Tesi: "Confocal fluorescence microscopy"

1

Eigenbrot, Ilya Vladimirovich. "A time-resolved confocal fluorescence microscope". Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342331.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

2

Alawadhi, Fahimah. "Statistical image analysis and confocal microscopy". Thesis, University of Bath, 2001. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341639.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

3

Jiang, Shihong. "Non-scanning fluorescence confocal microscopy using laser speckle illumination". Thesis, University of Nottingham, 2005. http://eprints.nottingham.ac.uk/10139/.

Testo completo

Abstract (sommario):

Confocal scanning microscopy (CSM) is a much used and advantageous form of microscopy. Although CSM is superior to conventional microscopy in many respects, a major disadvantage is the complexity of the scanning process and the sometimes long time to perform the scan. In this thesis a novel non-scanning fluorescence confocal microscopy is investigated. The method uses a random time-varying speckle pattern to illuminate the specimen, recording a large number of independent full-field frames without the need for a scanning system. The recorded frames are then processed in a suitable way to give a confocal image. The goal of this research project is to confirm the effectiveness and practicality of speckle-illumination microscopy and to develop this proposal into a functioning microscope system. The issues to be addressed include modelling of the system performance, setting up experiments, computer control and image processing. This work makes the following contributions to knowledge: * The development of criteria for system performance evaluation * The development of methods for speckle processing, whereby the number of frames required for an image of acceptable quality can be reduced * The implementation of non-scanning fluorescence confocal microscopy based upon separate recording of the speckle patterns and the fluorescence frames, demonstrating the practicality and effectiveness of this method * The realisation of real-time image processing by optically addressed spatial light modulator, showing how this new form of optical arrangement may be used in practice The thesis is organised into three main segments. Chapters 1-2 review related work and introduce the concepts of fluorescence confocal microscopy. Chapters 3-5 discuss system modelling and present results of performance evaluation. Chapters 6-8 present experimental results based upon the separate recording scheme and the spatial light modulation scheme, draw conclusions and offer some speculative suggestions for future research.

Gli stili APA, Harvard, Vancouver, ISO e altri

4

Wang, Xiao. "Confocal angle resolved linear dichroism microscopy for structural fluorescence imaging". Ecole centrale de Marseille, 2013. http://tel.archives-ouvertes.fr/docs/00/87/10/10/PDF/Wang-Thesis.pdf.

Testo completo

Abstract (sommario):

La microscopie de fluorescence a récemment été complétée par une technique appelée dichroïsme linéaire résolu angulairement, basé sur le fait que l'absorption de la lumière est un processus sensible à l'orientation moléculaire. En analysant la réponse d'émission de fluorescence en fonction de l'orientation de la polarisation de la lumière excitatrice, cette technique permet de remonter à l'information d'orientation sur un ensemble de molécules fluorescentes, plus précisément son angle d'orientation moyenne et l'amplitude de ses fluctuations angulaires autour de cette moyenne. Dans cette thèse, nous mettons en oeuvre de nouvelle méthodes et instrumentations capables d'améliorer la robustesse et la rapidité de l'analyse de données de réponses résolues en polarisation, la vitesse de l'acquisition de données, et d'explorer la possibilité de mesurer l'orientation 3D de molécules. Nous proposons une méthode capable de mesurer les propriétés d'orientation de sondes lipidiques fluorescentes par l'utilisation d'un disque de Nipkow couplé à une imagerie par caméra, et combiné avec la modulation rapide de la polarisation par modulateur électro-optique. Une nouvelle méthode de traitement de données est développée pour considérablement améliorer la rapidité et la précision de l'information par une étude des sources de bruit et d'incertitude, dues au bruit et aux facteurs instrumentaux. Cette technique a été testée avec succés sur des vésicules géantes uni-lamellaires et sur cellules vivantes, marquées par les sondes lipidiques DiIC18 et di-8-ANEPPQ. Cette méthode est capable d'acquérir une information précise sur l'orientation moléculaire à une cadence d'une image par seconde. Enfin, afin de sonder de manière non ambiguë l'orientation 3D d'un ensemble de molécules, une nouvelle méthode est proposée, supportée par des simulations numériques, basée sur la variation hors plan de la polarisation d'excitation dans le volume focal par une somme cohérente de champs polarisés linéairement et radialement
Based on the fact that the absorption of light is a molecular-orientation sensitive process, fluorescence microscopy has been recently completed by a technique called angle-resolved linear dichroism. By analyzing the fluorescence emission response with respect to the polarization orientation of the exciting light, this technique allows retrieving orientation information of an ensemble of fluorescent molecules, namely the average orientation angle and the amplitude of the angular fluctuations around this average. In this PhD thesis, we implement new methods and instrumentation tools able to improve the robustness and speed of the polarization resolved data analysis, the rate of the data acquisition, and at last to explore the possibility to record molecular 3D orientation information. A scheme able to monitor the real-time orientation properties of fluorescent lipid probes is proposed using a high-speed spinning disk coupled to camera imaging, combined with fast switching of the polarization state by an electro optical modulator. A new data processing method is developed which considerably improves the speed and the precision of the retrieved information by investigating the sources of bias and uncertainty due to noise and instrumentation factors. The technique has been successfully tested on giant unilamellar vesicles and on living cells labeled with different fluorescent lipid probes, DiIC18 and di-8-ANEPPQ. It was able to acquire precise molecular orientation images at full frame rates in the range of one frame per second. At last in order to probe unambiguously the 3D orientation information of an ensemble of molecules, a new method is proposed and supported by simulations, based on the out-of-plane tuning of the excitation polarization realized in the focusing volume by coherently summing linearly and radially polarized fields

Gli stili APA, Harvard, Vancouver, ISO e altri

5

Gösch, Michael. "Microfluidic analysis and parallel confocal detection of single molecules /". Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-663-4/.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

6

Risi, Matthew D. "Advances In Combined Endoscopic Fluorescence Confocal Microscopy And Optical Coherence Tomography". Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/332772.

Testo completo

Abstract (sommario):

Confocal microendoscopy provides real-time high resolution cellular level images via a minimally invasive procedure. Results from an ongoing clinical study to detect ovarian cancer with a novel confocal fluorescent microendoscope are presented. As an imaging modality, confocal fluorescence microendoscopy typically requires exogenous fluorophores, has a relatively limited penetration depth (100μm), and often employs specialized aperture configurations to achieve real-time imaging in vivo. Two primary research directions designed to overcome these limitations and improve diagnostic capability are presented. Ideal confocal imaging performance is obtained with a scanning point illumination and confocal aperture, but this approach is often unsuitable for real-time, in vivo biomedical imaging. By scanning a slit aperture in one direction, image acquisition speeds are greatly increased, but at the cost of a reduction in image quality. The design, implementation, and experimental verification of a custom multi-point-scanning modification to a slit-scanning multi-spectral confocal microendoscope is presented. This new design improves the axial resolution while maintaining real-time imaging rates. In addition, the multi-point aperture geometry greatly reduces the effects of tissue scatter on imaging performance. Optical coherence tomography (OCT) has seen wide acceptance and FDA approval as a technique for ophthalmic retinal imaging, and has been adapted for endoscopic use. As a minimally invasive imaging technique, it provides morphological characteristics of tissues at a cellular level without requiring the use of exogenous fluorophores. OCT is capable of imaging deeper into biological tissue (~1-2 mm) than confocal fluorescence microscopy. A theoretical analysis of the use of a fiber-bundle in spectral-domain OCT systems is presented. The fiber-bundle enables a flexible endoscopic design and provides fast, parallelized acquisition of the optical coherence tomography data. However, the multi-mode characteristic of the fibers in the fiber-bundle affects the depth sensitivity of the imaging system. A description of light interference in a multi-mode fiber is presented along with numerical simulations and experimental studies to illustrate the theoretical analysis.

Gli stili APA, Harvard, Vancouver, ISO e altri

7

Slimani, Amel. "Photonic approach for the study of dental hard tissues and carious lesion detection". Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT125.

Testo completo

Abstract (sommario):

Les propriétés photoniques des tissus durs dentaires nous ont permis d’étudier l’email et la dentine a un niveau moléculaire (in vitro) en utilisant des techniques de microscopie optique non linéaires. La microscopie confocale Raman est technique d’imagine de haute résolution permettant d’analyse d’échantillon sans préparation spécifique ni marquage. Cette méthode nous a permis de reconstituer une cartographie de la réticulation du collagène et de la cristallinité au niveau de la jonction émail-dentine et cela avec une résolution spatiale non atteinte jusque-là. Cette analyse chimique de la jonction émail-dentine a permis de redéfinir la largeur de cette zone de transition. Cette largeur est nettement supérieure à celles proposées par les études précédentes. Par ailleurs, l’étude portant sur les changements de fluorescence intrinsèque entre les tissues dentaires sains et cariés suggèrent l’implication de la protoporphyrin IX et de la pentosidine dans l’expression de la fluorescence rouge des tissus cariés. La microscopie multiphotonique quant à elle nous a permis de détecter la lésion carieuse et de suivre son développement en utilisant la génération de seconde harmonique (SHG) et la fluorescence par excitation à deux photons (2PEF). Nos études ont démontré la validité du ratio SHG/2PEF comme paramètre fiable pour la détection de la lésion carieuse. Les études proposées par cette thèse montrent le potentiel des propriétés photoniques de l’émail et de la dentine en utilisant les microscopies Raman et multiphotoniques dans l’étude de ces tissus au niveau moléculaire. Cela offre de nouvelles perspectives en recherche et en applications cliniques
Photonic properties of dental hard tissues allowed us to proceed to in vitro analysis of enamel and dentin on a molecular level. Confocal Raman microscopy has been used to produce a mapping of collagen cross-link and crystallinity of human dentin–enamel junction (DEJ) with a spatial resolution not achieved up to now. The method is a non-invasive, label-free and a high spatial resolution imaging technique. This chemical analysis of DEJ led us to redefine a wider width of this transition zone and advance our understanding of dental histology. A study on the intrinsic fluorescence changes of sound and carious tissues using conventional fluorescence microscopy suggests the involvement of protoporphyrin IX and pentosidine in the fluorescence red-shift observed in carious tissues. Multiphoton microscopy allowed to detect nonlinear optical signal changes during caries process using second harmonic generation (SHG) and two-photon excitation fluorescence (2PEF). Our studies led us to propose the ratio SHG/2PEF as valuable parameter to monitor caries lesion. Collectively, advances described in this thesis show the potential of photonic properties of enamel and dentin using Raman and multiphoton microcopies for molecular investigations on sound as much as on carious tissues. It opens new perspective in dental research and clinical applications

Gli stili APA, Harvard, Vancouver, ISO e altri

8

Tsutae, Fernando Massayuki. "Espectroscopia de correlação de fluorescência aplicada em estudos de sistemas moleculares, biológicos e celulares". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-14102016-101124/.

Testo completo

Abstract (sommario):

A espectroscopia de correlação de fluorescência (FCS) é uma das diferentes técnicas de análise por imagens de alta resolução espacial e temporal de biomoléculas em concentrações extremamente baixas. Ela se tornou uma técnica extremamente poderosa e sensível em áreas como bioquímica e biofísica. Como uma técnica bem estabelecida, ela é utilizada para medir concentrações locais de biomoléculas, através da marcação com moléculas fluorescentes. Coeficientes de difusão e constantes cinéticas também podem ser medidos através de FCS assim como detecção de molécula única. Ela também pode dar informação precisa sobre interações de antígeno-anticorpo, ácidos nucleicos e proteínas. Através de uma combinação de marcadores de alto rendimento quântico, fontes de luz estável (lasers), detecção ultrassensível e microscopia confocal, é possível realizar medidas de FCS em volumes de fentolitros (fL) e em concentrações de nanomolar (nM) em soluções aquosas ou em células vivas. Em contraste com outras técnicas de fluorescência, a sensibilidade da FCS aumenta com a diminuição da concentração do fluoróforo marcador, porque o parâmetro de interesse não é a intensidade de emissão de fluorescência, mas sim as flutuações espontâneas da fluorescência. Durante o tempo em que a partícula ou molécula atravessa o volume de medida pode ocorrer mudanças conformacionais e reações químicas e fotofísicas que alteram as características de emissão do fluoróforo e causam flutuações no sinal detectado. Estas flutuações são então monitoradas e transformadas em uma curva de autocorrelação, por intermédio de um software comercial que emprega um modelo físico apropriado para FCS. Em nosso estudo, utilizamos um marcador comercial (ALEXA 488®) para marcar proteínas. Primeiramente utilizamos a técnica de FCS para medir concentrações extremamente baixas de marcadores fluorescentes. Também realizamos um experimento testando a influência da viscosidade do meio na difusão livre do fluoróforo, assim como as melhores condições em que temos um melhor sinal de FCS. Por fim, estudamos a difusão de proteínas marcadas (PUC II e IV) em meio aquoso (PBS) e no interior de células.
Fluorescence correlation spectroscopy (FCS) is one of the many different modes of high-resolution spatial and temporal analysis of extremely low concentrated biomolecules. It has become a powerful and sensitive tool in fields like biochemistry and biophysics. As a well established technique, it is used to measure local concentrations of fluorescently labeled biomolecules, diffusion coefficients, kinetic constants and single molecule studies. Through a combination of high quantum yield fluorescent dyes, stable light sources (lasers), ultrasensitive detection and confocal microscopy is possible to perform FCS measurements in femtoliters volumes and nanomolar concentrations in aquous solution or in live cells. Unlike with other fluorescence technics, its sensibility increases with the decrease of dye concentrarion, because the main factor is not the emission intensity itself. Instead this, spontaneous statistical fluctuation of fluorescence becomes the main factor in FCS analisys. During the time that the conjugated-dye cross the volume detection can occur conformational changes, chemical reaction and photophysical processes that can change the emission properties of the dye and, then, change the detected sinal. This fluctuations are tracked and changed into a autocorrelation curve, by a specific software, appropriate to perform FCS analisys. In our study, we use comercial dye (Alexa 488) to label proteins. Firstly, we applied FCS to measure extremally diluted concentrations of dyes (~1 nM). We have performed experiments testing the influence of the viscosity medium in the free difusion of the dyes and the optical apparatus and conditions that result in the best FCS signal. We also have studied protein diffusion (PUC II e IV) in aquous medium (PBS) and toward the inner of the cells.

Gli stili APA, Harvard, Vancouver, ISO e altri

9

Kakade, Rohan. "Improved resolution and signal-to-noise ratio performance of a confocal fluorescence microscope". Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33699/.

Testo completo

Abstract (sommario):

A culmination of theory, techniques and devices stemming from a wide variety of sources and disciplines, optical microscopy presents vast possibilities for visualisation of small structures. One of the most fundamental yet significant optical microscopy techniques is Confocal Fluorescence Microscopy (CFM). CFM is studied here by analysing its performance with respect to the two most important metrics - Signal-to-noise ratio and 3D optical resolution. Several authors have commented on the inherent inefficiency of imaging systems such as CFM to utilise the available light when providing resolution beyond the well-known diffraction limit, primarily due to the precise mechanisms that help realise the resolution gain in the first place. In CFM, the detection pinhole is the key mechanism that helps realise up to 1.4 times resolution improvement over conventional wide-field microscopy techniques by trading off SNR. First, an investigation of the inherent SNR-resolution trade-off in a CFM system is studied; the impact of the detection pinhole geometry on the performance of a CFM is examined by means of an effective trade-off curve. Using alternative pinhole geometries in conjunction with new detection schemes, it is next shown how performance gains are realised in both the lateral and axial directions. Examined next is a recently developed detection scheme called subtractive imaging; wherein a special annular pinhole is used to divide the confocal point spread function signal into two detectors. By using fast point detectors in place of CCD arrays, it is shown how using numerical optimisation yields an optimum “differential pinhole” to achieve considerable 3D resolution gains over conventional (circular pinhole based) CFM systems. By examining the trade-off curves it is also shown that the proposed design is able to offer simultaneous and maximum performance gains up to a considerably high SNR in comparison to conventional (circular pinhole) based CFM systems. Lastly, the work will propose the use of a deconvolution technique and an alternative detection scheme to demonstrate substantially higher improvements in the quality of images acquired by a CFM system. Image reconstruction is a tried and tested image post processing strategy to realise super resolution. An image reconstruction technique, based on an expectation maximisation maximum likelihood (EM-ML) algorithm is used in conjunction with array detectors to demonstrate enhanced resolution and noise performance of a CFM system. The point scan method used here renders the algorithm slow with long run times. To mitigate this, structured illumination is used to show how similar resolution gains in the array detector based CFM systems could be realised but in a much shorter time.

Gli stili APA, Harvard, Vancouver, ISO e altri

10

Ferro, Daniela Peixoto 1981. "Aplicação da biofotônica para o estudo de cicatrizes". [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/312786.

Testo completo

Abstract (sommario):

Orientador: Konradin Metze
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
Made available in DSpace on 2018-08-26T20:44:11Z (GMT). No. of bitstreams: 1 Ferro_DanielaPeixoto_D.pdf: 2964245 bytes, checksum: 202d309cf65f632d47c7811d4958535d (MD5) Previous issue date: 2015
Resumo: A aplicação integrada de técnicas modernas, como a Geração do Segundo Harmônico (SHG) e os tempos de vida da fluorescência (FLIM), com análise de imagens matemáticas nos permitem visualizar detalhes não vistos por microscopia de luz convencional. O objetivo deste estudo foi investigar se isto também pode ser aplicado para a investigação de tecido cicatricial. Foram estudados 28 casos de preparações histológicas de rotina, de quelóides, cicatrizes hipertróficas e normais. A Fluorescência de dois fótons e SHG foram obtidas por um microscópio multifóton (LSM 780 NLO-Zeiss), em objetiva de 40X e excitados por um laser Mai Tai de Ti: Safira (comprimento de onda de 940 nm). Foram adquiridas imagens em 3D e foram criadas imagens justapostas a fim de comparar diferentes cicatrizes ou várias regiões no interior da mesma cicatriz com análise de imagens informatizadas. Variáveis de Textura derivadas a partir da matriz de coocorrência das imagens de fluorescência mostraram diferenças significativas entre as cicatrizes normais, cicatrizes hipertróficas e quelóides. Para a análise do FLIM, foi utilizado um sistema composto por um microscópio confocal (LSM780-NLO- Zeiss), com objetiva de 40x e um sistema FLIM acoplado. As amostras foram excitadas por um laser de diodo a 405nm. Estudamos secções não coradas de 32 casos processados rotineiramente de tecido cicatricial incluídos em parafina. As áreas das regiões centrais e periféricas foram selecionadas aleatoriamente e comparadas. Os tempos de vida de fluorescência das hemácias serviram como padrão interno. Os tempos de vida do colágeno em áreas centrais em todos os tipos de cicatrizes foram significativamente mais longo do que em áreas periféricas. Houve correlação positiva entre os tempos de vida de fluorescência das hemácias e as fibras de colágeno entre os casos. Em resumo, o SHG e a técnica Flim revelam em cicatrizes rotineiramente processadas, características morfológicas dos tecidos, que não podem ser detectadas por microscopia de luz convencional
Abstract: The integrated application of modern techniques such as Second Harmonic Generation (SHG) and fluorescence lifetime imaging (FLIM) with mathematical image analysis enable us to visualize details not seen by conventional light microscopy. The aim of this study was to investigate whether this could also be true for the investigation of scar tissue. 28 routine histological preparations of keloids, hypertrophic and normal scars were studied. Two-photon fluorescence and SHG was obtained by a multiphoton microscope (LSM 780 NLO-Zeiss (at 40X objective magnification) and a Mai Tai Ti: Sapphire laser with excitation at 940 nm wavelength. 3D reconstructed patchwork images were created in order to compare different scars or various regions inside the same scar with computerized image analysis. Texture variables derived from the co- occurrence matrix of the fluorescence images showed significant differences between normal scars, hypertrophic scars and keloids. For FLIM analysis we used a system composed of a confocal microscope Zeiss LSM780 Upright-NLO with the 40x objective and a FLIM detection system. The samples were excited by a laser diode at 405nm. We studied unstained sections of 32 routinely processed and paraffin-embedded cases of scar tissue. Randomly selected areas of the central and peripheral regions were compared. The fluorescence lifetimes of red blood cells served as internal standard. Lifetimes of collagen in central areas of all scar types were significantly longer than in the periphery. There was a significant positive correlation between the fluorescence lifetimes of red blood cells and collagen fibers among the cases. In summary, SHG and FLIM techniques reveal in routinely processed scar tissue morphological characteristics, which cannot be detected by conventional light microscopy
Doutorado
Biologia Estrutural, Celular, Molecular e do Desenvolvimento
Doutora em Fisiopatologia Médica

Gli stili APA, Harvard, Vancouver, ISO e altri

11

Maggiano, Corey. "CONFOCAL LASER SCANNING MICROSCOPY AS A TOOL FOR THE INVESTIGATION OF TETRACYCLINE FLUORESCENCE IN ARCHAEOLOGICALHUMAN BONE". Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2752.

Testo completo

Abstract (sommario):

Fluorochromes such as tetracycline have been used to label bone for histomorphometric analysis, measuring bone formation, growth, maintenance, and pathology. More recently, similar fluorescence has been observed in ancient human bone. Attributed to tetracycline (TC) exposure, this phenomenon could affect various aspects of health during life and/or preservation of remains postmortem. Standard epifluorescence microscopy is the most common tool employed in the analysis of these labels. Though valuable, this technique is limited by its inability to penetrate bone three-dimensionally and its inclusion of out-of-focus light, possibly disrupting accurate analysis. Confocal Laser Scanning Microscopy (CLSM) has been demonstrated as a valuable tool for three-dimensional histology. Its application to the study of compact bone fluorescence has been lacking, especially in archaeological and forensic sciences. In the following two papers, modern TC-controlled bone is compared to well preserved archaeological bone recovered from the Dakhleh Oasis, Egypt, using both standard wide-field and more modern confocal techniques for imaging and analysis. Spectral analysis via CLSM shows that both modern and ancient fluorescent labels in bone share the exact same fluorescence emission peak at 525 nm. Differences in the shape of the spectral curve and photobleaching characteristics are discussed. In addition, CLSM's high-resolution two- and three-dimensional imaging capabilities (in polarized light, scattered light, and fluorescence light) are found to increase the flexibility and creativity of investigations into the occurrence of tetracycline labels in archaeological bone and could have added benefits for modern medical and anatomical experimentation.
M.S.
Department of Biology
Arts and Sciences
Biology

Gli stili APA, Harvard, Vancouver, ISO e altri

12

Hu, Yan. "Quantitative confocal imaging of nanoporous silica". Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/3106.

Testo completo

Abstract (sommario):

Nanoporous materials have been widely used in the fields of biological and chemical sensing, chemical separation, heterogeneous catalysis and biomedicine due to their merits of high surface area-to-volume ratio, chemical and thermal stabilities, and flexible surface modification. However, as the nature of nanoporous materials, they are inherently heterogeneous in the micro- and nanoenvironments. The environmental heterogeneity plays a decisive role in determining the performance of various applications of nanoporous materials. In order to provide an in-depth understanding of the nanoporous materials, it is of great interest to investigate the environmental heterogeneity in them. Single molecule spectroscopy, combined the quantitative confocal fluorescence imaging which possesses the capability of optical sectioning, has demonstrated to be a powerful tool to approach the environmental heterogeneity inside nanoporous materials. Single molecule spectroscopy is an ultrasensitive technique for probing molecular transport and properties of individual molecules. This technique has been extensively used in the research of environmental heterogeneity in nanoporous materials since it removes the issues of ensemble averaging and directly approaches detailed information that is obscured in ensemble measurements. In order to proficiently interpret single molecule data, we developed a comprehensive methodology – single molecule counting – for characterizing molecular transport in nanoporous silica. With this methodology as a tool, the nanoenvironmental heterogeneity inside the nanopores of C18-derivatized silica particles was explored by probing single molecular diffusion inside the pores. By employing single molecule ratiometric spectroscopy and a solvatochromic fluorophore as viii reporter of local environment, the gradient in nanopolarity as well as the nanoviscosity along the C18 layer after the inclusion of solvent was uncovered. The chemical properties of solute molecules at the nanopore surface are ultimately controlled by the energetics of the solute-interface interactions. The imaging of distribution of energies would be a decisive approach to assess the fundamental heterogeneity of the interface. To this end, we investigated the ΔG distribution of C18-derivatized nanoporous silica particles with quantitative confocal imaging. The pixel-to-pixel and particle-to-particle analysis showed the existence of ΔG heterogeneity between particles as well as within individual particles. The heterogeneity in ΔG could be partially responsible for band broadening in chemical separations and significantly affect overall reaction yield when using nanoporous materials as solid support for heterogeneous catalysis.

Gli stili APA, Harvard, Vancouver, ISO e altri

13

Hermann, Martin, Oliver Nussbaumer, Ralf Knöfler, Paul Hengster, Walter Nussbaumer e Werner Streif. "Real-Time Live Confocal Fluorescence Microscopy as a New Tool for Assessing Platelet Vitality". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-136619.

Testo completo

Abstract (sommario):

Background: Assessment of platelet vitality is important for patients presenting with inherited or acquired disorders of platelet function and for quality assessment of platelet concentrates. Methods: Herein we combined live stains with intra-vital confocal fluorescence microscopy in order to obtain an imaging method that allows fast and accurate assessment of platelet vitality. Three fluorescent dyes, FITC-coupled wheat germ agglutinin (WGA), tetramethylrhodamine methyl ester perchlorate (TMRM) and acetoxymethylester (Rhod-2), were used to assess platelet morphology, mitochondrial activity and intra-platelet calcium levels. Microscopy was performed with a microlens-enhanced Nipkow spinning disk-based system allowing live confocal imaging. Results: Comparison of ten samples of donor platelets collected before apheresis and platelets collected on days 5 and 7 of storage showed an increase in the percentage of Rhod-2positive platelets from 3.6 to 47 and finally to 71%. Mitochondrial potential was demonstrated in 95.4% of donor platelets and in 92.5% of platelets stored for 7 days. Conclusion: Such fast and accurate visualization of known key parameters of platelet function could be of relevance for studies addressing the quality of platelets after storage and additional manipulation, such as pathogen inactivation, as well as for the analysis of inherited platelet function disorders
Hintergrund: Die Vitalitätsbestimmung von Blutplättchen ist sowohl für die Analyse angeborener Plättchendefekte als auch für die Qualitätsbestimmung von Plättchenkonzentraten von zentraler Bedeutung. Methoden: In der vorliegenden Arbeit stellen wir eine Methode vor, die mittels einer Kombination von Vitalfarbstoffen und konfokaler «Real time»-Mikroskopie neue Einblicke in die Vitalitätsbestimmung lebender Plättchen ermöglicht. Mittels der Zugabe von FITC-gekoppeltem Weizenkeimlektin (WGA), Tetramethylrhodamin-Methylesterperchlorat (TMRM) und Acetoxymethylester (Rhod-2) wurde bei lebenden Blutplättchen deren Morphologie, mitochondriale Aktivität und Veränderungen im Calcium-Haushalt im Rahmen der Lagerung analysiert. Für die Mikroskopie wurde ein Nipkow-System gewählt, das eine konfokale Mikroskopie lebender Zellen ermöglicht. Ergebnisse: Der Vergleich von 10 humanen Blutplättchenproben zu Beginn bzw. nach 5 und 7 Tagen Lagerung zeigte einen Anstieg der Rhod-2-positiven Plättchen von 3,6 über 47 auf 71%. Die Anzahl der Blutplättchen mit TMRM-positiven Mitochondrien hingegen lag vor der Lagerung bei 95,4% und nach den 7 Tagen Lagerung bei 92,5%. Schlussfolgerung: Die hier vorgestellte Methodik der Bildgebung zur Bestimmung vitaler Parameter von Blutplättchen eignet sich als ergänzende Analysemodalität für eine bessere Bestimmung der Blutplättchenqualität
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

Gli stili APA, Harvard, Vancouver, ISO e altri

14

Hermann, Martin, Oliver Nussbaumer, Ralf Knöfler, Paul Hengster, Walter Nussbaumer e Werner Streif. "Real-Time Live Confocal Fluorescence Microscopy as a New Tool for Assessing Platelet Vitality". Karger, 2010. https://tud.qucosa.de/id/qucosa%3A26667.

Testo completo

Abstract (sommario):

Background: Assessment of platelet vitality is important for patients presenting with inherited or acquired disorders of platelet function and for quality assessment of platelet concentrates. Methods: Herein we combined live stains with intra-vital confocal fluorescence microscopy in order to obtain an imaging method that allows fast and accurate assessment of platelet vitality. Three fluorescent dyes, FITC-coupled wheat germ agglutinin (WGA), tetramethylrhodamine methyl ester perchlorate (TMRM) and acetoxymethylester (Rhod-2), were used to assess platelet morphology, mitochondrial activity and intra-platelet calcium levels. Microscopy was performed with a microlens-enhanced Nipkow spinning disk-based system allowing live confocal imaging. Results: Comparison of ten samples of donor platelets collected before apheresis and platelets collected on days 5 and 7 of storage showed an increase in the percentage of Rhod-2positive platelets from 3.6 to 47 and finally to 71%. Mitochondrial potential was demonstrated in 95.4% of donor platelets and in 92.5% of platelets stored for 7 days. Conclusion: Such fast and accurate visualization of known key parameters of platelet function could be of relevance for studies addressing the quality of platelets after storage and additional manipulation, such as pathogen inactivation, as well as for the analysis of inherited platelet function disorders.
Hintergrund: Die Vitalitätsbestimmung von Blutplättchen ist sowohl für die Analyse angeborener Plättchendefekte als auch für die Qualitätsbestimmung von Plättchenkonzentraten von zentraler Bedeutung. Methoden: In der vorliegenden Arbeit stellen wir eine Methode vor, die mittels einer Kombination von Vitalfarbstoffen und konfokaler «Real time»-Mikroskopie neue Einblicke in die Vitalitätsbestimmung lebender Plättchen ermöglicht. Mittels der Zugabe von FITC-gekoppeltem Weizenkeimlektin (WGA), Tetramethylrhodamin-Methylesterperchlorat (TMRM) und Acetoxymethylester (Rhod-2) wurde bei lebenden Blutplättchen deren Morphologie, mitochondriale Aktivität und Veränderungen im Calcium-Haushalt im Rahmen der Lagerung analysiert. Für die Mikroskopie wurde ein Nipkow-System gewählt, das eine konfokale Mikroskopie lebender Zellen ermöglicht. Ergebnisse: Der Vergleich von 10 humanen Blutplättchenproben zu Beginn bzw. nach 5 und 7 Tagen Lagerung zeigte einen Anstieg der Rhod-2-positiven Plättchen von 3,6 über 47 auf 71%. Die Anzahl der Blutplättchen mit TMRM-positiven Mitochondrien hingegen lag vor der Lagerung bei 95,4% und nach den 7 Tagen Lagerung bei 92,5%. Schlussfolgerung: Die hier vorgestellte Methodik der Bildgebung zur Bestimmung vitaler Parameter von Blutplättchen eignet sich als ergänzende Analysemodalität für eine bessere Bestimmung der Blutplättchenqualität.
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Gli stili APA, Harvard, Vancouver, ISO e altri

15

Clarke, Oliver J. "Isothiocyanato porphyrins for bioconjugation : synthesis and applications in targeted photochemotherapy and fluorescence imaging". Thesis, University of Essex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327076.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

16

Kaldaras, Leonora. "Single Molecule Studies of Enzymes Horseradish Peroxidase and Alkaline Phosphatase Using Total Internal Reflection Fluorescence Microscopy and Confocal Microscopy". Bowling Green State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1374686174.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

17

Dubaj, Vladimir, e n/a. "Novel optical fluorescence imaging probe for the investigation of biological function at the microscopic level". Swinburne University of Technology, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20060905.084615.

Testo completo

Abstract (sommario):

Existing optic fibre-bundle based imaging probes have been successfully used to image biological signals from tissue in direct contact with the probe tip (Hirano et al. 1996). These fibre-bundle probe systems employed conventional fluorescence microscopy and thus lacked spatial filtering or a scanned light source, two features used by laser scanning confocal microscopes (LSCMs) to improve signal quality. Improving the methods of imaging tissue in its natural state, deep in-vivo and at cellular resolution is an ever-present goal in biological research. Within this study, a novel (580 μm diameter) optic fibre-bundle direct-contact imaging probe, employing a LSCM, was developed to allow for improved imaging of deep biological tissue in-vivo. The new LSCM/probe system possessed a spatial resolution of 10 μm, and a temporal resolution of 1 msec. The LSCM/probe system was compared to a previously used direct-contact probe system that employed a conventional fluorescence microscope. Quantitative and qualitative data indicated that the LSCM/probe system possessed superior image contrast and quality. Furthermore, the LSCM/probe system was approximately 16 times more effective at filtering unwanted contaminating light from regions below the imaging plane (z-axis). The unique LSCM/probe system was applied to an exploratory investigation of calcium activity of both glial and neuronal cells within the whisker portion of the rat primary somatosensory cortex in-vivo. Fluorescence signals of 106 cells were recorded from 12 female Sprague Dawley rats aged between 7-8 weeks. Fluo-3(AM) fluorophore based calcium fluctuations that coincided with 10 - 14 Hz sinusoidal stimulation of rat whiskers for 0.5-1 second were observed in 8.5% of cells (9 of 106). Both increases and decreases in calcium levels that coincided with whisker stimulation were observed. Of the 8.5 % of cells, 2.8% (3 cells) were categorized as glial and 5.7% (6 cells) as neuronal, based on temporal characteristics of the observed activity. The remaining cells (97 of 106) displayed sufficient calcium-based intensity but no fluctuations that coincided with an applied stimulus. This was partially attributed to electronic noise inherent in the prototype system obscuring potential very weak cell signals. The results indicate that the novel LSCM/probe system is an advancement over previously used systems that employed direct-contact imaging probes. The miniature nature of the probe allows for insertion into soft tissue, like a hypodermic needle, and provides access to a range of depths with minimal invasiveness. Furthermore, when combined with selected dyes, the system allows for imaging of numerous forms of activity at cellular resolution.

Gli stili APA, Harvard, Vancouver, ISO e altri

18

Araújo, Cíntia Tereza Pimenta de 1968. "Use of fluorescence in the performance evaluation of adhesive systems = Uso da fluorescência na avaliação do comportamento de sistemas adesivos". [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289658.

Testo completo

Abstract (sommario):

Orientador: Luis Alexandre Maffei Sartinni Paulillo
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-21T22:09:59Z (GMT). No. of bitstreams: 1 Araujo_CintiaTerezaPimentade_D.pdf: 9367664 bytes, checksum: 6c7161dae0f158a143f829e530249b20 (MD5) Previous issue date: 2013
Resumo: A microscopia confocal de varredura a laser (MCVL) é um recurso de visualização microscópica que permite a análise de materiais ou estruturas com requisitos mínimos de preparação de amostras de modo não destrutivo. Assim, os objetivos deste estudo foram: avaliar a influência da incorporação do corante fluorescente Rodamina B (R) nas propriedades mecânicas resistência coesiva (RC), módulo de elasticidade (ME) e resistência à flexão (RF) de 2 sistemas adesivos, o autocondicionante Clearfil SE Bond e o convencional Scotchbond Multi-Purpose (estudo 1); validar o método modificado de microtração (?TBS), em que micro-amostras de secção transversal de 0,09 mm2 foram testadas e verificar a influência da R na resistência à união a dentina e integridade interfacial através de microscopia confocal (estudo 2). Para avaliar a influência do corante, 0,16 mg/ml de R foram incorporados aos adesivos constituindo assim dois grupos para cada adesivo: grupos dos adesivos corados e não corados totalizando 4 grupos experimentais. Para a análise da RC, E e RF, os corpos de prova foram confeccionados a partir de uma matriz de silicone por adição. Sobre a matriz, foram dispensados 10 ?L de adesivo variando de acordo com cada grupo de adesivos corados e não corados. RC (n= 10), E e RF (n= 5) foram avaliadas em máquina de ensaio universal a 0,5 mm/min, até a ruptura da amostra. Para visualização em microscopia confocal e análise da resistência à união os adesivos foram aplicados à superfície plana da dentina oclusal de 32 pré-molares humanos. Após a realização dos procedimentos adesivos, realizaram-se as restaurações (blocos de 16 mm2) com Charisma Opal (Kulzer - cor A3). Em seguida, para a realização do teste modificado de microtração, micro-amostras em forma de palito (secção transversal 0,09 mm2) foram confeccionadas. Previamente ao ensaio mecânico, foi realizada através de MVCL a análise micromorfológica das microamostras dos grupos de adesivos corados. Posteriormente a resistência à união foi mensurada através do ensaio modificado de microtração a velocidade de 0,5 mm/min em máquina de ensaio universal. Os dados de todos os testes avaliados foram submetidos à análise de variância dois fatores. Os resultados mostraram que o comportamento dos sistemas adesivos investigados não se modificou, independente da presença do corante, pois não foram observadas diferenças significativas nas propriedades mecânicas estudadas: resistência à união, resistência coesiva, resistência flexural, módulo de elasticidade, bem como a integridade interfacial. A preparação de micro-amostras não comprometeu os resultados do ensaio de resistência adesiva. De acordo com os resultados obtidos e análise dos parâmetros: coeficiente de variação, porcentagem de padrão de fratura e incidência de falhas prematuras, concluiu-se que o teste modificado de microtração foi considerado um método confiável para a avaliação da resistência à união de sistemas adesivos. A técnica de visualização microscópica confocal produziu informações detalhadas da interface adesiva e pode ser bem indicada para a avaliação da efetividade de união de sistemas adesivos. Desta forma, é possível associar ambas as metodologias obtendo-se uma avaliação mais realista e confiável dos materiais restauradores
Abstract: The confocal laser scanning microscopic (CLSM) is a tool of visualization that allows microscopic analysis of materials or structures labeled with fluorescent dyes with minimal requirements of specimen's preparation nondestructively. The aims of this study were: to evaluate the influence of incorporation of fluorescent dye Rhodamine B (R) in the properties mechanical: cohesive strength (CS), elastic modulus (E) and flexural strength (FS) of the selfetching Clearfil SE Bond and etch-and-rinse Scotchbond Multi-Purpose (Study 1); validating the modified microtensile method using micro-specimens cross section of 0.09 mm2 (?TBS) and evaluate the influence of R in bond strength in dentin and interfacial integrity by confocal microscopy (study 2). To evaluate the influence of the dye, 0.16 mg/ml of R were incorporated into adhesives thus forming two groups for each adhesive: groups of labeled adhesives and no-labeled totaling 4 experimental groups. For the analysis of CS, E and FS the specimens were made from a silicone matrix. About the matrix were 10 ?L dispensed adhesive varying according to each group of adhesives stained or not. CS (n = 10), E and FS (n = 5) were evaluated in a universal testing machine at 0.5 mm/min until failure of the specimen. For visualization in confocal microscopy and bond strength analysis (n = 8), the adhesives were applied to the occlusal dentine surface 32 of human premolars. After procedures adhesives, composite crowns approximately (16 mm2) were built up with Charisma Opal (Kulzer - color A3). Then for testing modified microtensile, micro-specimens beam-shaped were prepared. Prior to mechanical testing micromorphological analysis of micro-sticks of the groups of labeled adhesives was performed using CLSM. Subsequently bond strength was measured using the modified microtensile test in a universal testing machine speed of 0.5 mm/min. The results showed that the behavior of the adhesive systems investigated did not change regardless of the presence of the dye, as there were no significant differences in mechanical properties studied: bond strength, tensile strength, flexural strength, modulus of elasticity, as well as interfacial integrity. The preparation of micro-specimens did not affect the results of the bond strength test. According to the analysis results and parameters: coefficient of variation percentage of fracture pattern and incidence of early failures, it is concluded that the modified microtensile test was considered a reliable method for evaluating the bond strength of adhesive systems. The confocal microscopic visualization technique yielded detailed information of the adhesive interface and can be well suited for evaluating the effectiveness of adhesive systems. Thus, it is possible to associate both methods give a more realistic and reliable adhesive restoration on the presence of fluorescent dye
Doutorado
Dentística
Doutora em Clínica Odontológica

Gli stili APA, Harvard, Vancouver, ISO e altri

19

Beaufort, Sandra. "Développement d'outils et de méthodologies pour l'étude de l'organisation et de la localisation in vivo de micro-organismes dans des structures biologiques complexes". Thesis, Toulouse, INSA, 2010. http://www.theses.fr/2010ISAT0037/document.

Testo completo

Abstract (sommario):

Ce projet concerne l’analyse de l’organisation de populations microbiennes au sein de structures complexescomme des dépôts ou des biofilms.Si différentes méthodes sont couramment utilisées pour étudier la structure globale ou l’organisation localed’agrégats microbiens, peu d’entre elles, permettent de réaliser simultanément ces deux analyses et nécessitentsouvent des étapes de préparation qui pénalisent un approche in-vivo et en dynamique.La stratégie proposée repose sur la mise en oeuvre de micro-organismes modèles autofluorescents (levures etbactéries) qui peuvent sans aucun traitement être directement observés en microscopie. La similitude ducomportement physiologique de ces micro-organismes avec celui des souches sauvages a été démontrée. Lesconditions d’acquisition des images en microscopie confocale ont été optimisées. Des dispositifs spécifiques ontété conçus pour générer des dépôts ou des biofilms dans des conditions de contraintes physico-mécaniques etbiochimiques maîtrisées afin d’analyser simultanément leurs caractéristiques et les performances du bioprocédé.Ainsi les dépôts ont pu être observés in-vivo et in-situ grâce à une cellule de filtration équipée d’une fenêtred’observation. Le développement d’un biofilm mixte composé de levures et bactéries modèles autofluorescentes,dans un réacteur continu spécifique, a également été analysé par microscopie confocale.Le traitement et les analyses des images acquises au cours des expériences ont été effectués et ont permisd‘étudier la structure globale des agrégats biologiques et l’organisation tridimensionnelle des micro-organismesdans ces structures, en mettant par exemple en évidence une répartition hétérogène de deux populationsmicrobiennes dans des dépôts de filtration ou en comparant la capacité de deux espèces microbiennes à formerdes biofilms en étudiant in-vivo la dynamique de croissance de chacune des espèces.Cette étude a en outre permis de démontrer la pertinence de la méthode proposée, de définir ses limites et sonchamp d’application
The aim of this project deals with the analysis of both the local localization and organization of microbialpopulations in complex structures such as deposits or biofilms. Different methods are currently used to study theglobal structure or the local organization of biological aggregates but only few ones allow a combined approachand require ex-vivo analyses.The proposed strategy uses home-designed model auto-fluorescent microorganisms (yeasts and bacteria) whichcan be observed directly by microscopy without any dying treatment. Same kinetic behaviours between the wildstrains and their recombinant ones were demonstrated. The confocal microscopy conditions were optimised.Specific devices were developed to generate deposits or biofilms under controlled and known hydrodynamic orbiochemical environment conditions to analyse their structure characteristics linked to the bioprocessperformances.Based on the proposed strategy, microbial deposits modifications due to pressure constraints were observed invivo in a specifically designed flow cell equipped with a microscope glass coverslip. A mixed biofilm composedby our auto-fluorescent yeasts and bacteria was carried out in a specific bioreactor allowing the sampling ofbiofilms during their development to be analysed by confocal microscopy. Both studies have shown specificorganisations between yeasts and bacteria mainly depending on their size and on the environment conditions(pressure or dilution rate).These studies of both local and global structure of biological aggregates and 3D-organisation of themicroorganisms within theses structures demonstrated the relevance of the proposed strategy defining the limitsof the method and proposing various perspectives for further characterizations and applications

Gli stili APA, Harvard, Vancouver, ISO e altri

20

Doroshenko, Mikheil [Verfasser]. "Diffusion in heterogeneous systems studied by laser scanning confocal microscopy and fluorescence correlation spectroscopy / Mikheil Doroshenko". Mainz : Universitätsbibliothek Mainz, 2014. http://d-nb.info/104870758X/34.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

21

Sirdeshmukh, Ranjani. "Biological functionalization of single-wall carbon nanotubes". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 0.97Mb, 59 p, 2005. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1428206.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

22

Vaillancourt, Benoit. "Novel biophysical appliations [sic] of STICS". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=111550.

Testo completo

Abstract (sommario):

The object of this thesis is to present two novel applications of Spatiotemporal Image Correlation Spectroscopy (STICS) to biological systems. STICS is a technique which uses the correlations in pixel intensity fluctuations of an image time series, captured under fluorescence microscopy, to measure the speed and direction of a flowing population of fluorescently labeled molecules. The method was first applied to measure the dynamics of transport vesicles inside growing pollen tubes of lily flowers. The measured vector maps allowed to confirm the presence of actin filaments along the periphery of the tubes, as well as the presence of a reverse-fountain pattern in the apical region. In a second set of experiments, STICS was used to measure the retrograde flow of filamentous actin in migrating chick DRG neuronal growth cones. These results serve as proof of principle that STICS can be used to probe the response of the growth cone cytoskeleton to external chemical cues.

Gli stili APA, Harvard, Vancouver, ISO e altri

23

Grunwald, Matthias. "Molekulare Orientierung als Kontrastmechanismus in der Fluoreszenzmikroskopie und konfokale Multidetektor-Scanning-Mikroskopie". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://hdl.handle.net/11858/00-1735-0000-0028-87C4-9.

Testo completo

Abstract (sommario):

Die vorliegende Arbeit befasst sich mit zwei neuen methodischen Ansätzen auf dem Gebiet der Fluoreszenzmikroskopie. Im ersten Teil der Arbeit wir eine Methode vorgestellt, mit der die Winkelselektivität der Fluoreszenzanregung verbessert werden kann. Die ExPAN (excitation polarization angle narrowing) genannte Technik nutzt stimulierte Emission, um den Effekt der Photoselektion zu vergrößern. ExPAN lässt sich potentiell für verschiedene Methoden einsetzen, in denen fluoreszenzmarkierte Proben untersucht werden und ist insbesondere im Kontext von Fluoreszenzanisotropie-Messungen oder der Bestimmung von molekularen Orientierungen von Interesse. Solche Methoden finden in den Biowissenschaften breite Anwendung und werden z.B. zum Studium von Rezeptor-Liganden-Interaktionen oder der Proteindynamik eingesetzt. Im Rahmen der Arbeit wird ExPAN in Kombination mit einem neuen Ansatz in der Weitfeldmikroskopie untersucht, bei der die Orientierung von Farbstoffmolekülen als Kontrastmechanismus genutzt wird. Dabei wird die Polarisationsrichtung des Anregungslichts rotiert, um Informationen über die molekulare Orientierung zu gewinnen. Aufgrund der Photoselektion weist das Fluoreszenzsignal von Molekülen mit bevorzugter Ausrichtung dadurch eine periodische Modulation auf. Es wird gezeigt, dass diese Information zur Unterscheidung von Molekülen mit abweichender Orientierung genutzt werden kann, selbst wenn sich deren Signale räumlich überlagern. Für die Versuche wurde ein modifiziertes Weitfeld-Mikroskop konstruiert und die Methode zum einen experimentell an Einzelmolekülen und zum anderen mittels Simulationen erprobt. Dabei konnten Signale von Farbstoffmolekülen mit einem Abstand von bis zu 80 nm separiert werden. Darüber hinaus wurde ein moduliertes Fluoreszenzsignal bei oberflächenmarkierten Mikropartikeln in wässriger Lösung sowie bei fixierten biologischen Proben beobachtet. Eine Verbesserung der Photoselektion durch ExPAN wird experimentell nachgewiesen und gezeigt, dass mit ExPAN auch ähnlich orientierte Moleküle unterschieden werden können. Im zweiten Teil der Arbeit wird eine Methode zur Verbesserung der Auflösung von konfokalen Laser-Scanning-Mikroskopen vorgestellt, die als Multidetektor-Scanning (MDS) bezeichnet wird und auf dem Prinzip der Image-Scanning-Mikroskopie (ISM) beruht. Mit ISM lässt sich die Auflösung von Fluoreszenzmikroskopen theoretisch verdoppeln. Da ISM einen Flächendetektor voraussetzt, wurden in der Vergangenheit hauptsächlich CCD oder CMOS Kameras als Detektoren eingesetzt. In dieser Arbeit werden anstelle einer Kamera mehrere Einzelphotonendetektoren verwendet und über ein Glasfaserbündel zu einem Flächendetektor kombiniert. Dadurch ist es erstmals möglich, die Methode in Verbindung mit Fluoreszenzlebensdauer-Mikroskopie (FLIM) einzusetzen. FLIM hat sich in den Biowissenschaften als wichtige Mikroskopie-Technik etabliert und wird unter anderem bei Protein-Protein-Interaktionsstudien oder zur Untersuchung des NADH-Metabolismus eingesetzt. Die Verbesserung der räumlichen Auflösung von FLIM mit MDS ist somit für eine Reihe von biologischen Fragestellungen von potentiellem Interesse. Im Rahmen der Arbeit wurde ein Multidetektor-Scanning-Mikroskop konstruiert und durch die Vermessung von fluoreszierenden Mikropartikeln charakterisiert. Eine Verbesserung der Auflösung durch MDS wird an fixierten biologischen Proben demonstriert. Dabei wurde eine Auflösung von 168 nm mit MDS sowie 146 nm mit MDS und Dekonvolution erreicht. Schließlich wird die Kombination der Methode mit Fluoreszenzlebensdauer-Mikroskopie demonstriert.

Gli stili APA, Harvard, Vancouver, ISO e altri

24

Gao, Yongxiang. "Direct observation of correlated motions in colloidal gels and glasses". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115677.

Testo completo

Abstract (sommario):

Dynamical heterogeneity (DH) has been observed in many systems approaching the glass or jamming transition. Whether DH has a structural origin is under heated debate. To provide a deeper understanding, in this thesis I investigate the microscopic dynamics in weakly attractive colloidal systems by confocal fluorescence microscopy. The van Hove density-density correlation function is applied to our systems. Separable fast and slow populations emerge in the self part (svH), while the distinct part shows a strong signature of DH close to the gel transition. At intermediate time, svH shows a purely exponential tail, mainly arising from the fast population. I show that this broad tail is a direct consequence of the occurrence of rare large jumps that are statistically distributed. The slow population tends to form a space-spanning backbone, and its mean squared displacement close to the gel transition exhibits a plateau, whose height is consistent with the range of attraction, suggesting a bonding mechanism for the dynamical arrest. I further examine various quantities characterizing local structure and local dynamics and a strong correlation is identified between them. Subsequently, I develop order parameters for quantifying amorphous structure and apply them to our systems. I find that attractive colloidal systems exhibit higher order under higher attraction tension, while hard spheres become more ordered under higher compression. Finally, I investigate the effect of the range of attraction on the structure and dynamics of attractive colloidal systems. I observe that the system with shorter range of attraction forms a denser and more heterogeneous structure. Meanwhile, I observe an even stronger dynamical heterogeneity. These observations provide further evidence of a connection between structural heterogeneity and dynamical heterogeneity in these systems, providing guidance for a theoretical description of the dynamical arrest as well as the relaxation mechanisms upon gelation and its relation to solidification in glasses.
In order to do all of this, I first implemented full 3D subpixel resolution localization of particles and improved particle tracking algorithms tailored for the sorts of heterogenous dynamics these systems exhibit, that otherwise confounds existing methods such that the very relaxation mechanisms would be missed. This allows us to obtain unprecedented precision in positions of all of the particles and complete tracking, both of which are essential for correctly determining system properties that depend on measured particle dynamics.

Gli stili APA, Harvard, Vancouver, ISO e altri

25

Falvo, Maurício. "Método de mapeamento espaço-espectral em imagens multi-espectrais e sua aplicação em tecidos vegetais". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-15012016-164547/.

Testo completo

Abstract (sommario):

Imagens multiespectrais são utilizadas em diferentes aplicações, que vão desde sensoriamento remoto a processos médicos. No caso de imagens multiespectrais oriundas de microscopia confocal de varredura à laser (Confocal Laser Scanning Microscopy-CLSM), a extração da informação se inicia pela conversão das assinaturas espectrais, em uma imagem RGB. Esta imagem é a referência para a seleção da região de interesse, da qual se obtém a assinatura espectral média, originada do arquivo multiespectral (LSM). Mesmo utilizando um padrão muito bem estabelecido de conversão, alguns pontos devem ser considerados: i) o processo de conversão reduz a informação, a uma ordem de 10-145%; ii) a cor é uma experiência sensorial, subjetiva e pessoal, interferindo na seleção da região de interesse e; iii) a assinatura é obtida pela média espectral, da região de interesse, selecionada manualmente.Assim, esta tese de doutorado propõem um método de mapeamento e visualização das informações de imagens multiespectrais, combinando um algoritmo de agrupamento não supervisionado(kmeans) e um algoritmo que define uma paleta de cores coerentes com a informação espectral das regiões mapeadas. Aplicou-se o método em três casos de estudos de tecidos vegetais: i) no pré-tratamento de paredes celulares da cana-de-açúcar; ii) na plasticidade foliar do Jacaranda caroba e; iii) no uso de assinaturas espectrais na classificação de plantas do Cerrado. Os resultados demonstraram que o método é bastante robusto, permitindo de forma inovadora a: visualização, análise e comparação de imagens multiespectrais qualitativa e quantitativamente, e que seu uso é viável em qualquer área de pesquisa que utilize imagens multiespectrais.
Multispectral images are used in different applications, ranging from remote sensing images to medical images. In the case of multispectral images derived from confocal laser scanning microscopy (CLSM), the extraction of information begins with the conversion of spectral signatures in an RGB image. This is the reference for selecting the region of interest, from which it gets the average spectral signature, originated from multispectral file (LSM). Even using a very well established pattern of conversion, some points should be considered: i) the conversion process reduces the information on the order of 10-145%; ii) the color is a sensory experience, subjective and personal, interfering in the selection of the interest region and; the signature is obtained by the spectral average, from interest region which is selected manually. Thus, this doctoral thesis proposes a method of mapping and visualization of multispectral imaging information, combining an unsupervised clustering algorithm (kmeans) and an algorithm that defines a consistent color palette with the spectral information of mapped regions. The proposed method was applied in three cases plant tissue studies: i) in the pre-treating the cell walls of sugarcane; ii) in the leaf plasticity of Jacaranda caroba; iii) in the use of spectral signatures in the Cerrado plant classification. The results showed that the proposed method is quite robust. It presents innovation to the visualization and analysis of multispectral images and makes possible a qualitative and quantitative comparison of a group of multispectral images. Besides that, its use is feasible in any area of research, which are using multispectral images.

Gli stili APA, Harvard, Vancouver, ISO e altri

26

Zdankowski, Piotr. "Adaptive optics stimulated emission depletion microscope for thick sample imaging". Thesis, University of Dundee, 2018. https://discovery.dundee.ac.uk/en/studentTheses/90e27151-f51c-4c12-b9dd-2bc78beb2321.

Testo completo

Abstract (sommario):

Over the past few decades, fluorescence microscopy has proven to become the most widely used imaging technique in the field of life sciences. Unfortunately, all classical optical microscopy techniques have one thing in common: their resolution is limited by the diffraction. Thankfully, due to the very strong interest, development of fluorescent microscopy techniques is very intense, with novel solutions surfacing repeatedly. The major breakthrough came with the appearance of super-resolution microscopy techniques, enabling imaging well below the diffraction barrier and opening the new era of nanoscopy. Among the fluorescent super-resolution techniques, Stimulated Emission Depletion (STED) microscopy has been particularly interesting, as it is a purely optical technique which does not require post image processing. STED microscopy has proven to resolve structures down to the molecular resolution. However, super-resolution microscopy is not a cure to all the problems and it also has its limits. What has shown to be particularly challenging, was the super-resolution imaging of thick samples. With increased thickness of biological structures, the aberrations increase and signal-to-noise (SNR) decreases. This becomes even more evident in the super-resolution imaging, as the nanoscopic techniques are especially sensitive to aberrations and low SNR. The aim of this work is to propose and develop a 3D STED microscope that can successfully image thick biological samples with nanoscopic resolution. In order to achieve that, adaptive optics (AO) has been employed for correcting the aberrations, using the indirect wavefront sensing approach. This thesis presents a custom built 3D STED microscope with the AO correction and the resulting images of thick samples with resolution beyond diffraction barrier. The developed STED microscope achieved the resolution of 60nm in lateral and 160nm in axial direction. What is more, it enabled super-resolution imaging of thick, aberrating samples. HeLa, RPE-1 cells and dopaminergic neuron differentiated from human IPS cells were imaged using the microscope. The results shown in this thesis present 3D STED imaging of thick biological samples and, what is particularly worth to highlight, 3D STED imaging at the 80μm depth, where the excitation and depletion beams have to propagate through the thick layer of tissue. 3D STED images at such depth has not been reported up to date.

Gli stili APA, Harvard, Vancouver, ISO e altri

27

Makhlouf, Houssine. "Integrated Multi-Spectral Fluorescence Confocal Microendoscope and Spectral-Domain Optical Coherence Tomography Imaging System for Tissue Screening". Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202761.

Testo completo

Abstract (sommario):

A multi-modality imaging system intended for clinical utilization has been developed. It is constructed around an existing fiber-bundle-based fluorescence confocal microendoscope. Additional imaging modalities have been implemented to expand the capabilities of the system and improve the accuracy of disease diagnosis. A multi-spectral mode of operation is one such modality. It acquires fluorescence images of a biological sample across a spectral range of sensitivity and explores the collected image data at any specified wavelength within that spectral range. Cellular structures can be differentiated according to their spectral properties. The relative distribution and concentration of the different cellular structures can potentially provide useful pathologic information about the imaged tissue. A spectral-domain optical coherence tomography (SDOCT) modality is another imaging technique integrated into the system. It provides a cross-sectional imaging perspective that is comparable to microscopic images obtained from histology slides and complementary to the en face view obtained from the confocal imaging modality. The imaging system uses a parallelized architecture (fiber-optic bundle, line of illumination) to increase the data acquisition speed. A one-dimensional scan is needed to capture 2D images in the confocal modality or a 3D data cube (two spatial dimensions and one spectral dimension) in the multi-spectral mode of operation. No scanning is required to capture a 2D OCT image. The fiber-bundle design is particularly critical for the SDOCT modality as it paves the way to novel fast endoscopic OCT imaging that has a high potential for translation into the clinic. The integrated multi-modality imaging system can readily switch between different imaging modalities, which will make it a powerful diagnostic tool in a clinical environment. It can provide valuable information about the morphology, the spectral and biochemical features, and the macroscopic architecture of tissue. It is believed that fast and accurate disease diagnosis can potentially be made based on all these characteristics.

Gli stili APA, Harvard, Vancouver, ISO e altri

28

Junior, Odair Bim. "Estratégias para adição de rodamina B em sistemas adesivos". Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/25/25148/tde-14082013-102351/.

Testo completo

Abstract (sommario):

A rodamina B e outros marcadores fluorescentes vêm sendo empregados na avaliação morfológica da interface de adesão com o auxílio de microscopia confocal de varredura a laser. Acrescentando-se rodamina B a sistemas adesivos, é possível observar as características de espessura da camada de adesivo, micromorfologia da camada híbrida, extensão e quantidade de tags, bem como diagnosticar defeitos ou alterações na interface de adesão. A literatura revela, entretanto, uma falta de precedentes sobre as quantidades de marcadores nos componentes resinosos. Além disso, ainda não se avaliou o efeito da concentração de rodamina B sobre a qualidade da análise da interface de adesão, bem como sobre o comportamento fotofísico dos marcadores nos sistemas adesivos. Este estudo foi realizado com o propósito de sistematizar um método de adição de rodamina B a sistemas adesivos, incluindo-se estratégias para a determinação de concentrações mínimas de rodamina nos componentes resinosos, porém, ainda viáveis para a realização da análise morfológica da interface de adesão através de microscopia confocal de varredura a laser. Para tal, os sistemas adesivos não simplificados e considerados padrão-ouro em suas categorias Adper™ Scotchbond™ Multi-Purpose (convencional de três passos) e Clearfil™ SE Bond (auto-condicionante de dois passos) foram modificados com rodamina B em cinco diferentes concentrações: C1 (0,5 mg/mL), C2 (0,10 mg/mL), C3 (0,02 mg/mL), C4 (0,004 mg/mL) e C5 (0,0008mg/mL) e o comportamento fluorescente da rodamina nos adesivos foi avaliado tanto no âmbito espectroscópico (espectroscopia de fotoluminescência), como no âmbito microscópico (microscopia confocal de varredura a laser). Para a modificação dos adesivos, utilizou-se uma técnica precisa de proporcionamento na qual o marcador fluorescente foi incorporado às resinas fluidas a partir de soluções de rodamina B em etanol. Os espectros de fluorescência mostraram diferenças nos máximos das bandas de emissão e de excitação, de acordo com as concentrações de rodamina B em cada material dispersante. A análise microscópica dos espécimes em dentina confirmou que é possível utilizar sistemas adesivos contendo rodamina B em concentrações muitas vezes menores do que as mencionadas na literatura. Ambos os sistemas avaliados puderam ser visualizados, microscopicamente, quando marcados com rodamina B nas três concentrações pré-selecionadas para a avaliação da interface de adesão: C2 (0,10 mg/mL), C3 (0,02 mg/mL) e C4 (0,004 mg/mL), sendo que C3 forneceu os melhores resultados em relação ao contraste e à saturação nas fotomicrografias. Concluiu-se que o comportamento fotofísico da rodamina B é influenciado tanto pela concentração, como pelo sistema adesivo no qual o marcador está dissolvido. A concentração de rodamina B também interfere na qualidade da análise morfológica da interface de adesão, sendo que o excesso do marcador pode dificultar a distinção de detalhes micromorfológicos.
Rhodamine B and other fluorescent markers have been used for the assessment of the bonding interface via confocal laser scanning microscopy. By adding rhodamine into adhesive systems, it is possible to study morphological characteristics of the hybrid layer, the extent and amount of resin tags and the adhesive layer thickness, as well as detecting potential defects or alterations at bonding interface. Meantime the literature reveals lack of standards among the quantities of fluorescent markers in resin-based polymers. The effects of rhodamine B concentration on the quality of the microscopic analysis, as well as on the photophysics of labeled adhesive systems were not assessed up to now. This study aimed to systematize methodologies for adding rhodamine B into adhesive systems, including suitable strategies for determining the minimum serviceable rhodamine concentrations to perform the morphological analysis of the bonding interface. Two non-simplified adhesive system considered gold standard categories Adper™ Scotchbond™ Multi-Purpose (3 steps conventional) and Clearfil™ SE Bond (2 steps self-etching) were modified with rhodamine B at five concentrations: C1 (0.5 mg/ml), C2 (0.10 mg/ml), C3 (0.02 mg/ml), C4 (0.004 mg/ml) and C5 (0.0008 mg/ml ) and the fluorescent behavior of the labeled resins was assessed both by photoluminescence spectroscopy and by confocal laser microscopy The preparation of the labeled resins was proceed by means of a precise proportioning technique in which the fluorescent marker was incorporated into the bonding agents from solutions of rhodamine B in ethanol. The fluorescence spectra showed differences in the intensity and wavelength fluorescence according to the rhodamine B concentration. Microscopic analysis of the dentin specimens confirmed adhesive systems can be modified with rhodamine B at far lower concentrations than those mentioned in the literature. Both evaluated systems were microscopically visualized while labeled with Rhodamine B at three pre-selected concentrations: C2 (0.10 mg/mL), C3 (0.02 mg/ml) and C4 (0.004 mg/ml), and C3 offered the best outcome with respect to contrast and saturation in photomicrographs. It was concluded that the photophysical behavior of rhodamine B depends on both the concentration and labeled adhesive system. The rhodamine B concentration also interferes with the quality of morphological analysis of the bonding interface, and the excess of the fluorescent marker may jeopardize the discrimination of morphological details.

Gli stili APA, Harvard, Vancouver, ISO e altri

29

King, Mathias. "Development of new bioorthogonal ligation reactions". Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAF021.

Testo completo

Abstract (sommario):

Le principal objectif de cette thèse a consisté au développement d’une méthode de screenning pour la découverte de nouvelles réactions de ligations bioorthogonales ainsi que son application sur une bibliothèque développée pour cette étude. Par conséquent, un système de screening a été conçu en trois étapes consistant au départ en une analyse HPLC, puis une évaluation basée sur la fluorescence de haute résolution et finalement un test de microscopie confocal in cellulo. Puis, nous avons standardisé toutes les analyses avec les réactions CuAAC et SpAAC. En outre, nous avons synthétisés 18 réactifs d’intérêts et effectué un screening de 58 expériences de ligation avec une évaluation par méthode HPLC. Parmi les 9 réponses positives obtenues figure 6 réactions impliquant de nouveaux réactifs et les analyses LC‐MS ont pu tous les valider comme des réactions de cycloaddition directe à l’exception d’une réaction. Finalement, nous avons pu appliquer la méthode in cellulo développée, afin d’évaluer la pertinence des réactions de chélation CuAAC pour une application sur cellules
The main goal of this thesis was the development of a screening method for the discovery of new bioorthogonal ligation reactions as well as its application on a self‐designed library. Therefore we designed a three step screening system consisting of a preliminary HPLC assay, a high resolution fluorescence based assay and a final in cellulo confocal microscopy assay.Subsequently we standardized all assays with the highly established CuAAC and SpAAC. Furthermore, we successfully synthesized 18 reagents of interest and screened 58 ligation experiments with the help of the HPLC setup. The 9 positive hits from this screening contained 6 reactions involving novel reagents and LCMS analysis was able to validate all but one as straight forward cycloaddition reaction. Finally we were able to apply the newly developed in cellulo assay to assess the suitability of chelating CuAAC for in cell application

Gli stili APA, Harvard, Vancouver, ISO e altri

30

Jones, Christopher Wynne. "Laser scanning confocal arthroscopy in orthopaedics : examination of chondrial and connective tissues, quantification of chondrocyte morphology, investigation of matirx-induced autologous chondrocyte implantation and characterisation of osteoarthritis". University of Western Australia. School of Mechanical Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0061.

Testo completo

Abstract (sommario):

[Truncated abstract] Articular cartilage (AC) covers the surface of synovial joints providing a nearly frictionless bearing surface and distributing mechanical load. Joint trauma can damage the articular surface causing pain, loss of mobility and deformation. Currently there is no uniform treatment protocol for managing focal cartilage defects, with most treatment options targeted towards symptomatic relief but not limiting the progression into osteoarthritis (OA). Autologous chondrocyte implantation (ACI) and more recently matrix-induced autologous chondrocyte implantation (MACI), have emerged as promising methods for producing hyaline or hyaline-like repair tissue, however there remains some controversy regarding the exact histological nature of the tissue formed. Histological characterisation of AC repairs requires destructive tissue biopsy potentially inducing further joint pathology thereby negating the treatment effect. OA is recognised as a major cause of pain, loss of function and disability in Western populations, however the exact aetiology is yet to be elucidated. The assessment of both OA and cartilage repair has been limited to macroscopic observation, radiography, magnetic resonance imaging (MRI) or destructive biopsy. The development of non-destructive AC assessment modalities will facilitate further development of AC repair techniques and enable early monitoring of OA changes in both experimental animal models and clinical subjects. Confocal laser scanning microscopy (CLSM) is a type of fluorescence microscopy that generates high-resolution three-dimensional images from relatively thick sections of tissue. ... Biomechanical analysis suggested that the mechanical properties of MACI tissue remain inferior for at least three months. This study showed the potential of a multi-site sheep model of articular cartilage defect repair and validated its assessment via LSCA. Finally, the LSCA was used to arthroscopically image the cartilage of an intact fresh frozen cadaveric knee from a patient with clinically diagnosed OA. Images were correlated to ICRS (Outerbridge) Grades I-IV and histology. The LSCA gave excellent visualization of cell morphology and cell density to a depth of up to 200'm. Classical OA changes including clustering chondrocytes, surface fibrillation and fissure formation were imaged. Fair to moderate agreement was demonstrated with statistically significant correlations between all modalities. This study confirmed the viability of the LSCA for non-destructive imaging of the microstructure of the OA cartilage. In conclusion, the LSCA identified histological features of orthopaedic tissues, accurately quantified chondrocyte morphology and demonstrated classical OA changes. While the development and investigation of an ovine model of cartilage repair showed the treatment benefit of MACI, some biomechanical issues remain. Ultimately, the LSCA has been demonstrated as a reliable nondestructive imaging modality capable of providing optical histology without the need for mechanical biopsy. Medical Subject Headings (MESH): articular cartilage; autologous chondrocyte implantation; matrix-induced autologous chondrocyte implantation; biomechanics; cartilage; confocal microscopy; diagnosis; histology; image analysis; immunohistochemistry; magnetic resonance imaging; microscopy; osteoarthritis

Gli stili APA, Harvard, Vancouver, ISO e altri

31

Reitan, Nina Kristine. "Methods for studying critical barriers to the delivery of nanomedicine : The potential of fluorescence correlation spectroscopy, confocal microscopy and MRI". Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-5760.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

32

Schumacher, William Charles. "Development of Novel Fluorescence-Based Methods for Detection of Bacillus Anthracis Spores". The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1222046829.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

33

Wenzel, Margot. "Synthèse de complexes organobimétalliques à activité biologique". Thesis, Dijon, 2013. http://www.theses.fr/2013DIJOS089.

Testo completo

Abstract (sommario):

Un axe de recherche particulièrement développé en chimie organométallique moderneconcerne la recherche d’agents chimiothérapeutiques alternatifs au cisplatine dans lestraitements contre le cancer. Dans ce domaine, plusieurs stratégies ont été développées depuisplusieurs dizaines d’années, parmi lesquelles nous pouvons citer la multinucléarité, consistanten la création d’édifices polymétalliques. L’objectif de la première partie de ce manuscrits’inscrit dans cette thématique, par la conception, l’obtention et l’étude des propriétésbiologiques de complexes hétérobimétalliques "early-late" (Ti-Ru, Ti-Au, Ti-Pt, Ti-Os, Ti-Rh, Ti-Ir) et "late-late" (Pt-Au). Un deuxième concept développé au cours de ce manuscritconsiste en la génération de nouvelles espèces théranostiques, par association au sein d’unmême complexe d’un fragment métallique à activité thérapeutique et d’une sonde fluorescentepermettant de visualiser le trajet et les cibles biologiques de ce premier. Dans ce cadre, deuxséries parallèles de complexes bimétalliques ont été synthétisées à partir des squelettesRu(bipy)32+ et Ru(bipy)2(dipy)2+ dont les propriétés de luminescence ont été largementdécrites et utilisées pour diverses applications. Ces composés bimétalliques ont pu fairel’objet de mesures sur les deux fronts, à savoir leur activité cytotoxique envers des lignéescellulaires cancéreuses et leurs propriétés photophysiques
A research theme especially developed in modern organometallic chemistry deals withnew chemotherapeutic agents as alternatives to cisplatin for the treatments against cancer. Inthis area, several strategies have been considered since decades, among which one can citemultinuclearity, meaning the creation of polymetallic structures. The objective of the first partof this manuscript deals with this theme, with the design, synthesis and study of the biologicalproperties of "early-late" hetero-bimetallic complexes (Ti-Ru, Ti-Au, Ti-Pt, Ti-Os, Ti-Rh, Ti-Ir) and "late-late" (Pt-Au). A second concept developed in this thesis consists in thegeneration of new theranostic agents by association inside a same unit of a metal fragmentwith therapeutic activity, and of a fluorescent probe allowing the visualization of thebiological targets. In this field, two parallel series of bimetallic compounds have beenobtained based on the skeletons Ru(bipy)32+ and Ru(bipy)2(dipy)2+, whose luminescenceproperties have been widely described and used for several applications. These bimetalliccomplexes have been tested both for their cytotoxic activity against cancer cells lines andtheir photophysical properties

Gli stili APA, Harvard, Vancouver, ISO e altri

34

Romano, Renan Arnon. "Aumento da eficácia da inativação fotodinâmica pela incorporação de fotossensibilizador induzida por luz em Candida Albicans". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-21102016-103320/.

Testo completo

Abstract (sommario):

Devido à grande preocupação com a geração de novas tecnologias mais ágeis, eficientes e de baixo custo, as reações fotodinâmicas (RF) têm ganhado destaque. Estas envolvem a ativação de um fármaco fotossensível (fotossensibilizador (FS)), pela iluminação em uma faixa específica de comprimentos de onda, gerando assim espécies reativas altamente citotóxicas levando as células à morte. As RF são divididas em duas categorias: terapia fotodinâmica (TFD) e inativação fotodinâmica (IFD). A primeira é utilizada para tratamentos oncológicos, dermatológicos, entre outros. A segunda é utilizada para descontaminação de micro-organismos em infecções localizadas. Atualmente a IFD tem sido alvo de muitos estudos pois tem diversas vantagens quando comparadas com as técnicas de descontaminação atuais. Duas das mais importantes são: a seletividade e a não geração de micro-organismos resistentes aos FSs. Apesar desta técnica ser utilizada com sucesso em diversos campos, ela ainda apresenta baixa eficiência quando comparada às técnicas tradicionais. Neste contexto, o objetivo deste trabalho foi criar um novo protocolo de aplicação da IFD visando o aumento de eficiência, bem como um estudo profundo das interações dos FSs com as células, e o monitoramento da dinâmica do FS nestas. O presente estudo utiliza-se de células da levedura Candida albicans e demonstra a interação destas células com dois FSs: Photogem® e Curcumina. Foi proposto um novo protocolo que promove o aumento da internalização de FS pelas células baseado na pré-iluminação de baixa dose durante o tempo de incubação. Foi possível demonstrar através da medida dos espectros de absorção do sobrenadante de uma solução com células e Photogem®, que as amostras que tiveram pré-iluminação internalizaram mais FS do meio do que as células mantidas no escuro. Além disso, a partir de ensaios de viabilidade com a levedura e o Photogem® foi demonstrado que as amostras que tiveram pré-iluminação apresentaram diminuição de até seis ordens de grandeza nas unidades formadoras de colônia quando comparadas com as amostras tratadas pelo protocolo tradicional de IFD. Através das técnicas de microscopia confocal de fluorescência e de imagem de tempo de vida de fluorescência foi possível compreender a interação entre os FSs e as células, bem como estudar a ligação deste FS em diferentes regiões da célula. Além disso, foi estudada ainda a mobilidade destas moléculas dentro das células sob condições com e sem iluminação de baixa dose. Através deste estudo pôde-se inferir que as moléculas de curcumina tem tempos característicos de entrada nas células mais lentos que os tempos característicos do Photogem®. Ainda foi possível tomar vantagem da fluorescência do Photogem® para monitorar a entrada deste nas células de levedura, bem como monitorar a formação do seu fotoproduto, determinando assim que 7,5 minutos é o tempo médio de iluminação durante a incubação com FS necessário para que pelo menos 80% das células tivessem o FS internalizado, sem significante formação de fotoprodutos. Conclui-se ainda que este novo protocolo de incubação com iluminação leva a maior eficiência e seletividade da IFD, abrindo caminho para uma nova linha de pesquisa nas RF em geral, possivelmente podendo este protocolo ser aplicado em diversos tipos de células.
In the last years, due to the increasing need of generation of novel faster and cheaper technologies, the photodynamic reactions (PR) have been highlighted. These reactions involves the activation of a photosensitive drug, named photosensitizer (PS), by light in proper spectral window and generation of highly cytotoxic reactive species, leading cells to death. The photodynamic reactions may be divided in two categories: photodynamic therapy (PDT) and photodynamic inactivation (PDI). The first one is performed in order to treat oncologic, dermatologic and other diseases, whereas the second one is employed in the decontamination of microorganisms in localized infections. When compared with existing decontamination techniques, PDI has several advantages, among which two of the most important are its selectivity of the PS that acts only at the delivered site, as well as not inducing antibiotic resistance, for such reasons are subjected of many current studies. Althought this technique has been performed with great success in many fields, it still has a lack of efficiency. In this context, the purpose of this study was create a new application protocol of this technique in order to increase the efficiency, as well as understand the interactions of the PS with the cells and monitoring the drug dynamic in cells. In this study, Candida albicans cells were utilized and the interaction of two PSs (Photogem® and Curcumin) were demonstrated. A new protocol which promotes an increase of the PS cells uptake was proposed, this protocol is based on the low dose illumination during the incubation time. By measuring absorption spectra of the supernatant of two solutions with cells and Photogem®, in which in one of them were applied a low dose light, was demonstrated that the illuminated cells had an uptake increased when compared with the sample kept in the dark. Moreover, viability assays with the Photogem® and the cells proved that the cells that receive low dose light in the incubation stage had more damage in the PDI, showing a decrease of six orders of magnitude when compared with the traditional PDI. Through confocal and lifetime fluorescence microscopy techniques it was possible not only to comprehend the interaction between the PS and cells, as well as to study the binding of this molecules in different regions of the cells. Furthermore, the mobility of the PS molecules inside the cells was studied in conditions of illumination and dark, it could be inferred that the curcumin molecules has higher characteristic time than Photogem® molecules. Monitoring the cell Photogem® uptake, and the photoproduct formation was possible by take advantage of the PS fluorescence. Thus it was possible to determine the average illumination time (7.5 minutes) during the incubation time so at least 80% of the cells had the PS internalized, without much generation of photoproducts. It follows also that this new incubation protocol with low dose illumination leads to greater efficiency of PDI, so this study leads a new field of research in overall photodynamic reaction.

Gli stili APA, Harvard, Vancouver, ISO e altri

35

Sadler, Emma Elizabeth. "Single-molecule fluorescence studies of KirBac1.1". Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:214fcd74-7384-4ade-ac17-7cac5c44a05c.

Testo completo

Abstract (sommario):

Inwardly rectifying potassium (Kir) channels are essential for controlling the excitability of eukaryotic cells, forming a key part of the inter-cellular signalling system in multi-cellular organisms. However, as prokaryotic (KirBac) channels are less technically challenging to study in vitro and have been shown to be directly homologous to eukaryotic channels, they are often studied in lieu of their mammalian counterparts. A vital feature of Kir and KirBac channels is their mechanism for opening and closing, or their gating: this study predominantly features observations of open and/or closed channel populations. A well-characterised member of the KirBac family, KirBac1.1, has been successfully expressed, purified into detergent micelles, and doubly labelled with fluorescent maleimide dyes in order to enable observation of confocal-in-solution Förster Resonance Energy Transfer (FRET) at the single molecule level. Results demonstrate single-molecule FRET signals from KirBac1.1 and therefore represent the first single-molecule FRET observations from a KirBac channel. Perturbation of the open-closed dynamic equilibrium was performed via activatory point mutations, changes in pH, and ligand binding. A protocol for reconstitution into nanodiscs was optimised in order to more closely approximate native conditions, and the single-molecule FRET observations repeated. This thesis presents a comparison between measurements made using the detergent solubilisation system and those made using nanodiscs.

Gli stili APA, Harvard, Vancouver, ISO e altri

36

Ying, Jia. "Structural Change and Its Assessment by Fluorescence Spectroscopy in Functional Polymers". 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/192187.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

37

Garcia, Pérez José Antonio. "Microscopies Optiques et Spectroscopies de Matériaux Épais : Mesures et Simulations Appliquées à des Photosensibilisateurs de l'Oxygène Singulet en Matrice de Silice". Thesis, Pau, 2013. http://www.theses.fr/2013PAUU3015/document.

Testo completo

Abstract (sommario):

Ce travail présente une étude, par microscopie optique et de fluorescence, de matériaux hybrides, basés sur des monolithes de silice contenant des dérivés du cyano-anthracène : 9,10-dicyano-anthracène (DCA) ou 9,14-dicyano-benzo(b)triphénylène (DBTP), qui sont des photo-sensibilisateurs de l'oxygène singulet. Alors que ces matériaux sont bien caractérisés du point de vue de la photo-oxydation des sulfures sous des conditions hétérogènes par des études macroscopiques, certaines propriétés concernant l'association du photosensibilisateur avec l'absorbant peuvent être masquées, dominées ou encore mal interprétées par uniquement des mesures d'ensemble. Ici, nous combinons la spectroscopie d'ensemble et la microscopie optique et de fluorescence, et développons des protocôles expérimentaux concernant des échantillons solides épais, dans le but d'étudier la distribution spatiale et la mobilité des photosensiblisateurs dans la matrice hôte ainsi que d'analyser les interactions entre ces deux entités. La microscopie optique montre dans tous les cas des inhomogénéités localisées à l'interface du monolithe et attribuées à la formation de bulles pendant la synthèse et une accumulation locale du DBTP. A partir de simulations Monte-Carlo de lancer de rayons, nous développons un protocôle pour corriger les artéfacts de réfraction dans les profils d'intensité de fluorescence en fonction de la profondeur, obtenus par des mesures confocales, pour déterminer la distribution axiale du photosensibilisateur ce qui permet de mettre en évidence une nette augmentation de la concentration en photosensibilisateurs dans les premiers 50—100 m dessous la surface. L'analyse FRAP montre la très lente mobilité de tous les photosensibilisateurs et un retour partiel de l'intensité ce qui signifie que les photosensibilisateurs se trouvent dans des régions compartimentées, probablement dues à des contraintes aléatoires du réseau de pores. De plus, l'analyse FLIM montrent des propriétés photo physiques semblables pour le DBTP inclus et greffé ce qui permet d'envisager l'inefficacité de la fonctionnalisation. Ces observations soulignent que les monolithes à base de silice sont des systèmes hors d'équilibre et correspondent à un instantané des inhomogénéités gelées pendant les derniers instants du processus de condensation-hydrolyse des monomères de silice. Enfin, corréler la spectroscopie classique avec nos observations confocales sur différentes formes de DBTP, nous permet d'établir que la bande d'émission de fluorescence non-structurée et fortement déplacée vers le rouge est probablement due à la formation d'excimères
This work presents an optical and fluorescence microscopy study of hybrid materials based on porous silica monoliths containing derivatives of cyano-anthracene: 9,10-dicyano-anthracene (DCA) or 9,14-dicyano-benzo(b)triphenylene (DBTP), photo-sensitizers of singlet oxygen. While these materials are well known from bulk studies for the efficient photo-oxidation of sulphides under heterogeneous conditions, some characteristics of the association of the photo-sensitizer and the absorbent may be masked, overlooked or otherwise misinterpreted by bulk investigations alone. Here, we combine classical bulk spectroscopy with optical and fluorescence microscopy, and develop experimental protocols for thick solid state samples, to study the spatial distribution and the mobility of the guest in the host matrix, and analyse guest-host interactions. Optical microscopy shows in all cases localised inhomogeneities at monolith interface, ascribed to bubble formation during synthesis; wide-field fluorescence microscopy shows that these features are associated with local accumulation of the larger, more hydrophobic of the two photo-sensitizers, DBTP. Photo-sensitizer lateral distribution at the monolith interface is otherwise homogeneous. Based on Monte Carlo ray-tracing simulations, we develop a protocol for correcting refraction artefacts in measured confocal fluorescence depth profiles, to obtain the photo-sensitizer axial distribution. While it in general exhibits a sharp increase in concentration in the first 50—100 m below the surface compared to the bulk, this layer contributes negligibly to the total content of the monoliths. FRAP analysis shows mobility of the photo-sensitizers in all cases, but with diffusion constants implying months or years to equilibrate the centimetre-sized monoliths. Classical bulk and confocal spectroscopy with FLIM analysis show similar photo-physical properties of DBTP included and grafted. The main effects of funcionalization in this photo-sensitizer are to slow down diffusion and to counter its aggregation. Incomplete FRAP recovery implies photo-sensitizer mobility is compartmented, probably due to random constrictions in the pore network. These observations underline that silica-based monoliths are non-equilibrium systems encapsulating a snapshot of any homogeneities frozen in during the later stages of hydrolysis-condensation of silicate units. Correlating classical bulk spectroscopy with our confocal observations on the different DBTP forms, conclude that its unusual structureless, red-shifted emission is probably due to excimer emission

Gli stili APA, Harvard, Vancouver, ISO e altri

38

Barsan, Cristina Ioana. "Caractérisation du chromoplaste de tomate par approche protéomique". Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0046/document.

Testo completo

Abstract (sommario):

La maturation des fruits est un processus complexe, principalement régulé par l'hormone végétal éthylène, qui entraîne d'importants changements métaboliques et physiologiques, ayant pour résultat la dispersion des graines. Le changement le plus visible qui se produit pendant la maturation des fruits est le changement de couleur. L'organite responsable de ce phénomène est le chromoplaste, lieu d’accumulation des caroténoïdes. Toutefois, ce n'est pas son unique rôle. Il a été montré qu’il est aussi impliqué dans la biosynthèse des lipides, de l’amidon, des vitamines et des arômes. Parce que la plupart des protéines (95%) qui composent le protéome du chromoplaste sont codées par le noyau, l’approche génomique n'est pas suffisante pour connaître les fonctions de chromoplaste dans la synthèse des métabolites d'intérêt. La protéomique de haut débit associée à la bio- nformatique a été utilisée pour caractériser le chromoplaste de tomate. L’analyse du protéome de chromoplastes de fruits de tomate rouges a révélé la présence de 988 protéines correspondantes à 802 unigènes d’Arabidopsis, dont 209 n’ont pas été répertoriés jusqu'à présent dans des banques de données plastidiales. Ces données ont révélé plusieurs caractéristiques du chromoplaste. Les protéines du métabolisme des lipides et de trafic sont bien représentées, y compris toutes les protéines de la voie de la lipoxygénase nécessaire à la synthèse des arômes volatiles dérivés de lipides. Les protéines impliquées dans la synthèse de l'amidon coexistent avec plusieurs protéines qui dégradent l'amidon. Les chromoplastes ne contiennent plus les protéines de biosynthèse de la chlorophylle mais contiennent des protéines impliquées dans la dégradation de la chlorophylle. Aucun des protéines impliquées dans le mécanisme de transport thylacoïdal n’ont été trouvées. Étonnamment, les chromoplastes contiennent l'ensemble des protéines du cycle de Calvin, y compris la Rubisco, ainsi que la voie des pentoses phosphates (OxPPP). L'analyse de l'évolution du transcriptome des gènes codant pour des protéines chromoplastiques a été réalisée. Ces données ont confirmé la réduction de la photosynthèse et le maintien du cycle de Calvin, ainsi que la biosynthèse de l'amidon et des lipides. Des analyses biochimiques complémentaires ont montré dans des chromoplastes isolés la présence d’une activité de deux enzymes importantes dans la biosynthèse des arômes (lipoxygénase et l'alcool déshydrogénase). Par ailleurs, à l’aide du couplage de protéines à la GFP et à leur expression dans des protoplastes, nous avons montré que des protéines ne présentant pas de peptide signal peuvent être localisées dans le chromoplaste. Enfin, un protocole d'isolement des plastes de fruits de tomate à différents stades de maturation a été mis au point et les fractions plastidiales ainsi obtenues ont été caractérisées par la microscopie confocale à balayage laser. La transition du chloroplaste à chromoplaste est un processus qui n'a jamais été décrit par la protéomique. Ce travail est en cours et devrait répondre à certaines questions concernant les changements qui ont lieu dans l'organite, et apporter des informations nouvelles pour la compréhension de la maturation des fruits
Fruit ripening is a complex process, mainly regulated by the fruit hormone ethylene, resulting in significant metabolic and physiological changes, having as outcome seed dispersal. The most flagrant change taking place during ripening is the change in color. The organelle responsible for this is the chromoplast, the place of carotenoids accumulation. However this is not its unique role. It was found to be involved in lipid, starch, vitamins and aroma biosynthesis. Due to the fact that most proteins (95%) composing the chromoplast are codified by the nucleus knowledge on gene expression and genome sequences is not useful in the investigation of the functions of chromoplast in the synthesis of the metabolites of interest. High- hroughput proteomics associated with bio-informatics was used to characterize the tomato chromoplast and to reveal its intimate structure. Analysis of the proteome of red fruit chromoplasts revealed the presence of 988 proteins corresponding to 802 Arabidopsis unigenes, among which 209 had not been listed so far in plastidial data banks. These data revealed several features of the chromoplast. Proteins of lipid metabolism and trafficking were well represented, including all the proteins of the lipoxygenase pathway required for the synthesis of lipid-derived aroma volatiles. Proteins involved in starch synthesis co- xisted with several starch-degrading proteins and starch excess proteins. Chromoplasts lacked proteins of the chlorophyll biosynthesis branch and contained proteins involved in chlorophyll degradation. None of the proteins involved in the thylakoid transport machinery were discovered. Surprisingly, chromoplasts contain the entire set of Calvin cycle proteins including Rubisco, as well as the oxidative pentose phosphate pathway (OxPPP). The analysis of the evolution of the transcriptome of chromoplastic protein-encoding genes was performed. This data confirmed the reduction of the photosynthesis and the maintenance of the Calvin cycle, and of the lipid and starch biosynthesis. Further analysis is performed showing the activity of two important actors in the aroma biosynthesis (lipoxygenase and alcohol dehydrogenase). Several proteins with possible chromoplastic location were coupled with the GFP and expressed in the single cell system. A protocol for isolating tomato fruit chloroplasts and immature chromoplasts was described along with the characterization of the plastidial fractions by confocal microscopy. The transition of the chloroplast to chromoplast is a process that was never described by means of proteomics. This work answers some questions regarding the changes that take place in the organelle, and brings novel information for the understanding of fruit ripening process

Gli stili APA, Harvard, Vancouver, ISO e altri

39

Wang, Huan. "Multiphotonic study of a new NADPH-derivative compound targeting NO-synthase". Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2013. http://tel.archives-ouvertes.fr/tel-00958076.

Testo completo

Abstract (sommario):

Dans cette étude, nous avons développé un composé dérivé du NADPH, nommé Nanoshutter (NS). NS a été conçu pour inhiber l'activité catalytique de la NOS, c'est à dire la synthèse de NO, en occupant la place du NADPH dans le domaine réductase du NOS. La voie de synthèse de NO chez les mammifère correspond à l'oxydation de la L-arginine catalysée par la NOS, qui se produit dans son domaine oxygénase. Basée sur des données de modélisation moléculaire, la structure de NS est composée deux sous-unités: (i) le motif nucléotidique de reconnaissance du NADPH a été retenu, permettant au composé NS un ciblage approprié du site de liaison au NADPH de la NOS, (ii) le motif nicotinamide de NADPH a été remplacé par un groupe stilbène lié à un groupement terminal accepteur d'électrons. De plus, ce fragment est caractérisé par une très bonne section efficace d'absorption à deux photons (130 GM à 840 nm). NS1, le composé prototype de la famille NS, contient un groupe terminal NO2 en tant que groupe accepteur d'électrons. La valeur de Kd (~ 4,2 µM) a été estimée dans des expériences de titrage sous excitation un- ou deux-photons, et suggère une bonne affinité de liaison de NS1 à la NOS. De façon inattendue, NS1 présente une bonne sélectivité, en terme de rendement quantique de fluorescence, pour les isoformes de NOS par rapport à d'autres protéines qui contiennent ou non un site de liaison NADPH. En outre, il a été montré que NS1 inhibait de façon compétitive NOS par rapport au NADPH. Dans les expériences d'imagerie de fluorescence réalisées sur des cellules endothéliales (HUVEC), NS1 a démontré une internalisation rapide et efficace, avec un signal de fluorescence mis en évidence principalement dans la région périnucléaire, accompagné d'un signal plus sporadique à la membrane plasmique. Cette observation est en parfait accord avec la colocalisation de NS1 et eNOS mesurée par immunomarquage, démontrant ainsi que NS1 cible eNOS dans les cellules endothéliales. La vasoconstriction NO-dépendante attendue dans les anneaux aortiques isolés de souris a été montrée, mais uniquement en présence de catalase qui convertit H2O2 en H2O et O2. En revanche, en l'absence de catalase, la vasorelaxation a plutôt été observée. Ce résultat indique que la NOS n'est très certainement pas l'unique cible de NS1 dans le système endothélial, et que d'autres cibles en rapport avec la modulation de ROS (Reactive Oxygen Species) sont impliquées. En accord avec ce résultat, NS1 provoque une réponse biphasique de la production de ROS dans les cellules HUVEC : Une phase d'augmentation est observée aux faibles concentrations de NS1 (en dessous de 2 µM), suivie d'une diminution (inhibition de ROS) pour des concentrations de NS1 plus élevées. En outre, NS1 inhibe la production de O2- dans les macrophages de souris et les productions de H2O2 et de O2- survenant dans des conditions de découplage de nNOS in vitro. Des explications possibles pour interpréter ces données sont: NS1 probablement inhibe la production de ROS, soit produites au niveau de la NADPH oxydase ou (et) au cours du découplage de la NOS. L'origine de la phase d'augmentation reste plus difficile à interpréter, mais pourrait correspondre au ciblage de la glucose-6-phosphate deshydrogénase. Enfin, NS1 exerce un effet anti -angiogénique sur les cellules endothéliales et empêche la prolifération de cellules du mélanome. En conclusion, NS1 rempli l'objectif principal de cibler et inhiber la NOS en ciblant plus particulièrement le domaine réductase - il est aussi caractérisé par des propriétés d'absorption et de fluorescence à deux photons intéressantes permettant des applications in vitro et in vivo. L'ensemble de ces caractéristiques présentent un profil intéressant pour de futures applications d'imagerie en temps réel et non-invasive, avec également un fort potentiel pour des applications cliniques liées aux maladies NO-dépendantes.

Gli stili APA, Harvard, Vancouver, ISO e altri

40

Larsson, Mina. "Application of Raman and Fluorescence Spectroscopy to Single Chromatographic Beads". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5741.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

41

Chimenez, Tiago Andrade. "Estudos de sistemas poliméricos naturais e sintéticos utilizando técnicas avançadas de microscopia". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-26072016-152852/.

Testo completo

Abstract (sommario):

O bagaço de cana-de-açúcar é um abundante coproduto obtido a partir da produção convencional de etanol. No entanto, o bagaço vem se mostrando como uma importante fonte para a produção de etanol de segunda geração. No primeiro capítulo da tese é apresentado um estudo referente à distribuição espacial dos compostos na matriz de bagaço de cana-de-açúcar. A investigação foi realizada utilizando microscopia de fluorescência confocal e espectroscopia por excitação com um e dois fótons. Imagens de autofluorescência em combinação com as medidas de fluorescência e tempos de vida forneceram uma gama de informações necessárias para a caracterização de amostras de bagaço. Além disso, a técnica permite o acompanhamento de processos relacionados com a remoção de lignina. A nanocelulose cristalina (NCC) é um material promissor devido as suas propriedades intrínsecas, tais como seu formato alongado, medindo de 1 a 100 nm de diâmetro e seu comprimento variando de algumas dezenas a centenas de nanômetros. No capítulo 2, a nanocelulose cristalina foi obtida através da hidrólise da celulose cristalina (de Avicel®) com ácido sulfúrico. Em seguida, o material foi caracterizado por técnicas de microscopia SEM e TEM, confirmando a morfologia em forma de haste e a estrutura de tamanho nanométrico. A microscopia de campo largo convencional foi utilizada como ferramenta na caracterização da NCC dispersa em soluções poliméricas de PVA e PVP. A última parte do capítulo 2 descreve a caracterização de estruturas de NCC usando a microscopia de super-resolução de fluorescência STED (depleção de emissão estimulada). As imagens mostraram uma resolução de até 50 nm, permitindo a comparação com resultados de TEM e AFM. No capítulo 3, a nanocelulose cristalina foi covalentemente marcada com o corante ATTO-532, através da chamada reação \"click\". As propriedades relacionadas com o coeficiente de difusão da NCC foram determinadas por espectroscopia de correlação de fluorescência (FCS). Em uma etapa posterior, a NCC foi colocada em diferentes soluções do polímero PEG, contendo quantidades diferentes. As propriedades dinâmicas foram analisadas por métodos de FCS e WFM. O uso de técnicas de espectroscopia e microscopia revelou detalhes relacionados à heterogeneidade das dispersões de NCC, as quais estão relacionadas com as propriedades hidrofílicas e hidrofóbicas das soluções poliméricas.
The sugarcane bagasse is an abundant co-product obtained from the conventional production of ethanol. However, sugarcane bagasse has been proving to be an important source to the production of second-generation ethanol. In the first chapter, the spatial distribution of compounds in the sugarcane bagasse matrix was investigated by confocal fluorescence microscopy and spectroscopy with one and two-photon excitation. Autofluorescence images in combination to spectral emission and lifetime measurements provided a tool for the characterization of natural bagasse samples. Moreover, the technique allows the following of processes related to the lignin removal. Nanocrystalline cellulose (NCC) is a promisor material because of its properties, such as rod-shape with 1-100 nm in diameter, and tens to hundreds of nanometres in length. In the Chapter 2, NCC was obtained via sulphuric acid hydrolysis from Avicel®. Afterwards, the material was characterized by classic electronic microscopy SEM and TEM, confirming the rod-shaped morphology and the nano-sized structure. Conventional wide field microscopy was used as fluorescence microscopy tool in the characterization of NCC, when dispersed in polymeric solutions of PVA and PVP. The last part of the chapter 2 describes the characterization of NCC structures by using the super-resolution fluorescence microscopy STED (Stimulated Emission Depletion). The STED images showed a resolution down to 50 nm, allowing the comparison with TEM and AFM microscopy results. In the Chapter 3, the NCC was covalently labelled, by a click-chemistry reaction, with the ATTO-532 dye. Properties related to diffusion coefficient of NCC were determined by Fluorescence Correlation Spectroscopy (FCS) method. Afterwards, NCC was placed into a solution of PEG, containing different amounts polymer. The dynamic properties were evaluated by FCS and WFM methods. The use of spectroscopy and microscopy imaging techniques revealed heterogeneity details of NCC dispersions, which are related to the hydrophilic and hydrophobic properties of the polymer solution. A better understanding of polymer systems is achieved by investigation of diffusion properties, that allows the comprehension of rheological parameters, and, consequently, in polymer processing and assembly of plastics, films, and fibres. In the Chapter 4 is presented a study where fluorescence correlation spectroscopy (FCS) and wide-field fluorescence microscopy (WFM) were used to follow changes in the diffusion coefficients of growing polymer chains, during the controlled radical polymerization process. Linear and star-shaped polystyrene were grown via nitroxide-mediated polymerization (NMP) from alkoxyamine-based initiators containing a highly fluorescent perylene diimide moiety. This study demonstrates that direct investigation of heterogeneity emerging during a controlled radical polymerization process by means of fluorescence of single-molecule chain initiator allows unravelling information related to the diffusion processes of the growing polymer chain.

Gli stili APA, Harvard, Vancouver, ISO e altri

42

Fujita, Alessandra Keiko Lima. "Avaliação do efeito fotodinâmico a partir da associação dos precursores da PPIX (ALA e MAL) em epitélio suíno". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-03102016-160420/.

Testo completo

Abstract (sommario):

A terapia fotodinâmica (TFD) utilizando ácido 5-aminolevulinico (ALA) e derivados em aplicação tópica e, como precursor da protoporfirina IX (PPIX) apresenta alguns limitantes relativos a baixa permeação das substâncias na pele. Comportamento este que afeta a produção e homogeneidade da distribuição da PPIX na superfície e camadas mais profundas da pele. Para resolver essa limitação muitos autores propõem alternativas modificando a molécula do ALA e derivados, bem como modificando as propriedades químicas da fase externa da emulsão (mais hidrofílica ou hidrofóbica) ou então o sistema de entrega para a emulsão. O objetivo desse estudo é avaliar qual a proporção de ALA e metil-5-aminolevulinato (MAL) que quando misturados levam ao aumento da quantidade e uniformidade da formação da PPIX na superfície e em profundidade na pele. Para esse estudo foi realizada análises de fluorescência e histologia. O estudo foi conduzido in vivo e ex vivo usando biópsias de pele de porco cultivadas in vitro. A produção de PPIX foi monitorada utilizando espectroscopia de fluorescência, imagem de fluorescência de campo amplo e microscopia confocal de fluorescência. E para a aplicação da TFD os parâmetros usados foram de 125 mW/cm2 de intensidade e 150 J/cm2 de dose. A análise do dano causado pela irradiação foi realizada por meio de histologia da pele após 24 e 48 horas da aplicação da TFD. O ALA e MAL na concentração de 20% foram misturados nas seguintes proporções: ALA ou M, M2 (80% ALA - 20% MAL), M3 (60% ALA 40% MAL), M4 (50% ALA MAL), M5 (40% ALA 60% MAL), M6 (20% ALA 80% MAL) e MAL como M7. As diferentes proporções foram incorporadas em emulsões óleo em água (O/A) e água em óleo (A/O). De acordo com os resultados, as misturas M3, M4 e M5 mostraram maior produção de PPIX na superfície da pele segundo as medidas de fluorescência em 3h de incubação e, no estudo da cinética mostraram produzir PPIX em menor tempo. No estudo de permeação do creme in vitro em pele ex vivo, por microscopia confocal de fluorescência, observou-se que as misturas M3, M4 e M5 produziram mais PPIX nas camadas da pele do que ALA e MAL. As análises histológicas das misturas apresentaram maior dano fotodinâmico na superfície e profundidade das camadas da pele após a TFD, independente da emulsão. A análise em até 48h observou-se predominantemente a fase do processo de reparo referente à fase inflamatória, mas existem indícios ao longo das análises tanto macroscópicas e histológicas que o processo de reparo referente as fases subsequentes de proliferação e remodelamento estão iniciando-se em paralelo. A mistura M4 em ambas as emulsões apresentou elevada quantidade de formação de PPIX em menor tempo de incubação. M4 em emulsão O/A apresentou menor dano fotodinâmico já que a evolução do processo reparo foi mais rápida sugerindo-se potencial de aplicação em TFD voltado para área cosmética-estética. Já M4 em emulsão A/O levou a um maior dano fotodinâmico já que a evolução do processo de reparo foi mais lenta sugerindo-se potencial de aplicação em TFD voltado para área oncológica e de doenças de pele. De modo geral o estudo proposto apresentou impacto positivo para a otimização da terapia fotodinâmica em aplicação tópica.
Photodynamic therapy (PDT) using 5-aminolevulinic acid and derivatives on topical application and as a precursor of protoporphyrin (PPIX) has some limitations for low permeation of substances into the skin. This behavior affects PPIX production and homogeneous distribution on the surface and deeper layers of the skin. To resolve this limitation, many authors propose alternatives such as modifying the molecule of ALA and its derivatives, as well as changing the chemical properties of the external phase of the emulsion (more hydrophilic or hydrophobic) or the delivery system to the emulsion. The aim of this study is to assess the proportion of ALA and methyl-5-aminolevulinate (MAL) that when mixed leads to an increase in the amount and uniformity of the PPIX formation on surface and deep skin. For this study we performed fluorescence analysis and histology. The studies were conducted in vivo and also using pig skin biopsies (ex vivo) cultured in vitro. The PPIX production was monitored using fluorescence spectroscopy, widefield fluorescence imaging, and fluorescence confocal microscopy. For the application of PDT an intensity of 125 mW/cm2 and a dose 150 J/cm2 were used. Analysis of the damage caused by irradiation was performed through skin histology after 24 and 48 hours after PDT application. ALA and MAL in concentration of 20% were mixed in the following proportions: ALA or M, M2 (80% ALA - 20% MAL), M3 (60% ALA - 40% MAL), M4 (50% ALA - MAL) M5 (40% ALA - 60% MAL), M6 (20% ALA - 80% MAL) MAL and as M7. Different proportions were incorporated in oil-in-water emulsions (O/W) and water-in-oil (W/O). The fluorescence measurements for 3h of incubation showed better PPIX production in the skin surface for mixtures M3, M4 and M5. Moreover, the kinetics study showed PPIX production in less time for these mixtures. In the study of cream permeation of ex vivo skin in vitro by confocal fluorescence microscopy, we observed that the mixtures M3, M4 and M5 produced more PPIX in the skin layers than ALA and MAL. The histological analyses of the mixtures showed higher photodynamic damage on the surface and deeper layers of the skin after PDT, independent of the emulsion. The analysis in 48 hours predominantly observed the phase of the healing process regarding the inflammatory phase but there are signs along both macroscopic and histological analysis that the healing process concerning the subsequent stages of proliferation and remodeling are initiating in parallel. The mixture M4 in both emulsions had high amounts of PPIX formation in shorter incubation time. M4 emulsion O/A showed a lower photodynamic damage since the evolution of the healing process was faster suggesting to potential application in PDT facing cosmetic-aesthetic area. M4 already in W/O emulsion led to a greater photodynamic damage since the evolution of the healing process was slower suggesting to potential application in PDT facing oncology and skin diseases. Overall the proposed study had a positive impact on the optimization of photodynamic therapy for topical application.

Gli stili APA, Harvard, Vancouver, ISO e altri

43

Walter, Vivien. "Lipid membrane interaction with self-assembling cell-penetrating peptides". Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE032/document.

Testo completo

Abstract (sommario):

Les peptides pénétrateurs de cellule (CPP) sont des oligopeptides cationiques faisant parti des vecteurs les plus étudiés dans le cadre du développement du transport ciblé de médicament à l’intérieur de l’organisme. Les applications principales sont par exemple le traitement des cancers ou la thérapie génique. Néanmoins, certaines caractéristiques des CPPs rendent leur utilisation médicale compliquée, tels que leur manque de spécificité à l’égard des cellules cibles ou la perte de leurs propriétés pénétrantes lorsqu’un cargo moléculaire leur est greffé. L’une des solutions envisagées pour résoudre ces problèmes est le greffage sur des polypeptides di-blocs auto-assemblés basés sur de l’élastine (ELPBC), des systèmes développés par l’équipe d’Ashutosh Chilkoti à l’Université de Duke (USA). Des travaux précédents ont montré que ces macromolécules, que l’on appelle CPP-ELPBC, retrouvaient les propriétés pénétrantes du CPP même en présence d’un cargo et permettaient également d’induire une spécificité à l’encontre des cellules cancéreuses. En revanche, le mécanisme de pénétration de ces systèmes restait inconnu.Dans cette thèse, je me suis concentré sur l’étude du mécanisme de pénétration des CPP et des CPP-ELPBC au travers de membranes lipidiques modèles, et en particulier sur l’adsorption de ces molécules à la surface de vésicules unilamellaires géantes (GUV). Le développement d’une nouvelle méthode de quantification de la fluorescence en microscopie confocale m’a permis de réaliser des mesures simples de comptage de peptides à la surface des vésicules, ce qui m’a permis par la suite de procéder à des mesures thermodynamiques de l’adsorption des peptides
Cell-penetrating peptides (CPP) are cationic oligopeptides currently investigated as potential vectors for targeted drug delivery design, for applications in cancer treatment and/or gene therapy. Nevertheless, some drawbacks make the CPP complex for medical applications, such as their lack of specificity toward target cells or the loss of their penetrating properties once they have been grafted with a molecular cargo. One of the solutions studied to overcome these issues is the binding of the CPP unit on a self-assembling elastin-like diblock polypeptide (ELPBC), a macromolecular system designed by the team of Ashutosh Chilkoti from Duke University (USA). While it has already been proven that these molecules, named CPP-ELPBC, recover the penetrating properties of the CPP despite the presence of a cargo and also induce a selectivity toward tumorous cells, the exact mechanism of translocation is still under debate.In this PhD thesis, I focused on the investigation of the translocation mechanism of the CPP and CPP-ELPBC using model lipid membranes, and specifically the adsorption of these molecules at the surface of giant unilamellar vesicles (GUV). The development of a new quantification method of fluorescence in confocal microscopy allowed me to directly count the peptides adsorbed on the surface of the GUVs, which I used to perform thermodynamic measurements on the peptide adsorption

Gli stili APA, Harvard, Vancouver, ISO e altri

44

Torella, Joseph Peter. "Confocal single-molecule fluorescence as a tool for investigating biomolecular dynamics in vitro and in vivo". Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:f57d1984-8db9-4d79-b333-f1be507ca3bf.

Testo completo

Abstract (sommario):

Confocal single-molecule fluorescence is a powerful tool for monitoring conformational dynamics, and has provided new insight into the enzymatic activities of complex biological molecules such as DNA and RNA polymerases. Though useful, such studies are typically qualitative in nature, and performed almost exclusively in highly purified, in vitro settings. In this work, I focus on improving the methodology of confocal single-molecule fluorescence in two broad ways: (i) by enabling the quantitative identification of molecular dynamics in proteins and nucleic acids in vitro, and (ii) developing the tools needed to perform these analyses in vivo. Toward the first goal, and together with several colleagues, I have developed three novel methods for the quantitative identification of dynamics in biomolecules: (i) Burst Variance Analysis (BVA), which unambiguously identifies dynamics in single-molecule FRET experiments; (ii) Dynamic Probability Density Analysis (PDA), which hypothesis-tests specific kinetic models against smFRET data and extracts rate information; and (iii) a novel molecular counting method useful for studying single-molecule thermodynamics. We validated these methods against Monte Carlo simulations and experimental DNA controls, and demonstrated their practical application in vitro by analyzing the “fingers-closing” conformational change in E.coli DNA Polymerase I; these studies identified unexpected conformational flexibility which may be important to the fidelity of DNA synthesis. To enable similar studies in the context of a living cell, we generated a nuclease-resistant DNA analogue of the Green Fluorescent Protein, or “Green Fluorescent DNA,” and developed an electroporation method to efficiently transfer it into the cytoplasm of E.coli. We demonstrate in vivo confocal detection of smFRET from this construct, which is both bright and photostable in the cellular milieu. In combination with PDA, BVA and our novel molecular counting method, this Green Fluorescent DNA should enable the characterization of DNA and protein-DNA dynamics in living cells, at the single-molecule level. I conclude by discussing the ways in which these methods may be useful in investigating the dynamics of processes such as transcription, translation and recombination, both in vitro and in vivo.

Gli stili APA, Harvard, Vancouver, ISO e altri

45

Kao, Min-Tzu. "Nano-rubans et cristaux anisotropes d’anthracènes et tétracènes à émission accordable : étude de la photophysique et des transferts d’énergie par microscopie confocale de fluorescence". Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14647/document.

Testo completo

Abstract (sommario):

De nouveaux nano-objets anisotropes fluorescents sont obtenus par l’assemblage d’acènes spécifiquement conçus. Dans des cristaux, nano-rubans et nanoparticules anisotropes de 2,3-dialkyldiphenylanthracènes, les efficacités et la polarisation de l’émission bleue sont remarquables. La couleur de l’émission est accordée par le dopage avec des émetteurs verts et oranges (di- et tétra-phényltétracènes). La microscopie confocale de fluorescence permet d’étudier les cinétiques des états excités et des transferts d’énergie photo-induits, ainsi que la dispersion et les orientations des émetteurs. Pour la première fois, l’influence de la largeur de nano-rubans sur la cinétique d’annihilations triplet-triplet de tétracènes est mise en évidence. La microscopie révèle également le polymorphisme inhabituel d’un dérivé diéthynylphényl-anthracène. Ce travail ouvre des perspectives pour le développement et l’étude de processus fondamentaux de nano-matériaux luminescents
New fluorescent anisotropic nano-objects are obtained by the assembly of specifically designed acenes. In crystals, nano-ribbons and anisotropic nanoparticles of 2,3-dialkyldiphenylanthracenes, the efficiencies and the polarization of the blue emission is remarkable. The color of the emission is tuned by doping with green and orange emitters (di-and tetra-phenyltetracenes). Confocal fluorescence microscopy is used to study the kinetics of excited states and photo-induced energy transfers, as well as the dispersion and orientation of the emitters. For the first time, the influence of the width of the nano-ribbons on the kinetics of tetracene triplet-triplet annihilations is highlighted. Microscopy also reveals the unusual polymorphism of a diethynylphenyl anthracene derivative. This work opens perspectives for the development and study of fundamental processes of luminescent nano-materials

Gli stili APA, Harvard, Vancouver, ISO e altri

46

Bridier, Arnaud. "Architecture des biofilms et résistance à la désinfection : apport de l'imagerie de fluorescence multimodale". Phd thesis, AgroParisTech, 2011. http://pastel.archives-ouvertes.fr/pastel-01002653.

Testo completo

Abstract (sommario):

Dans les environnements naturels, industriels ou médicaux, les microorganismes sont majoritairement présents en étant associés aux surfaces dans des communautés hautement organisées appelées biofilms. Ces édifices biologiques constituent une stratégie de survie étonnement efficace témoignant d'une grande capacité de résistance à différent stress environnementaux tels que les traitements de nettoyage et de désinfection. L'impact des biofilms d'un point de vue sanitaire est donc considérable du fait qu'ils permettent la persistance et la transmission de germes pathogènes dans l'environnement. Dans ce contexte, ce travail de thèse avait pour objectif une meilleure compréhension des phénomènes limitant l'efficacité de désinfectants au sein des biofilms en s'appuyant notamment sur des techniques innovantes d'imagerie de fluorescence non-invasive. Le but final étant d'apporter des éléments utiles à l'optimisation des traitements de désinfection. Dans une première partie, une méthode d'investigation structurale à haut-débit par microscopie confocale a été développée et utilisée pour étudier la diversité architecturale des biofilms bactériens formés par un large panel de souches. Cette étude nous a permis d'identifier des souches d'intérêt en termes de structures de biofilms formés pour la suite du travail. Nous avons notamment pu mettre en évidence la capacité de B. subtilis à former des structures importantes et avec une architecture spécifique dans un système immergé. Dans une deuxième partie, les dynamiques d'action spatiotemporelles de désinfectants ont été visualisées dans les biofilms de souches de P. aeruginosa ou B. subtilis par des approches de microscopie confocale de fluorescence en temps réel. L'utilisation de cette technique nous a permis de mettre en évidence les difficultés de pénétration du chlorure de benzalkonium au sein des structures formées par différentes souches de P. aeruginosa. La corrélation des paramètres cinétiques d'inactivation et des données obtenues par la caractérisation biochimique de la matrice suggère un rôle majeur des substances extracellulaires dans la limitation de pénétraton du désinfectant. Nous avons également pu montrer une résistance marquée du biofilm formé par une souche de B. subtilis isolée d'un dispositif médical à l'acide péracétique, à la concentration et au temps d'utilisation du biocide dans le milieu médical. De plus, les structures tridimensionnelles formées par cette souche étaient capables de protéger le pathogène Staphylococcus aureus dans un biofilm mixte vis-à-vis du même traitement soulignant l'importance des interactions multi-espèces dans la résistance des bactéries aux désinfectants et la persistance de pathogènes dans nos environnements.

Gli stili APA, Harvard, Vancouver, ISO e altri

47

Zuo, Li. "Molecular Mechanisms of Stress-induced Reactive Oxygen Species Formation in Skeletal Muscle". The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1038853894.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

48

Solař, Jan. "Hodnocení migrace značených buněk v tkáni". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-241961.

Testo completo

Abstract (sommario):

This diploma thesis deals with analysing of modern methods for cell detection, visualization and quantification in 3D space. The first section deals with optical methods for cells detection. There is detailed discussion about cell labeling and detection on confocal microscopy. There is also description about developed algorithm for whole cell volume quantification from microscopy images. This could made a comparsion of fluorescence signal according to time of cell labeling and according to cell shapes. There was also optimalization of handmade tissue phantoms visualization. It could be compared a possibilities of cell detections in these phantoms by confocal microscopy and OCT. It was also implemented algorithm for quantification of cells from OCT images. Besides confocal microscopy and OCT cells are also analyzed by other methods. The last part is the Conclusion of results and comparison of used methods.

Gli stili APA, Harvard, Vancouver, ISO e altri

49

Do, Le Duy. "Relation entre l’annexine A6 et la phospholipase D1 pendant le processus d’exocytose dans les cellules PC12". Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10160/document.

Testo completo

Abstract (sommario):

L'exocytose régulée, est un processus qui permet la communication entre les cellules à travers la sécrétion des hormones et des neurotransmetteurs. Dans les neurones et les cellules neuroendocrines, l'exocytose est strictement contrôlée par des signaux extracellulaires tels que le potentiel trans-membranaire et la fixation des ligands sur des récepteurs. Des progrès substantiels ont été effectués afin de comprendre le mécanisme moléculaire de l'exocytose. Les composants majeurs de la machinerie de sécrétion ont été dévoilés. Maintenant, la question qui émerge concerne le rôle de la plateforme de protéines qui semble avoir une action coordonnée entre chaque protéine. Dans le cas de la famille des annexines, qui est bien connue pour son action dans l'exocytose, leurs modes d'interactions séquentielles ou concertées avec d'autres protéines ainsi que leurs effets régulateurs sur l'exocytose ne sont pas encore bien établis. Des résultats précédents indiquent que l'Annexine A6 (AnxA6) affecte l'homéostasie du calcium et la sécrétion de la dopamine à partir des cellules PC12, utilisées comme un modèle cellulaire de neurosécrétion (Podszywalow Bartnicka et al., 2010). Afin de déterminer l'effet inhibiteur de l'AnxA6 sur l'exocytose de la dopamine, nous cherchons des partenaires moléculaires de l'AnxA6 dans les cellules PC12. Nous faisons l'hypothèse que l'AnxA6 interagit avec la PLD1, une enzyme active dans l'étape de la fusion des vésicules avec la membrane plasmique. En utilisant la microscopie confocale et la microscopie à onde évanescente, nous avons trouvé que l'isoforme 1 de l'AnxA6 et la PLD1 sont tous les deux recrutés sur la surface des vésicules au cours de la stimulation des cellules PC12. AnxA6 inhibait l'activité de la PLD comme indiqué par notre méthode d'analyse enzymatique au moyen de la spectroscopie infrarouge. En conclusion, nous proposons que l'AnxA6 n'est pas seulement impliquée dans la réorganisation des membranes par ses capacités à se lier avec des phospholipides négativement chargés et avec le cholestérol, mais elle influence également l'activité de la PLD1, changeant la composition lipidique des membranes
The regulated exocytosis is a key process allowing cell-cell communication through the release of hormone and neurotransmitters. In neurons and neuroendocrine cells, it is strictly controlled by extracellular signal such as transmembrane potential and ligand bindings to receptors. Substantial progress has been made to understand the molecular mechanism of exocytosis. Major components of secretory machinery have been brought to light. Now the emergent question concerns the role of scaffolding proteins that are thought to coordinate the action of each other. In the case of annexin family well known to be involved in exocytosis, their modes of –sequential or concerted- interactions with other proteins, and their regulatory effects on exocytosis are not very well established. Previous findings indicated that Annexin A6 (AnxA6) affected calcium homeostasis and dopamine secretion from PC12 cells, used as cellular model of neurosecretion (Podszywalow-Bartnicka et al., 2010). To determine the inhibitory effect of AnxA6 on exocytosis of dopamine, we were looking for molecular partners of AnxA6 in PC12 cells. We hypothesized that AnxA6 interacts with phospholipase D1 (PLD1), an enzyme involved in the fusion step. By using confocal microscopy and total internal reflection fluorescence microscopy, we found that isoform 1 of AnxA6 and Phospholipase D1 are both recruited on the surface of vesicles upon stimulation of PC12 cells. AnxA6 inhibited phospholipase D activity as revealed by our enzymatic assay based on infrared spectroscopy. To conclude, we propose that AnxA6 is not only implicated in membrane organization by its capacity to bind to negative charged phospholipids and to cholesterol, but AnxA6 is also affecting PLD1 activity, changing membrane lipids composition

Gli stili APA, Harvard, Vancouver, ISO e altri

50

Travascio, Francesco. "Modeling Molecular Transport and Binding Interactions in Intervertebral Disc". Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_dissertations/322.

Testo completo

Abstract (sommario):

Low back pain represents a significant concern in the United States, with 70% of individuals experiencing symptoms at some point in their lifetime. Although the specific cause of low back pain remains unclear, symptoms have been strongly associated with degeneration of the intervertebral disc. Insufficient nutritional supply to the disc is believed to be a major mechanism for tissue degeneration. Understanding nutrients' transport in intervertebral disc is crucial to elucidate the mechanisms of disc degeneration, and to develop strategies for tissue repair (in vivo), and tissue engineering (in vitro). Transport in intervertebral disc is complex and involves a series of electromechanical, chemical and biological coupled events. Despite of the large amount of studies performed in the past, transport phenomena in the disc are still poorly understood. This is partly due to the limited number of available experimental techniques for investigating transport properties, and the paucity of theoretical or numerical methods for systematically predicting the mechanisms of solute transport in intervertebral disc. In this dissertation, a theoretical and experimental approach was taken in order to investigate the mechanisms of solute transport and binding interactions in intervertebral disc. New imaging techniques were developed for the experimental determination of diffusive and binding parameters in biological tissues. The techniques are based on the principle of fluorescence recovery after photobleaching, and allow the determination of the anisotropic diffusion tensor, and the rates of binding and unbinding of a solute to the extracellular matrix of a biological tissue. When applied to the characterization of transport properties of intervertebral disc, these methods allowed the establishment of a relationship between solute anisotropic and inhomogeneous diffusivity and the unique morphology of human lumbar annulus fibrosus. A mixture theory for charged hydrated soft tissues was presented as a framework for theoretical investigations on solute transport and binding interactions in cartilaginous tissues. Based on this theoretical framework and on experimental observations, a finite element model was developed to predict solute diffusive-convective-reactive transport in cartilaginous tissues. The numerical model was applied to simulate the effect of mechanical loading on solute transport and binding interactions in cartilage explants and intervertebral disc.

Gli stili APA, Harvard, Vancouver, ISO e altri

Tesi sul tema "Confocal fluorescence microscopy"

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili