Combined transmission, dark field and fluorescence microscopy for intact, 3D tissue analysis of biopsies

SIGNIFICANCE: Currently, tissue biopsies are sectioned into 3- to 5-μm-thick slices that are used for conventional pathology analysis. Previous work by confocal microscopy and light-sheet microscopy has shown that analyzing biopsies intact in three-dimensions (3D) is possible and may lead to a better understanding of cancer growth patterns. Although accurate, these methods require fluorescent staining of the tissue, in addition to tissue clearing. If the 3D biopsy analysis could be done sufficiently swiftly, this approach may be used for on-site assessment of the adequacy of a biopsy taken. AIM: We aim to show that, by transmission microscopy of optically cleared tissue punches, the tissue architecture can be determined without the need for fluorescent staining. APPROACH: Transmission microscopy is used by combining bright field microscopy with dark field and epifluorescent microscopy to compare samples that have also been analyzed by fluorescent confocal microscopy. RESULTS: With increasing distance to the focal plane, the higher-frequency part of the spatial frequency spectrum of transmitted light is attenuated increasingly. This property is exploited for tissue segmentation, detecting whether tissue is present at a certain position in the focal plane image. Using this approach, we show that a 3D rendering of the internal cavity or tubules structure of punch biopsies, which are up to 1-mm thick, can be acquired in ≈1 min scan time per imaging modality. The images of the overall tissue architecture that are obtained are similar to those from the confocal microscopy benchmark, without requiring fluorescent staining. CONCLUSIONS: Images of the overall tissue architecture can be obtained from transmission microcopy; they are similar to those from the confocal microscopy benchmark without requiring fluorescent staining. Tissue clearing is still needed. The total scan time of the present method is significantly shorter at a fraction of the device costs

Manipulation of molecular structures with magnetic fields

Contains fulltext : 19255.pdf (publisher's version ) (Open Access)The present thesis deals with the use of magnetic fields as a handle to manipulate matter at a molecular level and as a tool to probe molecular properties or inter molecular interactions. The work consists of in situ optical studies of (polymer) liquid crystals and molecular aggregates in high magnetic fields up to 20T, together with a description of the methods and set-ups developed and the theoretical interpretations of the obtained results. Chapter 2 gives a general treatment of the magnetic field induced orientation mechanism and shows how this effect can be described in the frame of the Boltzman Statistics. More specifically, the Liquid Crystals, Polymer Liquid Crystals and Molecular Aggregates systems are studied in the presence of magnetic fields. The chapter continues with a presentation of the set-ups developed and used for the purpose of this thesis and it ends with a section of data analysis methods. Chapter 3 describes the magnetic field induced alignment of Side Chain Polymer Liquid Crystals and the particular role of the mesogen/backbone coupling in this phenomenon. Chapter 4 focuses on the Isotropic-Nematic phase transition of Side Chain Polymer Liquid Crystals in magnetic fields, an example of nonlinear physical phenomena: the magnetic field produces an energetic effect much larger that the direct energy it introduces into the system. Chapter 5 presents a study of thin Liquid Crystals cells in magnetic fields, discussing the effect of magnetic field on the surface anchoring and presents the first direct observation of a surface Isotropic-Nematic transition. Finally, Chapter 6 deals with Molecular Aggregates solutions in the presence of magnetic fields; a combined study of magnetic field induced orientation and system characterization116 p

Magnetic-field-induced changes of the isotropic-nematic transition in side-chain polymer liquid crystals

Contains fulltext : 115677.pdf (publisher's version ) (Open Access)4 p

Alignment of molecular materials in high magnetic fields

Contains fulltext : 60193.pdf (publisher's version ) (Closed access)The potential of using high magnetic fields to align functional molecular materials is discussed, illustrated by magnetic orientation of two different types of materials. Alignment of side chain polymer liquid crystals leads to macroscopically ordered, transparant and strongly birefringent material. The alignment process strongly depends on the chemical structure of the material and can be used to determine the strength of the coupling between the polymer backbone and the liquid-crystalline units. Alignment of cyanine dye J-aggregates results in material exhibiting strongly polarized optical properties, from which the internal molecular arrangement of the aggregates can be inferred. (C) 2004 Elsevier B.V. All rights reserved

Alignment of Phthalocyanine molecular aggregates by magnetic fields

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Magnetic fields as an investigation technique and manipulation tool for phthalocyanine molecular aggregates

Contains fulltext : 57109.pdf (publisher's version ) (Closed access)A polarized absorption spectroscopy (PAS) study of molecular aggregate solutions of phthalocyanine molecules in high magnetic fields is presented. We show that a magnetic field can induce macroscopic ordering of molecular aggregates (MAs), in a clean, non-contact method, which is well suited for MA manipulation. We also demonstrate that magnetic-field-induced alignment in combination with PAS can be used to determine the MA size and the precise position of the absorption lines in concentrated solutions, as well as probe interaggregate interactions

Side chain polymer liquid crystals in high magnetic fields

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Magnetic field induced alignment of cyanine dye J-aggregates

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