland

Abstract: Atomic Force Microscopy (AFM) has emerged as a valuable technique for providing three-dimensional images of surface topography of biological specimens in liquid and in air. The Atomic force Microscope can also probe adhesion and binding properties by way of force curves thus having great importance for the study of protein-surface interactions. Attachment of a protein-conjugated microsphere to a cantilever increases the area of contact between the cantilever and the sample surface. Thus the adhesive force between the ligand and a target biomolecule can be more easily measured. Our current research has been involved in the conjugation of Fibronectin (Fn) to 10µm polystyrene microspheres and adherence of a single microsphere to cantilevers using epoxy resin. These cantilevers were used to measure tip interactions with anti-fibronectin antibody coated surfaces thus determining the binding force using Tapping Mode™ under aqueous buffer. The forces of interaction between the Fn coated microsphere and the Fn receptors on 3T3 fibroblasts cell surfaces provided a map of the distribution of the Fn binding sites on the cell surface. These techniques provide valuable information on the measurement on cell-surface interactions with biomaterials. QUANTUM DOTS FOR BIOMEDICAL APPLICATIONS Y. Volkov,1* S. Mitchell,1 D. Kelleher,1 Y. Gun’ko,1 Y. Rakovich,1 E. Alphandery,1 J. Donegan,1 N. Gaponik,2 and A. Rogach.3 1 Dublin Molecular Medicine Centre, Chemistry and Physics Departments of Trinity College

Dublin, Ireland 2 Department of Physics and CeNS, University of Munich, Germany 3 Institute of Physical Chemistry, University of Hamburg, Germany Abstract: Fluorescent semiconductor nanocrystals (colloidal quantum dots) have recently attracted the focus of attention of scientists working in biological imaging worldwide. The properties of quantum dots such as a wide spectrum of emission wavelengths tunable by particle size and the possibility of custom modifications of surface characteristics make them prospectively very powerful and versatile tools for biomedical research and clinical applications. We have combined the expertise of researchers specializing in chemistry, physics and cell biology to explore the potential applications of quantum dots for biological systems at cellular and subcellular levels. We used water-soluble CdTe nanocrystals capped by thioglycolic acid with distinctive spectral characteristics to analyse their uptake and intracellular distribution in epithelial, lymphoid and macrophage-like cell lines by live cell confocal microscopy and 3-D imaging. We demonstrate here that quantum dots can be selectively targeted to the intracellular structures on the basis of their size and chemical properties of the particle surface. Small green-emitting dots (2.5 nm size, emission at 525 nm) undergo a rapid partially reversible accumulation in the paranuclear rough endoplasmic reticulum, cell nucleus and nucleolar structures in THP1 macrophage-like cell line. Larger red-emitting dots (4.5 nm size, emission at 600

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nm) were retained in the cytoplasm and smooth cell reticulum in all the cell types under study. Nanocrystal accumulation and distribution were affected by cytoskeletal and Golgi complex disruptors as well as by the changes in intracellular pH. Further studies exploring the opportunities of selective surface functionalization of quantum dots for directed intracellular delivery are currently being carried out. TEM OBSERVATIONS OF TI6AL4V GLAZED WITH AN APATITE-MULLITE GLASS-CERAMIC K.T. Stanton,1* N. Healy,1 and S.B. Newcomb.2 1 Department of Materials Science and Technology, University of Limerick, National

Technological Park, Limerick, Ireland 2 Director, Sonsam Ltd., Glebe Laboratories, Newport, Co. Tipperary, Ireland Abstract: Ti-6Al-4V is a fatigue-resistant biocompatible alloy that is commonly used to manufacture load-bearing prostheses, such as total-hip replacements. In order to promote oseointegration in vivo, these implants are often coated with synthetic hydroxyapatite [Ca10(PO4)6(OH)2] by plasma spraying although there are a number of problems associated with this line-of-sight deposition process. For this reason we have developed a novel glazing method that is significantly cheaper than plasma spraying and which provides a number of further potential advantages for the production of suitable parts for use in the medical field. A glass that is based on the system SiO2-P2O5-Al2O3-CaO-CaF2 has been deposited on Ti-6Al-4V metal substrates by sedimentation, and samples subsequently heated to an appropriate temperature for crystallisation of the glass to occur (as determined by Differential Thermal Analysis). It is critical that the crystallisation temperature be below the α → β transition of the titanium (970 °C) if the fatigue strength of the metal is not to be compromised. The glass has been found to crystallise in situ with the formation of fluorapatite [Ca10(PO4)6F2], a biocompatible and stable apatitic isomorph, and mullite [Al6Si2O13]. The apatite-mullite glass-ceramic has a thermal expansion coefficient that is well matched with the Ti-6Al-4V metal substrate thereby suppressing potentially deleterious effects such as delamination (on cooling). The interfacial reaction between the metal and the glass has been examined using transmission electron microscopy (TEM) and a range of methods used to determine the nature of the microstructures formed and the identity of the reaction products. The cross-sectional microstructural observations are described, and the results discussed in relation to the specialised application of the materials and the need for the control of properties such as adhesion. IMAGING AND SIZE DETERMINATION OF A SPHERICAL MICROCAVITY BY CONFOCAL FLUORESCENCE MICROSCOPY. Y.P. Rakovich,1* L. Yang,1 C.M. Taylor,1 L.A. Dunbar,2 A. MacRaighne,1 J.F. Donegan,1 and E.M. McCabe.1 1 Physics Department, Trinity College Dublin, Dublin 2, Ireland 2 Institut de Photonique et d'Electronique Quantique, EPFL, CH-1015 Lausanne, Switzerland Abstract: Spherical particles of a few microns in diameter can act as three dimensional optical resonators making them potential candidates in the fabrication of microlasers. The emission images and resonance spectra of a microspheres doped by dye molecules or semiconductor nanocrystals have been widely studied in recent years. A better understanding of the imaging and spectral characteristics associated with spherical microcavities will advance the field. In this report, we experimentally study both the bright-field and fluorescence images of microspheres by conventional and confocal scanning polarization microscopes. A qualitative analysis have been given to show a

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physical picture on the imaging of the microspheres. Emission spectra from melamine formaldehyde microspheres stained with Ethidium Bromide or covered by thin shell of CdTe nanocrystals have been experimentally studied. TE and TM modes of the whispering gallery modes (WGMs) have been selectively detected using polarization spectroscopy. We adopted two analytical expressions describing the resonance spacing under different size parameter conditions. Also we presented an alternative approach for whispering gallery mode identification and size determination of a spherical microcavity. The results have been compared with our numerical calculation of Mie theory. It shows that the proposed approach agrees very well with the Mie fitting. A WGM spectral shift has also been studied which is due to the size deviation of the microspheres. MEASUREMENTS OF THE HARDNESS OF MESOPOROUS ALUMINOSILICATE AND BOROSILICATE THIN FILMS. J.D. Holmes,1 K. Ryan,1 R. Farrell,1 E. Brennan,1 P. Cotter,1 N. Ray,2 G. Kloster,3 W. Lawton,1 and M.A. Morris.1 1 Dimensional Solids Group, Dept. of Chemistry, University College Cork, Cork, Ireland. 2 Dept. of Restorative Dentistry. 3 Intel Corporation. Abstract: Mesoporous alumino- and boro- silicate thin films were prepared by sol-gel synthesis. These were spin coated onto silicon wafer substrates and calcined to give well adhered thin films. The films were characterised by BET, nanoindentation, PXRD and SEM. The Vickers hardness of these films was studied. It was found that the addition of aluminium and boron to the preparation have profound effects on the hardness of the films. The process temperature (calcination) and pore size of the films also have strong effects. It was also found that very hard films could be prepared by filling of the pores with secondary material. STRAIN, COMPOSITION AND CRYSTALLINE DISORDER IN THIN SIGE LAYERS STUDIED BY RAMAN SPECTROSCOPY. D. Fitzgerald,1* T.S. Perova,1 R.A. Moore,1 K. Lyutovich,2 M. Oehme,2 and E. Kasper.2 1 Department of Electronic and Electrical Engineering, University of Dublin, Trinity

College, Dublin 2, Ireland. 2 Institut für Halbleitertechnik, Universtät Stuttgart, Pfaffenwaldring 47, D-7059 Stuttgart,

Germany Abstract: Virtual substrates intended for use in the fabrication of nMOSFET’s consist of standard Si wafers with epitaxially overgrown SiGe buffer layers. In the SiGe buffer layers, a high Ge content and a high degree of relaxation are essential because they provide the required strain in the Si channel, which acts as a quantum well for electrons. Si1-xGex epitaxial layers were grown by molecular beam epitaxy (MBE) with Ge content of 0.2

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dependence of Si-Si line width on Ge content in samples obtained under a variation of growth conditions, within and outside of the optimum process window, and with the addition of surfactant (Sb) was also analysed. The line width varies between ~6 and ~11 cm-1. These values are between the line width for the bulk SiGe layer (4 cm-1) and the polycrystalline SiGe layer (~ 12 cm-1) obtained in the literature. The low values of linewidth correspond to layers grown inside the optimum process window, the higher values to layers outside. Moreover, for the majority of samples studied in this work the phonon line width of both Si-Si and Si-Ge modes increases with decrease of temperature in the VLT regime, even for samples grown inside the optimum process window. This implies that i) the SiGe/Si interface is not very sharp, ii) there is a strain variation at this interface, iii) there are some defects (probably vacancy clusters) in the layers grown at lower temperature. Due to the lattice mismatch between the Si substrate and the SiGe layer, the interface lattice will be disordered and strained. Despite the fact that typically the interface must be very thin (a few atomic layers), there is some evidence that it may be relatively larger for thin films (

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models for assessing oil composition. Finally we have analysed a range of microscopic (~100 �m in diameter), entrapped in calcite and fluorite from the Cave-in-Rock mining district, Illinois, USA. We have correlated the fluorescence data from these ca. 200 million year old inclusions with probable composition from our calibration models. References: 1) A time-resolved fluorescence spectroscopic study of crude petroleum oils: influence of chemical

composition. A.G. Ryder. Appl. Spectrosc., 58(5), 613-623, (2004). 2) A compact violet diode laser based fluorescence lifetime microscope. A.G. Ryder, T.J. Glynn,

M. Przyjalgowski, B. Szczupak. J. Fluorescence, 12(2), 177-180, (2002). BACK-ILLUMINATED ELECTRON MULTIPLYING CCD TECHNOLOGY AND ITS IMPACT ON ULTRA LOW-LIGHT MICROSCOPY C. Coates,1* D. Denvir,1 N. Mchale,2 K. Thornbury,2 and M. Hollywood.2 1 Andor Technology Ltd., 9 Millennium Way, Springvale Business Park, Belfast, BT12 7AL. 2 Smooth Muscle Group, Medical Biology Centre, The Queen’s University of Belfast,

Belfast BT9 7BL. Abstract: Ultrasensitive detection of extremely low photon fluxes in live-cell confocal imaging microscopy has been performed using Electron Multiplying Charge Coupled Devices (EMCCDs) from Andor Technology. Front-illuminated versions of the technology were compared to back-illuminated EMCCD sensors, and the degree of reliable detection ability under extreme ultra low-light conditions was determined for each. Photon flux levels were of a level which is undetectable under ‘normal’ CCD operation, and were reduced by: (a) using shorter exposure times, facilitating more dynamic experiments; (b) using lower excitation power, reducing rate of photodecomposition; (c) using higher magnifications (d) using lower fluorophore concentrations. The EMCCD is an imaging sensor with single photon detection ability. Signal amplification is achieved by way of a unique electron multiplying structure built into the silicon, rather than the incorporation of an image intensifier tube. Like an ICCD, the gain can be varied – in the case of Andor’s EMCCD technology, ranging from unity (normal operation) up to x1000. However the camera is not limited by the highly restricted QE otherwise imposed by intensifier tubes, enabling the combined advantages of both amplification and the unimpaired harnessing of the higher/broader QE curves of the CCD chips, particularly that of the back-illuminated version. Furthermore, a direct comparison to Gen III ICCD performance has been carried out, demonstrating the significant boost in sensitivity offered by the EMCCD technology innovation, and confirming its position as the new standard in ultra low light dynamic imaging. MICROSCOPICAL TECHNIQUES FOR ARTERIAL ENDOLUMINAL DEVICES STUDY M. Galloni,1 E. Pasquino,2 M. Prunotto,1 V. Smaniotto,2 and C. Vignolini.1 1 Veterinary Morphophysiology Dept., Via Leonardo da Vinci, 44 – 10095 Grugliasco

(Torino), University of Turin, Italy. 2 Medical Affairs, Sorin Biomedica Cardio S.p.A. Abstract: Today the implant of a metal stent inside the arterial lumen is becoming a widespread endovascular technique that improves the efficacy of balloon catheter percutaneous therapy of vascular stenosis, both in the coronary and in peripheral districts. This procedure was developed in

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recent years and allows good clinical success but nevertheless in-stent restenosis, that is the pathologic growth of an excessive neointimal layer, occurs in a great number of patients. The study of the morphology of the vessel wall is of fundamental importance in order to assess the efficacy of the device, mostly in experimental tests. The complex shape of the thin metal stent does not permit the removal of the device from the biologic specimen, so histological procedures must allow the sectioning of soft and hard materials together in the same slice. We set up a standard histological method to achieve optimal results in light microscopy and immunohistochemistry, by using modified resin embedding which give us important information about inflammation, neointimal growth, cell cycle and luminal endothelialization of the vessel stented portion. MICRO-RAMAN SPECTROSCOPY OF PROTECTIVE COATINGS DEPOSITED ONTO C/C-SiC COMPOSITES K.Hosie,1* T.S. Perova,1 R.A. Moore,1 E. Roos,2 K. Berreth,2 and A. Lyutovich.2 1 Department of Electronic and Electrical Engineering, University of Dublin, Trinity

College, Dublin 2, Ireland. 2 MPA Stuttgart, University of Stuttgart, 70569 Stuttgart, Germany Abstract: Protective coatings are used on C/C-SiC composites to prevent oxidation and corrosion. Depending on the properties required, these coatings can be multilayers of pyrolytical carbon (PyC), SiC, TiSi2, Si3N4 and others. However, choosing the most suitable coating can often be complex. The use of SiC, for example, which has excellent thermal properties, is hampered by the mismatch in expansion coefficients between C/C and C/C-SiC, leading to the formation of cracks in the surface. Fortunately, it appears that this problem can be overcome by growing graded C/SiC layers. These layers consist of PyC, which result in smoothing of the substrate, followed by a controlled graded SixCy transition coating for bonding to the stoichiometric SiC layers. The PyC possesses either a diamond or onion-like structure depending on the process conditions. Micro-Raman spectroscopy has been used in this work to investigate the structure and composition of different protective coatings formed under different deposition conditions. The Raman instrument incorporated a Renishaw 1000 micro-Raman spectrometer with a laser excitation of 514.5nm. Analysis of spectra obtained from Raman line-mapping experiments in the region of ~ 800 cm-1 generated information on the different graded SiC polytypes. The crystalline size was calculated from results obtained in the range 1200-1700 cm-1. For pure PyC films, it was found that the properties of these coatings depend on the process conditions. The properties of SiN and TiSi2 films deposited onto C/C-SiC substrates are also discussed. Acknowledgments: The financial support towards this work from HEA Ireland (PRTLI Grant) is greatly acknowledged.

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COMPOSITION AND STRESS ANALYSIS IN SI STRUCTURES USING MICRO-RAMAN SPECTROSCOPY. J.McCarthy,1* T.S. Perova,1 R.A. Moore,1 F. Meyer,2 S. Bhattacharya,3 H. Gamble,3 and B. M. Armstrong.3 1 Department of Electronic and Electrical Engineering, University of Dublin, Trinity

College, Dublin 2, Ireland. 2 Inst.d’Electronique,Universite Paris XI,Orsay , France. 3 The Queens University Belfast Abstract: SiGeC is rapidly becoming the leading process technology for wireless applications at gigahertz frequencies and its high-speed low-power capabilities makes it a likely candidate to replace silicon BiCMOS in RF applications. The incorporation of carbon (C) into substitutional sites in SiGe films allows one to tailor the Ge concentration and strain independently and might serve to overcome some of the limitations occurring for SiGe epitaxially grown on Si. Here we present the results of FTIR and Raman investigations of two series of RTCVD grown SiGeC films with Ge content of ~10% and C content varied from 0 to 1.8% with thickness ranging from ~500 Å to 1000Å. The quantitative determination of the amount of substitutional carbon in SiGeC alloys is not well established. The Si-C band intensity at ~605 cm-1 is used to investigate the possible linear dependency of this band with increasing substitutional carbon content . Strained silicon is an important innovation and is now an integral part of the semiconductor industry's roadmap. Strained Si technology enables improvements in CMOS performance and functionality via replacement of the bulk, cubic-crystal Si substrate with a Si substrate that contains a tetragonally distorted, biaxially strained Si thin film at the surface. Investigating both CVD and MBE deposited samples, Raman Microscopy is used to investigate Ge content in the SiGe virtual substrate, along with the relaxation factor present in this layer. This is then used to investigate the possibility of misfit dislocation in this layer, which causes greater surface roughness and reduced strain levels in the strained silicon layer. Analysis of the spectrum allows the calculation of strain and stress in the layer. SOI (Silicon On Insulator) increases the basic transistor switching speed of a circuit by burying a sheath of oxide insulator material below the source and drain of the transistor to isolate it from the silicon substrate. Raman Microscopy is used to investigate levels of stress in thermal via deposited SOI. Acknowledgments: The financial support towards this work from HEA Ireland (PRTLI Grant) is greatly acknowledged. INVESTIGATION OF CORRELATION BETWEEN CHARACTERISTICS OF RAMAN SPECTRA AND PARAMETERS OF DATA-SCATTERING OBTAINED FROM PHASE COHERENCE THEORY. R.A. Moore,1 S. Unnikrishnan,1* T.S. Perova,1 N.D. McMillan,2 M. O’Neill,2 and G. Doyle.2 1 Department of Electronic and Electrical Engineering, Trinity College, Dublin 2, Ireland, 2 Institute of Technology Carlow, Carlow, Ireland Abstract: Micro-Raman spectroscopy is being increasingly used for composition and defect analysis in semiconductor structures. During these analyses, all the characteristics of Raman spectra, i.e. the peak position (νmax), the peak intensity (Imax), and the full width at half maximum (FWHM), can be used to gain information on different properties of materials, and in particular, at the materials fabrication stage. However, in many cases the difference in aforementioned properties is not so easy to detect. For example, the shift of the phonon lines in stressed semiconductors from the unstressed

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value can be as small as 0.05 cm-1 (at maximum spectral resolution of ~1 cm-1). We must note that this shift is directly related to the stress value, so it is important to estimate the shift with higher accuracy. Up until now the fitting of the phonon bands with Lorentzian or Gaussian functions has been employed in order to determine the peak position with accuracy

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available. While stereology can provide useful quantitative information about the structure of this dynamic tissue, other anatomical methods which could be applied to better define the relationships between structure and function include: confocal microscopy, to examine the dynamic physiological interactions of the different tissue compartments, and the use of low temperature electron microscopy techniques such as cryosubstitution to allow better access to the biochemical information resident in the tissue. The complex and dynamic nature of the tissue requires a multidisciplinary approach and central to these investigations is a comprehensive understanding of its fine structure. APPLICATION OF SYNCHROTRON RADIATION TO BIOLOGICAL TISSUES IMAGING. M. Galloni,1 M. Prunotto,1 F. Arfelli,2 R. Menk, 3 L. Rigon, and G. Tromba.3 1 Veterinary Morphophysiology Dept., Via Leonardo da Vinci, 44 – 10095 Grugliasco

(Torino), University of Turin, Italy. 2 Physics Dept. University of Trieste, Italy. 3 Elettra Synchrotron Light Laboratories, Basovizza (Trieste), Italy. Abstract: In conventional radiology the image formation relies on the X-ray absorption properties of the sample. The image contrast is originated by a variation of density, composition or thickness of the sample and is based exclusively on the detection of amplitude variation (or absorption) of the transmitted X-rays. The main limitation of this technique is the poor inherent contrast among the different types of soft tissue. Phase sensitive imaging techniques [1] are based on the observation of the phase-shifts produced by the object on the incoming wave. In general, the phase contribution becomes relevant if the X-ray source has a high spatial coherence as occurs in case of third generation Synchrotron light sources like Elettra [2]. In the X-ray energy range of 15÷25 keV, the phase shift is up to 1000 times more sensitive to variation of structure and composition of soft biological tissues when compared to absorption. Therefore it is possible to reveal phase effects even if absorption is negligible. Phase sensitive techniques, specifically PHase Contrast radiology (PHC) and Diffraction Enhanced Imaging (DEI), have been implemented at the SYRMEP beamline of Elettra to observe a range of biological specimen. Samples were observed both fresh, paraffin and methyl methacrylate resin (MMA) embedded. In particular the fine structure of parotid gland and mammary tumors was studied. The results obtained through this technique, compared with conventional radiography, allow to obtain considerable improvement in the contrast and spatial resolution of images without increasing the radiation dose. References: 1 R.Fitzgerald: “Phase-sensitive X-Ray Imaging”, Physics Today, July 2000. 2 F.Arfelli, et al: “Low Dose Phase Contrast X-Ray Medical Imaging”, Phys. Med. Biol, 43(10),

2845-2852, (1998).

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UNIO PICTORUM MANCUS (MOLLUSCA, BIVALVIA) AS FRESH WATERS BIOREMEDIATOR. AN HISTOCHEMICAL STUDY OF THE ANNUAL CYCLE OF ACTIVITY. B. Dore,1 M. Prunetto,2* D. Donna,1 A. Versace,1 S. Olmo,1 P. Pattono,1 and B. Sicuro.3 1 Animal and Human Biology Dept., via Accademia Albertina, 13 – 10123, Torino, Italy. 2 Veterinary Morphophysiology Dept. 3 Animal Production, Ecology and Epidemiology Dept., University of Turin, Italy. Abstract: Fresh water mussel Unio pictorum mancus is used to attempt the bioremediation of Avigliana Lakes, Piedmont, Italy. Clearly the metabolic and filtering activity may be strongly influenced by environmental factors and reproductive activity, as demonstrated in other fresh water mussel species. In order to optimise the bioremediation effort by assessing such influences, we applied some morphological and histochemical techniques on slices of the mantle. This is the organ lining the animal body, directly involved in metal absorption and shell mineralization. During one year we collected Unio samples from this fresh water lake. Representative portions of mantle are cut off, then cryostabilized in ethylene glycol 50% aqueous mixture, at –20 °C. The samples are dehydrated in increasing EG concentrations, at –20 °C. Finally tissue fragments are infiltrated by resin monomer (Glycol methacrylate - Technovit 7100) at 4° C; then polymerisation is achieved at 6-10 °C. Corresponding pieces of tissue are fixed in paraformaldehyde 1% (0.1M Na-cacodylate buffer, pH 7.2), then dehydrated in acetone and embedded in resin. In cryostabilized specimens connective tissue cells related to metal accumulation and detoxification can be easily observed and characterised. The activation of metal binding processes in these cells is detected only after cryostabilization. The annual metabolism cycle of wild animals, concerning also the shell calcification may be studied, in particular by the revelation of alkaline phosphatase activity in the fixed specimens. On the basis of these preliminary results the harvesting of Unio samples to be used as marker of bioremediation and detoxification should be performed only in the period of higher filtering and metabolic activity. POROUS SILICON - RARE EARTH DOPED GLASS COMPOSITES S. Balakrishnan,1* A. Rafferty,2 T. S. Perova,2 and Y. Gun’ko.1 1 Department of Chemistry, University of Dublin, Trinity College, Dublin 2, Ireland. 2 Department of Electronic and Electrical Engineering, University of Dublin, Trinity

College, Dublin 2, Ireland. Abstract: The development of components for photonics applications is growing exponentially. Currently, a key functionality requirement for photonics is that of optical amplification (gain) through the use of rare-earth dopants. In rare-earth ions such as erbium, the population of electronic levels within one of the inner shells can be inverted to provide optical gain. Because erbium’s band structure supports emission in the center of the telecommunications band at 1.54 µm, it is used in fiber amplifiers worldwide. Various erbium-doped host systems have been used to realize planar waveguide amplifiers [1-3]. In the present work we incorporated erbium and europium doped sol-gel glass into porous silcon and developed porous silicon – rare earth doped glass composites. The sol-gel method is now recognised as a convenient and flexible way to deposit oxide or glass films on a variety of substrates [4]. Some preliminary research on sol-gel derived films in meso-porous matrices has been recently reported. Various characteristion techniques, including FTIR, Raman Spectroscopy, Thermal Gravimetric Analysis and Scanning Electron Microscopy were employed in this work. Acknowledgements. The financial support of this work from Enterprise Ireland (Basic Research Grant Scheme, Grant SC/2001/209) is greatly acknowledged. References:

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1. R. N. Ghosh, J. Shmulovich, C. F. Cane, M.R.X. Debarros G. Nykolak, A. J. Bruce and P. C. Becker, IEEE Photonic Technol. Lett., 8, 518 (1996).

2. G. N. Vandenhoven, R. J. I. M. Koper, A. Polman, C. Vandam, J. W. M. Vanuffelen, M. K. Smit, Appl. Phys. Lett., , 68, 1886 (1996).

3. K. Hattori, T. Kitagawa, M. Oguma, H. Okazaki, Y. Ohmori, J. Appl. Phys., 80, 5301 (1996). 4. N. V. Gaponenko., Synthetic Metals., 124, 125 (2001). SPECTROSCOPIC CHARACTERISTICS OF NANOCOMPOSITE STRUCTURES IN 3D, 2D AND 1D SIZE CONFINEMENTS. S. Unnikrishnan,1 I.I. Shaganov,2 T.S. Perova,1 and R.A. Moore.1 1 Department of Electronic and Electrical Engineering, Trinity College, Dublin 2, Ireland 2 Vavilov State Optical Institute, 199034, St.-Petersburg, Russia Abstract: Nanocomposite materials, embedded into the host matrix with refractive index nh, such as nanospheres (3D confinement), nanowires (2D confinement) and nanowalls (1D confinement) are extremely attractive since they possess unique linear, and non-linear optical behaviour. The optical properties of composite materials can, in many ways, be understood in terms of local (effective) field effects. The optical response, compcompcomposite i 21ˆ εεε −= , for the different types of aforementioned structures has been calculated in Refs. [1-3] using Maxwell-Garnett and Bruggeman equations for two-composite media, based on the Lorentz-Lorenz model of the effective field. In this work, the concept of effective field dispersion of electromagnetic waves [3] was used in order to establish the relation between micro- and macro-characteristics of condensed matter. This concept uses the so called spectrum of Einstein coefficient B(ν) and the intrinsic properties of the optical transition, which are related to the macroscopic properties of condensed matter (refractive, n, and absorption, k, indices) via the local field factor θ(ν). In Ref. [4,5] the relationship between B(ν) and comp2ε for nanostructural materials with different types of size confinement has been established. Here we perform the numerical calculation and analysis of comp2ε and B(ν) functions using both dispersive and non-dispersive effective field approaches for a number of harmonic oscillators with different dispersive parameters (oscillator strength, decay factor and peak frequency). It has been shown that the spectral properties (peak position, peak intensity and half width) of comp2ε strongly depend upon the type of size confinement. In contrast, the spectrum B(ν) is the same for all cases of composite media and therefore has a fundamental meaning. Differences in dielectric functions observed for all studied cases arise as a result of the variation in the local field factor for 3D, 2D and 1D size confinements. Acknowledgments. The financial support towards this work from HEA Ireland (PRTLI Grant) is greatly acknowledged. References: 1. D.E. Aspnes, Am. J. Phys., 50, 704 (1982). 2. R.W. Boyd, R.J. Gehr, G.L. Fischer and J.E. Sipe, Pure Appl. Opt., 5, 505 (1996). 3. A.V. Ghiner and G.I. Surdutovich, Phys. Rev. A, 49, 1313 (1994). 4. N.G. Bakhshiev, O.P. Girin and V.S. Libov, Sov. Phys. Dokl. 7, 719 (1963); Sov. Opt. & Spectr.,

14, 476; 634; 745 (1963). 5. I.I. Shaganov, T.S. Perova, R.A. Moore and K. Berwick, International Conference on Optics of

Surfaces and Interfaces, OSI-5, Leon, Mexico, 26-30 May, 2003.

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FROM FUNCTIONALISED POLYHEDRAL SILSESQUIOXANES TO NOVEL NANOPOROUS MATERIALS M. Bent and Y.K. Gun’ko.* Department of Chemistry, Trinity College Dublin, Ireland.

Abstract: This work is to design new polyhedral silsesquioxanes, which contain cyclopentadienyl functionalities and use these compounds as building blocks for new materials. Silanetriols [RSi(OH)3], bis-silanetriols [(OH)3SiR’Si(OH)3; R = -(CH2)3(C10H10)(CH2)3-] and several polyhedral silsesquioxanes, (RSiO1.5)n (n = 8 and 10) with cyclopentadienyl (R = -C5H5 or -(CH2)3-C5H5 ) functionalities have been prepared by the acid-assisted hydrolytic condensation of the correspondent silicon organic precursors RSiCl3 or RSi(OC2H5)3. The products of these reactions were varied depending of the nature of organic solvent, amount of water and catalyst used. The products with cyclopentadienyl groups have been used to prepare new cross-linked 3D oligomers and polymers by Diels-Alder reaction. The compounds have been characterised by multinuclear (1H, 13C, and 29Si) NMR, ES MS and IR spectroscopy, UV-Vis spectrometry, GPC and electronic microscopy (TEM and SEM). The approach above seems to be promising for the preparation of novel controlled pore size nanostructured materials.

Fig. 1: SEM image of silsesquioxane polymer particles.

MICROARCHITECTURAL CHARACTERIZATION OF COLLAGEN ORIENTATION IN BOVINE KNEE JOINTS. T. Scarpa,1,2* V. Barron,2 S. Brody,2 and A. Pandit.2 1 Universita’ degli Studi di Trieste, Dipartimento di Biochimica Biofisica e Chimica delle

Macromolecole, Trieste, Italy. 2 National Centre for Biomedical Engineering Science, National University of Ireland,

Galway, Ireland. Abstract: Tissue engineering has an important role to play in the repair and regeneration of damaged cartilage and has the potential to improve the quality of life for patients where traumatic injuries and arthritis have resulted in pain and restriction of movement. To achieve the goal of tissue engineered cartilage three main components are critical; chondrogenic cells for the generation of tissue, a 3-D scaffold to support cells during growth, and bioactive growth factors to promote growth and integration with native cartilage.

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Collagen fibres are the structural elements of articular cartilage and are the main load-bearing components. The structure of the collagen network is thought to be related to the mechanical stability of the tissue. Hence the characterisation of the orientation of collagen fibres is essential to deduce the optimum mechanical properties for scaffold design. Collagen is a fibrillar structure, with birefringence properties, i.e. is capable of altering the state of polarized light. Therefore, it is possible to determine the orientation of the collagen fibres in cartilage using polarized light microscopy. In this research study, 10 unstained cartilage samples from bovine knee joints were harvested, fixed and viewed under a polarized light microscope. A composite image of the general orientation of the collagen fibres in the samples is created by assembling all the orientation images as shown in Fig. 1.

Fig. 1: Composite image of collagen orientation Acknowledgement: Department of Mechanical and Biomedical Engineering, NUI Galway, Irish Research Council for Science Engineering and Technology, ERDISU – Progetto MOVE, Universita’ degli Studi di Trieste. THE EFFECT OF DYNAMIC MECHANICAL STIMULATION ON VASCULAR ENDOTHELIAL CELLS IN-VITRO. K. Coghlan,* V. Barron, E. McLucas, M. O’Brien, M. Ball, P.E. McHugh. National Centre of Biomedical Engineering and Science, National University of Ireland, Galway, Ireland. Abstract: Atherosclerosis is a major cause of death in the US, Europe and the Western world. This cardiovascular disease is characterised by thickening of the intima and the development of the atherosclerotic plaques, which at later stages may result in partial or total occlusion of the artery. Current surgical treatments include the use of bypass grafts. However, small diameter grafts have seen limited success with reports of short-term high patency rates and revision surgeries. Tissue engineering offers the possibility of developing a biological substitute material with the inherent mechanical, chemical, biological and morphological properties required for vascular grafts. However, there are still many issues that need to be addressed before a biological replacement material is routinely used in clinical practice. This research aims to address some of these issues. Previous research has shown that cell and tissue growth increases in response to mechanical stimuli. The vascular endothelium lines the inner side of blood vessels and regulates a variety of biological responses and physiological functions. Mechanical conditions affect cell function in vivo. Exposing

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the endothelial cells to cyclic strain replicates this affect in vitro. The main objective of this study is to develop a better understanding of the response of vascular endothelium to dynamic mechanical stimulation. Human Umbilical Vein Endothelial Cells (HUVEC’s) were cultured under static conditions between passage 7 and 11. When confluence was reached the cells were subsequently seeded onto sterilized silicone elastomer sheets and subjected to various levels of cyclic strain at a frequency of 1Hz, that of the pulse of a normal healthy adult. Prior to stretching, confluent HUVEC’s were examined by conventional light microscopy and digital imagery. HUVEC’s were characterised by their ‘cobblestone’ morphology. Von Willebrand Factor, a cellular marker, was identified by immunohistochemistry. The effect of stretching was examined using various different microscopy techniques. Cell morphology and cell orientation was studied using Scanning Electron Microscopy (SEM). ICAM-1 (Intra Cellular Adhesion Molecule-1) and VCAM-1 (Vascular Cellular Adhesion Molecule-1) belong to the immunoglobulin superfamily group of adhesion molecules. The expression of endothelial cell specific markers was investigated by employing immunofluorescence techniques. The samples to be imaged with the Confocal Laser Scanning Microscope were labelled with a fluorescent probe conjugated to monoclonal antibodies and other molecules. Results were compared to a control sample of HUVEC’s grown under static conditions. Initial results indicated that the cells reoriented perpendicular to the direction of stretch and HUVEC’s exposed to strain showed greater levels of ICAM-1 expression, whereas VCAM-1 expression of HUVEC’s under strain appeared to be similar to HUVEC’s under static condition. Acknowledgements: B. Clarke, C. Peppiatt, E. Timmins. THE INFLUENCE OF TITANIUM SURFACE POROSITY ON ADHERENCE AND GROWTH OF OSTEOBLAST-LIKE CELLS FROM THE SAOS-2 CELL LINE IN VITRO: AN ELECTRON MICROSCOPICAL STUDY. N. Murtagh,1,2 A. Black,1 and M. Ball.2 1 Department of Anatomy, National University of Ireland, Galway 2 National Centre for Biomedical Engineering Science, National University of Ireland,

Galway Abstract: Novel orthopaedic implants are often composed of porous titanium coatings, fabricated by sintering titanium beads onto the surface. These may be preferred owing to concerns regarding delamination of traditional hydroxyapatite coatings and associated potential for releasing ceramic particles at the implant site. Osteoblast-like cells from the osteosarcoma cell line Saos-2 were cultured for a range of time periods (7, 14, 21, 28 day) on both smooth (non-porous) and porous (DePuy coated) titanium (Ti) discs. Cell growth and thus osseointegrative potential was investigated using both scanning and transmission electron microscopy. On smooth Ti surfaces, cells formed a flattened adherent patchy monolayer by day 14, with noticeably improved coverage by day 21. Cells presented an elongated profile with raised nuclear bulges and numerous surface microvilli. Cell-cell contact was maintained via a network of filopodia. Porous Ti discs presented a noticeably different morphology. Cells remained adherent to individual beads and were well dispersed throughout the pores. Individual cells and cell clusters demonstrated bridging capabilities by extending filopodia between neighbouring Ti beads. Cells attached, spread and proliferated on both surfaces; but this was more readily observed on the smooth Ti surface. The results of this study demonstrate the influence of porosity on the growth of osteoblast-like cells cultured on titanium, and may prove beneficial in the development of orthopaedic devices where osseointegrative potential is desirable.

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FUNCTIONALISED MAGNETIC NANOPARTICLES S. Corr* and Y.K. Gun’ko. Department of Chemistry, Trinity College, University of Dublin, Ireland Abstract: The main objective of this work is to design stable magnetic fluids of magnetite nanoparticles via functionalisation, with a view to using these as MRI contrast agents. Porphyrins are well known to be very important biomedical materials with excellent biocompatibility. The porphyrin groups may be easily functionalised with different bioreagents via OH-groups. The combination of these properties of porphyrins with magnetic nanoparticles might lead to a new class of materials with a very wide range of applications. Despite these prospects, the utilization of porphyrins for coating and functionalisation of magnetic nanoparticles is actually unexplored. The magnetic nanoparticles are prepared by a new, novel method based on sol-gel techniques and ultrasonic processing. This is a very quick, one-step method for the preparation of magnetic nanoparticles from an Fe(II) tert-butoxide precursor. These particles have been characterised by electron microscopy (TEM and SEM), IR, UV-vis, photoluminescence and 1H NMR spectroscopy. Two products have been obtained, one from a reaction of porphyrin derivatives with amorphous nanoparticles and the other with nanocrystalline magnetite. From these, interesting conclusions may be drawn as to the stability of the magnetite nanoparticles when reacted with porphyrin surfactants. Microscopy results confirm the presence of a core-shell structure, with IR and photoluminescence spectroscopy confirming the presence of porphyrin in this shell. This approach is proving successful in the preparation of magnetite nanoparticles with a core-shell structure and is very promising for the preparation of stable magnetic fluids.