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Concept: Dark field microscopy

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Orthogonal polarized spectral (OPS) and sidestream dark field (SDF) imaging video microscope devices were introduced for observation of the microcirculation but, due to technical limitations, have remained as research tools. Recently, a novel handheld microscope based on incident dark field illumination (IDF) has been introduced for clinical use. The Cytocam-IDF imaging device consists of a pen-like probe incorporating IDF illumination with a set of high-resolution lenses projecting images on to a computer controlled image sensor synchronized with very short pulsed illumination light. This study was performed to validate Cytocam-IDF imaging by comparison to SDF imaging in volunteers.

Concepts: Optics, Light, Microscope, Computer graphics, Microscopy, IMAGE, Image processing, Dark field microscopy

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Here we describe an ultra-low-cost origami-based approach for large-scale manufacturing of microscopes, specifically demonstrating brightfield, darkfield, and fluorescence microscopes. Merging principles of optical design with origami enables high-volume fabrication of microscopes from 2D media. Flexure mechanisms created via folding enable a flat compact design. Structural loops in folded paper provide kinematic constraints as a means for passive self-alignment. This light, rugged instrument can survive harsh field conditions while providing a diversity of imaging capabilities, thus serving wide-ranging applications for cost-effective, portable microscopes in science and education.

Concepts: Optics, Light, Microscope, Microscopy, Lens, Fluorescence microscope, Microscopes, Dark field microscopy

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We report a highly sensitive biomolecule detection by plasmonic nanoantenna arrays with selective binding at the optical hotspots. The plasmonic nanoantennas consist of two separated Au nanorods with a thin Ti disk placed in between. By using selective surface modification chemistry, controlled binding occurs only in the gaps between the plasmonic nanoantennas, which ensures a high detection sensitivity. Both optical characterization using a dark field microscope and the FDTD simulation show that after the streptavidin binding, the signal increases with decreasing gap size. Compared to a single nanorod, the signal obtained per bound molecule in the nanoantennas increases by a factor of six, which is promising with respect to the future detection of single molecules.

Concepts: Electron, Oxygen, Molecule, Microscope, Chemistry, Atom, Molecules, Dark field microscopy

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We demonstrated a practical method to analyze carbohydrate-protein interaction based on single plasmonic nanopar-ticles by conventional dark field microscope (DFM). Protein concanavalin A (ConA) was modified on large sized gold nanoparticles (AuNPs), and dextran was conjugated on small sized AuNPs. As the interaction between ConA and dex-tran resulted in two kinds of gold nanoparticles coupled together, which caused coupling of plasmonic oscillations, apparent color changes (from green to yellow) of the single AuNPs were observed through DFM. Then, the color in-formation was instantly transformed into statistic peak wavelength distribution in less than 1 min by nanoparti-cleAnalysis program. In addition, the interaction between ConA and dextran was proved bio-specific recognition. This approach is high-throughput, and real-time, which is a convenient method to analyze carbohydrate-protein interac-tion at the single nanoparticle level efficiently.

Concepts: Scientific method, Nanoparticle, Light, Nanotechnology, Gold, Surface plasmon resonance, Microscopy, Dark field microscopy

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Plasmonic resonances of metal-based nanoparticles are increasingly used for ultrasensitive imaging assays. In this context, the Cytoviva™ microscopy platform has greatly gained in popularity. In essence, Cytoviva is an optimized dark field microscope that permits detection of particles down to a few nanometers in size. A significant limitation of Cytoviva up to now has been that it only provided for single plane imaging. The datasets produced by this technique therefore only show a partial view of the sample - not ideally suited to analysis. Here we explain how to overcome this limitation by mounting the Cytoviva condenser on an automated microscope with Z-scanning capability. Our method allows three-dimensional mapping of nanoparticles in their full three-dimensional cellular context. We apply this technique to study the interaction of silver and cerium dioxide nanoparticles with cells of the green alga, Pseudokirchneriella subcapitata, a system of significant environmental relevance because algae underlie much of the aquatic food chain. Our objective was to develop a technique to visualize in detail the interaction of nanoparticles with cells in three dimensions, such that one may, for example, determine whether a particular nanoparticle is inside a cell, at its very surface, or at a distance from it.

Concepts: Cyanobacteria, Plastid, Microscope, Dimension, Euclidean space, Surface plasmon resonance, Microscopy, Dark field microscopy

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Maintenance of Leptospira species in liquid or semi-solid media is time-consuming and at risk of contamination due to the needs of routine subculture and dark field microscopy. Using Leptospira Vanaporn Wuthiekanun (LVW) agar, we maintained 100 pathogenic Leptospira isolates for 12 months without the need of subculture, and could confirm the viability of all isolates by the naked eye.

Concepts: Microscope, Eye, Microscopy, Need, Leptospira, Dark field microscopy

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Spectral shift of localized plasmon resonance scattering of guanine-rich DNA modified single Au nanoparticles is observed under a dark field microscope equipped with a spectrometer. The spectra continuously red-shift with the conformational change of the guanine-rich DNA upon associating with K(+), hemin and the biocatalytic growth of the polymer. The scattering spectrum of single nanoparticles is proved to be sensitive both to a subtle conformational change and the biocatalysis process. 20 mM K(+) or 100 μM H2O2 can trigger a detectable peak shift. The present study paves a new and efficient way to extract chemical information from micro/nanospace.

Concepts: Present, Scattering, Nanotechnology, Surface plasmon resonance, Spectrum, Spectra, Spectre, Dark field microscopy

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In this work, a novel methodology based on hyperspectral imagery with enhanced Darkfield microscopy for probing and characterizing changes in blood cell components was tested. Two main categories of blood cells were analyzed, red and white blood cells. Unique spectral signatures of ordinary and most common deformed morphologies of red blood cells were identified. Moreover, examination of white blood cells allowed to characterize and differentiate active from inactive cells. The findings indicate the ability of this technique to detect changes in light scattering property of blood cells due to their morphological properties Since pathological states can alterate the discocyte shape, this preliminary, but promising application of the hyperspectral analysis to blood cells can be useful to evaluate significant correlations of blood cell spectral features in healthy and pathological conditions. The combination of the quali- and quantitative spectral signatures of hyperspectral imaging microscopy with the information of the subject health conditions may provide a new tool for clinical applications. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

Concepts: Cell nucleus, Blood, Red blood cell, Bone marrow, Microscope, Hematology, Microscopy, Dark field microscopy

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Abstract The main cause of peri-implantitis and crestal bone resorption is bacterial infection. The present study aimed to comparatively assess the microbiological parameters in sulci around teeth and crowns supported by dental implants and also compare microbiological parameters around deep and shallow implant sulci. In this cross-sectional study, 34 partially edentulous patients with a total of 72 implants (22 deep vs. 50 shallow sulci) were included. Excluded were the patients with compromised systemic and periodontal health or smoking habits. All Implants (ITI) were at least 6 month in place covered by definite prostheses. Samples of gingival sulci were taken around teeth and implants with paper points and transported in Stuart Transport Medium. Samples were cultured and examined by dark field microscope to determine the microorganisms. Data were evaluated statistically in SPSS (v11.5) using chi-square test. Cocci G+, Cocci G-, Prevotella, Porphyromonas gingivalis, Bacteroid fragilis and Fusobacterium were found. The relative frequency of P. gingivalis was significantly higher in deep implant sulci compared to shallow implant sulci (p = 0.044) and natural sulci (p = 0.009). B. fragilis was also significantly more isolated from the deep implant sulci compared to shallow implant sulci (p = 0.001) and natural sulci (p = 0.064). Within the limitations of the present study, it may be concluded that peri-implantitis is more likely in deep sulci compared with shallow sulci in partial edentulousness.

Concepts: Bacteria, Gut flora, Microbiology, Implants, Dental implant, Porphyromonas gingivalis, Bacteroides fragilis, Dark field microscopy