Dissertations / Theses on the topic 'Nanomaterials - Light Harvesting Systems'
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Stevens, Amy L. "Energy transfer processes in supramolecular light-harvesting systems." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:43833f3a-96b0-432a-9608-8f08a9096be7.
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This dissertation attempts to understand how energy transfer in a molecular wire and a spherical organic assembly are affected by molecular structure. The molecular wire is a DNA-hybrid structure composed of a strand of thymine bases appended by a cyanine dye. Hydrogen bonded to each base is a naphthalene-derivative molecule. Using time-integrated photoluminescence and time-correlated single photon counting measurements, energy transfer from the naphthalene donors to the cyanine acceptors was confirmed, and its dependence on temperature and DNA-template length investigated. Donor-thymine bonding was disrupted at temperatures above about 25 degrees Celcius resulting in poor donor template decoration and low rates of energy transfer. Increasing numbers of donors attach to the scaffold, forming an orderly array, as the template length increases due to the stabilising effects of the donor-donor pi-stacking interactions. Conversely, modelled energy transfer rates fall as the scaffold length increases because of the longer donor-acceptor distances involved. Therefore, the energy transfer rate was greatest for a template built from 30 thymines. The spherical organic assemblies (nanoparticles) are formed by fast injection of a small volume of molecularly dissolved fluorene-derivative amphiphilic molecules into a polar solvent. The amphiphilic molecules contained either a naphthalene (donor) or a benzothiadiazole (acceptor) core. The donor-acceptor mixed nanoparticles resemble an amorphous polymer film and were modelled as such using the Foerster resonance energy transfer theory. The Foerster radii extracted from the measurements depends intricately on the donor-acceptor spectral overlap and distance. The latter effect was controlled by the stacking interactions between the molecules. Altering the morphology of the structural units is the key to optimising energy transfer in molecular structures. To achieve efficient organic molecule-based devices, the importance of this property needs to be fully appreciated and effectively exploited.
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Huang, Xia. "Fabrication of artificial light-harvesting systems for energy transfer studies." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/21488/.
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Molukanele, Palesa Patricia. "Dynamics of energy transfer in light harvesting photosynthetic systems / P. Molukanele." Thesis, North-West University, 2009. http://hdl.handle.net/10394/5101.
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Photosynthesis is the process by which plants, algae and photo synthetic bacteria convert sunlight energy into chemical energy (ATP). The initial stages of this process (harvesting solar energy and transferring it to the reaction centres) occur extremely fast and with an efficiency of close to 100%. Studying the dynamics of these reactions will enable us to develop artificial functional light harvesting arrays and energy transfer systems that mimic the process in nature, thus helping us use light as an energy source that is environmentally clean, efficient, sustainable and carbon-neutral. These reactions can be measured using femtosecond pump-probe spectroscopy (transient absorption in the liquid phase and monitoring the subsequent kinetics in the wavelength region: 400 nm-700 nm). In order to perform these experiments, photo synthetic pigment-protein complexes must be isolated, purified and characterised. In this work, these photo synthetic complexes were isolated from spinach leaves and characterised using various biological and spectroscopic techniques. Finally, the first results of pump-probe application to biological samples in South Africa were discussed.Thesis (M.Sc. (Environmental Sciences))--North-West University, Potchefstroom Campus, 2009.
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Gullo, Maria Pia <1987>. "Photophysical investigation of light-harvesting systems for solar-to-fuel conversion." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/6927/1/Gullo_Maria_Pia_Tesi.pdf.
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In recent years, an increasing attention has been given to the optimization of the performances of new supramolecular systems, as antennas for light collection.
In such background, the aim of this thesis was the study of multichromophoric architectures capable of performing such basic action.
A synthetic antenna should consist of a structure with large UV-Vis absorption cross-section, panchromatic absorption, fixed orientation of the components and suitable energy gradients between them, in order to funnel absorbed energy towards a specific site, through fast energy-transfer processes.
Among the systems investigated in this thesis, three suitable classes of compounds can be identified: 1) transition metal-based multichromophoric arrays, as models for antenna construction, 2) free-base trans-A2B-phenylcorroles, as self-assembling systems to make effective mimics of the photosynthetic system, and 3) a natural harvester, the Photosystem I, immobilized on the photoanode of a solar-to-fuel conversion device.
The discussion starts with the description of the photophysical properties of dinuclear quinonoid organometallic systems, able to fulfil some of the above mentioned absorption requirements, displaying in some cases panchromatic absorption.
The investigation is extended to the efficient energy transfer processes occurring in supramolecular architectures, suitably organized around rigid organic scaffolds, such as spiro-bifluorene and triptycene.
Furthermore, the photophysical characterization of three trans-A2B-phenylcorroles with different substituents on the meso-phenyl ring is introduced, revealing the tendency of such macrocycles to self-organize into dimers, by mimicking natural self-aggregates antenna systems.
In the end, the photophysical analysis moved towards the natural super-complex PSI-LHCI, immobilized on the hematite surface of the photoanode of a bio-hybrid dye-sensitized solar cell.
The importance of the entire work is related to the need for a deep understanding of the energy transfer mechanisms occurring in supramolecules, to gain insights and improve the strategies for governing the directionality of the energy flow in the construction of well-performing antenna systems.
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Gullo, Maria Pia <1987>. "Photophysical investigation of light-harvesting systems for solar-to-fuel conversion." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/6927/.
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In recent years, an increasing attention has been given to the optimization of the performances of new supramolecular systems, as antennas for light collection.
In such background, the aim of this thesis was the study of multichromophoric architectures capable of performing such basic action.
A synthetic antenna should consist of a structure with large UV-Vis absorption cross-section, panchromatic absorption, fixed orientation of the components and suitable energy gradients between them, in order to funnel absorbed energy towards a specific site, through fast energy-transfer processes.
Among the systems investigated in this thesis, three suitable classes of compounds can be identified: 1) transition metal-based multichromophoric arrays, as models for antenna construction, 2) free-base trans-A2B-phenylcorroles, as self-assembling systems to make effective mimics of the photosynthetic system, and 3) a natural harvester, the Photosystem I, immobilized on the photoanode of a solar-to-fuel conversion device.
The discussion starts with the description of the photophysical properties of dinuclear quinonoid organometallic systems, able to fulfil some of the above mentioned absorption requirements, displaying in some cases panchromatic absorption.
The investigation is extended to the efficient energy transfer processes occurring in supramolecular architectures, suitably organized around rigid organic scaffolds, such as spiro-bifluorene and triptycene.
Furthermore, the photophysical characterization of three trans-A2B-phenylcorroles with different substituents on the meso-phenyl ring is introduced, revealing the tendency of such macrocycles to self-organize into dimers, by mimicking natural self-aggregates antenna systems.
In the end, the photophysical analysis moved towards the natural super-complex PSI-LHCI, immobilized on the hematite surface of the photoanode of a bio-hybrid dye-sensitized solar cell.
The importance of the entire work is related to the need for a deep understanding of the energy transfer mechanisms occurring in supramolecules, to gain insights and improve the strategies for governing the directionality of the energy flow in the construction of well-performing antenna systems.
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Roth, Johannes S. "Light harvesting in low dimensional systems : application of driven Brownian ratchets in supported lipid bilayers for the creation of light harvesting mimics." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/8626/.
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Supported lipid bilayers are a well known model system for the cell membrane. They allow for the investigation of the membrane in a controlled environment. The solid supported bilayer is accessible through the surface it is formed on and allows for different experimental techniques to be applied. This thesis presents work on free diffusion in the membrane and electrophoretically driven transport concentration of charged membrane components. In addition to that, novel supports for the support of membrane proteins have been investigated and surface enhanced Raman spectroscopy is presented as a label-free method for the detection of membrane components. Brownian ratchets have been used for applications such as molecular sorting with and without the use of lipid bilayers. So far the work has mainly been focussed on their use without a thorough investigation of their properties and the parameters influencing their efficiency. Here, the size and time parameters are varied in experiment and calculation and their role in the ratcheting process is discussed. The efficiency of the ratchets can be significantly reduced when the parameters are chosen in an optimal manner. The use of electrophoresis in lipid bilayers for the concentration and separation of membrane components has focussed on using two electrodes in simple patterns such as squares or lines. This is expanded here on more complex patterns which also allow for the retention of charged material in trapping regions. The pattern was then used to demonstrate the ability to determine binding coefficients in the trapping regions even for membrane components with a low initial concentration or low fluorescence quantum yield. More complex electrode systems using four patterned electrodes are also presented which allow for the application of electric fields in two dimensions where the strength and orientation of the field can be chosen almost arbitrarily. Polymer supports have the ability to support lipid bilayers with membrane proteins which exhibit significant extramembranous domains. Two novel supports are investigated here and different lipid bilayer formation routes are explored. To allow for label free detection of lipids, peptides or proteins within the membrane, surface enhanced Raman spectroscopy is used. The ability of this method to distinguish between different lipids and to detect peptides within the membrane is shown, as well.
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Dietzek, Benjamin. "Ultrafast linear and non-linear spectroscopy from biological light receptors to artificial light harvesting systems /." Doctoral thesis, [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=978743733.
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Bhise, Anil Dnyanoba. "A biomimetic approach for synthesizing artificial light-harvesting systems using self-assembly." Karlsruhe : FZKA, 2004. http://bibliothek.fzk.de/zb/berichte/FZKA7174.pdf.
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Bhise, Anil Dnyanoba. "A biomimetic approach for synthesizing artificial light-harvesting systems using self-assembly /." Karlsruhe : Forschungszentrum, 2005. http://www.gbv.de/dms/bs/toc/503994367.pdf.
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Univ., Diss.--Karlsruhe, 2005.Auch als elektronische Ressource vorh. Literaturverz. S. 126 - 133. Unterschiede zwischen dem gedruckten Dokument und der elektronischen Ressource können nicht ausgeschlossen werden. Zsfassung in dt. Sprache.
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Valleau, Stephanie. "Theoretical study of exciton transport in natural and synthetic light-harvesting systems." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493387.
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In the first part of this dissertation, we investigate on the presence of quantum effects in the exciton dynamics of the Fenna-Matthews-Olson photosynthetic complex of green sulfur bacteria using an atomistic Quantum Mechanics / Molecular Mechanics (QM/MM) model combined with open quantum systems methods. Subsequently, we explore the theoretical connection between the atomistic QM/MM approach and the open quantum system methods and propose the correct theoretical expressions to maintain consistency when using both approaches contemporarily. In particular we show that when using the correct prefactor to extract the spectral density - the strength of coupling between excitation and other degrees of freedom - the atomistic results are in good agreement with experimental predictions. We then describe a first atomistic study of the full light-harvesting complex of green sulfur bacteria. The various units are treated atomistically and the full system's exciton dynamics is obtained using a Markovian open quantum system master equation. To conclude the first part, we describe a Machine Learning algorithm which we developed and implemented to learn time-dependent density functional theory energies by using trained neural networks and supplying these with coulomb matrices extracted from molecular dynamics simulations. This approach provides a much more rapid solution to obtaining a QM/MM Hamiltonian and subsequently extracting dynamics. It is particularly useful when multiple identical molecules are found in similar environments as one can train the network on a single molecule and predict all others. We applied this method to the Fenna-Matthews-Olson complex.
In the second part of this dissertation we focus on model systems and synthetic aggregates. In particular, we investigate the exciton dynamics in thin-film J-aggregates using a Markovian stochastic Schrödinger equation approach. We derive expressions to obtain diffusion constants from the dynamics and compare a series of different thin-film J-aggregates. The parameters of the model are obtained atomistically. From this model we obtain information on the parameters which lead to optimal exciton diffusion. This can guide the design of new exciton transfer materials.Chemistry and Chemical Biology
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Soleiman, Andreas. "Battery-free Visible Light Sensing." Thesis, Uppsala universitet, Avdelningen för datorteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-381370.
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In this thesis, we show that it is possible to design a battery-free light sensing system that can sense and communicate hand gestures while operating fully on harvested power from indoor light. We present two main innovations that push our system to tens of microwatts of power to enable battery-free operation. First, we introduce a novel visible light sensing system that can track variations in light intensity by using a solar cell as a sensor. Solar cells are unlike photodiodes optimized for energy yield in the visible light region and hence do not require any power hungry active components such as an operational amplifier. Furthermore, solar cells can operate under more diverse light conditions as they are not susceptible to saturation under bright light. Second, we devise two ultra-low power communication mechanisms based on radio frequency backscatter to transmit sensor readings at various resolutions without the need of any energy-expensive computational blocks. We design two battery-free and self-powered hardware prototypes that are based on these two innovations. Our first design utilizes an on-board comparator based circuit to perform a 1-bit digitization of changes in light readings, consuming only sub-microwatt of power for digitization. For our second prototype, we design an analog backscatter mechanism that can map raw sensor readings directly to backscatter transmissions. We demonstrate the feasibility of our designs when sensing significant changes in light intensity caused by shadows from hand gestures, and reconstruct these at a receiving device. Our results demonstrate the ability to sense and communicate various hand gestures at a peak power of 20 microwatts when performing 1-bit digitization, and a mean power of 60 microwatts when performing analog backscatter. Both designs represent orders of magnitude improvement in terms of power consumption over state-of-the-art visible light sensing systems.Battery-free Visible Light Sensing
MobiCom: G: Battery-free Visible Light Sensing
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Fassioli, Olsen Francesca Daniela. "Energy transfer in light-harvesting systems: implications of structural adaptations, quantum coherence and correlations." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526773.
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Olbrich, Carsten [Verfasser]. "Time-Dependent Atomistic View on the Electronic Relaxations in Light-Harvesting Systems / Carsten Olbrich." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2012. http://d-nb.info/1035209403/34.
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Bhise, Anil Dnyanoba [Verfasser]. "A biomimetic approach for synthesizing artificial light-harvesting systems using self-assembly / Forschungszentrum Karlsruhe GmbH, Karlsruhe. Anil Dnyanoba Bhise." Karlsruhe : FZKA, 2005. http://d-nb.info/978596900/34.
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Chandrasekaran, Suryanarayanan [Verfasser], Ulrich [Akademischer Betreuer] [Gutachter] Kleinekathöfer, Thorsten [Gutachter] Klüner, and Arnulf [Gutachter] Materny. "Computational study of Excitation Energy Transfer Dynamics in Light-Harvesting Systems / Suryanarayanan Chandrasekaran ; Gutachter: Ulrich Kleinekathöfer, Thorsten Klüner, Arnulf Materny ; Betreuer: Ulrich Kleinekathöfer." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2017. http://d-nb.info/1130868516/34.
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Chandrasekaran, Suryanarayanan Verfasser], Ulrich [Akademischer Betreuer] [Kleinekathöfer, Thorsten [Gutachter] Klüner, and Arnulf [Gutachter] Materny. "Computational study of Excitation Energy Transfer Dynamics in Light-Harvesting Systems / Suryanarayanan Chandrasekaran ; Gutachter: Ulrich Kleinekathöfer, Thorsten Klüner, Arnulf Materny ; Betreuer: Ulrich Kleinekathöfer." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2017. http://nbn-resolving.de/urn:nbn:de:gbv:579-opus-1007002.
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Chandrasekaran, Suryanarayanan Verfasser], Ulrich [Akademischer Betreuer] [Kleinekathöfer, Thorsten Gutachter] Klüner, and Arnulf [Gutachter] [Materny. "Computational study of Excitation Energy Transfer Dynamics in Light-Harvesting Systems / Suryanarayanan Chandrasekaran ; Gutachter: Ulrich Kleinekathöfer, Thorsten Klüner, Arnulf Materny ; Betreuer: Ulrich Kleinekathöfer." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2017. http://d-nb.info/1130868516/34.
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Menting, Raoul. "Light-induced energy and charge transfer processes in artificial photosynthetic systems." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16656.
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Der Gegenstand der vorliegenden Arbeit ist die Untersuchung von photoinduzierten Energietransferprozessen (EET) und Elektronentransferprozessen (ET) in Modellsystemen, die als potentiell geeignet für eine Nutzung in der artifiziellen Photosynthese angesehen werden. Den beiden wesentlichen Zugängen zur Architektur artifizieller Photosynthese-Systeme entsprechend wurden vergleichend kovalente und sich selbst organisierende Systeme untersucht. In beiden Zugängen wurden ähnliche chemische Komponenten als optisch aktive Moleküle eingesetzt, insbesondere Phthalocyanine mit einem Silizium-Zentralatom (SiPc). Durch eine Kombination von stationären und zeitaufgelösten optisch-spektroskopischen Methoden konnten die lichtinduzierten ET- und EET-Prozesse identifiziert und quantifiziert werden. Im ersten Teil der Arbeit wurden mehrere kovalent gebundene Triaden und eine Pentade untersucht. In allen Systemen finden sehr effiziente ET und EET Prozesse statt. Es wurde gezeigt, dass das Lösungsmittel großen Einfluss auf die photophysikalischen Eigenschaften der Systeme ausübt. Die Lebensdauer des ladungsseparierten Zustandes variiert von 1,7 ns in Toluol bis 30 ps in DMF. Im zweiten Teil der Arbeit wurde erstmals gezeigt, dass sich in wässriger Lösung ein supramolekularer Komplex, bestehend aus einem Beta-Cyklodextrin (CD), einem konjugierten Subphthylocyanin (SubPc), einem Porphyrin (Por) und einem SiPc bilden kann. Letzteres wurde über unterschiedliche Ketten an zwei CDs kovalent gebunden. Die Selbstorganisation wird über hydrophobe Wechselwirkungen vermittelt und die Bildung der Komplexe ist sehr effizient. Nach selektiver Anregung von SubPc finden sequenzielle ET- und EET-Prozesse von SubPc zu SiPc statt. Das Por spielt die Rolle einer energetischen und elektronischen Brücke und ermöglicht die ET und EET-Prozesse von SubPc zu SiPc. Die Ladungsrekombination in den Grundzustand geschieht innerhalb von 1,7 ns.The main objective of the present thesis was to conduct investigations of photo-induced electron transfer (ET) and excitation energy transfer (EET) processes in model compounds that are considered potentially appropriate for use in artificial photosynthesis. Two approaches have been used to construct the artificial photosynthetic systems, namely covalent and supramolecular approach. In both systems similar optically active molecules have been employed, particularly silicon-based phthalocyanines (SiPc). A comparative study between the covalently-linked and self-assembled systems had been conducted. For these purposes, thorough spectroscopic measurements in the UV/Vis range had been performed on these conjugates. A combination of steady-state and time-resolved experiments allowed an identification and quantification of the photo-induced ET and EET processes. In the first part of the work several covalently bound triads and a pentad bearing a central SiPc unit were studied. In all systems highly efficient ET and EET processes take place. It was found that the solvent exerts great influence on the photophysical properties of the systems. The lifetime of the charge-separated state varied from 1.7 ns (toluene) down to 30 ps (DMF). In the second part of the thesis, for the first time the formation of ternary supramolecular complexes consisting of a beta-cyclodextrin (CD), a conjugated subphthalocyanine (SubPc), a porphyrin (Por) and a series of SiPcs substituted axially with two CDs via different spacers was shown. These components are held in water by host-guest interactions and the formation of these host-guest complexes was found to be very efficient. Upon excitation of the SubPc-part of the complex sequential ET and EET processes from SubPc to SiPc take place. The Por dye acts as a transfer bridge enabling these processes. The probability of ET is controlled by the linker between CD and SiPc. Charge recombination to the ground state occurs within 1.7 ns.
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Beyer, Sebastian Reinhardt [Verfasser], and Jürgen [Akademischer Betreuer] Köhler. "Photophysics of Biological and Synthetic Multichromophoric Systems : Spectroscopic Investigations of Bacterial Light-Harvesting Complexes and of Carbonyl-Bridged Triarylamine Derivatives / Sebastian R. Beyer. Betreuer: Jürgen Köhler." Bayreuth : Universität Bayreuth, 2015. http://d-nb.info/1081264756/34.
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Macarone, Palmieri Adriano. "Quantum biology. Simulazioni di trasferimento di energia in una struttura dimerica." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7771/.
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La quantum biology (QB) è un campo di ricerca emergente che cerca di affronta- re fenomeni quantistici non triviali all’interno dei contesti biologici dotandosi di dati sperimentali di esplorazioni teoriche e tecniche numeriche. I sistemi biologici sono per definizione sistemi aperti, caldi,umidi e rumorosi, e queste condizioni sono per loro imprenscindibili; si pensa sia un sistema soggetto ad una veloce decoerenza che sopprime ogni dinamica quantistica controllata. La QB, tramite i principi di noise assisted transport e di antenna fononica sostiene che la presenza di un adeguato livello di rumore ambientale aumenti l’efficienza di un network di trasporto,inoltre se all’interno dello spettro ambientale vi sono specifici modi vibrazionali persistenti si hanno effetti di risonanza che rigenerano la coerenza quantistica. L’interazione ambiente-sistema è di tipo non Markoviano,non perturbativo e di forte non equi- librio, ed il rumore non è trattato come tradizionale rumore bianco. La tecnica numerica che per prima ha predetto la rigenerazione della coerenza all’interno di questi network proteici è stato il TEBD, Time Evolving Block Decimation, uno schema numerico che permette di simulare sistemi 1-D a molti corpi, caratterizzati da interazioni di primi vicini e leggermente entangled. Tramite gli algoritmi numerici di Orthopol l’hamiltoniana spin-bosone viene proiettata su una catena discreta 1-D, tenendo conto degli effetti di interazione ambiente-sistema contenuti nello spettro(il quale determina la dinamica del sistema).Infine si esegue l’evoluzione dello stato.
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O'Sullivan, Melanie Claire. "Template directed synthesis of porphyrin nanorings." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:c500c594-fa28-4857-b74e-b80d14b87202.
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This thesis describes supramolecular approaches to porphyrin nanorings. Cyclic porphyrin arrays resemble natural light harvesting systems, and it is of interest to probe the photophysical effects of bending the porphyrin aromatic π-system. A general overview of the synthesis and photophysical properties of porphyrins and their arrays is carried out in Chapter 1. The electronic structure of porphyrins is examined, and how conformational effects in oligomers, such as inter-porphyrin torsional angle and backbone bending influence the π-conjugation pathway. The structures of light harvesting complexes are discussed. Chapter 2 describes the design and synthesis of a complementary 12-armed template designed to coordinate linear porphyrin oligomers in the correct conformation for cyclisation to give a cyclic porphyrin dodecamer. Chapter 3 demonstrates two approaches to a cyclic porphyrin dodecamer ring. Firstly, a classical templating approach using the 12-armed template is described. The limitations of this approach in the quest for larger nanorings are discussed. Vernier templating, which utilises a mismatch in the number of binding sites between a ligand and its receptor is introduced as a general strategy to the synthesis of large nanorings. This is demonstrated by the synthesis of cyclic dodecamer from a linear porphyrin tetramer and a hexadentate template via a figure-of-eight intermediate. The general utility of the Vernier method to large nanorings is explored in Chapter 4 with steps towards the synthesis of a cyclic tetracosamer, consisting of 24 porphyrin subunits. In preliminary experiments, an improved route to the cyclic porphyrin octamer is described. Finally, the photophysical properties of the nanoring series are explored in Chapter 5 as a function of size and conformation. Femtosecond photoluminescence spectroscopy shows that even in cyclic dodecamer, exciton delocalisation over the entire porphyrin backbone occurs on a sub-picosecond timescale, and parallels are drawn with the dynamics of natural light harvesting complexes.
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Mirkovic, Tihana. "Synthesis, Dynamics and Photophysics of Nanoscale Systems." Thesis, 2009. http://hdl.handle.net/1807/17801.
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The emerging field of nanotechnology, which spans diverse areas such as nanoelectronics, medicine, chemical and pharmaceutical industries, biotechnology and computation, focuses on the development of devices whose improved performance is based on the utilization of self-assembled nanoscale components exhibiting unique properties owing to their miniaturized dimensions. The first phase in the conception of such multifunctional devices based on integrated technologies requires the study of basic principles behind the functional mechanism of nanoscale components, which could originate from individual nanoobjects or result as a collective behaviour of miniaturized unit structures.
The comprehensive studies presented in this thesis encompass the mechanical, dynamical and photophysical aspects of three nanoscale systems.
A newly developed europium sulfide nanocrystalline material is introduced. Advances in synthetic methods allowed for shape control of surface-functionalized EuS nanocrystals and the fabrication of multifunctional EuS-CdSe hybrid particles, whose unique structural and optical properties hold promise as useful attributes of integrated materials in developing technologies.
A comprehensive study based on a new class of multifunctional nanomaterials, derived from the basic unit of barcoded metal nanorods is presented. Their chemical composition affords them the ability to undergo autonomous motion in the presence of a suitable fuel. The nature of their chemically powered self-propulsion locomotion was investigated, and plausible mechanisms for various motility modes were presented. Furthermore functionalization of striped metallic nanorods has been realized through the incorporation of chemically controlled flexible hinges displaying bendable properties.
The structural aspect of the light harvesting machinery of a photosynthetic cryptophyte alga, Rhodomonas CS24, and the mobility of the antenna protein, PE545, in vivo were investigated. Information obtained through a combination of steady-state and time-resolved spectroscopy in conjunction with quantum chemical calculations aided in the elucidation of the dynamics and the mechanism of light harvesting in the multichromophoric phycobiliprotein phycocyanin PC645 in vitro. Investigation of the light-harvesting efficiency and optimization of energy transfer with respect to the structural organization of light-harvesting chromophores on the nanoscale, can provide us with fundamental information necessary for the development of synthetic light-harvesting devices capable of mimicking the efficiency of the natural system.
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Bentz, Jonathan Lee. "Influence of geometry on light harvesting in dendrimeric systems /." 2005.
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KEŞAN, Gürkan. "Excited States of Carotenoids and Their Roles in Light Harvesting Systems." Doctoral thesis, 2016. http://www.nusl.cz/ntk/nusl-263254.
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Carotenoids are an extensive group of natural pigments employed by a majority of organisms on earth. They are present in most organisms, including humans, but can be synthesized only by plants and microorganisms. They perform two major roles in photosynthesis, often in partnership with the more prevalent chlorophylls (Chls) / bacteriochlorophylls (BChls): light-harvesting and photoprotection. Carotenoids absorb radiation in a spectral region inaccessible to Chls and BChls and transfer the absorbed energy to (B)Chls which, in turn, funnel it into the photosynthetic reaction center (RC). It is determined that the structures and dynamics of excited states of carotenoids found in photosynthetic proteins provide an explanation of their roles as light-harvesting and photoprotective agents. The conjugation length and the type of carotenoids play a big part in understanding the energy transfer from carotenoids to Chls and BChls, because excited-state properties of carotenoids are affected by number of conjugated C=C bonds and their structures. An accurate description of these states is, therefore, the crucial first step in explaining carotenoid photochemistry and understanding the interactions between carotenoids and other molecules in photobiological processes. The research in this thesis, femtosecond ultrafast transient absorption spectroscopy was used to study the light-harvesting function of carotenoids both in solvent and protein environment. The findings were supported with computational methods. Based on spectroscopic indications, the light-harvesting function of carotenoids has a bearing on their structures, and specific light-harvesting strategies are explicitly dependent with the structure of the light-harvesting complexes.
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"Synthesis, Characterization And Functionalization Of Silicon Nanoparticle Based Hybrid Nanomaterials For Photovoltaic And Biological Applications." Tulane University, 2014.
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Silicon nanoparticles are attractive candidates for biological, photovoltaic and energy storage applications due to their size dependent optoelectronic properties. These include tunable light emission, high brightness, and stability against photo-bleaching relative to organic dyes (see Chapter 1). The preparation and characterization of silicon nanoparticle based hybrid nanomaterials and their relevance to photovoltaic and biological applications are described. The surface-passivated silicon nanoparticles were produced in one step from the reactive high-energy ball milling (RHEBM) of silicon wafers with various organic ligands. The surface structure and optical properties of the passivated silicon nanoparticles were systematically characterized. Fast approaches for purifying and at the same time size separating the silicon nanoparticles using a gravity GPC column were developed. The hydrodynamic diameter and size distribution of these size-separated silicon nanoparticles were determined using GPC and Diffusion Ordered NMR Spectroscopy (DOSY) as fast, reliable alternative approaches to TEM. Water soluble silicon nanoparticles were synthesized by grafting PEG polymers onto functionalized silicon nanoparticles with distal alkyne or azide moieties. The surface-functionalized silicon nanoparticles were produced from the reactive high-energy ball milling (RHEBM) of silicon wafers with a mixture of either 5-chloro-1-pentyne in 1-pentyne or 1,7 octadiyne in 1-hexyne to afford air and water stable chloroalkyl or alkynyl terminated nanoparticles, respectively. Nanoparticles with the ω-chloroalkyl substituents were easily converted to ω-azidoalkyl groups through the reaction of the silicon nanoparticles with sodium azide in DMF. The azido terminated nanoparticles were then grafted with monoalkynyl-PEG polymers using a copper catalyzed alkyne-azide cycloaddition (CuAAC) reaction to afford core-shell silicon nanoparticles with a covalently attached PEG shell. Covalently linked silicon nanoparticle clusters were synthesized via the CuAAC “click” reaction of functional silicon nanoparticles with α,ω-functional PEG polymers of various lengths. Dynamic light scattering studies show that the flexible globular nanoparticle arrays undergo a solvent dependent change in volume (ethanol> dichloromethane> toluene) similar in behavior to hydrogel nanocomposites. A novel light-harvesting complex and artificial photosynthetic material based on silicon nanoparticles was designed and synthesized. Silicon nanoparticles were used as nanoscaffolds for organizing the porphyrins to form light-harvesting complexes thereby enhancing the light absorption of the system. The energy transfer from silicon nanoparticles to porphyrin acceptors was investigated by both steady-state and time-resolved fluorescence spectroscopy. The energy transfer efficiency depended on the donor-acceptor ratio and the distance between the nanoparticle and the porphyrin ring. The addition of C60 resulted in the formation of silicon nanoparticle-porphyrin-fullerene nanoclusters which led to charge separation upon irradiation of the porphyrin ring. The electron-transfer process between the porphyrin and fullerene was investigated by femto-second transient absorption spectroscopy. Finally, the water soluble silicon nanoparticles were used as nanocarriers in photodynamic therapeutic application, in which can selectively deliver porphyrins into human embryonic kidney 293T (HEK293T) cells. In particular, the PEGylated alkynyl-porphyrins were conjugated onto the azido-terminated silicon nanoparticles via a CuAAC “click” reaction. The resultant PEGylated porphyrin grafted silicon nanoparticles have diameters around 13.5 ± 3.8 nm. The cryo-TEM and conventional TEM analysis proved that the PEGylated porphyrin grafted silicon nanoparticle could form the micelle-like structures at higher concentration in water via self-assembly. The UV-Vis absorption analysis demonstrated that the silicon nanoparticle could reduce the porphyrin aggregation in water which can reduce the photophysical activity of porphyrin. In addition, the nanoparticle complex was capable of producing singlet oxygen when the porphyrin units were excited by light. The cell studies demonstrated that the silicon nanoparticle could deliver the porphyrin drugs into HEK293T cells and accumulate in the mitochondria where the porphyrin could serve as an efficient photosensitizer to kill the cells via mitochondrial apoptotic pathway.acase@tulane.edu
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Ding, Shaohua [Verfasser]. "In vitro synthesis of the light-harvesting complex into artificial membrane systems / Shaohua Ding." 2010. http://d-nb.info/100987831X/34.
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Dietzek, Benjamin [Verfasser]. "Ultrafast linear and non-linear spectroscopy : from biological light receptors to artificial light harvesting systems / vorgelegt von Benjamin Dietzek." 2005. http://d-nb.info/978743733/34.
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DORIA, SANDRA. "Energy flow in complex molecular systems: Spectroscopic study by static and time-resolved techniques." Doctoral thesis, 2017. http://hdl.handle.net/2158/1077394.
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This thesis collects the results of a series of experiments aimed at the characterization of energy and charge transfer processes in organic systems, carried out during my PhD course. The complexity of the subject is connected to the identification of the micro-scale phenomena that occur after visible excitation of the systems. The goal is to control these processes in order to maximize the energy migration throughout the systems, aiming to their potential application in OPV devices. Stationary and time-resolved spectroscopic techniques are excellent experimental methods to investigate ET in organic molecular complexes, because the electronic properties are revealed in the absorption and emission spectra. The characterization of the spectral features and their time-evolution, on femtosecond timescale, gives important pieces of information about the nature and dynamics of the excited state, and its interaction with the surrounding. The first experimental work I carried out in the Ultrafast group of Prof. Paolo Foggi at LENS was focused on the spectroscopic investigation of a substituted Zn-Phtalocyanine (ZnPc) dye, that has a potential application as sensitizer in Dye Sensitized Solar Cells (DSSCs). Transient Absorption Spectroscopy (TAS), an ultrafast pump-probe technique with sub-picosecond time resolution, was employed to investigate the excited state dynamics of the dye in ethanol (EtOH) solution and adsorbed on nanocrystalline films of Titania (TiO2) and Zirconia (ZrO2). TAS results allowed us to identify the timescales of the different relaxation processes occurring after visible excitation, and to propose a scheme of the energetic levels involved in the excited state dynamics. Furthermore, we had evidence electron injection in the Titania conduction band,
which makes the molecule suitable for DSSCs applications. Many research group are focused toward the realization of artificial light-harvesting antennae for energy capture, based on organic molecules. The optimal electronic properties of such systems are still object of scientific debates, because different ET mechanisms take part in the overall exciton migration, which interplay is not trivial. During a one-year period spent in the M. G. Bawendi group at MIT, I studied the exciton transport properties in self-assembled light-harvesting nanotubes (LHNs), quasi one-dimensional aggregates consisting of ordered amphiphillic cyanine dyes. These systems present interesting excitonic properties, which derive from the unusual electronic coupling between the monomers. Because of the low static disorder, large exciton delocalization and the negligible reorganization energy (low coupling with the environment), LHNs represent an ideal model system to explore the quantum contribution and the influence of energetic disorder on the ET. The experimental investigation of LHNs was carried out by stationary and time resolved spectroscopy, at room temperature and as a function of temperature, from room temperature to 5K: the change in the spectral lineshape was interpreted in terms of homogeneous broadening. Intensity dependent fluorescence measurements gave evidence of exciton-exciton nnihilation (EEA). In order to get insight the effect of energetic disorder, a ballistic model for exciton diffusion was developed: two regimes of exciton migration were identified, depending on the relative value of the
2homogeneous and inhomogeneous timescales. Stationary fluorescence was measured as a function of the visible light irradiation, over several minutes, showing Photobrightening (PB) phenomena followed by Photodarkening (PD) on longer timescales. This results, confirmed also by 2D electronic spectroscopy (2DES), have been interpreted in terms of exciton migration mediated by super-radiance, a collective emission process arising from the coherent exciton delocalization. In order to deeply investigate the view on the molecular aggregate and their influence on exciton dynamics, I performed 2DES measurements on mixed monomer / H-aggregate systems made of ZnPc molecules. When dissolved in particular solvents, such as Cloroform (CHCl 3 ), the ZnPc molecules forms aggregates. Aggregation is one of the main issues that prevents a high efficiency of electron injection in the semiconductor conduction band. In the aggregation process, radiative channels of deactivation from the dye excited state are introduced. 2DES is a powerful multidimensional coherent spectroscopic technique that allows to: investigate the exciton dynamics and the lineshape time-evolution on femtosecond timescale, identifying the homogeneous and inhomogeneous timescales; highlight the coupling between electronic states and the possible coherent contribution. Broadband excitation of the sample allowed to discriminate between the monomer and aggregate kinetic traces. We had evidence of electronic coupling between the aggregate and the isolated molecules in close proximity. Furthermore, electronic coupling mediated by an internal vibrational mode was observed between two non-degenerate Q-states of the monomer.
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"Synthesis and photophysical characterization of re(i) and ru(ii) complexes: potential optical limiting materials and light harvesting systems." Tulane University, 2013.
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This dissertation can be divided into two parts project goals. The first one is the synthesis of rhenium (Re) complexes which are potential reverse saturable absorber (RSA) materials. The second one is the polymerization of ruthenium (Ru) polypyridyl monomers to have an oligomer ensemble for solar light harvesting purposes. THE FIRST part starts with an introduction to optical limiting materials (OLM) (chapter 1). The main discussion in chapter 4 is about the photophysical properties and energy-transfer reactions for three series of facial Re(I) tri-carbonyl complexes. The complexes are of the general type fac-[Re(CO)3(N-N)Cl], where Cl is the chloride and N-N are novel mono functionalized aryl-oligo(p-phenylene-vinylene) bipyridine (bpy) ligands. These series is as a result of changing the aryl group of the ligands to either anthracene or pyrene, and di-alkoxy attachments of phenyl ring in anthracene bipyridine ligands. The synthesis of the bpy ligands involved attaching various aryls by utilizing successive multi-step Wittig-Horner reactions (chapter 2). The ligands were later reacted with Re pentacarbonyl chloride to obtain the complexes. Chromium complexes synthesis is also included (chapter 3). The characterization involved 1H NMR, ESI-MS and elemental analysis. There is also another set of ligands where the aryl group is di-methylaminophenyl where the solvatochromic emission properties of the ligands were studied but were not coordinated to metals. The excited-state properties using both the nanosecond (ns) and picosecond (ps) time resolved transient absorption (TA) of Re(I) complexes shows strong positive excited-state absorption signals in 500-800 nm range. From the TA (ps) and time-resolved infrared of the carbonyl region, the excited state forms instantaneously after excitation. Their observed lifetimes are relatively long (2 μs-40 μs range) and they increase as the phenylene-vinylene linker increases. The excited state triplet energies values for the complexes were obtained experimentally using energy transfer method from the simple Sandros relation. They decreases as the π-conjugated phenylene-vinylene linker decreases, this is because the extended backbone bridge serves to lower the energy of the triplet excited state. Lastly, the Re(I) complexes triplet-triplet molar extinction coefficients(δex) were measured by energy transfer to a standard method and their ratios to the ground state molar absorptivity(δg ) are all (δex/δg ≥40) at 530nm which make them potential candidates for RSA. THE SECOND part involves RAFT polymerization of two new acrylamide functionalized Ru(II) polypyridyl monomers. Photoinduced electron transfer reactions for the obtained Ru oligomers and complexes were done using 10-methylphenothiazine (MPT) quencher (chapter 8). The synthesized acrylamide functionalized bipyridine ligand (chapter 6) was reacted with complex precursors cis-[Ru(L)2Cl2] where the ligand (L) is either 2,2’- bipyridine or biquinoline (chapter 7). The obtained Ru(II) photosensitizers acts as energy donating and accepting respectively. The attachment of these Ru complexes to oligomer backbone as side chains is by a C11 alkyl linker. 1H NMR, UV-Vis spectroscopy, and differential pulse voltammetry (DPV) were used to characterize the ligand, monomers and oligomers. The excited state REDOX potentials were determined using the cyclic voltammetry (CV) values and steady state emission values converted to electron volt (eV). Lastly, the TAs (ns) obtained in the presence of MPT electron donating quencher was in agreement with the ones calculated/ predicted from spectroelectrochemistry. These efforts are toward the goal of making a panchromatic solar light collector in the visible region (chapter 5).acase@tulane.edu
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"Tetrapyrrole derivatives with novel optical properties: part I, synthesis of ferrocene-containing push-pull diphenylporphyrins ; part II, Light-harvesting naphthalene-phthalocyanine systems." 2000. http://library.cuhk.edu.hk/record=b5895795.
Full textAbstract:
by Ka Lok Cheng.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.
Includes bibliographical references (leaves 115-122).
Abstracts in English and Chinese.
Abstract --- p.i
Abstract (in Chinese) --- p.ii
Acknowledgement --- p.iii
Table of Contents --- p.iv
List of Figures --- p.viii
List of Tables --- p.xi
Abbreviations --- p.xii
Chapter PART I --- SYNTHESIS OF FERROCENE-CONTAINING PUSH-PULL DIPHENYLPORPHYRINS --- p.1
Chapter Chapter 1 --- Introduction --- p.2
Chapter 1.1 --- Introduction to Nonlinear Optics --- p.2
Chapter 1.1.1 --- Interactions of Light with Matters --- p.2
Chapter 1.1.2 --- Structural Requirements of Second-Harmonic Generating Molecules --- p.4
Chapter 1.2 --- Ferrocene as an Electron Donor in Second Harmonic Generating Molecules --- p.7
Chapter 1.3 --- Porphyrin as a Platform of Second Harmonic Generating Molecules --- p.16
Chapter 1.4 --- Target Molecules of this Project --- p.22
Chapter Chapter 2 --- Result and Discussion --- p.23
Chapter 2.1 --- Preparation of Alkynyl Fragments --- p.23
Chapter 2.1.1 --- Preparation of 2-ferrocenylethyne (24) --- p.23
Chapter 2.1.2 --- Preparation of 1 -ethynyl-4-nitrobenzene (26) --- p.24
Chapter 2.1.3 --- "Preparation of l-ethynyl-4-(N,N-dimethylaminophenyl) benzene (28)" --- p.25
Chapter 2.2 --- Preparation of Porphyrin Precursors --- p.26
Chapter 2.3 --- "Synthesis and Characterizations of 5-(2'-Ferrocenylethynyl)-l5- formyl-10,20-diphenylporphyrinatonickel(II) (36)" --- p.29
Chapter 2.4 --- "Synthesis and Characterizations of 5-(2',2'-Dicyanoethenyl)-l5- (2""-Ferrocenylethynyl)-10,20-diphenylporphyrinatonickel(II) (38)" --- p.33
Chapter 2.5 --- "Synthesis and Characterizations of 5-Ferrocenylethynyl-l 5-(4""- nitrophenylethynyl)-10,20-diphenylporphyrinatonickel(II) (40)" --- p.37
Chapter 2.6 --- "Synthesis and Characterizations of 5-Ferrocenylethynyl-l 5-(4'- (N,N-dimethylamino)phenyl)ethynyl)-10,20-diphenyl porphyrinatonickel(II) (47)" --- p.43
Chapter 2.7 --- Conclusion for Part One --- p.47
Chapter Chapter 3 --- Experimental Section --- p.48
Chapter 3.1 --- General Information --- p.48
Chapter 3.2 --- Physical Measurements --- p.48
Chapter 3.3 --- Preparation of Alkynyl Fragments --- p.49
Chapter 3.4 --- Preparation of Some Known Porphyrins --- p.54
Chapter 3.5 --- "Synthesis of Ferrocenyl ""Push-pull"" Porphyrin" --- p.58
Chapter PART II --- LIGHT-HARVESTING NAPHTHALENE-PHTHALOCYANINE SYSTEMS --- p.65
Chapter Chapter 4 --- Introduction --- p.55
Chapter 4.1 --- Porphyrin-based Light-harvesting systems --- p.66
Chapter 4.1.1 --- Multiporphyrins --- p.57
Chapter 4.1.2 --- Carotenoid-porphyrins --- p.74
Chapter 4.1.3 --- Boron-dipyrrin porphyrins --- p.75
Chapter 4.1.4 --- Anthracene-porphyrin systems --- p.73
Chapter 4.1.5 --- Dendritic porphyrins --- p.79
Chapter 4.2 --- Phthalocyanine-based Light-harvesting systems --- p.80
Chapter 4.3 --- Objective of this project --- p.83
Chapter Chapter 5 --- Result and Discussion --- p.84
Chapter 5.1 --- Preparation of naphthalene-phthalocyanine systems --- p.84
Chapter 5.1.1 --- Synthesis of zinc(II) tetra( 1 -naphthoxy)phthalocyanines --- p.84
Chapter 5.1.2 --- Synthesis of tetra[2-(l´ة-naphthoxy)ethoxy] phthalocyaninatozinc(II) (83) --- p.85
Chapter 5.1.3 --- "Synthesis of 2,3,9,10,16,17,23,24-octa( 1 -naphthoxy) phthalocyaninatozinc(II) (89)" --- p.86
Chapter 5.2 --- Absorption spectra of naphthalene-phthalocyanine systems --- p.88
Chapter 5.2.1 --- Absorption spectra at different concentrations --- p.89
Chapter 5.2.2 --- Comparison of the absorption spectra of the naphthoxy phthalocyanine with the spectra of the mixture of corresponding 1-ethoxynaphthalene and alkoxyphthalocyanines --- p.92
Chapter 5.3 --- Fluorescence Quantum yields of Naphthalene-Phthalocyanine Systems --- p.96
Chapter 5.4 --- Singlet-singlet energy transfer efficiencies of Naphthalene- phthalocyanine Systems --- p.98
Chapter 5.4.1 --- Methodology --- p.98
Chapter 5.4.2 --- Determination of energy transfer quantum yields --- p.99
Chapter 5.5 --- Conclusion for Part II --- p.103
Chapter Chapter 6 --- Experimental Section --- p.104
Chapter 6.1 --- General Information --- p.104
Chapter 6.2 --- Synthesis of tetra( 1 -naphthoxy)phthalocyanines --- p.105
Chapter 6.3 --- Synthesis of tetra(naphthoxyethoxy)phthalocyanine --- p.108
Chapter 6.4 --- Synthesis of octa( 1 -naphthoxy)phthalocyanine --- p.111
References --- p.115
Appendix A: Spectra of new compounds not discussed in the main text --- p.123
Appendix B: X-ray crystallographic data of compound40 --- p.133
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Ghin, Leonardo. "Prokaryotic and eukaryotic expression systems for the production of recombinant proteins and nanoparticles for research and bio-industry." Doctoral thesis, 2015. http://hdl.handle.net/11562/915587.
Full textAbstract:
Gli organismi viventi sono in grado di produrre complesse strutture biologiche con funzioni specifiche per il loro metabolismo utilizzabili in settori industrali e di ricerca. In questo contesto le moderne tecnologie biotecnologiche sfruttano sistemi procariotici ed eucariotici per l'espressione di proteine ricombinanti, vaccini, anticorpi e nanoparticelle. In particolare il settore delle nanotecnologie sta conoscendo in questi ultimi anni un forte sviluppo e prodotti a base di nanoparticelle sono già stati approvati per la diagnostica e la terapia mentre altre sono attualmente in fase di sperimentazione clinica.
In questa tesi, è stata analizzata la possibilità di utilizzare diversi sistemi biologici per l’ espressione di proteine ricombinanti o di nanoparticelle sfuttando sia sistemi procariotici che eucariotici.
La prima parte del presente eleborato di tesi riguarda la purificazione di nanoparticelle magnetiche chiamate magnetosomi da Magnetospirillum gryphiswaldense , un batterio magnetotattico microaerofilo, nonché la successiva applicazione delle stesse come possibili agenti di contrasto in analisi NMR o come agenti terapeutici per termoterapia anti-tumorale. Nel presente elaborato di tesi è stato ottimizzato il metodo di coltura di M.gryphiswaldense, realizzando un'efficiente purificazione dei magnetosomi in lunghe catene, successivamente analizzati nelle loro caratteristiche chimico-fisiche (analisi DLS, TEM, misure di relassività e MRI) confermando la bontà come mezzi di contrasto e succesivamente impiegate in vivo come efficaci agenti terapeutici per ipertermia.
Nella seconda parte della tesi invece è stato sviluppato un sistema eucariotico per la produzione di un’importante proteina di membrana, LHCSR1, coinvolta nel delicato processo di regolazione della fotoprotezione in alghe e muschi. In particolare la proteina LHCSR1 del muschio Physcomitrella patens è stata espressa in due sistemi eucariotici ,Nicotiana benthamiana e Nicotiana tabacum realizzando l’isolamento della proteina e la preliminare determinazione delle principali proprietà spettroscopiche e biochimiche.Living organisms can produce complex structures with specific functions for their metabolism that are used in a range of bio-industry and research activities. Biotechnology exploits prokaryotic and eukaryotic systems for expression of recombinant proteins, vaccines and antibodies as well as nano-structures. Indeed a number of nanoparticle-based products have been approved for diagnostics and therapeutics and more are currently under clinical trials. In this thesis work, the possibility of using different expression systems for the preparation of bio-products has been exploited. The first part of this thesis concerns the purification of magnetic nanoparticles called magnetosomes from Magnetospirillum.gryphiswaldense, a magnetotactic microaerophilic bacterium. Subsequently these nanoparticles have been tested as contrast agents in NMR analysis or as therapeutic agents for tumor thermotherapy. The chemical-physical properties of magnetosomes efficiently purified have been studied, confirming the goodness of these nanoparticles as contrast agents. Then magnetosomes has been tested in thermotherapy in vitro and in vivo against two cancer cell lines. In the second part of the thesis instead has been developed a system for the production of an important eukaryotic membrane protein, LHCSR, involved in the delicate process of regulation photoprotection in algae and mosses. In particular the protein LHCSR1 from the moss Physcomitrella patens has been efficiently expressed in two eukaryotic systems, Nicotiana benthamiana and Nicotiana tabacum realizing its isolation from thylakoid membrane and the preliminary determination of its biochemical and spectroscopic properties.