1. 1-9 of 9
    1. In-Situ Optical Coherence Tomography (OCT) for the Time-Resolved Investigation of Crystallization Processes in Polymers

      In-Situ Optical Coherence Tomography (OCT) for the Time-Resolved Investigation of Crystallization Processes in Polymers

      Optical coherence tomography (OCT) is a low-coherence interferometric imaging method which was developed in the 1990s prevalently in the area of biomedical diagnostics. (1) It generates depth scans of samples in a contact-free, nondestructive manner. Having become a standard method for ophthalmologic examinations, (2, 3) within the past decade also applications outside the medical field were found, as summarized in a recent review (4) and with a special focus put on polymer science: in contrast to biological tissues, polymers usually do not contain water and therefore also light in the near-infrared (NIR) region, which otherwise would be absorbed, can be ...

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    2. Cross-Sectional Tracking of Particle Motion in Evaporating Drops: Flow Fields and Interfacial Accumulation

      Cross-Sectional Tracking of Particle Motion in Evaporating Drops: Flow Fields and Interfacial Accumulation

      The lack of an effective technique for three-dimensional flow visualization has limited the experimental exploration of the “coffee ring effect” to the two dimensional, top-down viewpoint. In this report, high-speed, cross-sectional imaging of the flow fields was obtained by using optical coherence tomography to track particle motion in an evaporating colloidal water drop. This approach enables z-dimensional mapping of primary and secondary flow fields and changes in these fields over time. These sectional images show that 1μm diameter polystyrene particles have a highly non-uniform vertical distribution with particles accumulating at both the air-water interface and water-glass interface during drop ...

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    3. Near-Field Spectroscopy of Broadband Emissions from γ-Al2O3 Nanocrystals in Cr-Doped Double-Clad Fibers

      Near-Field Spectroscopy of Broadband Emissions from γ-Al2O3 Nanocrystals in Cr-Doped Double-Clad Fibers
      Embedded nanocrystals (NCs) of γ-Al2O3 in SiO2 matrixes of Cr-doped double-clad fibers (CDFs) were fabricated by the codrawing laser-heated pedestal growth technique. The spatially resolved broadband emissions of these NCs were examined as a function of NC morphology and distribution by near-field scanning optical microscopy. Comparison of the measured emissions with crystal-field ligands together with careful examination of the NC morphologies by high-resolution transmission electron microscopy confirmed this broadband emission as being an effect of nanotwinning and the Cr3+–Cr6+ redox reaction. The impact of nanotwinning on the relative strength and emission wavelength of Cr3+ and Cr6+ is potentially beneficial ...
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    4. Three-Dimensional High-Resolution Imaging of Gold Nanorods Uptake in Sentinel Lymph Nodes

      Three-Dimensional High-Resolution Imaging of Gold Nanorods Uptake in Sentinel Lymph Nodes
      n this paper, we demonstrate an application of a noninvasive imaging modality, photothermal optical coherence tomography (PT-OCT), for imaging gold nanorods (GNRs) uptake in sentinel lymph node (SLN) of mice in situ. This application enables us to obtain higher quality images of SLN structures due to the photothermal contrast properties of the GNRs. It is also demonstrated that GNRs accumulate differently within several SLN structures, and this uptake is time dependent. Finally, we determine the average concentration of GNRs within the whole SLN which is used to demonstrate uptake kinetics of the nanoparticles.
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    5. Theranostic Nanoshells: From Probe Design to Imaging and Treatment of Cancer

      Theranostic Nanoshells: From Probe Design to Imaging and Treatment of Cancer
      Recent advances in nanoscience and biomedicine have expanded our ability to design and construct multifunctional nanoparticles that combine targeting, therapeutic, and diagnostic functions within a single nanoscale complex. The theranostic capabilities of gold nanoshells, spherical nanoparticles with silica cores and gold shells, have attracted tremendous attention over the past decade as nanoshells have emerged as a promising tool for cancer therapy and bioimaging enhancement. This Account examines the design and synthesis of nanoshell-based theranostic agents, their plasmon-derived optical properties, and their corresponding applications. We discuss the design and preparation of nanoshell complexes and their ability to enhance the photoluminescence of ...
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    6. Structural Examination of Easel Paintings with Optical Coherence Tomography

      Structural Examination of Easel Paintings with Optical Coherence Tomography
      Identification of the order, thickness, composition, and possibly the origin of the paint layers forming the structure of a painting, that is, its stratigraphy, is important in confirming its attribution and history as well as planning conservation treatments. The most common method of examination is analysis of a sample collected from the art object, both visually with a microscope and instrumentally through a variety of sophisticated, modern analytical tools. Because of its invasiveness, however, sampling is less than ideally compatible with conservation ethics; it is severely restricted with respect to the amount of material extirpated from the artwork. Sampling is ...
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    7. Photothermal Optical Coherence Tomography of Epidermal Growth Factor Receptor in Live Cells Using Immunotargeted Gold Nanospheres

      Photothermal Optical Coherence Tomography of Epidermal Growth Factor Receptor in Live Cells Using Immunotargeted Gold Nanospheres
      Molecular imaging is a powerful tool for investigating disease processes and potential therapies in both in vivo and in vitro systems. However, high resolution molecular imaging has been limited to relatively shallow penetration depths that can be accessed with microscopy. Optical coherence tomography (OCT) is an optical analogue to ultrasound with relatively good penetration depth (1−2 mm) and resolution (~1−10 μm). We have developed and characterized photothermal OCT as a molecular contrast mechanism that allows for high resolution molecular imaging at deeper penetration depths than microscopy. Our photothermal system consists of an amplitude-modulated heating beam that spatially overlaps ...
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    8. Gold Nanocages: Synthesis, Properties, and Applications

      Noble-metal nanocages comprise a novel class of nanostructures possessing hollow interiors and porous walls. They are prepared using a remarkably simple galvanic replacement reaction between solutions containing metal precursor salts and Ag nanostructures prepared through polyol reduction. The electrochemical potential difference between the two species drives the reaction, with the reduced metal depositing on the surface of the Ag nanostructure. In our most studied example, involving HAuCl4 as the metal precursor, the resultant Au is deposited epitaxially on the surface of the Ag nanocubes, adopting their underlying cubic form. Concurrent with this deposition, the interior Ag is oxidized and removed ...
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    9. Affinity-Based Turbidity Sensor for Glucose Monitoring by Optical Coherence Tomography: Toward the Development of an Implantable Sensor

      We investigated the feasibility of constructing an implantable optical-based sensor for seminoninvasive continuous monitoring of analytes. In this novel sensor, analyte concentration-dependent changes induced in the degree of optical turbidity of the sensing element can be accurately monitored by optical coherence tomography (OCT), an interferometric technique. To demonstrate proof-of-concept, we engineered a sensor for monitoring glucose concentration that enabled us to quantitatively monitor the glucose-specific changes induced in bulk scattering (turbidity) of the sensor. The sensor consists of a glucose-permeable membrane housing that contains a suspension of macroporous hydrogel particles and concanavalin A (ConA), a glucose-specific lectin, that are designed ...

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    1-9 of 9
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