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Hybrid organic-inorganic nanomaterials for applications at the biointerfaces
No full textIn the last few years, the application of nanomaterials (NMs) as theranostic devices, which combine diagnostic and therapeutic features, has gained a tremendous interest and development. Still, the major challenge is the understanding of the many and often complex processes that occur during the interaction of biological compounds with nanomaterials, in order to modulate their responses to the fixed target. A fine development of such smart nanosystems could occur only by a critical control of chemical/physical properties of NMs at the biological interfaces.
According to such premises, this thesis deals with the investigation of NMs at the biointerfaces for potential theranostic applications. Specifically, the work has been addressed to the synthesis and characterization of several inorganic and organic nanomaterials, including gold and silver nanoparticles, hydroxyapatite, graphene and graphene oxide nanosheets tailored at the surface with stimuli-responsive polymers (polyacrylate and/or polyacrylamide) or specific chemical functionalities (amine functionalisation, sulphur functionalisation). As to the biomolecular counterpart, the performed study involved proteins (ferritin and albumin), drugs (curcumin), peptides mimicking proteins of relevant biomedical interest (such as RGD - the cell adhesive sequence of several extracellular matrix proteins-, neurotrophin peptides, fragments of the vascular endothelial growth factor), artificial membranes (lipid liposomes and supported lipid bilayers), and cells (neuroblastoma, endothelial cells, retinal pigment epithelial cells).
The hybrid nano-bio-interface between the chosen NMs and biomolecules was scrutinized by a multi-technique approach, which relies on various physico-chemical spectroscopic (UV-visible, FT-IR, RAMAN, X-ray photoelectron spectroscopy), microscopic (atomic force microscopy, scanning electron microscopy, transmission electron microscopy, laser scanning confocal microscopy) and spectrometric (Time-of-Flight secondary ion mass spectrometry) methods. The research methodology used was interdisciplinary as well as the performed research, also including some biological assays on cell viability, nanoparticle internalisation by cellular uptake and nanotoxicity.
The obtained results suggest promising applications for further development of these smart nanosystems for theranostic purposes
Modified TiO2-based catalysts for energy production and environmental protection
No full textIn the next future commercial photocatalysis would become both technically and economically competitive to counterpart technologies, for example hydrogen production from hydrocarbon reforming, CO2 conversion by dry reforming and chemical synthesis, water treatment by adsorption, biological treatment or advanced oxidation processes (AOPs). Furthermore, compared to above industrial processes, air purification especially indoor air purification appears to be a promising field in which photocatalysis could potentially act as a commercialized technology, integrating with particulate matter removal technologies.
Since its commercial production in the early twentieth century, titanium dioxide (TiO2) has been widely used as pigment and in sunscreens, paints, ointments, toothpaste, ecc. Moreover after its first application in water splitting by Fujishima and Honda in 1972, TiO2 has been heavily investigated in photocatalysis, solar cells, lithium ion battery electrodes, biomedical devices and intelligent coatings. However, there are still some intrinsic drawbacks that have limited the wide application of TiO2 in its many multidimensional nanostructure forms. Withal wide band gap, TiO2 (anatase: 3.2 eV, rutile: 3.0 eV) has a low utilization of the solar light spectrum. Furthermore, a fast recombination of photo-generated electron-hole pairs and a large over potential for water splitting leads to low photocatalytic efficiency. Therefore, in these years in order to improve the TiO2 photoefficiency, more efforts have been devoted to enlarging the effective photocatalytic surface, forming Schottky junctions or heterojunctions, and engineering the band structure to match particular energy levels with structural or chemical modifications.
In this work three different approaches were used to modify the chemico-physical properties of TiO2 investigating the effects of these changes on the photocatalytic performance both in the photo-oxidation and photo reduction reactions either under UV than solar light irradiation.
The first strategy was to add at the commercial TiO2 another oxide as CeO2 and noble metals as gold or silver to exploit their surface Plasmon resonance effect. In particular the Au/TiO2-CeO2 catalyst has showed good performance both in the photocatalytic water splitting than in the photo-oxidation of 2-propanol in the gas-phase. The enhanced charge carrier separation due to the presence of gold and the redox properties of cerium oxide were the key factors to increase the photoactivity of TiO2.
The second approach was a structural modification of TiO2 with the introduction of Ti3+ and oxygen vacancies through laser irradiation. The remarkable increase of hydrogen production by photocatalytic water splitting was related to the presence of defects inside the crystalline structure of TiO2.
The combinationon (third approach) of a TiO2 structural modification as the synthesis of inverse opal materials, and chemical modifications as the addition of a host component as BiVO4, CeO2, CuO or doping agent as N, W or Hf can be a promising strategy to enhance the titania photoactivity under solar light irradiation.
The high performance of these catalysts was due to the peculiar porous backbone of inverse opal TiO2 that led to have a high light absorption inside the material and to exploit the photonic effects. Moreover, the presence of a photosensitizer as BiVO4 or the introduction of defects, eased by the presence of doping agents, further enhances the light absorption and the electron-hole charge separation of TiO2.
The contemporaneous presence of structural and chemical modifications of titanium dioxide could be a promising approach to achieve an efficient use of solar energy applied to the TiO2-based photocatalysis for energy production and environmental protection
Characterization of active tectonic structures of the Etna volcano, through geophysical surveys, analysis of site response and deformation
No full textIn this thesis are shown the results of a multidisciplinary research, including geophysical, structural and geodetic surveys, carried out along the Tremestieri-Trecastagni-San Gregorio-Acitrezza fault system with the aim to provide additional insightful about its geometry and kinematics; also, additional geophysical surveys were performed at various sites of the municipalities most affected by the fault segments presence in order to obtain information on site response. This fault system, considered as "laboratory structure", was selected for the different kinematic characteristics and different modes of strain-energy release, that characterized its fault segments.
In the northernmost portion, this system has a kinematic behavior of normal fault and releases energy during coseismic deformation, while in the southernmost portion presents a kinematic behavior of a right-lateral strike-slip fault with releases energy during aseismic creep. Furthermore, this fault system, which can be considered the southern boundary of the sliding of Etnean eastern slope, was less studied than the northern sliding boundary and very little is known about the depth geometry of its fault segments.
The surveys were performed after an analysis of the data relating to shallow geology and to morphological, structural, stratigraphic, geophysical and seismological aspects; these detailed surveys have confirmed and highlighted a variety of geological and geomorphological conditions that can determine the existence of different stress following the occurrence of an earthquake.
After have performed a detailed structural survey, the project has planned the acquisition and analysis of many ambient noise samplings, and of other geophysical surveys, undertaken within the municipalities affected by the presence of the fault segments, increasing the surveys near the fault. All this in order to reconstruct the resonance frequency distribution and detect the possible presence of areas affected by amplification effects.
Moreover, in some areas, the surface deformation process was characterized through the design, implementation and installation, across the fault segments, of a geodetic monitoring network, in order to obtain information on the fault kinematics and on the local stress field.
The integration of the results obtained from structural, geological and geophysical surveys, with a complete literature review has provided important information on the development in depth of the fault segments; it was thus possible to reconstruct a 3D model of geometry that characterized the southern boundary of Etnean eastern slope sliding.
Various deformation data such as GPS displacements, InSAR images, level data and measures with extensometers suggest that the slip along the fault system is not uniform, but can be better described by a distribution of dislocation sources along the fault surfaces. In order to model the slip distribution along the fault surfaces, an inverse modeling of DInSAR deformation data was carried out.
This project was aimed to the recognizing site effects, that characterize the studied areas, in order to highlight the seismo-stratigraphic and tectonic behavior of subsoil, as well as, to the characterization of the deformation field related to the fault segments, through the implementation of a new geodetic monitoring network (GEO-UNICT geodetic network).
The results allowed to obtain important information on all parameters that can increment the local seismic hazard; all these different but converging approaches, have permitted a complete study of the investigated area. This study providing essential information for a proper land use planning, having as main objective the mitigation of risks that can affect the population
role of pentazocine in an in vitro model of hypoxia/reoxygenation
No full textExperimental research is making considerable efforts to understand the rules that regulate
the balance between toxic and protective brain innate immunity. Sigma-1 receptor is
expressed in both neurons and glia is a unique class of intracellular proteins and is
involved in neurodegeneration. Our aim was to evaluate the biological effects of sigma-1 selective ligands, and bifunctional sigma-1 selective ligands conjugated with lipoil
function in microglia following hypoxia/reoxygenation condition. BV2 cells were exposed
to 3 hours of hypoxia and 24h of reoxygenation. Cells were treated with sigma-1 agonist
(+)-Pentazocine, various bifunctional sigma-1 agonists conjugated with lipoil function and
with lipoic acid alone. We assessed cell viability, apoptosis, reactive oxygen species (ROS)
formation, mitochondria membrane potential, and total thiol groups content (GSH). Our
results showed that 24h of reoxygenation resulted in a significant decrease of cell viability
and increase in apoptosis when compared to control. No significant effect of (+)Pentazocine and tested compounds was observed on cell viability following 24h of
reoxygenation. Furthermore, all treatments resulted in a significant decrease of ROS
formation when compared to untreated cells. Finally, pharmacological treatments restored
mitochondrial membrane potential when compared to the untreated group. Consistently
with these results we also showed that GSH content was restored following
pharmacological treatments. Our results showed that newly synthetized bifunctional
sigma-1 compounds exhibited significant antioxidant activity and induce apoptosis in
activated microglia thus providing a new tool for effective manipulation of brain
inflammation, with the specific aim of favoring its protective arm and boosting innate
neuroprotective mechanisms
6
GENERAL INTRODUCTION MICROGLIA
The concept of microglia was introduced by Pio del Rio-Hortega as a defined cellular
elemen
La biodiversité alimentaire : sa mesure, ses conditions d accès et le rôle des politiques : cas de la Tunisie
No full textRésumé
Cette thèse étudie la biodiversité dans sa dimension alimentaire. En premier lieu la compréhension de la « biodiversité alimentaire » et les différents éléments qui la constituent était nécessaire. Il est en effet confirmé que la biodiversité est l une des solutions pour combattre la faim cachée. Disposons-nous des instruments nécessaires pour la mesurer au niveau de l offre et de la demande ? Comment l intégrer dans le pilotage des politiques publiques ? Quelles mesures et actions faut-il mettre en uvre pour conserver la biodiversité alimentaire et la mettre au service de la sécurité alimentaire? Une étude de cas a été réalisée en Tunisie dans le gouvernorat de Sidi Bouzid. Des enquêtes et des outils ont été élaborés pour recenser toutes les données nécessaires à l étude de la biodiversité alimentaire à tous les niveaux de la chaine alimentaire. Une analyse spécifique du rôle des produits sauvages comestibles a été menée. Largement connues et utilisées, les plantes sauvages sont encore sous-valorisées. Une méthodologie générique de l étude de l utilité nutritionnelle de la biodiversité alimentaire disponible a été proposée, avec une application aux marchés (indice de richesse spécifique, indice de Shannon et indice de Piélou, adaptés). L utilité nutritionnelle de la biodiversité disponible est variable d un nutriment à un autre. Une seconde partie a été consacrée à l étude des politiques publiques. Une sélection d options stratégiques pouvant être des leviers à la biodiversité a été faite à dires d experts. La méthode « Multicriteria Mapping (MCM) » a été utilisée auprès de différentes parties prenantes pour l étude de la performance des options et les hiérarchiser à des fins de propositions d actions. L éducation nutritionnelle a été estimée comme l action la plus performante suivie de la conservation et la protection de la mer et de sa biodiversité et enfin des options de politiques agricoles en faveur des plantes autochtones. Le lien entre biodiversité et nutrition et le rôle des espèces sauvages n étaient pas évident pour les participants. La conservation et l amélioration de la biodiversité doit être orientée pour remédier au manque de trois nutriments, le calcium et les vitamines A et B12. Cependant une sensibilisation et une responsabilisation des différentes parties prenantes est indispensable surtout dans un contexte socio-économique difficile de la Tunisie post-révolution
Space-time evolution of particle emission in Heavy Ion collisions at Fermi energy studied with CHIMERA and perspectives
No full textIn Heavy Ion Collisions (HIC) at Fermi energies (E/A between 10 MeV/nucleon and 100 MeV/nucleon) hot nuclear systems are produced and they may disassemble by a variety of dynamical and statistical mechanisms with vastly different time scales (neck emission, fission, multifragmentation, fusion-evaporation, ecc.). The study of the Space-Time properties of the emission pattern of the particles produced in the reactions represents one the most challenge topics of the modern investigation in nuclear physics. For this reason special geometrically flexible particle-particle correlation arrays are powerful tools to be used in coincidence mode with a 4pi detectors. Sensitivity to both space-time and spectroscopic properties of nuclear systems produced in HIC needs accurate measurements of both high angular and energy resolution over a large solid angle coverage. One of these arrays is FARCOS, presently under construction at the INFN Sezione di Catania and LNS. The FARCOS (Femtoscope ARray for COrrelations and Spectroscopy) consists of a number of twenty telescopes, each composed by two Double Sided Silicon Strip Detectors (DSSSD), of thickness 300 micron and 1500 micron, respectively, followed by four CsI(Tl) crystals of 6 cm of thickness read-out by silicon photodiodes. In this PhD thesis a report of the experimental characteristics of the FARCOS array is presented. In particular, tests with alpha sources and on-beams measurements coming from the recent experiment INKIISSY are discussed. A basic study of the particle-particle correlation function is also an important step of this large experimental effort in order to characterize the time scale of the reaction in different experimental configurations. In this work, the space-time sensitivity of the fragment-fragment Correlation Function to the emission of Intermediate Mass Fragments (the IMFs have atomic number between 3 and 25) has been investigated. In particular, IMF-IMF correlation function methods have been applied to 124Sn+64Ni at E/A= 35 MeV reverse kinematics reactions for the physics case of dynamical and statistical fission processes. The IMF-IMF correlation function shows good sensitivity in order to disentangle between dynamical and statistical processes. Some comparisons between data and theoretical simulations, are also discussed
Natural or bio-inspired polyphenols in the synthesis of potential chemotherapeutic agents
No full textMy doctoral research activity was focused mainly on natural or bioinspired polyphenols, aimed to the synthesis of new bioinspired compounds and to their evaluation as potential chemotherapeutic agents. More specifically, my research activity was devoted to lignans and neolignans, synthetized by chemical and/or enzimatic methodology. Hence, in particular, two polyphenol groups were studied, namely benzoxanthene lignans, their related phenazines and bisphenol neolignans; furthermore during the synthesis of magnolol-inspired neolignans, an unexpected dihydrobenzofuran neolignan was also obtained and characterized. The products have been studied in collaboration with others research team for the interaction with Gquadruplex DNA, as alpha-glucosidase inhibitors, as ABCG2 inhibitors, as agonist/antagonist of the Bile X receptors, antioxidant and antimicrobial agents. Further goal of this work was an inverse virtual screening focused on magnolol analogues, carried out during my short internship in the lab of prof. G. Bifulco (University of Salerno). In addition, the last part of my work was carried out at the University of Bordeaux, under the guidance of Prof. Stéphane Quideau, and was devoted to synthetic work on ellagitannins, an important subgroup of tannin family. In this context I gave a contribution to the total synthesis of vescalin and a vescalagin conjugate
iNSCs transplantation and prospects for stem cell-based therapy
No full textDespite the remarkable beneficial effects of disease-modifying agents in relapsing-remitting multiple
sclerosis (MS) patients, progressive forms of (P)MS still lack effective treatments. This stark contrast is
partially dependent on the difficulties researchers have found in tackling the complex pathophysiology of this
phase of disease, in which chronic inflammation within the central nervous system (CNS) is coupled by
ongoing neurodegeneration and demyelination.
Cell transplantation is among the most promising therapeutic approaches in regenerative medicine,
combining tissue trophic and immunomodulatory effects of the graft with its intrinsic potential for cellreplacement.
These are all attributes that can be harnessed to treated patients with PMS.
As such, within this thesis, I have focused my attention on investigating how cellular therapies could be used
to (i) prevent neuronal damage, (ii) modulate the chronic activation of the immune system and (iii) replace
the damaged myelin in PMS.
Olfactory Ensheathing Cells (OECs) are a special population of glial cells known to exert neuroprotective
mechanisms and capable of promoting neuroprotection. Using in vitro models of neuron-like cells, I have
demonstrated that OECs exert their neuroprotective effect by reducing Cx43-mediated cell-to-cell and cell-toextracellular
environment communications. Despite this important finding, the immunomodulatory and
remyelinating potential of OECs is still limited. As such, I decided to study a complementary stem cell
approach that conjugates these attributes with ease in clinical applicability.
Induced Neural Stem Cells (iNSCs) are a source of autologous, stably expandable, tissue specific and easily
accessible stem cells, which have the potential to differentiate into the three main neural lineages. Mouse
iNSCs were characterized in vitro and in vivo and their immunomodulatory potential was initially studied. This
work uncovered a novel mechanism that underpins the potential of iNSCs to interact with the chronic CNS
compartmentalised activation of the innate immune system. Specifically, I found that iNSCs are able to
sense extracellular metabolites, which accumulate in the chronically inflamed CNS, and to ameliorate
neuroinflammation via succinate-SUCNR1-dependend mechanisms. To characterize the potential for tissue
replacement and remyelination of such a promising cell line, I have also analysed how iNSCs grafts
differentiate in an experimental model of focal demyelination. I found that iNSCs are able to integrate and
differentiate into remyelinating oligodendrocytes (OLs) in chronic demyelinated CNS. These data suggest
that iNSCs are indeed an effective source of stem cell transplantation, being able to modulate inflammation
and to effectively replace lost tissue in mouse models of PMS.
Altogether the evidences gathered in this thesis are important new steps in the field of cell transplantation,
which will be pivotal in the march forward for future clinical applications in chronic demyelinating CNS
disorders
The role of nanostructured targets in Laser-Produced Plasmas for Nuclear Astrophysics studies
No full textThis PhD thesis documents the experimental study of plasmas produced from the interaction of a high-power laser in ns domain with nanostructured materials compared with ordinary bulk target. The study is focused on the effect of solid targets with different physical and geometric characteristics, and has the purpose to asses the effects of nanoscale structures in laser-matter interaction and in plasma formation.
The motivation for these experiments arises from the fact that there is the possibility of producing plasmas with density and temperature characteristics suitable for nuclear fusion studies, relevant in astrophysics.
The optimization of the specific characteristics of nanomaterials, containing metal nanowires, could lead to a stagnant, hotter and denser plasma and to implement the above mentioned studies successfully.
The nanostructured targets used in this study are metamaterials consisting in aligned metal nanowires grown by electrodeposition into a porous alumina matrix, obtained on a thick aluminium substrate. These materials were developed with different length, diameter, metal and deposition technique in order to maximize absorption in the visible and IR wavelengths.
Various diagnostics were employed for the characterization of the Laser Produced Plasma (LPP).
In particular, an Intensified CCD camera in visible domain has been a useful diagnostic tools to understand the expansion dynamics of laser created plumes, by providing a two-dimensional snap shots of the three-dimensional LPP propagation. Depending upon the target material, the generated plume s ion emission features (velocity, flux) as well as plasma properties (temperature, density) are varied even at constant laser intensity.
The use of a CCD-camera in X-rays domain has allowed to investigate the X-ray emissivity of laser-produced plasmas. By coupling the detector with an array of pinhole, spectral selection of X-ray emission has been implemented.
The Time of Flight measurements have provided a technique to determine the velocity distribution of the plasma at large distances from the target surface, complementarily to velocity estimated by visible imaging close to target surface.
Moreover, morphological analysis of craters formed for the laser irradiation was performed by using an optical microscope.
The cross-analysis of various diagnostics has immediately showed the differences between an ordinary Al-bulk target and nanostructured materials: bulk aluminium plasma has shorter duration, X-ray flux and ablation efficiency than all other.
Finally, preliminary investigations of ion energy spectra, obtained with a Thomson Parabola Spectrometer, were carried out to better understand the nuclear fusion process in a plasma. Temperature estimated are in good agreement with the occurrence of nuclear fusions.
All these experimental evidences have taken a further step towards the application of laser driven nuclear reactions
Neurophysiological correlates of process and progress in Vascular Cognitive Impairment
No full textTranscranial magnetic stimulation (TMS) highlighted functional changes in dementia, whereas there are few data in patients with Vascular Cognitive Impairment No Dementia (VCI-ND) at risk for cognitive worsening. Similarly, little is known about the neurophysiological impact of Vascular Depression (VD) on deterioration of cognitive functions. We performed a longitudinal TMS study to test whether the presence of depression might affect not only cognition but also the functioning of specific cortical circuits in patients with subcortical vascular damage. In this study, 16 VCI-ND and 11 VD patients, age-matched with 15 healthy controls, underwent a baseline evaluation including clinical-cognitive, neuroimaging and TMS assessment. After approximately two years of follow-up, all participants were prospectively re-evaluated. At baseline, a significant more pronounced intracortical facilitation (ICF) at paired-pulse TMS was found in VCI-ND patients only. Re-evaluation revealed an increase of the global excitability at single-pulse TMS in both VCI-ND and VD. At follow-up, the ICF of VCI-ND become similar to the other groups. Only VD patients showed cognitive deterioration. In conclusion, in VCI-ND specific measures of cortical excitability, namely the high level of ICF found at baseline, suggests an enhanced glutamatergic neurotransmission that might contribute to the preservation of cognitive functioning; conversely, a lack of this hyperfacilitation in VD might be associated with clinical progression. The hyperexcitability to single-pulse TMS observed at follow-up in both group of patients also suggests functional changes in glutamatergic neurotransmission. This suggests that the mechanisms enhancing the risk of dementia in VD might be related either to subcortical changes produced by vascular lesions or to the lack of compensatory functional cortical changes