Scanning light-sheet microscopy in the whole mouse brain with HiLo background rejection

PubMed Central

Mertz, Jerome; Kim, Jinhyun

2010-01-01

It is well known that light-sheet illumination can enable optically sectioned wide-field imaging of macroscopic samples. However, the optical sectioning capacity of a light-sheet macroscope is undermined by sample-induced scattering or aberrations that broaden the thickness of the sheet illumination. We present a technique to enhance the optical sectioning capacity of a scanning light-sheet microscope by out-of-focus background rejection. The technique, called HiLo microscopy, makes use of two images sequentially acquired with uniform and structured sheet illumination. An optically sectioned image is then synthesized by fusing high and low spatial frequency information from both images. The benefits of combining light-sheet macroscopy and HiLo background rejection are demonstrated in optically cleared whole mouse brain samples, using both green fluorescent protein (GFP)-fluorescence and dark-field scattered light contrast. PMID:20210471

A high rigor temperature, not sarcomere length, determines light scattering properties and muscle colour in beef M. sternomandibularis meat and muscle fibres.

PubMed

Hughes, J; Clarke, F; Purslow, P; Warner, R

2018-05-18

Beef meat colour is impacted by both myoglobin status and the light scattering properties of the muscle, and the specific causative scattering elements of the latter are still unknown. We hypothesize that stretching muscles during rigor will generate a structure which favours light scattering, by increasing the length of the I-band (longer sarcomeres) and that a high rigor temperature will cause protein reconfiguration, changing the muscle structure and promoting light scattering. Muscle fibre fragments were isolated from four beef M. sternomandibularis and subjected to stretching (plus, minus) and three incubation temperatures (5, 15, 35 °C). Reflectance confocal laser scanning microscopy (rCLSM) revealed sarcomere stretching alone was not solely responsible for light scattering development. A high rigor temperature (35 °C) was more favourable for light scattering. Stretching and taking muscle into rigor at 35 °C promoted transverse shrinkage of muscle fibres and increased light scattering and could be applied post-mortem (PM) to reduce the occurrence of problematic dark meat. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

Coherent beam control through inhomogeneous media in multi-photon microscopy

NASA Astrophysics Data System (ADS)

Paudel, Hari Prasad

Multi-photon fluorescence microscopy has become a primary tool for high-resolution deep tissue imaging because of its sensitivity to ballistic excitation photons in comparison to scattered excitation photons. The imaging depth of multi-photon microscopes in tissue imaging is limited primarily by background fluorescence that is generated by scattered light due to the random fluctuations in refractive index inside the media, and by reduced intensity in the ballistic focal volume due to aberrations within the tissue and at its interface. We built two multi-photon adaptive optics (AO) correction systems, one for combating scattering and aberration problems, and another for compensating interface aberrations. For scattering correction a MEMS segmented deformable mirror (SDM) was inserted at a plane conjugate to the objective back-pupil plane. The SDM can pre-compensate for light scattering by coherent combination of the scattered light to make an apparent focus even at a depths where negligible ballistic light remains (i.e. ballistic limit). This problem was approached by investigating the spatial and temporal focusing characteristics of a broad-band light source through strongly scattering media. A new model was developed for coherent focus enhancement through or inside the strongly media based on the initial speckle contrast. A layer of fluorescent beads under a mouse skull was imaged using an iterative coherent beam control method in the prototype two-photon microscope to demonstrate the technique. We also adapted an AO correction system to an existing in three-photon microscope in a collaborator lab at Cornell University. In the second AO correction approach a continuous deformable mirror (CDM) is placed at a plane conjugate to the plane of an interface aberration. We demonstrated that this "Conjugate AO" technique yields a large field-of-view (FOV) advantage in comparison to Pupil AO. Further, we showed that the extended FOV in conjugate AO is maintained over a relatively large axial misalignment of the conjugate planes of the CDM and the aberrating interface. This dissertation advances the field of microscopy by providing new models and techniques for imaging deeply within strongly scattering tissue, and by describing new adaptive optics approaches to extending imaging FOV due to sample aberrations.

Confocal Light Absorption and Scattering Spectroscopic (CLASS) imaging: From cancer detection to sub-cellular function

NASA Astrophysics Data System (ADS)

Qiu, Le

Light scattering spectroscopy (LSS), an optical technique that relates the spectroscopic properties of light elastically scattered by small particles to their size, refractive index and shape, has been recently successfully employed for sensing morphological and biochemical properties of epithelial tissues and cells in vivo. LSS does not require exogenous markers, is non-invasive, and, due to its multispectral nature, can sense biological structures well beyond the diffraction limit. All that makes LSS be a very good candidate to be used both in clinical medicine for in vivo detection of disease and in cell biology to monitor cell function on the organelle scale. Recently we developed two LSS-based imaging modalities: clinical Polarized LSS (PLSS) Endoscopic Technique for locating early pre-cancerous changes in GI tract and Confocal Light Absorption and Scattering Spectroscopic (CLASS) Microscopy for studying cells in vivo without exogenous markers. One important application of the clinical PLSS endoscopic instrument, a noncontact scanning imaging device compatible with the standard clinical endoscopes and capable of detecting dysplastic changes, is to serve as a guide for biopsy in Barrett's esophagus (BE). The instrument detects parallel and perpendicular components of the polarized light, backscattered from epithelial tissues, and determines characteristics of epithelial nuclei from the residual spectra. It also can find tissue oxygenation, hemoglobin content and other properties from the diffuse light component. By rapidly scanning esophagus the PLSS endoscopic instrument makes sure the entire BE portion is scanned and examined for the presence of dysplasia. CLASS microscopy, on the other hand, combines principles of light scattering spectroscopy (LSS) with confocal microscopy. Its main purpose is to image cells on organelle scale in vivo without the use of exogenous labels which may affect the cell function. The confocal geometry selects specific region and images are obtained by scanning the confocal volume across the sample. The new beam scanning CLASS microscope is a significant improvement over the previous proof-of-principle device. With this new device we have already performed experiments to monitor morphological changes in cells during apoptosis, differentiated fetal from maternal nucleated red blood cells, and detected plasmon scattering spectra of single gold nanorod.

Predicting scattering scanning near-field optical microscopy of mass-produced plasmonic devices

NASA Astrophysics Data System (ADS)

Otto, Lauren M.; Burgos, Stanley P.; Staffaroni, Matteo; Ren, Shen; Süzer, Özgün; Stipe, Barry C.; Ashby, Paul D.; Hammack, Aeron T.

2018-05-01

Scattering scanning near-field optical microscopy enables optical imaging and characterization of plasmonic devices with nanometer-scale resolution well below the diffraction limit. This technique enables developers to probe and understand the waveguide-coupled plasmonic antenna in as-fabricated heat-assisted magnetic recording heads. In order to validate and predict results and to extract information from experimental measurements that is physically comparable to simulations, a model was developed to translate the simulated electric field into expected near-field measurements using physical parameters specific to scattering scanning near-field optical microscopy physics. The methods used in this paper prove that scattering scanning near-field optical microscopy can be used to determine critical sub-diffraction-limited dimensions of optical field confinement, which is a crucial metrology requirement for the future of nano-optics, semiconductor photonic devices, and biological sensing where the near-field character of light is fundamental to device operation.

Flow Cytometry with Gold Nanoparticles and their Clusters as scattering Contrast Agents: FDTD Simulation of Light-Cell Interaction

PubMed Central

Tanev, Stoyan; Sun, Wenbo; Pond, James; Tuchin, Valery V.; Zharov, Vladimir P.

2010-01-01

The formulation of the Finite-Difference Time-Domain (FDTD) approach is presented in the framework of its potential applications to in vivo flow cytometry based on light scattering. The consideration is focused on comparison of light scattering by a single biological cell alone in controlled refractive index matching conditions and by cells labeled by gold nanoparticles. The optical schematics including phase contrast (OPCM) microscopy as a prospective modality for in vivo flow cytometry is also analyzed. The validation of the FDTD approach for the simulation of flow cytometry may open a new avenue in the development of advanced cytometric techniques based on scattering effects from nanoscale targets. PMID:19670359

Plane wave analysis of coherent holographic image reconstruction by phase transfer (CHIRPT).

PubMed

Field, Jeffrey J; Winters, David G; Bartels, Randy A

2015-11-01

Fluorescent imaging plays a critical role in a myriad of scientific endeavors, particularly in the biological sciences. Three-dimensional imaging of fluorescent intensity often requires serial data acquisition, that is, voxel-by-voxel collection of fluorescent light emitted throughout the specimen with a nonimaging single-element detector. While nonimaging fluorescence detection offers some measure of scattering robustness, the rate at which dynamic specimens can be imaged is severely limited. Other fluorescent imaging techniques utilize imaging detection to enhance collection rates. A notable example is light-sheet fluorescence microscopy, also known as selective-plane illumination microscopy, which illuminates a large region within the specimen and collects emitted fluorescent light at an angle either perpendicular or oblique to the illumination light sheet. Unfortunately, scattering of the emitted fluorescent light can cause blurring of the collected images in highly turbid biological media. We recently introduced an imaging technique called coherent holographic image reconstruction by phase transfer (CHIRPT) that combines light-sheet-like illumination with nonimaging fluorescent light detection. By combining the speed of light-sheet illumination with the scattering robustness of nonimaging detection, CHIRPT is poised to have a dramatic impact on biological imaging, particularly for in vivo preparations. Here we present the mathematical formalism for CHIRPT imaging under spatially coherent illumination and present experimental data that verifies the theoretical model.

A line scanned light-sheet microscope with phase shaped self-reconstructing beams.

PubMed

Fahrbach, Florian O; Rohrbach, Alexander

2010-11-08

We recently demonstrated that Microscopy with Self-Reconstructing Beams (MISERB) increases both image quality and penetration depth of illumination beams in strongly scattering media. Based on the concept of line scanned light-sheet microscopy, we present an add-on module to a standard inverted microscope using a scanned beam that is shaped in phase and amplitude by a spatial light modulator. We explain technical details of the setup as well as of the holograms for the creation, positioning and scaling of static light-sheets, Gaussian beams and Bessel beams. The comparison of images from identical sample areas illuminated by different beams allows a precise assessment of the interconnection between beam shape and image quality. The superior propagation ability of Bessel beams through inhomogeneous media is demonstrated by measurements on various scattering media.

Bio-inspired, colorful, flexible, defrostable light-scattering hybrid films for the effective distribution of LED light.

PubMed

An, Seongpil; Jo, Hong Seok; Kim, Yong Il; Song, Kyo Yong; Kim, Min-Woo; Lee, Kyu Bum; Yarin, Alexander L; Yoon, Sam S

2017-07-06

Bioluminescent jellyfish has a unique structure derived from fiber/polymer interfaces that is advantageous for effective light scattering in the dark, deep sea water. Herein, we demonstrate the fabrication of bio-inspired hybrid films by mimicry of the jellyfish's structure, leading to excellent light-scattering performance and defrosting capability. A haze value reaching 59.3% and a heating temperature of up to 292 °C were achieved with the films. Accordingly, the developed surface constitutes an attractive optical device for lighting applications, especially for street or vehicle luminaries for freezing Arctic-climate countries. The morphological details of the hybrid films were revealed by scanning electron microscopy. The light-scattering properties of these films were examined by ultraviolet-visible-infrared spectrophotometry and anti-glare effect analyses. The defrosting performance of the hybrid films was evaluated via heating tests and infra-red observations.

On the influence of lipid-induced optical anisotropy for the bioimaging of exo- or endocytosis with interference microscopic imaging.

PubMed

Marques, D; Miranda, A; Silva, A G; Munro, P R T; DE Beule, P A A

2018-05-01

Some implementations of interference microscopy imaging use digital holographic measurements of complex scattered fields to reconstruct three-dimensional refractive index maps of weakly scattering, semi-transparent objects, frequently encountered in biological investigations. Reconstruction occurs through application of the object scattering potential which assumes an isotropic refractive index throughout the object. Here, we demonstrate that this assumption can in some circumstances be invalid for biological imaging due to the presence of lipid-induced optical anisotropy. We show that the nanoscale organization of lipids in the observation of cellular endocytosis with polarized light induces a significant change in far-field scattering. We obtain this result by presenting a general solution to Maxwell's equations describing light scattering of core-shell particles near an isotropic substrate covered with an anisotropic thin film. This solution is based on an extension of the Bobbert-Vlieger solution for particle scattering near a substrate delivering an exact solution to the scattering problem in the near field as well as far field. By applying this solution to study light scattering by a lipid vesicle near a lipid bilayer, whereby the lipids are represented through a biaxial optical model, we conclude through ellipsometry concepts that effective amounts of lipid-induced optical anisotropy significantly alter far-field optical scattering in respect to an equivalent optical model that neglects the presence of optical anisotropy. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

Bessel light sheet structured illumination microscopy

NASA Astrophysics Data System (ADS)

Noshirvani Allahabadi, Golchehr

Biomedical study researchers using animals to model disease and treatment need fast, deep, noninvasive, and inexpensive multi-channel imaging methods. Traditional fluorescence microscopy meets those criteria to an extent. Specifically, two-photon and confocal microscopy, the two most commonly used methods, are limited in penetration depth, cost, resolution, and field of view. In addition, two-photon microscopy has limited ability in multi-channel imaging. Light sheet microscopy, a fast developing 3D fluorescence imaging method, offers attractive advantages over traditional two-photon and confocal microscopy. Light sheet microscopy is much more applicable for in vivo 3D time-lapsed imaging, owing to its selective illumination of tissue layer, superior speed, low light exposure, high penetration depth, and low levels of photobleaching. However, standard light sheet microscopy using Gaussian beam excitation has two main disadvantages: 1) the field of view (FOV) of light sheet microscopy is limited by the depth of focus of the Gaussian beam. 2) Light-sheet images can be degraded by scattering, which limits the penetration of the excitation beam and blurs emission images in deep tissue layers. While two-sided sheet illumination, which doubles the field of view by illuminating the sample from opposite sides, offers a potential solution, the technique adds complexity and cost to the imaging system. We investigate a new technique to address these limitations: Bessel light sheet microscopy in combination with incoherent nonlinear Structured Illumination Microscopy (SIM). Results demonstrate that, at visible wavelengths, Bessel excitation penetrates up to 250 microns deep in the scattering media with single-side illumination. Bessel light sheet microscope achieves confocal level resolution at a lateral resolution of 0.3 micron and an axial resolution of 1 micron. Incoherent nonlinear SIM further reduces the diffused background in Bessel light sheet images, resulting in confocal quality images in thick tissue. The technique was applied to live transgenic zebra fish tg(kdrl:GFP), and the sub-cellular structure of fish vasculature genetically labeled with GFP was captured in 3D. The superior speed of the microscope enables us to acquire signal from 200 layers of a thick sample in 4 minutes. The compact microscope uses exclusively off-the-shelf components and offers a low-cost imaging solution for studying small animal models or tissue samples.

Perspective: Differential dynamic microscopy extracts multi-scale activity in complex fluids and biological systems

NASA Astrophysics Data System (ADS)

Cerbino, Roberto; Cicuta, Pietro

2017-09-01

Differential dynamic microscopy (DDM) is a technique that exploits optical microscopy to obtain local, multi-scale quantitative information about dynamic samples, in most cases without user intervention. It is proving extremely useful in understanding dynamics in liquid suspensions, soft materials, cells, and tissues. In DDM, image sequences are analyzed via a combination of image differences and spatial Fourier transforms to obtain information equivalent to that obtained by means of light scattering techniques. Compared to light scattering, DDM offers obvious advantages, principally (a) simplicity of the setup; (b) possibility of removing static contributions along the optical path; (c) power of simultaneous different microscopy contrast mechanisms; and (d) flexibility of choosing an analysis region, analogous to a scattering volume. For many questions, DDM has also advantages compared to segmentation/tracking approaches and to correlation techniques like particle image velocimetry. The very straightforward DDM approach, originally demonstrated with bright field microscopy of aqueous colloids, has lately been used to probe a variety of other complex fluids and biological systems with many different imaging methods, including dark-field, differential interference contrast, wide-field, light-sheet, and confocal microscopy. The number of adopting groups is rapidly increasing and so are the applications. Here, we briefly recall the working principles of DDM, we highlight its advantages and limitations, we outline recent experimental breakthroughs, and we provide a perspective on future challenges and directions. DDM can become a standard primary tool in every laboratory equipped with a microscope, at the very least as a first bias-free automated evaluation of the dynamics in a system.

High-frame-rate imaging of biological samples with optoacoustic micro-tomography

NASA Astrophysics Data System (ADS)

Deán-Ben, X. Luís.; López-Schier, Hernán.; Razansky, Daniel

2018-02-01

Optical microscopy remains a major workhorse in biological discovery despite the fact that light scattering limits its applicability to depths of ˜ 1 mm in scattering tissues. Optoacoustic imaging has been shown to overcome this barrier by resolving optical absorption with microscopic resolution in significantly deeper regions. Yet, the time domain is paramount for the observation of biological dynamics in living systems that exhibit fast motion. Commonly, acquisition of microscopy data involves raster scanning across the imaged volume, which significantly limits temporal resolution in 3D. To overcome these limitations, we have devised a fast optoacoustic micro-tomography (OMT) approach based on simultaneous acquisition of 3D image data with a high-density hemispherical ultrasound array having effective detection bandwidth around 25 MHz. We performed experiments by imaging tissue-mimicking phantoms and zebrafish larvae, demonstrating that OMT can provide nearly cellular resolution and imaging speed of 100 volumetric frames per second. As opposed to other optical microscopy techniques, OMT is a hybrid method that resolves optical absorption contrast acoustically using unfocused light excitation. Thus, no penetration barriers are imposed by light scattering in deep tissues, suggesting it as a powerful approach for multi-scale functional and molecular imaging applications.

Scattering-type scanning near-field optical microscopy with low-repetition-rate pulsed light source through phase-domain sampling

PubMed Central

Wang, Haomin; Wang, Le; Xu, Xiaoji G.

2016-01-01

Scattering-type scanning near-field optical microscopy (s-SNOM) allows spectroscopic imaging with spatial resolution below the diffraction limit. With suitable light sources, s-SNOM is instrumental in numerous discoveries at the nanoscale. So far, the light sources have been limited to continuous wave or high-repetition-rate pulsed lasers. Low-repetition-rate pulsed sources cannot be used, due to the limitation of the lock-in detection mechanism that is required for current s-SNOM techniques. Here, we report a near-field signal extraction method that enables low-repetition-rate pulsed light sources. The method correlates scattering signals from pulses with the mechanical phases of the oscillating s-SNOM probe to obtain near-field signal, by-passing the apparent restriction imposed by the Nyquist–Shannon sampling theorem on the repetition rate. The method shall enable s-SNOM with low-repetition-rate pulses with high-peak-powers, such as femtosecond laser amplifiers, to facilitate investigations of strong light–matter interactions and nonlinear processes at the nanoscale. PMID:27748360

Separation of ballistic and diffusive fluorescence photons in confocal Light-Sheet Microscopy of Arabidopsis roots.

PubMed

Meinert, Tobias; Tietz, Olaf; Palme, Klaus J; Rohrbach, Alexander

2016-08-24

Image quality in light-sheet fluorescence microscopy is strongly affected by the shape of the illuminating laser beam inside embryos, plants or tissue. While the phase of Gaussian or Bessel beams propagating through thousands of cells can be partly controlled holographically, the propagation of fluorescence light to the detector is difficult to control. With each scatter process a fluorescence photon loses information necessary for the image generation. Using Arabidopsis root tips we demonstrate that ballistic and diffusive fluorescence photons can be separated by analyzing the image spectra in each plane without a priori knowledge. We introduce a theoretical model allowing to extract typical scattering parameters of the biological material. This allows to attenuate image contributions from diffusive photons and to amplify the relevant image contributions from ballistic photons through a depth dependent deconvolution. In consequence, image contrast and resolution are significantly increased and scattering artefacts are minimized especially for Bessel beams with confocal line detection.

Separation of ballistic and diffusive fluorescence photons in confocal Light-Sheet Microscopy of Arabidopsis roots

PubMed Central

Meinert, Tobias; Tietz, Olaf; Palme, Klaus J.; Rohrbach, Alexander

2016-01-01

Image quality in light-sheet fluorescence microscopy is strongly affected by the shape of the illuminating laser beam inside embryos, plants or tissue. While the phase of Gaussian or Bessel beams propagating through thousands of cells can be partly controlled holographically, the propagation of fluorescence light to the detector is difficult to control. With each scatter process a fluorescence photon loses information necessary for the image generation. Using Arabidopsis root tips we demonstrate that ballistic and diffusive fluorescence photons can be separated by analyzing the image spectra in each plane without a priori knowledge. We introduce a theoretical model allowing to extract typical scattering parameters of the biological material. This allows to attenuate image contributions from diffusive photons and to amplify the relevant image contributions from ballistic photons through a depth dependent deconvolution. In consequence, image contrast and resolution are significantly increased and scattering artefacts are minimized especially for Bessel beams with confocal line detection. PMID:27553506

Label-free volumetric optical imaging of intact murine brains

NASA Astrophysics Data System (ADS)

Ren, Jian; Choi, Heejin; Chung, Kwanghun; Bouma, Brett E.

2017-04-01

A central effort of today’s neuroscience is to study the brain’s ’wiring diagram’. The nervous system is believed to be a network of neurons interacting with each other through synaptic connection between axons and dendrites, therefore the neuronal connectivity map not only depicts the underlying anatomy, but also has important behavioral implications. Different approaches have been utilized to decipher neuronal circuits, including electron microscopy (EM) and light microscopy (LM). However, these approaches typically demand extensive sectioning and reconstruction for a brain sample. Recently, tissue clearing methods have enabled the investigation of a fully assembled biological system with greatly improved light penetration. Yet, most of these implementations, still require either genetic or exogenous contrast labeling for light microscopy. Here we demonstrate a high-speed approach, termed as Clearing Assisted Scattering Tomography (CAST), where intact brains can be imaged at optical resolution without labeling by leveraging tissue clearing and the scattering contrast of optical frequency domain imaging (OFDI).

Light scattering and light transmittance of cadaver eye-explanted intraocular lenses of different materials.

PubMed

Morris, Caleb; Werner, Liliana; Barra, Daniel; Liu, Erica; Stallings, Shannon; Floyd, Anne

2014-01-01

To evaluate light scattering and light transmittance in cadaver eye-explanted intraocular lenses (IOLs) manufactured from different materials. John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. Experimental study. Forty-nine pseudophakic cadaver eyes were selected according to IOL material/type and implantation duration, and the IOLs were explanted. Hydrophobic acrylic, hydrophilic acrylic, poly(methyl methacrylate) (PMMA), and silicone IOLs were included. Gross and light microscopy was performed for all IOLs. Light scattering was measured with an EAS 1000 Scheimpflug camera, and light transmittance was assessed using a Lambda 35 UV/Vis spectrophotometer (single-beam configuration with an RSA PE-20 integrating sphere). Analyses were performed at room temperature in the hydrated state and compared with analyses of controls. The highest levels of surface light scattering were measured for 3-piece hydrophobic acrylic, which was also the IOL type with the longest implantation duration among the Acrysof hydrophobic acrylic IOLs. Hydrophilic acrylic, PMMA, and silicone IOLs exhibited relatively low light-scattering levels. The lowest light-scattering levels were observed with PMMA IOLs (1-piece looped and 3-piece) and plate silicone IOLs, which represent the IOL types with the longest implantation duration in this series. Light transmittance values measured for all IOL types appeared to be similar to the values of the corresponding control IOLs. The phenomenon of surface light scattering (nanoglistenings) is more particularly related to hydrophobic acrylic IOLs and increases with implantation time. No significant effect of surface light scattering on IOL light transmittance was found. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Automatic and adaptive heterogeneous refractive index compensation for light-sheet microscopy.

PubMed

Ryan, Duncan P; Gould, Elizabeth A; Seedorf, Gregory J; Masihzadeh, Omid; Abman, Steven H; Vijayaraghavan, Sukumar; Macklin, Wendy B; Restrepo, Diego; Shepherd, Douglas P

2017-09-20

Optical tissue clearing has revolutionized researchers' ability to perform fluorescent measurements of molecules, cells, and structures within intact tissue. One common complication to all optically cleared tissue is a spatially heterogeneous refractive index, leading to light scattering and first-order defocus. We designed C-DSLM (cleared tissue digital scanned light-sheet microscopy) as a low-cost method intended to automatically generate in-focus images of cleared tissue. We demonstrate the flexibility and power of C-DSLM by quantifying fluorescent features in tissue from multiple animal models using refractive index matched and mismatched microscope objectives. This includes a unique measurement of myelin tracks within intact tissue using an endogenous fluorescent reporter where typical clearing approaches render such structures difficult to image. For all measurements, we provide independent verification using standard serial tissue sectioning and quantification methods. Paired with advancements in volumetric image processing, C-DSLM provides a robust methodology to quantify sub-micron features within large tissue sections.Optical clearing of tissue has enabled optical imaging deeper into tissue due to significantly reduced light scattering. Here, Ryan et al. tackle first-order defocus, an artefact of a non-uniform refractive index, extending light-sheet microscopy to partially cleared samples.

Even illumination in total internal reflection fluorescence microscopy using laser light.

PubMed

Fiolka, R; Belyaev, Y; Ewers, H; Stemmer, A

2008-01-01

In modern fluorescence microscopy, lasers are a widely used source of light, both for imaging in total internal reflection and epi-illumination modes. In wide-field imaging, scattering of highly coherent laser light due to imperfections in the light path typically leads to nonuniform illumination of the specimen, compromising image analysis. We report the design and construction of an objective-launch total internal reflection fluorescence microscopy system with excellent evenness of specimen illumination achieved by azimuthal rotation of the incoming illuminating laser beam. The system allows quick and precise changes of the incidence angle of the laser beam and thus can also be used in an epifluorescence mode. 2007 Wiley-Liss, Inc

Characterization of the angular memory effect of scattered light in biological tissues.

PubMed

Schott, Sam; Bertolotti, Jacopo; Léger, Jean-Francois; Bourdieu, Laurent; Gigan, Sylvain

2015-05-18

High resolution optical microscopy is essential in neuroscience but suffers from scattering in biological tissues and therefore grants access to superficial brain layers only. Recently developed techniques use scattered photons for imaging by exploiting angular correlations in transmitted light and could potentially increase imaging depths. But those correlations ('angular memory effect') are of a very short range and should theoretically be only present behind and not inside scattering media. From measurements on neural tissues and complementary simulations, we find that strong forward scattering in biological tissues can enhance the memory effect range and thus the possible field-of-view by more than an order of magnitude compared to isotropic scattering for ∼1 mm thick tissue layers.

Characterization of magnetic nanoparticle by dynamic light scattering

PubMed Central

2013-01-01

Here we provide a complete review on the use of dynamic light scattering (DLS) to study the size distribution and colloidal stability of magnetic nanoparticles (MNPs). The mathematical analysis involved in obtaining size information from the correlation function and the calculation of Z-average are introduced. Contributions from various variables, such as surface coating, size differences, and concentration of particles, are elaborated within the context of measurement data. Comparison with other sizing techniques, such as transmission electron microscopy and dark-field microscopy, revealed both the advantages and disadvantages of DLS in measuring the size of magnetic nanoparticles. The self-assembly process of MNP with anisotropic structure can also be monitored effectively by DLS. PMID:24011350

Plum pudding random medium model of biological tissue toward remote microscopy from spectroscopic light scattering

PubMed Central

Xu, Min

2017-01-01

Biological tissue has a complex structure and exhibits rich spectroscopic behavior. There has been no tissue model until now that has been able to account for the observed spectroscopy of tissue light scattering and its anisotropy. Here we present, for the first time, a plum pudding random medium (PPRM) model for biological tissue which succinctly describes tissue as a superposition of distinctive scattering structures (plum) embedded inside a fractal continuous medium of background refractive index fluctuation (pudding). PPRM faithfully reproduces the wavelength dependence of tissue light scattering and attributes the “anomalous” trend in the anisotropy to the plum and the powerlaw dependence of the reduced scattering coefficient to the fractal scattering pudding. Most importantly, PPRM opens up a novel venue of quantifying the tissue architecture and microscopic structures on average from macroscopic probing of the bulk with scattered light alone without tissue excision. We demonstrate this potential by visualizing the fine microscopic structural alterations in breast tissue (adipose, glandular, fibrocystic, fibroadenoma, and ductal carcinoma) deduced from noncontact spectroscopic measurement. PMID:28663913

Flow cytometry with gold nanoparticles and their clusters as scattering contrast agents: FDTD simulation of light-cell interaction.

PubMed

Tanev, Stoyan; Sun, Wenbo; Pond, James; Tuchin, Valery V; Zharov, Vladimir P

2009-09-01

The formulation of the finite-difference time-domain (FDTD) approach is presented in the framework of its potential applications to in-vivo flow cytometry based on light scattering. The consideration is focused on comparison of light scattering by a single biological cell alone in controlled refractive-index matching conditions and by cells labeled by gold nanoparticles. The optical schematics including phase contrast (OPCM) microscopy as a prospective modality for in-vivo flow cytometry is also analyzed. The validation of the FDTD approach for the simulation of flow cytometry may open up a new avenue in the development of advanced cytometric techniques based on scattering effects from nanoscale targets. 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Three-Dimensional Orientation of Anisotropic Plasmonic Aggregates at Intracellular Nuclear Indentation Sites by Integrated Light Sheet Super-Resolution Microscopy.

PubMed

Chakkarapani, Suresh Kumar; Sun, Yucheng; Lee, Seungah; Fang, Ning; Kang, Seong Ho

2018-05-22

Three-dimensional (3D) orientations of individual anisotropic plasmonic nanoparticles in aggregates were observed in real time by integrated light sheet super-resolution microscopy ( iLSRM). Asymmetric light scattering of a gold nanorod (AuNR) was used to trigger signals based on the polarizer angle. Controlled photoswitching was achieved by turning the polarizer and obtaining a series of images at different polarization directions. 3D subdiffraction-limited super-resolution images were obtained by superlocalization of scattering signals as a function of the anisotropic optical properties of AuNRs. Varying the polarizer angle allowed resolution of the orientation of individual AuNRs. 3D images of individual nanoparticles were resolved in aggregated regions, resulting in as low as 64 nm axial resolution and 28 nm spatial resolution. The proposed imaging setup and localization approach demonstrates a convenient method for imaging under a noisy environment where the majority of scattering noise comes from cellular components. This integrated 3D iLSRM and localization technique was shown to be reliable and useful in the field of 3D nonfluorescence super-resolution imaging.

Phenotypic and functional characterization of earthworm coelomocyte subsets: Linking light scatter-based cell typing and imaging of the sorted populations.

PubMed

Engelmann, Péter; Hayashi, Yuya; Bodó, Kornélia; Ernszt, Dávid; Somogyi, Ildikó; Steib, Anita; Orbán, József; Pollák, Edit; Nyitrai, Miklós; Németh, Péter; Molnár, László

2016-12-01

Flow cytometry is a common approach to study invertebrate immune cells including earthworm coelomocytes. However, the link between light-scatter- and microscopy-based phenotyping remains obscured. Here we show, by means of light scatter-based cell sorting, both subpopulations (amoebocytes and eleocytes) can be physically isolated with good sort efficiency and purity confirmed by downstream morphological and cytochemical applications. Immunocytochemical analysis using anti-EFCC monoclonal antibodies combined with phalloidin staining has revealed antigenically distinct, sorted subsets. Screening of lectin binding capacity indicated wheat germ agglutinin (WGA) as the strongest reactor to amoebocytes. This is further evidenced by WGA inhibition assays that suggest high abundance of N-acetyl-d-glucosamine in amoebocytes. Post-sort phagocytosis assays confirmed the functional differences between amoebocytes and eleocytes, with the former being in favor of bacterial engulfment. This study has proved successful in linking flow cytometry and microscopy analysis and provides further experimental evidence of phenotypic and functional heterogeneity in earthworm coelomocyte subsets. Copyright © 2016 Elsevier Ltd. All rights reserved.

Label-free and live cell imaging by interferometric scattering microscopy.

PubMed

Park, Jin-Sung; Lee, Il-Buem; Moon, Hyeon-Min; Joo, Jong-Hyeon; Kim, Kyoung-Hoon; Hong, Seok-Cheol; Cho, Minhaeng

2018-03-14

Despite recent remarkable advances in microscopic techniques, it still remains very challenging to directly observe the complex structure of cytoplasmic organelles in live cells without a fluorescent label. Here we report label-free and live-cell imaging of mammalian cell, Escherischia coli , and yeast, using interferometric scattering microscopy, which reveals the underlying structures of a variety of cytoplasmic organelles as well as the underside structure of the cells. The contact areas of the cells attached onto a glass substrate, e.g. , focal adhesions and filopodia, are clearly discernible. We also found a variety of fringe-like features in the cytoplasmic area, which may reflect the folded structures of cytoplasmic organelles. We thus anticipate that the label-free interferometric scattering microscopy can be used as a powerful tool to shed interferometric light on in vivo structures and dynamics of various intracellular phenomena.

Dynamic light scattering study on vesicles of Netaine-Cholesterol system

NASA Astrophysics Data System (ADS)

Alenaizi, R.; Radiman, S.; Mohamed, F.; Rahman, I. Abdul

2014-09-01

The morphology of vesicles system with defined particle size and shape is one of interest in our technical applications. Here we have used dynamic light scattering technique and transmission electron microscopy for structural characterization of N-dimethylglycine Betaine with 5-cholesten-3β-ol vesicles in aqueous solutions. An isotropic one phase region is found in the very diluted regions depending on Betaine/Cholesterol ratio. The isotropic region was stable for more than 3 months at room temperature, with monodispersed unilamellar vesicles ˜ 300nm.

Light scattering microscopy measurements of single nuclei compared with GPU-accelerated FDTD simulations

NASA Astrophysics Data System (ADS)

Stark, Julian; Rothe, Thomas; Kieß, Steffen; Simon, Sven; Kienle, Alwin

2016-04-01

Single cell nuclei were investigated using two-dimensional angularly and spectrally resolved scattering microscopy. We show that even for a qualitative comparison of experimental and theoretical data, the standard Mie model of a homogeneous sphere proves to be insufficient. Hence, an accelerated finite-difference time-domain method using a graphics processor unit and domain decomposition was implemented to analyze the experimental scattering patterns. The measured cell nuclei were modeled as single spheres with randomly distributed spherical inclusions of different size and refractive index representing the nucleoli and clumps of chromatin. Taking into account the nuclear heterogeneity of a large number of inclusions yields a qualitative agreement between experimental and theoretical spectra and illustrates the impact of the nuclear micro- and nanostructure on the scattering patterns.

Light scattering microscopy measurements of single nuclei compared with GPU-accelerated FDTD simulations.

PubMed

Stark, Julian; Rothe, Thomas; Kieß, Steffen; Simon, Sven; Kienle, Alwin

2016-04-07

Single cell nuclei were investigated using two-dimensional angularly and spectrally resolved scattering microscopy. We show that even for a qualitative comparison of experimental and theoretical data, the standard Mie model of a homogeneous sphere proves to be insufficient. Hence, an accelerated finite-difference time-domain method using a graphics processor unit and domain decomposition was implemented to analyze the experimental scattering patterns. The measured cell nuclei were modeled as single spheres with randomly distributed spherical inclusions of different size and refractive index representing the nucleoli and clumps of chromatin. Taking into account the nuclear heterogeneity of a large number of inclusions yields a qualitative agreement between experimental and theoretical spectra and illustrates the impact of the nuclear micro- and nanostructure on the scattering patterns.

Impact of wavefront distortion and scattering on 2-photon microscopy in mammalian brain tissue

PubMed Central

Chaigneau, Emmanuelle; Wright, Amanda J.; Poland, Simon P.; Girkin, John M.; Silver, R. Angus

2011-01-01

Two-photon (2P) microscopy is widely used in neuroscience, but the optical properties of brain tissue are poorly understood. We have investigated the effect of brain tissue on the 2P point spread function (PSF2P) by imaging fluorescent beads through living cortical slices. By combining this with measurements of the mean free path of the excitation light, adaptive optics and vector-based modeling that includes phase modulation and scattering, we show that tissue-induced wavefront distortions are the main determinant of enlargement and distortion of the PSF2P at intermediate imaging depths. Furthermore, they generate surrounding lobes that contain more than half of the 2P excitation. These effects reduce the resolution of fine structures and contrast and they, together with scattering, limit 2P excitation. Our results disentangle the contributions of scattering and wavefront distortion in shaping the cortical PSF2P, thereby providing a basis for improved 2P microscopy. PMID:22109156

Differential dynamic microscopy to characterize Brownian motion and bacteria motility

NASA Astrophysics Data System (ADS)

Germain, David; Leocmach, Mathieu; Gibaud, Thomas

2016-03-01

We have developed a lab module for undergraduate students, which involves the process of quantifying the dynamics of a suspension of microscopic particles using Differential Dynamic Microscopy (DDM). DDM is a relatively new technique that constitutes an alternative method to more classical techniques such as dynamic light scattering (DLS) or video particle tracking (VPT). The technique consists of imaging a particle dispersion with a standard light microscope and a camera and analyzing the images using a digital Fourier transform to obtain the intermediate scattering function, an autocorrelation function that characterizes the dynamics of the dispersion. We first illustrate DDM in the textbook case of colloids under Brownian motion, where we measure the diffusion coefficient. Then we show that DDM is a pertinent tool to characterize biological systems such as motile bacteria.

Photoisomerisation and light-induced morphological switching of a polyoxometalate-azobenzene hybrid.

PubMed

Markiewicz, Grzegorz; Pakulski, Dawid; Galanti, Agostino; Patroniak, Violetta; Ciesielski, Artur; Stefankiewicz, Artur R; Samorì, Paolo

2017-06-29

The functionalization of a spherical Keplerate-type polyoxometalate {Mo 72 V 30 } with a cationic azobenzene surfactant has been achieved through ionic self-assembly. The photoisomerisation reaction of this complex, which emerges in a light-triggered aggregation-disaggregation process, has been followed by 1 H NMR spectroscopy, dynamic light scattering, absorption spectroscopy and scanning electron microscopy analyses.

Heterodyne holographic microscopy of gold particles.

PubMed

Atlan, Michael; Gross, Michel; Desbiolles, Pierre; Absil, Emilie; Tessier, Gilles; Coppey-Moisan, Maïté

2008-03-01

We report experimental results on heterodyne holographic microscopy of subwavelength-size gold particles. The apparatus uses continuous green-laser illumination of the metal beads in a total internal reflection configuration for dark-field operation. Detection of the scattered light at the illumination wavelength on a charge-coupled-device array detector enables 3D localization of brownian particles in water.

Measuring the Refractive Index of Bovine Corneal Stromal Cells Using Quantitative Phase Imaging

PubMed Central

Gardner, Steven J.; White, Nick; Albon, Julie; Knupp, Carlo; Kamma-Lorger, Christina S.; Meek, Keith M.

2015-01-01

The cornea is the primary refractive lens in the eye and transmits >90% of incident visible light. It has been suggested that the development of postoperative corneal haze could be due to an increase in light scattering from activated corneal stromal cells. Quiescent keratocytes are thought to produce crystallins that match the refractive index of their cytoplasm to the surrounding extracellular material, reducing the amount of light scattering. To test this, we measured the refractive index (RI) of bovine corneal stromal cells, using quantitative phase imaging of live cells in vitro, together with confocal microscopy. The RI of quiescent keratocytes (RI = 1.381 ± 0.004) matched the surrounding matrix, thus supporting the hypothesis that keratocyte cytoplasm does not scatter light in the normal cornea. We also observed that the RI drops after keratocyte activation (RI = 1.365 ± 0.003), leading to a mismatch with the surrounding intercellular matrix. Theoretical scattering models showed that this mismatch would reduce light transmission in the cornea. We conclude that corneal transparency depends on the matching of refractive indices between quiescent keratocytes and the surrounding tissue, and that after surgery or wounding, the resulting RI mismatch between the activated cells and their surrounds significantly contributes to light scattering. PMID:26488650

Integrated one- and two-photon scanned oblique plane illumination (SOPi) microscopy for rapid volumetric imaging

NASA Astrophysics Data System (ADS)

Kumar, Manish; Kishore, Sandeep; Nasenbeny, Jordan; McLean, David L.; Kozorovitskiy, Yevgenia

2018-05-01

Versatile, sterically accessible imaging systems capable of in vivo rapid volumetric functional and structural imaging deep in the brain continue to be a limiting factor in neuroscience research. Towards overcoming this obstacle, we present integrated one- and two-photon scanned oblique plane illumination (SOPi) microscopy which uses a single front-facing microscope objective to provide light-sheet scanning based rapid volumetric imaging capability at subcellular resolution. Our planar scan-mirror based optimized light-sheet architecture allows for non-distorted scanning of volume samples, simplifying accurate reconstruction of the imaged volume. Integration of both one-photon (1P) and two-photon (2P) light-sheet microscopy in the same system allows for easy selection between rapid volumetric imaging and higher resolution imaging in scattering media. Using SOPi, we demonstrate deep, large volume imaging capability inside scattering mouse brain sections and rapid imaging speeds up to 10 volumes per second in zebrafish larvae expressing genetically encoded fluorescent proteins GFP or GCaMP6s. SOPi flexibility and steric access makes it adaptable for numerous imaging applications and broadly compatible with orthogonal techniques for actuating or interrogating neuronal structure and activity.

Integrated one- and two-photon scanned oblique plane illumination (SOPi) microscopy for rapid volumetric imaging.

PubMed

Kumar, Manish; Kishore, Sandeep; Nasenbeny, Jordan; McLean, David L; Kozorovitskiy, Yevgenia

2018-05-14

Versatile, sterically accessible imaging systems capable of in vivo rapid volumetric functional and structural imaging deep in the brain continue to be a limiting factor in neuroscience research. Towards overcoming this obstacle, we present integrated one- and two-photon scanned oblique plane illumination (SOPi, /sōpī/) microscopy which uses a single front-facing microscope objective to provide light-sheet scanning based rapid volumetric imaging capability at subcellular resolution. Our planar scan-mirror based optimized light-sheet architecture allows for non-distorted scanning of volume samples, simplifying accurate reconstruction of the imaged volume. Integration of both one-photon (1P) and two-photon (2P) light-sheet microscopy in the same system allows for easy selection between rapid volumetric imaging and higher resolution imaging in scattering media. Using SOPi, we demonstrate deep, large volume imaging capability inside scattering mouse brain sections and rapid imaging speeds up to 10 volumes per second in zebrafish larvae expressing genetically encoded fluorescent proteins GFP or GCaMP6s. SOPi's flexibility and steric access makes it adaptable for numerous imaging applications and broadly compatible with orthogonal techniques for actuating or interrogating neuronal structure and activity.

Biophysical interpretation and ex-vivo characterization of scattered light from tumor-associated breast stroma

NASA Astrophysics Data System (ADS)

Laughney, Ashley; Krishnaswamy, Venkat; Schwab, Mary; Wells, Wendy A.; Paulsen, Keith D.; Pogue, Brian W.

2009-02-01

The purpose of this study was to extract scatter parameters related to tissue ultra-structures from freshly excised breast tissue and to assess whether evident changes in scatter across diagnostic categories is primarily influenced by variation in the composition of each tissues subtypes or by physical remodeling of the extra-cellular environment. Pathologists easily distinguish between epithelium, stroma and adipose tissues, so this classification was adopted for macroscopic subtype classification. Micro-sampling reflectance spectroscopy was used to characterize single-backscattered photons from fresh, excised tumors and normal reduction specimens with sub-millimeter resolution. Phase contrast microscopy (sub-micron resolution) was used to characterize forward-scattered light through frozen tissue from the DHMC Tissue Bank, representing normal, benign and malignant breast tissue, sectioned at 10 microns. The packing density and orientation of collagen fibers in the extracellular matrix (ECM) associated with invasive, normal and benign epithelium was evaluated using transmission electron microscopy (TEM). Regions of interest (ROIs) in the H&E stained tissues were identified for analysis, as outlined by a pathologist as the gold standard. We conclude that the scatter parameters associated with tumor specimens (Npatients=6, Nspecimens=13) significantly differs from that of normal reductions (Npatients=6, Nspecimens=10). Further, tissue subtypes may be identified by their scatter spectra at sub-micron resolution. Stromal tissue scatters significantly more than the epithelial cells embedded in its ECM and adipose tissue scatters much less. However, the scatter signature of the stroma at the sub-micron level is not particularly differentiating in terms of a diagnosis.

Application of SEM and EDX in studying biomineralization in plant tissues.

PubMed

He, Honghua; Kirilak, Yaowanuj

2014-01-01

This chapter describes protocols using formalin-acetic acid-alcohol (FAA) to fix plant tissues for studying biomineralization by means of scanning electron microscopy (SEM) and qualitative energy-dispersive X-ray microanalysis (EDX). Specimen preparation protocols for SEM and EDX mainly include fixation, dehydration, critical point drying (CPD), mounting, and coating. Gold-coated specimens are used for SEM imaging, while gold- and carbon-coated specimens are prepared for qualitative X-ray microanalyses separately to obtain complementary information on the elemental compositions of biominerals. During the specimen preparation procedure for SEM, some biominerals may be dislodged or scattered, making it difficult to determine their accurate locations, and light microscopy is used to complement SEM studies. Specimen preparation protocols for light microscopy generally include fixation, dehydration, infiltration and embedding with resin, microtome sectioning, and staining. In addition, microwave processing methods are adopted here to speed up the specimen preparation process for both SEM and light microscopy.

Label-free hyperspectral dark-field microscopy for quantitative scatter imaging

NASA Astrophysics Data System (ADS)

Cheney, Philip; McClatchy, David; Kanick, Stephen; Lemaillet, Paul; Allen, David; Samarov, Daniel; Pogue, Brian; Hwang, Jeeseong

2017-03-01

A hyperspectral dark-field microscope has been developed for imaging spatially distributed diffuse reflectance spectra from light-scattering samples. In this report, quantitative scatter spectroscopy is demonstrated with a uniform scattering phantom, namely a solution of polystyrene microspheres. A Monte Carlo-based inverse model was used to calculate the reduced scattering coefficients of samples of different microsphere concentrations from wavelength-dependent backscattered signal measured by the dark-field microscope. The results are compared to the measurement results from a NIST double-integrating sphere system for validation. Ongoing efforts involve quantitative mapping of scattering and absorption coefficients in samples with spatially heterogeneous optical properties.

Microscopic video observation of capillary vessel systems using diffuse back lighting

NASA Astrophysics Data System (ADS)

Sakai, Minako; Arai, Hiroki; Iwai, Toshiaki

2017-04-01

We have been developing a simple and practical video microscopy system based on absorption spectra of biological substance to perform spectroscopic observation of living tissues. The diffuse backlighting effect is actively used in the developed system, which is generated by multiple light scattering in the tissue. It is demonstrated that the light specularly reflected from the skin surface can be completely suppressed in the microscopic observation and the biological activity of the capillary vessel systems distributed under the skin can be successfully observed. As a result, we can confirm the effectiveness of the video microscopy system using diffuse backlighting and the applicability of our developed system.

Modulated-alignment dual-axis (MAD) confocal microscopy for deep optical sectioning in tissues

PubMed Central

Leigh, Steven Y.; Chen, Ye; Liu, Jonathan T.C.

2014-01-01

A strategy is presented to enable optical-sectioning microscopy with improved contrast and imaging depth using low-power (0.5 - 1 mW) diode laser illumination. This technology combines the inherent strengths of focal-modulation microscopy and dual-axis confocal (DAC) microscopy for rejecting out-of-focus and multiply scattered background light in tissues. The DAC architecture is unique in that it utilizes an intersecting pair of illumination and collection beams to improve the spatial-filtering and optical-sectioning performance of confocal microscopy while focal modulation selectively ‘labels’ in-focus signals via amplitude modulation. Simulations indicate that modulating the spatial alignment of dual-axis beams at a frequency f generates signals from the focal volume of the microscope that are modulated at 2f with minimal modulation of background signals, thus providing nearly an order-of-magnitude improvement in optical-sectioning contrast compared to DAC microscopy alone. Experiments show that 2f lock-in detection enhances contrast and imaging depth within scattering phantoms and fresh tissues. PMID:24940534

Symposium N: Materials and Devices for Thermal-to-Electric Energy Conversion

DTIC Science & Technology

2010-08-24

X - ray diffraction, transmission electron microscopy, scanning electron microscopy, and dynamic light scattering. Thermal conductivity measurements...SEM), X - ray diffraction (XRD) measurements as well as Raman spectroscopy. The results from these techniques indicate a clear modification...was examined by using scanning electron microscope (SEM; HITACHI S-4500 model) attached with an energy dispersive x - ray spectroscopy. The electrical

Development of functional nano-particle layer for highly efficient OLED

NASA Astrophysics Data System (ADS)

Lee, Jae-Hyun; Kim, Min-Hoi; Choi, Haechul; Choi, Yoonseuk

2015-12-01

Organic light emitting diodes (OLEDs) are now widely commercialized in market due to many advantages such as possibility of making thin or flexible devices. Nevertheless there are still several things to obtain the high quality flexible OLEDs, one of the most important issues is the light extraction of the device. It is known that OLEDs have the typical light loss such as the waveguide loss, plasmon absorption loss and internal total reflection. In this paper, we demonstrate the one-step processed light scattering films with aluminum oxide nano-particles and polystyrene matrix composite to achieve highly efficient OLEDs. Optical characteristics and surface roughness of light scattering film was optimized by changing the mixing concentration of Al2O3 nano-particles and investigated with the atomic force microscopy and hazemeter, respectively.

Dark-field optical coherence microscopy

NASA Astrophysics Data System (ADS)

Pache, C.; Villiger, M. L.; Lasser, T.

2010-02-01

Many solutions have been proposed to produce phase quantitative images of biological cell samples. Among these, Spectral Domain Phase Microscopy combines the fast imaging speed and high sensitivity of Optical Coherence Microscopy (OCM) in the Fourier domain with the high phase stability of common-path interferometry. We report on a new illumination scheme for OCM that enhances the sensitivity for backscattered light and detects the weak sample signal, otherwise buried by the signal from specular reflection. With the use of a Bessel-like beam, a dark-field configuration was realized. Sensitivity measurements for three different illumination configurations were performed to compare our method to standard OCM and extended focus OCM. Using a well-defined scattering and reflecting object, we demonstrated an attenuation of -40 dB of the DC-component and a relative gain of 30 dB for scattered light, compared to standard OCM. In a second step, we applied this technique, referred to as dark-field Optical Coherence Microscopy (dfOCM), to living cells. Chinese hamster ovarian cells were applied in a drop of medium on a coverslide. The cells of ~15 μm in diameter and even internal cell structures were visualized in the acquired tomograms.

Raman microspectrometer combined with scattering microscopy and lensless imaging for bacteria identification

NASA Astrophysics Data System (ADS)

Strola, S. A.; Schultz, E.; Allier, C. P.; DesRoches, B.; Lemmonier, J.; Dinten, J.-M.

2013-03-01

In this paper, we report on a compact prototype capable both of lensfree imaging, Raman spectrometry and scattering microscopy from bacteria samples. This instrument allows high-throughput real-time characterization without the need of markers, making it potentially suitable to field label-free biomedical and environmental applications. Samples are illuminated from above with a focused-collimated 532nm laser beam and can be x-y-z scanned. The bacteria detection is based on emerging lensfree imaging technology able to localize cells of interest over a large field-of-view of 24mm2. Raman signal and scattered light are then collected by separate measurement arms simultaneously. In the first arm the emission light is fed by a fiber into a prototype spectrometer, developed by Tornado Spectral System based on Tornado's High Throughput Virtual Slit (HTVS) novel technology. The enhanced light throughput in the spectral region of interest (500-1800 cm-1) reduces Raman acquisition time down to few seconds, thus facilitating experimental protocols and avoiding the bacteria deterioration induced by laser thermal heating. Scattered light impinging in the second arm is collected onto a charge-coupled-device. The reconstructed image allows studying the single bacteria diffraction pattern and their specific structural features. The characterization and identification of different bacteria have been performed to validate and optimize the acquisition system and the component setup. The results obtained demonstrate the benefits of these three techniques combination by providing the precise bacteria localization, their chemical composition and a morphology description. The procedure for a rapid identification of particular pathogen bacteria in a sample is illustrated.

Random-phase metasurfaces at optical wavelengths

NASA Astrophysics Data System (ADS)

Pors, Anders; Ding, Fei; Chen, Yiting; Radko, Ilya P.; Bozhevolnyi, Sergey I.

2016-06-01

Random-phase metasurfaces, in which the constituents scatter light with random phases, have the property that an incident plane wave will diffusely scatter, hereby leading to a complex far-field response that is most suitably described by statistical means. In this work, we present and exemplify the statistical description of the far-field response, particularly highlighting how the response for polarised and unpolarised light might be alike or different depending on the correlation of scattering phases for two orthogonal polarisations. By utilizing gap plasmon-based metasurfaces, consisting of an optically thick gold film overlaid by a subwavelength thin glass spacer and an array of gold nanobricks, we design and realize random-phase metasurfaces at a wavelength of 800 nm. Optical characterisation of the fabricated samples convincingly demonstrates the diffuse scattering of reflected light, with statistics obeying the theoretical predictions. We foresee the use of random-phase metasurfaces for camouflage applications and as high-quality reference structures in dark-field microscopy, while the control of the statistics for polarised and unpolarised light might find usage in security applications. Finally, by incorporating a certain correlation between scattering by neighbouring metasurface constituents new types of functionalities can be realised, such as a Lambertian reflector.

Direct wavefront sensing for high-resolution in vivo imaging in scattering tissue

PubMed Central

Wang, Kai; Sun, Wenzhi; Richie, Christopher T.; Harvey, Brandon K.; Betzig, Eric; Ji, Na

2015-01-01

Adaptive optics by direct imaging of the wavefront distortions of a laser-induced guide star has long been used in astronomy, and more recently in microscopy to compensate for aberrations in transparent specimens. Here we extend this approach to tissues that strongly scatter visible light by exploiting the reduced scattering of near-infrared guide stars. The method enables in vivo two-photon morphological and functional imaging down to 700 μm inside the mouse brain. PMID:26073070

Role of small oligomers on the amyloidogenic aggregation free-energy landscape.

PubMed

He, Xianglan; Giurleo, Jason T; Talaga, David S

2010-01-08

We combine atomic-force-microscopy particle-size-distribution measurements with earlier measurements on 1-anilino-8-naphthalene sulfonate, thioflavin T, and dynamic light scattering to develop a quantitative kinetic model for the aggregation of beta-lactoglobulin into amyloid. We directly compare our simulations to the population distributions provided by dynamic light scattering and atomic force microscopy. We combine species in the simulation according to structural type for comparison with fluorescence fingerprint results. The kinetic model of amyloidogenesis leads to an aggregation free-energy landscape. We define the roles of and propose a classification scheme for different oligomeric species based on their location in the aggregation free-energy landscape. We relate the different types of oligomers to the amyloid cascade hypothesis and the toxic oligomer hypothesis for amyloid-related diseases. We discuss existing kinetic mechanisms in terms of the different types of oligomers. We provide a possible resolution to the toxic oligomer-amyloid coincidence.

Label-free optical imaging of membrane patches for atomic force microscopy

PubMed Central

Churnside, Allison B.; King, Gavin M.; Perkins, Thomas T.

2010-01-01

In atomic force microscopy (AFM), finding sparsely distributed regions of interest can be difficult and time-consuming. Typically, the tip is scanned until the desired object is located. This process can mechanically or chemically degrade the tip, as well as damage fragile biological samples. Protein assemblies can be detected using the back-scattered light from a focused laser beam. We previously used back-scattered light from a pair of laser foci to stabilize an AFM. In the present work, we integrate these techniques to optically image patches of purple membranes prior to AFM investigation. These rapidly acquired optical images were aligned to the subsequent AFM images to ~40 nm, since the tip position was aligned to the optical axis of the imaging laser. Thus, this label-free imaging efficiently locates sparsely distributed protein assemblies for subsequent AFM study while simultaneously minimizing degradation of the tip and the sample. PMID:21164738

Spin waves in micro-structured yttrium iron garnet nanometer-thick films

DOE PAGES

Jungfleisch, Matthias B.; Zhang, Wei; Jiang, Wanjun; ...

2015-03-24

Here, we investigated the spin-wave propagation in a micro-structured yttrium iron garnet waveguide of 40 nm thickness. Utilizing spatially-resolved Brillouin light scattering microscopy, an exponential decay of the spinwave amplitude of 10 μm was observed. This leads to an estimated Gilbert damping constant of α = (8.79 ± 0.73) x 10 $-$4, which is larger than damping values obtained through ferromagnetic resonance measurements in unstructured films. Furthermore, we compared the theoretically calculated spatial interference of waveguide modes to the spin-wave pattern observed experimentally by means of Brillouin light scattering spectroscopy.

Opto-electrochemical In Situ Monitoring of the Cathodic Formation of Single Cobalt Nanoparticles.

PubMed

Brasiliense, Vitor; Clausmeyer, Jan; Dauphin, Alice L; Noël, Jean-Marc; Berto, Pascal; Tessier, Gilles; Schuhmann, Wolfgang; Kanoufi, Fréderic

2017-08-21

Single-particle electrochemistry at a nanoelectrode is explored by dark-field optical microscopy. The analysis of the scattered light allows in situ dynamic monitoring of the electrodeposition of single cobalt nanoparticles down to a radius of 65 nm. Larger sub-micrometer particles are directly sized optically by super-localization of the edges and the scattered light contains complementary information concerning the particle redox chemistry. This opto-electrochemical approach is used to derive mechanistic insights about electrocatalysis that are not accessible from single-particle electrochemistry. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Measurement of particle size distribution in mammalian cells in vitro by use of polarized light spectroscopy

NASA Astrophysics Data System (ADS)

Bartlett, Matthew; Huang, George; Larcom, Lyndon; Jiang, Huabei

2004-02-01

We demonstrate the feasibility of measuring the particle size distribution (PSD) of internal cell structures in vitro. We use polarized light spectroscopy to probe the internal morphology of mammalian breast cancer (MCF7) and cervical cancer (Siha) cells. We find that graphing the least-squared error versus the scatterer size provides insight into cell scattering. A nonlinear optimization scheme is used to determine the PSD iteratively. The results suggest that 2-μm particles (possibly the mitochondria) contribute most to the scattering. Other subcellular structures, such as the nucleoli and the nucleus, may also contribute significantly. We reconstruct the PSD of the mitochondria, as verified by optical microscopy. We also demonstrate the angle dependence of the PSD.

A high throughput spectral image microscopy system

NASA Astrophysics Data System (ADS)

Gesley, M.; Puri, R.

2018-01-01

A high throughput spectral image microscopy system is configured for rapid detection of rare cells in large populations. To overcome flow cytometry rates and use of fluorophore tags, a system architecture integrates sample mechanical handling, signal processors, and optics in a non-confocal version of light absorption and scattering spectroscopic microscopy. Spectral images with native contrast do not require the use of exogeneous stain to render cells with submicron resolution. Structure may be characterized without restriction to cell clusters of differentiation.

Characteristics of angular cross correlations studied by light scattering from two-dimensional microsphere films

NASA Astrophysics Data System (ADS)

Schroer, M. A.; Gutt, C.; Grübel, G.

2014-07-01

Recently the analysis of scattering patterns by angular cross-correlation analysis (CCA) was introduced to reveal the orientational order in disordered samples with special focus to future applications on x-ray free-electron laser facilities. We apply this CCA approach to ultra-small-angle light-scattering data obtained from two-dimensional monolayers of microspheres. The films were studied in addition by optical microscopy. This combined approach allows to calculate the cross-correlations of the scattering patterns, characterized by the orientational correlation function Ψl(q), as well as to obtain the real-space structure of the monolayers. We show that CCA is sensitive to the orientational order of monolayers formed by the microspheres which are not directly visible from the scattering patterns. By mixing microspheres of different radii the sizes of ordered monolayer domains is reduced. For these samples it is shown that Ψl(q) quantitatively describes the degree of hexagonal order of the two-dimensional films. The experimental CCA results are compared with calculations based on the microscopy images. Both techniques show qualitatively similar features. Differences can be attributed to the wave-front distortion of the laser beam in the experiment. This effect is discussed by investigating the effect of different wave fronts on the cross-correlation analysis results. The so-determined characteristics of the cross-correlation analysis will be also relevant for future x-ray-based studies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bunkin, N. F., E-mail: nbunkin@kapella.gpi.ru; Suyazov, N. V.; Shkirin, A. V.

Experiments using phase-modulation interference microscopy and Mueller-matrix polarimetry show that double-distilled water free of foreign solid matter contains macroscopic light scatterers. Numerical calculations suggest that these scatterers can be represented as micrometer-size clusters of polydisperse air bubbles with effective radii between 70 and 90 nm. The fractal dimension of the clusters varies from 2.4 to 2.8, and their concentration is on the order of 10{sup 6} cm{sup -3}.

Optical Interactions at Randomly Rough Surfaces

DTIC Science & Technology

2003-03-10

frequency range. The design of a random surface that acts as a Lambertian diffuser, especially in the infrared region of the optical spectrum, is...FTIR grazing angle microscopy. Recently, an experimental study was performed of the far-field scattering at small grazing angles, especially the enhanced...a specular component in the scattered light, in this frequency range. The design of a random surface that acts as a Lambertian diffuser, especially in

Multi-contrast light profile microscopy for the depth-resolved imaging of the properties of multi-ply thin films.

PubMed

Power, J F

2009-06-01

Light profile microscopy (LPM) is a direct method for the spectral depth imaging of thin film cross-sections on the micrometer scale. LPM uses a perpendicular viewing configuration that directly images a source beam propagated through a thin film. Images are formed in dark field contrast, which is highly sensitive to subtle interfacial structures that are invisible to reference methods. The independent focusing of illumination and imaging systems allows multiple registered optical sources to be hosted on a single platform. These features make LPM a powerful multi-contrast (MC) imaging technique, demonstrated in this work with six modes of imaging in a single instrument, based on (1) broad-band elastic scatter; (2) laser excited wideband luminescence; (3) coherent elastic scatter; (4) Raman scatter (three channels with RGB illumination); (5) wavelength resolved luminescence; and (6) spectral broadband scatter, resolved in immediate succession. MC-LPM integrates Raman images with a wider optical and morphological picture of the sample than prior art microprobes. Currently, MC-LPM resolves images at an effective spectral resolution better than 9 cm(-1), at a spatial resolution approaching 1 microm, with optics that operate in air at half the maximum numerical aperture of the prior art microprobes.

Brain Slice Staining and Preparation for Three-Dimensional Super-Resolution Microscopy

PubMed Central

German, Christopher L.; Gudheti, Manasa V.; Fleckenstein, Annette E.; Jorgensen, Erik M.

2018-01-01

Localization microscopy techniques – such as photoactivation localization microscopy (PALM), fluorescent PALM (FPALM), ground state depletion (GSD), and stochastic optical reconstruction microscopy (STORM) – provide the highest precision for single molecule localization currently available. However, localization microscopy has been largely limited to cell cultures due to the difficulties that arise in imaging thicker tissue sections. Sample fixation and antibody staining, background fluorescence, fluorophore photoinstability, light scattering in thick sections, and sample movement create significant challenges for imaging intact tissue. We have developed a sample preparation and image acquisition protocol to address these challenges in rat brain slices. The sample preparation combined multiple fixation steps, saponin permeabilization, and tissue clarification. Together, these preserve intracellular structures, promote antibody penetration, reduce background fluorescence and light scattering, and allow acquisition of images deep in a 30 μm thick slice. Image acquisition challenges were resolved by overlaying samples with a permeable agarose pad and custom-built stainless steel imaging adapter, and sealing the imaging chamber. This approach kept slices flat, immobile, bathed in imaging buffer, and prevented buffer oxidation during imaging. Using this protocol, we consistently obtained single molecule localizations of synaptic vesicle and active zone proteins in three-dimensions within individual synaptic terminals of the striatum in rat brain slices. These techniques may be easily adapted to the preparation and imaging of other tissues, substantially broadening the application of super-resolution imaging. PMID:28924666

Low-temperature fabrication and characterization of a symmetric hybrid organic–inorganic slab waveguide for evanescent light microscopy

NASA Astrophysics Data System (ADS)

Agnarsson, Björn; Mapar, Mokhtar; Sjöberg, Mattias; Alizadehheidari, Mohammadreza; Höök, Fredrik

2018-06-01

Organic and inorganic solid materials form the building blocks for most of today’s high-technological instruments and devices. However, challenges related to dissimilar material properties have hampered the synthesis of thin-film devices comprised of both organic and inorganic films. We here give a detailed description of a carefully optimized processing protocol used for the construction of a three-layered hybrid organic–inorganic waveguide-chip intended for combined scattering and fluorescence evanescent-wave microscopy in aqueous environments using conventional upright microscopes. An inorganic core layer (SiO2 or Si3N4), embedded symmetrically in an organic cladding layer (CYTOP), aids simple, yet efficient in-coupling of light, and since the organic cladding layer is refractive index matched to water, low stray-light (background) scattering of the propagating light is ensured. Another major advantage is that the inorganic core layer makes the chip compatible with multiple well-established surface functionalization schemes that allows for a broad range of applications, including detection of single lipid vesicles, metallic nanoparticles or cells in complex environments, either label-free—by direct detection of scattered light—or by use of fluorescence excitation and emission. Herein, focus is put on a detailed description of the fabrication of the waveguide-chip, together with a fundamental characterization of its optical properties and performance, particularly in comparison with conventional epi illumination. Quantitative analysis of images obtained from both fluorescence and scattering intensities from surface-immobilized polystyrene nanoparticles in suspensions of different concentrations, revealed enhanced signal-to-noise and signal-to-background ratios for the waveguide illumination compared to the epi-illumination.

Do protein crystals nucleate within dense liquid clusters?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maes, Dominique, E-mail: dommaes@vub.ac.be; Vorontsova, Maria A.; Potenza, Marco A. C.

2015-06-27

The evolution of protein-rich clusters and nucleating crystals were characterized by dynamic light scattering (DLS), confocal depolarized dynamic light scattering (cDDLS) and depolarized oblique illumination dark-field microscopy. Newly nucleated crystals within protein-rich clusters were detected directly. These observations indicate that the protein-rich clusters are locations for crystal nucleation. Protein-dense liquid clusters are regions of high protein concentration that have been observed in solutions of several proteins. The typical cluster size varies from several tens to several hundreds of nanometres and their volume fraction remains below 10{sup −3} of the solution. According to the two-step mechanism of nucleation, the protein-rich clustersmore » serve as locations for and precursors to the nucleation of protein crystals. While the two-step mechanism explained several unusual features of protein crystal nucleation kinetics, a direct observation of its validity for protein crystals has been lacking. Here, two independent observations of crystal nucleation with the proteins lysozyme and glucose isomerase are discussed. Firstly, the evolutions of the protein-rich clusters and nucleating crystals were characterized simultaneously by dynamic light scattering (DLS) and confocal depolarized dynamic light scattering (cDDLS), respectively. It is demonstrated that protein crystals appear following a significant delay after cluster formation. The cDDLS correlation functions follow a Gaussian decay, indicative of nondiffusive motion. A possible explanation is that the crystals are contained inside large clusters and are driven by the elasticity of the cluster surface. Secondly, depolarized oblique illumination dark-field microscopy reveals the evolution from liquid clusters without crystals to newly nucleated crystals contained in the clusters to grown crystals freely diffusing in the solution. Collectively, the observations indicate that the protein-rich clusters in lysozyme and glucose isomerase solutions are locations for crystal nucleation.« less

High-throughput isotropic mapping of whole mouse brain using multi-view light-sheet microscopy

NASA Astrophysics Data System (ADS)

Nie, Jun; Li, Yusha; Zhao, Fang; Ping, Junyu; Liu, Sa; Yu, Tingting; Zhu, Dan; Fei, Peng

2018-02-01

Light-sheet fluorescence microscopy (LSFM) uses an additional laser-sheet to illuminate selective planes of the sample, thereby enabling three-dimensional imaging at high spatial-temporal resolution. These advantages make LSFM a promising tool for high-quality brain visualization. However, even by the use of LSFM, the spatial resolution remains insufficient to resolve the neural structures across a mesoscale whole mouse brain in three dimensions. At the same time, the thick-tissue scattering prevents a clear observation from the deep of brain. Here we use multi-view LSFM strategy to solve this challenge, surpassing the resolution limit of standard light-sheet microscope under a large field-of-view (FOV). As demonstrated by the imaging of optically-cleared mouse brain labelled with thy1-GFP, we achieve a brain-wide, isotropic cellular resolution of 3μm. Besides the resolution enhancement, multi-view braining imaging can also recover complete signals from deep tissue scattering and attenuation. The identification of long distance neural projections across encephalic regions can be identified and annotated as a result.

Monitoring adsorption of gold nanoparticles on gold nanodisk array using dark-field hyperspectral microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zhao, Fusheng; Zenasni, Oussama; Li, Jingting; Shih, Wei-Chuan

2017-02-01

Localized surface plasmon resonance (LSPR) arises from the interaction of light with noble metal nanoparticles, which induces a collective oscillation in the free electrons. The size and shape of the metallic nanostructure significantly impact LSPR frequency and strength. Nanoplasmonic sensor has become a recent research focus due to its significant signal enhancement and robust signal transduction measured by extinction spectroscopy, fluorescence, Raman scattering, and absorption spectroscopy. Dark-field microscopy, in contrast, reports the scattered photons after light-matter interactions. In this case, the nanoparticles can be understood as dipole radiators whose free electrons oscillate in concert. Coupled with spectroscopy, this platform allows the collection of plasmonically scattered spectra from gold nanoparticles. Plasmonic coupling between electron-beam lithography patterned gold nanodisks (AuND) and colloidal gold nanoparticles (AuNP) can change the plasmonic resonance of the original entities, and can be effectively studied by dark-field hyperspectral microscopy. Typically, a pronounced redshift can be observed when plasmonic coupling occurs. When these nano-entities are functionalized with interactive surface moieties, biochemistry and molecular processes can be studied. In this paper, we will present the capability of assessing the process of immobilizing streptavidin-functionalized AuNPs on an array of biotin-terminated AuNDs. By monitoring changes in the LSPR band of AuNDs, we are able to evaluate similar processes in other molecular systems. In addition, plasmon coupling induced scattering intensity variations can be measured by an electron-multiplied charge-coupled device camera for rapid in situ monitoring. This method can potentially be useful in studying dynamic biophysical and biochemical processes in situ.

Effect of calcium concentration on the structure of casein micelles in thin films.

PubMed

Müller-Buschbaum, P; Gebhardt, R; Roth, S V; Metwalli, E; Doster, W

2007-08-01

The structure of thin casein films prepared with spin-coating is investigated as a function of the calcium concentration. Grazing incidence small-angle x-ray scattering and atomic force microscopy are used to probe the micelle structure. For comparison, the corresponding casein solutions are investigated with dynamic light-scattering experiments. In the thin films with added calcium three types of casein structures, aggregates, micelles, and mini-micelles, are observed in coexistence with atomic force microscopy and grazing incidence small-angle x-ray scattering. With increasing calcium concentration, the size of the aggregates strongly increases, while the size of micelles slightly decreases and the size of the mini-micelles increases. This effect is explained in the framework of the particle-stabilizing properties of the hairy layer of kappa-casein surrounding the casein micelles.

Effect of Calcium Concentration on the Structure of Casein Micelles in Thin Films

PubMed Central

Müller-Buschbaum, P.; Gebhardt, R.; Roth, S. V.; Metwalli, E.; Doster, W.

2007-01-01

The structure of thin casein films prepared with spin-coating is investigated as a function of the calcium concentration. Grazing incidence small-angle x-ray scattering and atomic force microscopy are used to probe the micelle structure. For comparison, the corresponding casein solutions are investigated with dynamic light-scattering experiments. In the thin films with added calcium three types of casein structures, aggregates, micelles, and mini-micelles, are observed in coexistence with atomic force microscopy and grazing incidence small-angle x-ray scattering. With increasing calcium concentration, the size of the aggregates strongly increases, while the size of micelles slightly decreases and the size of the mini-micelles increases. This effect is explained in the framework of the particle-stabilizing properties of the hairy layer of κ-casein surrounding the casein micelles. PMID:17496032

Dynamic light scattering microscopy

NASA Astrophysics Data System (ADS)

Dzakpasu, Rhonda

An optical microscope technique, dynamic light scattering microscopy (DLSM) that images dynamically scattered light fluctuation decay rates is introduced. Using physical optics we show theoretically that within the optical resolution of the microscope, relative motions between scattering centers are sufficient to produce significant phase variations resulting in interference intensity fluctuations in the image plane. The time scale for these intensity fluctuations is predicted. The spatial coherence distance defining the average distance between constructive and destructive interference in the image plane is calculated and compared with the pixel size. We experimentally tested DLSM on polystyrene latex nanospheres and living macrophage cells. In order to record these rapid fluctuations, on a slow progressive scan CCD camera, we used a thin laser line of illumination on the sample such that only a single column of pixels in the CCD camera is illuminated. This allowed the use of the rate of the column-by-column readout transfer process as the acquisition rate of the camera. This manipulation increased the data acquisition rate by at least an order of magnitude in comparison to conventional CCD cameras rates defined by frames/s. Analysis of the observed fluctuations provides information regarding the rates of motion of the scattering centers. These rates, acquired from each position on the sample are used to create a spatial map of the fluctuation decay rates. Our experiments show that with this technique, we are able to achieve a good signal-to-noise ratio and can monitor fast intensity fluctuations, on the order of milliseconds. DLSM appears to provide dynamic information about fast motions within cells at a sub-optical resolution scale and provides a new kind of spatial contrast.

Light Scattering Analysis of Irregularly Shaped Dust Particles: A Study Using 3-Dimensional Reconstructions from Focused Ion-Beam (FIB) Tomography and Q-Space Analysis

NASA Astrophysics Data System (ADS)

Ortiz-Montalvo, D. L.; Conny, J. M.

2017-12-01

We study the scattering properties of irregularly shaped ambient dust particles. The way in which they scatter and absorb light has implications for aerosol optical remote sensing and aerosol radiative forcing applications. However, understanding light scattering and absorption by non-spherical particles can be very challenging. We used focused ion-beam scanning electron microscopy and energy-dispersive x-ray spectroscopy (FIB-SEM-EDS) to reconstruct three-dimensional (3-D) configurations of dust particles collected from urban and Asian sources. The 3-D reconstructions were then used in a discrete dipole approximation method (DDA) to determine their scattering properties for a range of shapes, sizes, and refractive indices. Scattering properties where obtained using actual-shapes of the particles, as well as, (theoretical) equivalently-sized geometrical shapes like spheres, ellipsoids, cubes, rectangular prisms, and tetrahedrons. We use Q-space analysis to interpret the angular distribution of the scattered light obtained for each particle. Q-space analysis has been recently used to distinguish scattering by particles of different shapes, and it involves plotting the scattered intensity versus the scattering wave vector (q or qR) on a log-log scale, where q = 2ksin(θ/2), k = 2π/λ, and R = particle effective radius. Results from a limited number of particles show that when Q-space analysis is applied, common patterns appear that agree with previous Q-space studies done on ice crystals and other irregularly shaped particles. More specifically, we found similar Q-space regimes including a forward scattering regime of constant intensity when qR < 1, followed by the Guinier regime when qR ≈ 1, which is then followed by a complex power law regime with a -3 slope regime, a transition regime, and then a -4 slope regime. Currently, Q-space comparisons between actual- and geometric shapes are underway with the objective of determining which geometric shape best represents the angular distribution and magnitude of the scattered light. Current work also focuses on the effects of the imaginary part of the refractive index on the light scattering of our dust particles.

Accurate Modeling of Dark-Field Scattering Spectra of Plasmonic Nanostructures.

PubMed

Jiang, Liyong; Yin, Tingting; Dong, Zhaogang; Liao, Mingyi; Tan, Shawn J; Goh, Xiao Ming; Allioux, David; Hu, Hailong; Li, Xiangyin; Yang, Joel K W; Shen, Zexiang

2015-10-27

Dark-field microscopy is a widely used tool for measuring the optical resonance of plasmonic nanostructures. However, current numerical methods for simulating the dark-field scattering spectra were carried out with plane wave illumination either at normal incidence or at an oblique angle from one direction. In actual experiments, light is focused onto the sample through an annular ring within a range of glancing angles. In this paper, we present a theoretical model capable of accurately simulating the dark-field light source with an annular ring. Simulations correctly reproduce a counterintuitive blue shift in the scattering spectra from gold nanodisks with a diameter beyond 140 nm. We believe that our proposed simulation method can be potentially applied as a general tool capable of simulating the dark-field scattering spectra of plasmonic nanostructures as well as other dielectric nanostructures with sizes beyond the quasi-static limit.

Enhanced dye-sensitized solar cells performance using anatase TiO2 mesocrystals with the Wulff construction of nearly 100% exposed {101} facets as effective light scattering layer.

PubMed

Zhou, Yu; Wang, Xinyu; Wang, Hai; Song, Yeping; Fang, Liang; Ye, Naiqing; Wang, Linjiang

2014-03-28

Anatase TiO2 mesocrystals with a Wulff construction of nearly 100% exposed {101} facets were successfully synthesized by a facile, green solvothermal method. Their morphology, and crystal structure are characterized by powder X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). Accordingly, a possible growth mechanism of anatase TiO2 mesocrystals is elucidated in this work. The as-prepared single anatase TiO2 mesocrystal's mean center diameter is about 500 nm, and the length is about 1 μm. They exhibit high light adsorbance, high reflectance and low transmittance in the visible region due to the unique nearly 100% exposed {101} facets. When utilized as the scattering layer in dye-sensitized solar cells (DSSCs), such mesocrystals effectively enhanced light harvesting and led to an increase of the photocurrent of the DSSCs. As a result, by using an anatase TiO2 mesocrystal film as a scattering overlayer of a compact commercial P25 TiO2 nanoparticle film, the double layered DSSCs show a power conversion efficiency of 7.23%, indicating a great improvement compared to the DSSCs based on a P25 film (5.39%) and anatase TiO2 mesocrystal films, respectively. The synergetic effect of P25 and the mesocrystals as well as the latters unique feature of a Wulff construction of nearly 100% exposed (101) facets are probably responsible for the enhanced photoelectrical performance. In particular, we explore the possibility of the low surface area and exposed {101} facets as an efficient light scattering layer of DSSCs. Our work suggests that anatase TiO2 mesocrystals with the Wulff construction is a promising candidate as a superior scattering material for high-performance DSSCs.

Total internal reflection and dynamic light scattering microscopy of gels

NASA Astrophysics Data System (ADS)

Gregor, Brian F.

Two different techniques which apply optical microscopy in novel ways to the study of biological systems and materials were built and applied to several samples. The first is a system for adapting the well-known technique of dynamic light scattering (DLS) to an optical microscope. This can detect and scatter light from very small volumes, as compared to standard DLS which studies light scattering from volumes 1000x larger. The small scattering volume also allows for the observation of nonergodic dynamics in appropriate samples. Porcine gastric mucin (PGM) forms a gel at low pH which lines the epithelial cell layer and acts as a protective barrier against the acidic stomach environment. The dynamics and microscopic viscosity of PGM at different pH levels is studied using polystyrene microspheres as tracer particles. The microscopic viscosity and microrheological properties of the commercial basement membrane Matrigel are also studied with this instrument. Matrigel is frequently used to culture cells and its properties remain poorly determined. Well-characterized and purely synthetic Matrigel substitutes will need to have the correct rheological and morphological characteristics. The second instrument designed and built is a microscope which uses an interferometry technique to achieve an improvement in resolution 2.5x better in one dimension than the Abbe diffraction limit. The technique is based upon the interference of the evanescent field generated on the surface of a prism by a laser in a total internal reflection geometry. The enhanced resolution is demonstrated with fluorescent samples. Additionally. Raman imaging microscopy is demonstrated using the evanescent field in resonant and non-resonant samples, although attempts at applying the enhanced resolution technique to the Raman images were ultimately unsuccessful. Applications of this instrument include high resolution imaging of cell membranes and macroscopic structures in gels and proteins. Finally, a third section incorporating previous research on simulations of complex fluids is included. Two dimensional simulations of oil, water, and surfactant mixtures were computed with a lattice gas method. The simulated systems were randomly mixed and then the temperature was quenched to a predetermined point. Spontaneous micellization is observed for a narrow range of temperature quenches, and the overall growth rate of macroscopic structure is found to follow a Vogel-Fulcher growth law.

Characterizing string-of-pearls colloidal silica by multidetector hydrodynamic chromatography and comparison to multidetector size-exclusion chromatography, off-line multiangle static light scattering, and transmission electron microscopy.

PubMed

Brewer, Amandaa K; Striegel, André M

2011-04-15

The string-of-pearls-type morphology is ubiquitous, manifesting itself variously in proteins, vesicles, bacteria, synthetic polymers, and biopolymers. Characterizing the size and shape of analytes with such morphology, however, presents a challenge, due chiefly to the ease with which the "strings" can be broken during chromatographic analysis or to the paucity of information obtained from the benchmark microscopy and off-line light scattering methods. Here, we address this challenge with multidetector hydrodynamic chromatography (HDC), which has the ability to determine, simultaneously, the size, shape, and compactness and their distributions of string-of-pearls samples. We present the quadruple-detector HDC analysis of colloidal string-of-pearls silica, employing static multiangle and quasielastic light scattering, differential viscometry, and differential refractometry as detection methods. The multidetector approach shows a sample that is broadly polydisperse in both molar mass and size, with strings ranging from two to five particles, but which also contains a high concentration of single, unattached "pearls". Synergistic combination of the various size parameters obtained from the multiplicity of detectors employed shows that the strings with higher degrees of polymerization have a shape similar to the theory-predicted shape of a Gaussian random coil chain of nonoverlapping beads, while the strings with lower degrees of polymerization have a prolate ellipsoidal shape. The HDC technique is contrasted experimentally with multidetector size-exclusion chromatography, where, even under extremely gentle conditions, the strings still degraded during analysis. Such degradation is shown to be absent in HDC, as evidenced by the fact that the molar mass and radius of gyration obtained by HDC with multiangle static light scattering detection (HDC/MALS) compare quite favorably to those determined by off-line MALS analysis under otherwise identical conditions. The multidetector HDC results were also comparable to those obtained by transmission electron microscopy (TEM). Unlike off-line MALS or TEM, however, multidetector HDC is able to provide complete particle analysis based on the molar mass, size, shape, and compactness and their distributions for the entire sample population in less than 20 min. © 2011 American Chemical Society

Integrated pillar scatterers for speeding up classification of cell holograms.

PubMed

Lugnan, Alessio; Dambre, Joni; Bienstman, Peter

2017-11-27

The computational power required to classify cell holograms is a major limit to the throughput of label-free cell sorting based on digital holographic microscopy. In this work, a simple integrated photonic stage comprising a collection of silica pillar scatterers is proposed as an effective nonlinear mixing interface between the light scattered by a cell and an image sensor. The light processing provided by the photonic stage allows for the use of a simple linear classifier implemented in the electric domain and applied on a limited number of pixels. A proof-of-concept of the presented machine learning technique, which is based on the extreme learning machine (ELM) paradigm, is provided by the classification results on samples generated by 2D FDTD simulations of cells in a microfluidic channel.

Size fractionation and size characterization of nanoemulsions of lipid droplets and large unilamellar lipid vesicles by asymmetric-flow field-flow fractionation/multi-angle light scattering and dynamic light scattering.

PubMed

Vezočnik, Valerija; Rebolj, Katja; Sitar, Simona; Ota, Katja; Tušek-Žnidarič, Magda; Štrus, Jasna; Sepčić, Kristina; Pahovnik, David; Maček, Peter; Žagar, Ema

2015-10-30

Asymmetric-flow field-flow fractionation technique coupled to a multi-angle light-scattering detector (AF4-MALS) was used together with dynamic light-scattering (DLS) in batch mode and transmission electron microscopy (TEM) to study the size characteristics of the trioleoylglycerol lipid droplets covered by a monolayer of sphingomyelin and cholesterol, in water phase. These lipid droplet nanoemulsions (LD) were formed by ultrasonication. In parallel, the size characteristics of large unilamellar lipid vesicles (LUV) prepared by extrusion and composed of sphingomyelin and cholesterol were determined. LD and LUV were prepared at two different molar ratios (1/1, 4/1) of sphingomyelin and cholesterol. In AF4-MALS, various cross-flow conditions and mobile phase compositions were tested to optimize the separation of LD or LUV particles. The particle radii, R, as well as the root-mean-square radii, Rrms, of LD and LUV were determined by AF4-MALS, whereas the hydrodynamic radii, Rh, were obtained by DLS. TEM visualization revealed round shape particles of LD and LUV. Copyright © 2015 Elsevier B.V. All rights reserved.

Staining-free malaria diagnostics by multispectral and multimodality light-emitting-diode microscopy

NASA Astrophysics Data System (ADS)

Merdasa, Aboma; Brydegaard, Mikkel; Svanberg, Sune; Zoueu, Jeremie T.

2013-03-01

We report an accurate optical differentiation technique between healthy and malaria-infected erythrocytes by quasi-simultaneous measurements of transmittance, reflectance, and scattering properties of unstained blood smears using a multispectral and multimode light-emitting diode microscope. We propose a technique for automated imaging, identification, and counting of malaria-infected erythrocytes for real-time and cost-effective parasitaemia diagnosis as an effective alternative to the manual screening of stained blood smears, now considered to be the gold standard in malaria diagnosis. We evaluate the performance of our algorithm against manual estimations of an expert and show a spectrally resolved increased scattering from malaria-infected blood cells.

Light-sheet generation in inhomogeneous media using self-reconstructing beams and the STED-principle.

PubMed

Gohn-Kreuz, Cristian; Rohrbach, Alexander

2016-03-21

Self-reconstruction of Bessel beams in inhomogeneous media is beneficial in light-sheet based microscopy. Although the beam's ring system enables propagation stability, the resulting image contrast is reduced. Here, we show that by a combination of two self-reconstructing beams with different orbital angular momenta it is possible to inhibit fluorescence from the ring system by using stimulated emission depletion (STED) even in strongly scattering media. Our theoretical study shows that the remaining fluorescence γ depends non-linearly on the beams' relative radial and orbital angular momenta. For various scattering media we demonstrate that γ remains remarkably stable over long beam propagation distances.

Spectral analysis of scattered light from flowers' petals

NASA Astrophysics Data System (ADS)

Ozawa, Atsumi; Uehara, Tomomi; Sekiguchi, Fumihiko; Imai, Hajime

2009-07-01

A new method was developed for studying absorption characteristics of opaque samples based on the light scattering spectroscopy. Measurements were made in white, red and violet petals of Petunia hybrida, and gave the absorption spectra in a non-destructive manner without damaging the cell structures of the petal. The red petal has absorption peak at 550 nm and the violet has three absorption peaks: at 450, 670, and 550 nm. The results were discussed in correlation with the microscopic cell structures of the petal observed with optical microscope and transmission electron microscopy (TEM). Only the cells placed in the surface have the pigments giving the color of the petal.

Numerical Simulation of Partially-Coherent Broadband Optical Imaging Using the FDTD Method

PubMed Central

Çapoğlu, İlker R.; White, Craig A.; Rogers, Jeremy D.; Subramanian, Hariharan; Taflove, Allen; Backman, Vadim

2012-01-01

Rigorous numerical modeling of optical systems has attracted interest in diverse research areas ranging from biophotonics to photolithography. We report the full-vector electromagnetic numerical simulation of a broadband optical imaging system with partially-coherent and unpolarized illumination. The scattering of light from the sample is calculated using the finite-difference time-domain (FDTD) numerical method. Geometrical optics principles are applied to the scattered light to obtain the intensity distribution at the image plane. Multilayered object spaces are also supported by our algorithm. For the first time, numerical FDTD calculations are directly compared to and shown to agree well with broadband experimental microscopy results. PMID:21540939

Is the nuclear refractive index lower than cytoplasm? Validation of phase measurements and implications for light scattering technologies.

PubMed

Steelman, Zachary A; Eldridge, Will J; Weintraub, Jacob B; Wax, Adam

2017-12-01

The refractive index (RI) of biological materials is a fundamental parameter for the optical characterization of living systems. Numerous light scattering technologies are grounded in a quantitative knowledge of the refractive index at cellular and subcellular scales. Recent work in quantitative phase microscopy (QPM) has called into question the widely held assumption that the index of the cell nucleus is greater than that of the cytoplasm, a result which disagrees with much of the current literature. In this work, we critically examine the measurement of the nuclear and whole-cell refractive index using QPM, validating that nuclear refractive index is lower than that of cytoplasm in four diverse cell lines and their corresponding isolated nuclei. We further examine Mie scattering and phase-wrapping as potential sources of error in these measurements, finding they have minimal impact. Finally, we use simulation to examine the effects of incorrect RI assumptions on nuclear morphology measurements using angle-resolved scattering information. Despite an erroneous assumption of the nuclear refractive index, accurate measurement of nuclear morphology was maintained, suggesting that light scattering modalities remain effective. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Combining gas-phase electrophoretic mobility molecular analysis (GEMMA), light scattering, field flow fractionation and cryo electron microscopy in a multidimensional approach to characterize liposomal carrier vesicles

PubMed Central

Gondikas, Andreas; von der Kammer, Frank; Hofmann, Thilo; Marchetti-Deschmann, Martina; Allmaier, Günter; Marko-Varga, György; Andersson, Roland

2017-01-01

For drug delivery, characterization of liposomes regarding size, particle number concentrations, occurrence of low-sized liposome artefacts and drug encapsulation are of importance to understand their pharmacodynamic properties. In our study, we aimed to demonstrate the applicability of nano Electrospray Gas-Phase Electrophoretic Mobility Molecular Analyser (nES GEMMA) as a suitable technique for analyzing these parameters. We measured number-based particle concentrations, identified differences in size between nominally identical liposomal samples, and detected the presence of low-diameter material which yielded bimodal particle size distributions. Subsequently, we compared these findings to dynamic light scattering (DLS) data and results from light scattering experiments coupled to Asymmetric Flow-Field Flow Fractionation (AF4), the latter improving the detectability of smaller particles in polydisperse samples due to a size separation step prior detection. However, the bimodal size distribution could not be detected due to method inherent limitations. In contrast, cryo transmission electron microscopy corroborated nES GEMMA results. Hence, gas-phase electrophoresis proved to be a versatile tool for liposome characterization as it could analyze both vesicle size and size distribution. Finally, a correlation of nES GEMMA results with cell viability experiments was carried out to demonstrate the importance of liposome batch-to-batch control as low-sized sample components possibly impact cell viability. PMID:27639623

Time of flight imaging through scattering environments (Conference Presentation)

NASA Astrophysics Data System (ADS)

Le, Toan H.; Breitbach, Eric C.; Jackson, Jonathan A.; Velten, Andreas

2017-02-01

Light scattering is a primary obstacle to imaging in many environments. On small scales in biomedical microscopy and diffuse tomography scenarios scattering is caused by tissue. On larger scales scattering from dust and fog provide challenges to vision systems for self driving cars and naval remote imaging systems. We are developing scale models for scattering environments and investigation methods for improved imaging particularly using time of flight transient information. With the emergence of Single Photon Avalanche Diode detectors and fast semiconductor lasers, illumination and capture on picosecond timescales are becoming possible in inexpensive, compact, and robust devices. This opens up opportunities for new computational imaging techniques that make use of photon time of flight. Time of flight or range information is used in remote imaging scenarios in gated viewing and in biomedical imaging in time resolved diffuse tomography. In addition spatial filtering is popular in biomedical scenarios with structured illumination and confocal microscopy. We are presenting a combination analytical, computational, and experimental models that allow us develop and test imaging methods across scattering scenarios and scales. This framework will be used for proof of concept experiments to evaluate new computational imaging methods.

Fast, label-free super-resolution live-cell imaging using rotating coherent scattering (ROCS) microscopy

NASA Astrophysics Data System (ADS)

Jünger, Felix; Olshausen, Philipp V.; Rohrbach, Alexander

2016-07-01

Living cells are highly dynamic systems with cellular structures being often below the optical resolution limit. Super-resolution microscopes, usually based on fluorescence cell labelling, are usually too slow to resolve small, dynamic structures. We present a label-free microscopy technique, which can generate thousands of super-resolved, high contrast images at a frame rate of 100 Hertz and without any post-processing. The technique is based on oblique sample illumination with coherent light, an approach believed to be not applicable in life sciences because of too many interference artefacts. However, by circulating an incident laser beam by 360° during one image acquisition, relevant image information is amplified. By combining total internal reflection illumination with dark-field detection, structures as small as 150 nm become separable through local destructive interferences. The technique images local changes in refractive index through scattered laser light and is applied to living mouse macrophages and helical bacteria revealing unexpected dynamic processes.

Fast, label-free super-resolution live-cell imaging using rotating coherent scattering (ROCS) microscopy

PubMed Central

Jünger, Felix; Olshausen, Philipp v.; Rohrbach, Alexander

2016-01-01

Living cells are highly dynamic systems with cellular structures being often below the optical resolution limit. Super-resolution microscopes, usually based on fluorescence cell labelling, are usually too slow to resolve small, dynamic structures. We present a label-free microscopy technique, which can generate thousands of super-resolved, high contrast images at a frame rate of 100 Hertz and without any post-processing. The technique is based on oblique sample illumination with coherent light, an approach believed to be not applicable in life sciences because of too many interference artefacts. However, by circulating an incident laser beam by 360° during one image acquisition, relevant image information is amplified. By combining total internal reflection illumination with dark-field detection, structures as small as 150 nm become separable through local destructive interferences. The technique images local changes in refractive index through scattered laser light and is applied to living mouse macrophages and helical bacteria revealing unexpected dynamic processes. PMID:27465033

Shedding new light on lipid functions with CARS and SRS microscopy

PubMed Central

Yu, Yong; Ramachandran, Prasanna V.; Wang, Meng C.

2014-01-01

Modern optical microscopy has granted biomedical scientists unprecedented access to the inner workings of a cell, and revolutionized our understanding of the molecular mechanisms underlying physiological and disease states. In spite of these advances, however, visualization of certain classes of molecules (e.g. lipids) at the sub-cellular level has remained elusive. Recently developed chemical imaging modalities – Coherent Anti-Stokes Raman Scattering (CARS) microscopy and Stimulated Raman Scattering (SRS) microscopy – have helped bridge this gap. By selectively imaging the vibration of a specific chemical group, these non-invasive techniques allow high-resolution imaging of individual molecules in vivo, and circumvent the need for potentially perturbative extrinsic labels. These tools have already been applied to the study of fat metabolism, helping uncover novel regulators of lipid storage. Here we review the underlying principle of CARS and SRS microscopy, and discuss the advantages and caveats of each technique. We also review recent applications of these tools in the study of lipids as well as other biomolecules, and conclude with a brief guide for interested researchers to build and use CARS/SRS systems for their own research. PMID:24576891

Hollow-fiber flow field-flow fractionation and multi-angle light scattering investigation of the size, shape and metal-release of silver nanoparticles in aqueous medium for nano-risk assessment.

PubMed

Marassi, Valentina; Casolari, Sonia; Roda, Barbara; Zattoni, Andrea; Reschiglian, Pierluigi; Panzavolta, Silvia; Tofail, Syed A M; Ortelli, Simona; Delpivo, Camilla; Blosi, Magda; Costa, Anna Luisa

2015-03-15

Due to the increased use of silver nanoparticles in industrial scale manufacturing, consumer products and nanomedicine reliable measurements of properties such as the size, shape and distribution of these nano particles in aqueous medium is critical. These properties indeed affect both functional properties and biological impacts especially in quantifying associated risks and identifying suitable risk-mediation strategies. The feasibility of on-line coupling of a fractionation technique such as hollow-fiber flow field flow fractionation (HF5) with a light scattering technique such as MALS (multi-angle light scattering) is investigated here for this purpose. Data obtained from such a fractionation technique and its combination thereof with MALS have been compared with those from more conventional but often complementary techniques e.g. transmission electron microscopy, dynamic light scattering, atomic absorption spectroscopy, and X-ray fluorescence. The combination of fractionation and multi angle light scattering techniques have been found to offer an ideal, hyphenated methodology for a simultaneous size-separation and characterization of silver nanoparticles. The hydrodynamic radii determined by fractionation techniques can be conveniently correlated to the mean average diameters determined by multi angle light scattering and reliable information on particle morphology in aqueous dispersion has been obtained. The ability to separate silver (Ag(+)) ions from silver nanoparticles (AgNPs) via membrane filtration during size analysis is an added advantage in obtaining quantitative insights to its risk potential. Most importantly, the methodology developed in this article can potentially be extended to similar characterization of metal-based nanoparticles when studying their functional effectiveness and hazard potential. Copyright © 2014 Elsevier B.V. All rights reserved.

Label-free, multi-scale imaging of ex-vivo mouse brain using spatial light interference microscopy

NASA Astrophysics Data System (ADS)

Min, Eunjung; Kandel, Mikhail E.; Ko, Chemyong J.; Popescu, Gabriel; Jung, Woonggyu; Best-Popescu, Catherine

2016-12-01

Brain connectivity spans over broad spatial scales, from nanometers to centimeters. In order to understand the brain at multi-scale, the neural network in wide-field has been visualized in detail by taking advantage of light microscopy. However, the process of staining or addition of fluorescent tags is commonly required, and the image contrast is insufficient for delineation of cytoarchitecture. To overcome this barrier, we use spatial light interference microscopy to investigate brain structure with high-resolution, sub-nanometer pathlength sensitivity without the use of exogenous contrast agents. Combining wide-field imaging and a mosaic algorithm developed in-house, we show the detailed architecture of cells and myelin, within coronal olfactory bulb and cortical sections, and from sagittal sections of the hippocampus and cerebellum. Our technique is well suited to identify laminar characteristics of fiber tract orientation within white matter, e.g. the corpus callosum. To further improve the macro-scale contrast of anatomical structures, and to better differentiate axons and dendrites from cell bodies, we mapped the tissue in terms of its scattering property. Based on our results, we anticipate that spatial light interference microscopy can potentially provide multiscale and multicontrast perspectives of gross and microscopic brain anatomy.

Three-axis digital holographic microscopy for high speed volumetric imaging.

PubMed

Saglimbeni, F; Bianchi, S; Lepore, A; Di Leonardo, R

2014-06-02

Digital Holographic Microscopy allows to numerically retrieve three dimensional information encoded in a single 2D snapshot of the coherent superposition of a reference and a scattered beam. Since no mechanical scans are involved, holographic techniques have a superior performance in terms of achievable frame rates. Unfortunately, numerical reconstructions of scattered field by back-propagation leads to a poor axial resolution. Here we show that overlapping the three numerical reconstructions obtained by tilted red, green and blue beams results in a great improvement over the axial resolution and sectioning capabilities of holographic microscopy. A strong reduction in the coherent background noise is also observed when combining the volumetric reconstructions of the light fields at the three different wavelengths. We discuss the performance of our technique with two test objects: an array of four glass beads that are stacked along the optical axis and a freely diffusing rod shaped E.coli bacterium.

Diffuse light-sheet microscopy for stripe-free calcium imaging of neural populations.

PubMed

Taylor, Michael A; Vanwalleghem, Gilles C; Favre-Bulle, Itia A; Scott, Ethan K

2018-06-19

Light-sheet microscopy is used extensively in developmental biology and neuroscience. One limitation of this approach is that absorption and scattering produces shadows in the illuminating light sheet, resulting in stripe artifacts. Here, we introduce diffuse light-sheet microscopes that use a line diffuser to randomize the light propagation within the image plane, allowing the light sheets to reform after obstacles. We incorporate diffuse light sheets in two existing configurations: selective plane illumination microscopy (SPIM) in which the sample is illuminated with a static sheet of light, and digitally scanned light sheet (DSLS) in which a thin Gaussian beam is scanned across the image plane during each acquisition. We compare diffuse light-sheet microscopes to their conventional counterparts for calcium imaging of neural activity in larval zebrafish. We show that stripe artifacts can cast deep shadows that conceal some neurons, and that the stripes can flicker, producing spurious signals that could be interpreted as biological activity. Diffuse light sheets mitigate these problems, illuminating the blind spots produced by stripes and removing artifacts produced by the stripes' movements. The upgrade to diffuse light sheets is simple and inexpensive, especially in the case of DSLS, where it requires the addition of one optical element. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Near-field Light Scattering Techniques for Measuring Nanoparticle-Surface Interaction Energies and Forces.

PubMed

Schein, Perry; Ashcroft, Colby K; O'Dell, Dakota; Adam, Ian S; DiPaolo, Brian; Sabharwal, Manit; Shi, Ce; Hart, Robert; Earhart, Christopher; Erickson, David

2015-08-15

Nanoparticles are quickly becoming commonplace in many commercial and industrial products, ranging from cosmetics to pharmaceuticals to medical diagnostics. Predicting the stability of the engineered nanoparticles within these products a priori remains an important and difficult challenge. Here we describe our techniques for measuring the mechanical interactions between nanoparticles and surfaces using near-field light scattering. Particle-surface interfacial forces are measured by optically "pushing" a particle against a reference surface and observing its motion using scattered near-field light. Unlike atomic force microscopy, this technique is not limited by thermal noise, but instead takes advantage of it. The integrated waveguide and microfluidic architecture allow for high-throughput measurements of about 1000 particles per hour. We characterize the reproducibility of and experimental uncertainty in the measurements made using the NanoTweezer surface instrument. We report surface interaction studies on gold nanoparticles with 50 nm diameters, smaller than previously reported in the literature using similar techniques.

Eliminating Unwanted Far-Field Excitation in Objective-Type TIRF. Part I. Identifying Sources of Nonevanescent Excitation Light

PubMed Central

Brunstein, Maia; Teremetz, Maxime; Hérault, Karine; Tourain, Christophe; Oheim, Martin

2014-01-01

Total internal reflection fluorescence microscopy (TIRFM) achieves subdiffraction axial sectioning by confining fluorophore excitation to a thin layer close to the cell/substrate boundary. However, it is often unknown how thin this light sheet actually is. Particularly in objective-type TIRFM, large deviations from the exponential intensity decay expected for pure evanescence have been reported. Nonevanescent excitation light diminishes the optical sectioning effect, reduces contrast, and renders TIRFM-image quantification uncertain. To identify the sources of this unwanted fluorescence excitation in deeper sample layers, we here combine azimuthal and polar beam scanning (spinning TIRF), atomic force microscopy, and wavefront analysis of beams passing through the objective periphery. Using a variety of intracellular fluorescent labels as well as negative staining experiments to measure cell-induced scattering, we find that azimuthal beam spinning produces TIRFM images that more accurately portray the real fluorophore distribution, but these images are still hampered by far-field excitation. Furthermore, although clearly measureable, cell-induced scattering is not the dominant source of far-field excitation light in objective-type TIRF, at least for most types of weakly scattering cells. It is the microscope illumination optical path that produces a large cell- and beam-angle invariant stray excitation that is insensitive to beam scanning. This instrument-induced glare is produced far from the sample plane, inside the microscope illumination optical path. We identify stray reflections and high-numerical aperture aberrations of the TIRF objective as one important source. This work is accompanied by a companion paper (Pt.2/2). PMID:24606927

Determination of pitch rotation in a spherical birefringent microparticle

NASA Astrophysics Data System (ADS)

Roy, Basudev; Ramaiya, Avin; Schäffer, Erik

2018-03-01

Rotational motion of a three dimensional spherical microscopic object can happen either in pitch, yaw or roll fashion. Among these, the yaw motion has been conventionally studied using the intensity of scattered light from birefringent microspheres through crossed polarizers. Up until now, however, there is no way to study the pitch motion in spherical microspheres. Here, we suggest a new method to study the pitch motion of birefringent microspheres under crossed polarizers by measuring the 2-fold asymmetry in the scattered signal either using video microscopy or with optical tweezers. We show a couple of simple examples of pitch rotation determination using video microscopy for a microsphere attached with a kinesin molecule while moving along a microtubule and of a particle diffusing freely in water.

Nano-Se: Cheap and easy-to-obtain novel material for all-dielectric nano-photonics

NASA Astrophysics Data System (ADS)

Ivanova, A. K.; Ionin, A. A.; Khmel'nitskii, R. A.; Klevkov, Yu. K.; Kudryashov, S. I.; Levchenko, A. O.; Mel'nik, N. N.; Nastulyavichus, A. A.; Rudenko, A. A.; Saraeva, I. N.; Smirnov, N. A.; Zayarny, D. A.; Gonchukov, S. A.; Tolordava, E. R.; Baranov, A. N.

2017-09-01

Milligram-per-second production of selenium nanoparticles in water sols was realized through few W, kHz-rate nanosecond laser ablation of a solid selenium pellet. High-yield particle formation mechanism and ultimate mass-removal yield were elucidated by optical profilometry and scanning electron microscopy characterization of crater depths and topographies. Deposited particles were inspected by scanning electron microscopy, while optical transmission Raman and dynamic light scattering spectroscopy characterized their hydrosols.

A stress-controlled shear cell for small-angle light scattering and microscopy.

PubMed

Aime, S; Ramos, L; Fromental, J M; Prévot, G; Jelinek, R; Cipelletti, L

2016-12-01

We develop and test a stress-controlled, parallel plates shear cell that can be coupled to an optical microscope or a small angle light scattering setup, for simultaneous investigation of the rheological response and the microscopic structure of soft materials under an imposed shear stress. In order to minimize friction, the cell is based on an air bearing linear stage, the stress is applied through a contactless magnetic actuator, and the strain is measured through optical sensors. We discuss the contributions of inertia and of the small residual friction to the measured signal and demonstrate the performance of our device in both oscillating and step stress experiments on a variety of viscoelastic materials.

Polymer encapsulated inorganic black pigment nanoparticles and their electrophoretic characteristics.

PubMed

Sim, H H; Kim, Y J; Choi, H J

2012-12-01

Black inorganic pigment modified with poly(styrene-co-acrylonitrile) was fabricated via dispersion polymerization, and then the synthesized hybrid nanoparticles were examined by SEM to confirm their morphology, while their density and size were studied using a gas pycnometer and electrophoretic light scattering apparatus, respectively. We also confirmed their chemical structure and coated state via FT-IR and TGA. Electrophoretic characteristics including the zeta potential were examined via an electrophoretic light scattering apparatus, while the movement of particles was directly observed by an optical microscopy under an electric field applied. The hybrid nanoparticles were confirmed to possess an electrophoretic property as a potential candidate for the microcapsule-type electrophoretic display.

Four-flux model of the light scattering in porous varnish and paint layers: towards understanding the visual appearance of altered blanched easel oil paintings

NASA Astrophysics Data System (ADS)

Genty-Vincent, Anaïs; Van Song, Théo Phan; Andraud, Christine; Menu, Michel

2017-07-01

Blanching of easel oil paintings is a recurring alteration that can affect the varnish layer and also the paint layer itself, and strongly alter the visual appearance. Our examinations by field emission gun scanning electron microscopy (FEG-SEM) of altered and unaltered samples revealed the presence of spherical pores in the altered layers, with a pore size ranging from few nanometers to few micrometers. The aim of the present study is to corroborate that the visual appearance modification can be explained by light scattering theories (Mie or Rayleigh depending on the pore size of the considered layer). The four-flux model was used to resolve the radiative transfer equation (RTE) and model the light scattering in porous varnish layers as well as in porous green earth and raw umber oil paint layers. It enables to highlight that the pore size has an important impact on the visual appearance of the altered layer (color and opacity modification). The pore concentration and the thickness of the altered part affect, however, only the opacity. This work points out that the blanching of easel oil paintings is due to light scattering by the pores, which is an important result toward the proposal of adapted and durable future conservation treatments.

Using of dynamic speckled speckles with a small number of scatterers for study of suspension of Chlamydia

NASA Astrophysics Data System (ADS)

Ulyanov, Sergey; Filonova, Nadezhda; Ulianova, Onega; Utz, Sergey; Moiseeva, Yulia; Subbotina, Irina; Kalduzova, Irina; Larionova, Olga; Feodorova, Valentina

2018-04-01

Theory of formation of speckled speckles at diffraction of focused Gaussian beam in the suspension, containing of Chlamydia trachomatis (CT) is presented. Optical model of scattering of light in suspension of Chlamydia is suggested. Formula for bandwidth of spectrum of intensity fluctuations in speckled speckles is derived. It has been demonstrated, that speckle-microscopy can be used for detection of CT bacteria for any concentration of the relevant cells in suspension.

Fractal propagation method enables realistic optical microscopy simulations in biological tissues

PubMed Central

Glaser, Adam K.; Chen, Ye; Liu, Jonathan T.C.

2017-01-01

Current simulation methods for light transport in biological media have limited efficiency and realism when applied to three-dimensional microscopic light transport in biological tissues with refractive heterogeneities. We describe here a technique which combines a beam propagation method valid for modeling light transport in media with weak variations in refractive index, with a fractal model of refractive index turbulence. In contrast to standard simulation methods, this fractal propagation method (FPM) is able to accurately and efficiently simulate the diffraction effects of focused beams, as well as the microscopic heterogeneities present in tissue that result in scattering, refractive beam steering, and the aberration of beam foci. We validate the technique and the relationship between the FPM model parameters and conventional optical parameters used to describe tissues, and also demonstrate the method’s flexibility and robustness by examining the steering and distortion of Gaussian and Bessel beams in tissue with comparison to experimental data. We show that the FPM has utility for the accurate investigation and optimization of optical microscopy methods such as light-sheet, confocal, and nonlinear microscopy. PMID:28983499

Using Asymmetric Flow Field-Flow Fractionation (AF4) to Determine C60 Colloidal Size Distributions

EPA Science Inventory

The formation of aqueous fullerene suspensions by solvent exchange, sonication, or extended mixing in water is widely reported. Commonly used methods for determining the size of these aggregates rely on static and dynamic light scattering, electron microscopy (EM), or atomic forc...

Light sensitive polymer obtained by dispersion of azo-functionalized POSS nanoparticles

NASA Astrophysics Data System (ADS)

Miniewicz, A.; Tomkowicz, M.; Karpinski, P.; Sznitko, L.; Mossety-Leszczak, B.; Dutkiewicz, M.

2015-07-01

Hybrid inorganic-organic nanoparticles based on cubic siloxane cage (RSiO3/2)8, known as polyhedral oligosilsesquioxane (POSS), have been functionalized by eight groups of azo-benzene mesogens and dispersed in poly(methyl methacrylate) PMMA matrix. Presence of azo-benzene units adds an important light-driven functionality to the system due to their photoisomerization resulting in refractive index and/or absorption changes of the whole system. The polymer films containing various concentrations of azo-POSS nanoparticles show remarkable changes of surface morphology being either transparent (at low POSS concentration) or highly scattering (at high POSS concentration) for visible light. Surface structures were examined by optical microscopy as well as by atomic force microscopy (AFM). Results of photoinduced alignment are discussed in the framework of light-induced modification of the aliphatic chains containing azo-benzene photoisomerizing moieties and self-organization process.

Two-photon confocal microscopy in wound healing

NASA Astrophysics Data System (ADS)

Navarro, Fernando A.; So, Peter T. C.; Driessen, Antoine; Kropf, Nina; Park, Christine S.; Huertas, Juan C.; Lee, Hoon B.; Orgill, Dennis P.

2001-04-01

Advances in histopathology and immunohistochemistry have allowed for precise microanatomic detail of tissues. Two Photon Confocal Microscopy (TPCM) is a new technology useful in non-destructive analysis of tissue. Laser light excites the natural florophores, NAD(P)H and NADP+ and the scattering patterns of the emitted light are analyzed to reconstruct microanatomic features. Guinea pig skin was studied using TPCM and skin preparation methods including chemical depilation and tape striping. Results of TPCM were compared with conventional hematoxylin and eosin microscopy. Two-dimensional images were rendered from the three dimensional reconstructions. Images of deeper layers including basal cells and the dermo-epidermal junction improved after removing the stratum corneum with chemical depilation or tape stripping. TCPM allows good resolution of corneocytes, basal cells and collagen fibers and shows promise as a non-destructive method to study wound healing.

Redox-Active Carbohydrate-Coated Nanoparticles: Self-Assembly of a Cyclodextrin-Polystyrene Glycopolymer with Tetrazine-Naphthalimide.

PubMed

Gross, Andrew J; Haddad, Raoudha; Travelet, Christophe; Reynaud, Eric; Audebert, Pierre; Borsali, Redouane; Cosnier, Serge

2016-11-15

The controlled self-assembly of precise and well-defined photochemically and electrochemically active carbohydrate-coated nanoparticles offers the exciting prospect of biocompatible catalysts for energy storage/conversion and biolabeling applications. Here an aqueous nanoparticle system has been developed with a versatile outer layer for host-guest molecule encapsulation via β-cyclodextrin inclusion complexes. A β-cyclodextrin-modified polystyrene polymer was first obtained by copper nanopowder click chemistry. The glycopolymer enables self-assembly and controlled encapsulation of tetrazine-naphthalimide, as a model redox-active agent, into nanoparticles via nanoprecipitation. Cyclodextrin host-guest interactions permit encapsulation and internanoparticle cross-linking for the formation of fluorescent compound and clustered self-assemblies with chemically reversible electroactivity in aqueous solution. Light scattering experiments revealed stable particles with hydrodynamic diameters of 138 and 654 nm for nanoparticles prepared with tetrazine, of which 95% of the nanoparticles represent the smaller objects by number. Dynamic light scattering revealed differences as a function of preparation method in terms of size, 3-month stability, polydispersity, radius of gyration, and shape factor. Individual self-assemblies were visualized by atomic force microscopy and fluorescence microscopy and monitored in real-time by nanoparticle tracking analysis. UV-vis and fluorescence spectra provided insight into the optical properties and critical evidence for host-guest encapsulation as evidenced by solvachromatism and enhanced tetrazine uptake. Cyclic voltammetry was used to investigate the electrochemical properties and provided further support for encapsulation and an estimate of the tetrazine loading capacity in tandem with light scattering data.

Combining gas-phase electrophoretic mobility molecular analysis (GEMMA), light scattering, field flow fractionation and cryo electron microscopy in a multidimensional approach to characterize liposomal carrier vesicles.

PubMed

Urey, Carlos; Weiss, Victor U; Gondikas, Andreas; von der Kammer, Frank; Hofmann, Thilo; Marchetti-Deschmann, Martina; Allmaier, Günter; Marko-Varga, György; Andersson, Roland

2016-11-20

For drug delivery, characterization of liposomes regarding size, particle number concentrations, occurrence of low-sized liposome artefacts and drug encapsulation are of importance to understand their pharmacodynamic properties. In our study, we aimed to demonstrate the applicability of nano Electrospray Gas-Phase Electrophoretic Mobility Molecular Analyser (nES GEMMA) as a suitable technique for analyzing these parameters. We measured number-based particle concentrations, identified differences in size between nominally identical liposomal samples, and detected the presence of low-diameter material which yielded bimodal particle size distributions. Subsequently, we compared these findings to dynamic light scattering (DLS) data and results from light scattering experiments coupled to Asymmetric Flow-Field Flow Fractionation (AF4), the latter improving the detectability of smaller particles in polydisperse samples due to a size separation step prior detection. However, the bimodal size distribution could not be detected due to method inherent limitations. In contrast, cryo transmission electron microscopy corroborated nES GEMMA results. Hence, gas-phase electrophoresis proved to be a versatile tool for liposome characterization as it could analyze both vesicle size and size distribution. Finally, a correlation of nES GEMMA results with cell viability experiments was carried out to demonstrate the importance of liposome batch-to-batch control as low-sized sample components possibly impact cell viability. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

X-ray microscopy as an approach to increasing accuracy and efficiency of serial block-face imaging for correlated light and electron microscopy of biological specimens.

PubMed

Bushong, Eric A; Johnson, Donald D; Kim, Keun-Young; Terada, Masako; Hatori, Megumi; Peltier, Steven T; Panda, Satchidananda; Merkle, Arno; Ellisman, Mark H

2015-02-01

The recently developed three-dimensional electron microscopic (EM) method of serial block-face scanning electron microscopy (SBEM) has rapidly established itself as a powerful imaging approach. Volume EM imaging with this scanning electron microscopy (SEM) method requires intense staining of biological specimens with heavy metals to allow sufficient back-scatter electron signal and also to render specimens sufficiently conductive to control charging artifacts. These more extreme heavy metal staining protocols render specimens light opaque and make it much more difficult to track and identify regions of interest (ROIs) for the SBEM imaging process than for a typical thin section transmission electron microscopy correlative light and electron microscopy study. We present a strategy employing X-ray microscopy (XRM) both for tracking ROIs and for increasing the efficiency of the workflow used for typical projects undertaken with SBEM. XRM was found to reveal an impressive level of detail in tissue heavily stained for SBEM imaging, allowing for the identification of tissue landmarks that can be subsequently used to guide data collection in the SEM. Furthermore, specific labeling of individual cells using diaminobenzidine is detectable in XRM volumes. We demonstrate that tungsten carbide particles or upconverting nanophosphor particles can be used as fiducial markers to further increase the precision and efficiency of SBEM imaging.

X-ray Microscopy as an Approach to Increasing Accuracy and Efficiency of Serial Block-face Imaging for Correlated Light and Electron Microscopy of Biological Specimens

PubMed Central

Bushong, Eric A.; Johnson, Donald D.; Kim, Keun-Young; Terada, Masako; Hatori, Megumi; Peltier, Steven T.; Panda, Satchidananda; Merkle, Arno; Ellisman, Mark H.

2015-01-01

The recently developed three-dimensional electron microscopic (EM) method of serial block-face scanning electron microscopy (SBEM) has rapidly established itself as a powerful imaging approach. Volume EM imaging with this scanning electron microscopy (SEM) method requires intense staining of biological specimens with heavy metals to allow sufficient back-scatter electron signal and also to render specimens sufficiently conductive to control charging artifacts. These more extreme heavy metal staining protocols render specimens light opaque and make it much more difficult to track and identify regions of interest (ROIs) for the SBEM imaging process than for a typical thin section transmission electron microscopy correlative light and electron microscopy study. We present a strategy employing X-ray microscopy (XRM) both for tracking ROIs and for increasing the efficiency of the workflow used for typical projects undertaken with SBEM. XRM was found to reveal an impressive level of detail in tissue heavily stained for SBEM imaging, allowing for the identification of tissue landmarks that can be subsequently used to guide data collection in the SEM. Furthermore, specific labeling of individual cells using diaminobenzidine is detectable in XRM volumes. We demonstrate that tungsten carbide particles or upconverting nanophosphor particles can be used as fiducial markers to further increase the precision and efficiency of SBEM imaging. PMID:25392009

Teaching light scattering spectroscopy: the dimension and shape of tobacco mosaic virus.

PubMed Central

Santos, N C; Castanho, M A

1996-01-01

The tobacco mosaic virus is used as a model molecular assembly to illustrate the basic potentialities of light scattering techniques (both static and dynamic) to undergraduates. The work has two objectives: a pedagogic one (introducing light scattering to undergraduate students) and a scientific one (stabilization of the virus molecular assembly structure by the nucleic acid). Students are first challenged to confirm the stabilization of the cylindrical shape of the virus by the nucleic acid, at pH and ionic strength conditions where the coat proteins alone do not self-assemble. The experimental intramolecular scattering factor is compared with the theoretical ones for several model geometries. The data clearly suggest that the geometry is, in fact, a rod. Comparing the experimental values of gyration radius and hydrodynamic radius with the theoretical expectations further confirms this conclusion. Moreover, the rod structure is maintained over a wider range of pH and ionic strength than that valid for the coat proteins alone. The experimental values of the diffusion coefficient and radius of gyration are compared with the theoretical expectations assuming the dimensions detected by electron microscopy techniques. In fact, both values are in agreement (length approximately 300 nm, radius approximately 20 nm). PMID:8874039

Novel Crystalline SiO2 Nanoparticles via Annelids Bioprocessing of Agro-Industrial Wastes

PubMed Central

2010-01-01

The synthesis of nanoparticles silica oxide from rice husk, sugar cane bagasse and coffee husk, by employing vermicompost with annelids (Eisenia foetida) is reported. The product (humus) is calcinated and extracted to recover the crystalline nanoparticles. X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and dynamic light scattering (DLS) show that the biotransformation allows creating specific crystalline phases, since equivalent particles synthesized without biotransformation are bigger and with different crystalline structure. PMID:20802789

Diagnostics for the detection and evaluation of laser induced damage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheehan, L.; Kozlowski, M.; Rainer, F.

1995-12-31

The Laser Damage and Conditioning Group at LLNL is evaluating diagnostics which will help make damage testing more efficient and reduce the risk of damage during laser conditioning. The work to date has focused on photoacoustic and scattered light measurements on 1064-nm wavelength HfO{sub 2}/SiO{sub 2} multilayer mirror and polarizer coatings. Both the acoustic and scatter diagnostics have resolved 10 {mu}m diameter damage points in these coatings. Using a scanning stage, the scatter diagnostic can map both intrinsic and laser-induced scatter. Damage threshold measurements obtained using scatter diagnostics compare within experimental error with those measured using 100x Nomarski microscopy. Scattermore » signals measured during laser conditioning can be used to detect damage related to nodular defects.« less

Diagnostics for the detection and evaluation of laser induced damage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheehan, L.; Kozlowski, M.; Rainer, F.

1995-01-03

The Laser Damage and Conditioning Group at LLNL is evaluating diagnostics which will help make damage testing more efficient and reduce the risk of damage during laser conditioning. The work to date has focused on photoacoustic and scattered light measurements on 1064-nm wavelength HfO{sub 2}/SiO{sub 2} multilayer mirror and polarizer coatings. Both the acoustic and scatter diagnostics have resolved 10 {mu}m diameter damage points in these coatings. Using a scanning stage, the scatter diagnostic can map both intrinsic and laser-induced scatter. Damage threshold measurements obtained using scatter diagnostics compare within experimental error with those measured using 100x Nomarski microscopy. Scattermore » signals measured during laser conditioning can be used to detect damage related to nodular defects.« less

Conjugate adaptive optics with remote focusing in multiphoton microscopy

NASA Astrophysics Data System (ADS)

Tao, Xiaodong; Lam, Tuwin; Zhu, Bingzhao; Li, Qinggele; Reinig, Marc R.; Kubby, Joel

2018-02-01

The small correction volume for conventional wavefront shaping methods limits their application in biological imaging through scattering media. In this paper, we take advantage of conjugate adaptive optics (CAO) and remote focusing (CAORF) to achieve three-dimensional (3D) scanning through a scattering layer with a single correction. Our results show that the proposed system can provide 10 times wider axial field of view compared with a conventional conjugate AO system when 16,384 segments are used on a spatial light modulator. We demonstrate two-photon imaging with CAORF through mouse skull. The fluorescent microspheres embedded under the scattering layers can be clearly observed after applying the correction.

Shack-Hartmann wavefront-sensor-based adaptive optics system for multiphoton microscopy

PubMed Central

Cha, Jae Won; Ballesta, Jerome; So, Peter T.C.

2010-01-01

The imaging depth of two-photon excitation fluorescence microscopy is partly limited by the inhomogeneity of the refractive index in biological specimens. This inhomogeneity results in a distortion of the wavefront of the excitation light. This wavefront distortion results in image resolution degradation and lower signal level. Using an adaptive optics system consisting of a Shack-Hartmann wavefront sensor and a deformable mirror, wavefront distortion can be measured and corrected. With adaptive optics compensation, we demonstrate that the resolution and signal level can be better preserved at greater imaging depth in a variety of ex-vivo tissue specimens including mouse tongue muscle, heart muscle, and brain. However, for these highly scattering tissues, we find signal degradation due to scattering to be a more dominant factor than aberration. PMID:20799824

Shack-Hartmann wavefront-sensor-based adaptive optics system for multiphoton microscopy.

PubMed

Cha, Jae Won; Ballesta, Jerome; So, Peter T C

2010-01-01

The imaging depth of two-photon excitation fluorescence microscopy is partly limited by the inhomogeneity of the refractive index in biological specimens. This inhomogeneity results in a distortion of the wavefront of the excitation light. This wavefront distortion results in image resolution degradation and lower signal level. Using an adaptive optics system consisting of a Shack-Hartmann wavefront sensor and a deformable mirror, wavefront distortion can be measured and corrected. With adaptive optics compensation, we demonstrate that the resolution and signal level can be better preserved at greater imaging depth in a variety of ex-vivo tissue specimens including mouse tongue muscle, heart muscle, and brain. However, for these highly scattering tissues, we find signal degradation due to scattering to be a more dominant factor than aberration.

A mobile system for a comprehensive online-characterization of nanoparticle aggregates based on wide-angle light scattering and laser-induced incandescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huber, Franz J. T.; Will, Stefan, E-mail: stefan.will@fau.de; Erlangen Graduate School in Advanced Optical Technologies

A mobile demonstrator for the comprehensive online-characterization of gas-borne nanoparticle aggregates is presented. Two optical measurement techniques are combined, both utilizing a pulsed Nd:YAG laser as light source. Aggregate size and fractal dimension are measured by Wide-Angle Light Scattering (WALS). An ellipsoidal mirror images elastically scattered light from scattering angles between 10° and 165° onto a CCD-camera chip resulting in an almost complete scattering diagram with high angular resolution. Primary particle size and volume fraction are measured by time-resolved Laser-Induced Incandescence (TiRe-LII). Here, particles are heated up to about 3000 K by the short laser pulse, the enhanced thermal radiationmore » signal is detected with gated photomultiplier tubes. Analysis of the signal decay time and maximum LII-signal allows for the determination of primary particle diameter and volume fraction. The performance of the system is demonstrated by combined measurements on soot nanoparticle aggregates from a soot aerosol generator. Particle and aggregate sizes are varied by using different equivalence ratios of the combustion in the generator. Soot volume fraction can be adjusted by different levels of dilution with air. Online-measurements were carried out demonstrating the favorable performance of the system and the potential for industrial applications such as process control and product development. The particle properties obtained are confirmed through transmission electron microscopy analysis on representative samples.« less

A mobile system for a comprehensive online-characterization of nanoparticle aggregates based on wide-angle light scattering and laser-induced incandescence.

PubMed

Huber, Franz J T; Altenhoff, Michael; Will, Stefan

2016-05-01

A mobile demonstrator for the comprehensive online-characterization of gas-borne nanoparticle aggregates is presented. Two optical measurement techniques are combined, both utilizing a pulsed Nd:YAG laser as light source. Aggregate size and fractal dimension are measured by Wide-Angle Light Scattering (WALS). An ellipsoidal mirror images elastically scattered light from scattering angles between 10° and 165° onto a CCD-camera chip resulting in an almost complete scattering diagram with high angular resolution. Primary particle size and volume fraction are measured by time-resolved Laser-Induced Incandescence (TiRe-LII). Here, particles are heated up to about 3000 K by the short laser pulse, the enhanced thermal radiation signal is detected with gated photomultiplier tubes. Analysis of the signal decay time and maximum LII-signal allows for the determination of primary particle diameter and volume fraction. The performance of the system is demonstrated by combined measurements on soot nanoparticle aggregates from a soot aerosol generator. Particle and aggregate sizes are varied by using different equivalence ratios of the combustion in the generator. Soot volume fraction can be adjusted by different levels of dilution with air. Online-measurements were carried out demonstrating the favorable performance of the system and the potential for industrial applications such as process control and product development. The particle properties obtained are confirmed through transmission electron microscopy analysis on representative samples.

A mobile system for a comprehensive online-characterization of nanoparticle aggregates based on wide-angle light scattering and laser-induced incandescence

NASA Astrophysics Data System (ADS)

Huber, Franz J. T.; Altenhoff, Michael; Will, Stefan

2016-05-01

A mobile demonstrator for the comprehensive online-characterization of gas-borne nanoparticle aggregates is presented. Two optical measurement techniques are combined, both utilizing a pulsed Nd:YAG laser as light source. Aggregate size and fractal dimension are measured by Wide-Angle Light Scattering (WALS). An ellipsoidal mirror images elastically scattered light from scattering angles between 10° and 165° onto a CCD-camera chip resulting in an almost complete scattering diagram with high angular resolution. Primary particle size and volume fraction are measured by time-resolved Laser-Induced Incandescence (TiRe-LII). Here, particles are heated up to about 3000 K by the short laser pulse, the enhanced thermal radiation signal is detected with gated photomultiplier tubes. Analysis of the signal decay time and maximum LII-signal allows for the determination of primary particle diameter and volume fraction. The performance of the system is demonstrated by combined measurements on soot nanoparticle aggregates from a soot aerosol generator. Particle and aggregate sizes are varied by using different equivalence ratios of the combustion in the generator. Soot volume fraction can be adjusted by different levels of dilution with air. Online-measurements were carried out demonstrating the favorable performance of the system and the potential for industrial applications such as process control and product development. The particle properties obtained are confirmed through transmission electron microscopy analysis on representative samples.

Measuring aberrations in the rat brain by coherence-gated wavefront sensing using a Linnik interferometer

PubMed Central

Wang, Jinyu; Léger, Jean-François; Binding, Jonas; Boccara, A. Claude; Gigan, Sylvain; Bourdieu, Laurent

2012-01-01

Aberrations limit the resolution, signal intensity and achievable imaging depth in microscopy. Coherence-gated wavefront sensing (CGWS) allows the fast measurement of aberrations in scattering samples and therefore the implementation of adaptive corrections. However, CGWS has been demonstrated so far only in weakly scattering samples. We designed a new CGWS scheme based on a Linnik interferometer and a SLED light source, which is able to compensate dispersion automatically and can be implemented on any microscope. In the highly scattering rat brain tissue, where multiply scattered photons falling within the temporal gate of the CGWS can no longer be neglected, we have measured known defocus and spherical aberrations up to a depth of 400 µm. PMID:23082292

Measuring aberrations in the rat brain by coherence-gated wavefront sensing using a Linnik interferometer.

PubMed

Wang, Jinyu; Léger, Jean-François; Binding, Jonas; Boccara, A Claude; Gigan, Sylvain; Bourdieu, Laurent

2012-10-01

Aberrations limit the resolution, signal intensity and achievable imaging depth in microscopy. Coherence-gated wavefront sensing (CGWS) allows the fast measurement of aberrations in scattering samples and therefore the implementation of adaptive corrections. However, CGWS has been demonstrated so far only in weakly scattering samples. We designed a new CGWS scheme based on a Linnik interferometer and a SLED light source, which is able to compensate dispersion automatically and can be implemented on any microscope. In the highly scattering rat brain tissue, where multiply scattered photons falling within the temporal gate of the CGWS can no longer be neglected, we have measured known defocus and spherical aberrations up to a depth of 400 µm.

Optical Diagnostics in Medicine

NASA Astrophysics Data System (ADS)

Iftimia, Nicusor

2003-03-01

Light has a unique potential for non-invasive tissue diagnosis. The relatively short wavelength of light allows imaging of tissue at the resolution of histopathology. While strong multiple scattering of light in tissue makes attainment of this resolution difficult for thick tissues, most pathology emanates from epithelial surfaces. Therefore, high-resolution diagnosis of many important diseases may be achieved by transmitting light to the surface of interest. The recent fiber-optic implementation of technologies that reject multiple scattering, such as confocal microscopy and optical low coherence interferometry, have brought us one step closer to realizing non-invasive imaging of architectural and cellular features of tissue. Optical coherence tomography (OCT) can produce high-resolution cross-sectional images of biological structures. Clinical OCT studies conducted in the gastrointestinal tract and cardiovascular system have shown that OCT is capable of providing images of the architectural (> 20 µm) microanatomy of a variety of epithelial tissues, including the layered structure of squamous epithelium and arterial vessels. Fine Needle Aspiration- Low Coherence Interferometry (FNA-LCI) is another optical diagnostics technique, which is a suitable solution to increase the effectiveness of the FNA procedures. LCI is capable of measuring depth resolved (axial, z) tissue structure, birefringence, flow (Doppler shift), and spectra at a resolution of several microns. Since LCI systems are fiber-optic based, LCI probes may easily fit within the bore of a fine gauge needle, allowing diagnostic information to be obtained directly from the FNA biopsy site. Fiber optic spectrally encoded confocal microscopy (SECM) is a new confocal microscopy method, which eliminates the need for rapid beam scanning within the optical probe. This advance enables confocal microscopy to be performed through small diameter probes and will allow assessment of internal human tissues in vivo at the cellular level. A detailed description of several fiber optics based systems for early diseases diagnosis, as well as preliminary clinic results, will be presented.

Darkfield microspectroscopy of nanostructures on silver tip-enhanced Raman scattering probes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Itoh, Tamitake, E-mail: tamitake-itou@aist.go.jp; Yamamoto, Yuko S., E-mail: yamayulab@gmail.com; Department of Chemistry, School of Science and Technology, Kagawa University, Takamatsu, Kagawa 761-0396

2016-01-11

We report an evaluation method employing darkfield microspectroscopy for silver probes used in tip-enhanced Raman scattering (TERS). By adjusting the darkfield illumination, the diffracted light from the probe outlines disappears and the diffracted light from the surface nanostructures and tips of the probes appears as colorful spots. Scanning electron microscopy reveals that the spectral variations in these spots reflect the shapes of the surface nanostructures. The tip curvatures correlate to the spectral maxima of their spots. Temporal color changes in the spots indicate the deterioration due to the oxidation of the silver surfaces. These results show that the proposed methodmore » is useful for in situ evaluation of plasmonic properties of TERS probes.« less

Investigation of mixed saliva by optoelectronic methods

NASA Astrophysics Data System (ADS)

Savchenko, Ekaterina; Nepomnyashchaya, Elina; Baranov, Maksim; Velichko, Elena; Aksenov, Evgenii; Bogomaz, Tatyana

2018-04-01

At present, saliva and its properties are being actively studied. Human saliva is a unique biological material that has potential in clinical practice. A detailed analysis of the characteristics and properties of saliva is relevant for diagnostic purposes. In this paper, the properties and characteristics of saliva are studied using optoelectronic methods: dynamic light scattering, electrophoretic light scattering and optical microscopy. Mixed saliva from a healthy patient and patient with diabetes mellitus type 2 was used as an object of the study. The dynamics of the behavior of a healthy and patient with diabetes mellitus type 2 is visible according to the results obtained. All three methods confirm hypothesis of structural changes in mixed saliva in the disease of diabetes mellitus type 2.

Mechanical characterization at material interfaces through dark field Brillouin microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Fiore, Antonio; Scarcelli, Giuliano

2017-02-01

Brillouin microscopy allows high-resolution mapping of the mechanical properties of a sample by measuring the spectra of acoustically induced light scattering therein, and thus has been widely investigated for biomedical application. Measuring the Brillouin spectral shift is challenging when the light is focused onto the interfaces between two materials of different refractive index, because a sizeable portion of the incident light is Fresnel-reflected into the Brillouin spectrometer. To address this need, here, we designed a Brillouin confocal microscope in which the specular reflection at the interface between two materials is physically rejected without significant loss to the Brillouin signal. To achieve this goal, we illuminate the sample with a small-diameter Gaussian beam focused by a high numerical aperture objective lens. In the collection path, the beam reflected from the sample has the same diameter as the incident beam, while the scattered light beam is as large as the clear aperture of the microscope objective. Therefore, using a small blocking filter allows to efficiently reject the reflected light. We calculated the tradeoff between extinction improvement and signal loss when the diameter of the blocking filter is changed. Experimentally, we demonstrated extinction improvement of over 60dB with only 30% signal loss while achieving submicron resolutions. This innovation can be useful for in vivo measurements of the cornea to avoid artifacts in the epithelium and anterior portions of the stroma, as well as to investigate cells cultured on glass coverslips without necessity of index-matching materials.

Direct AFM observation of an opening event of a DNA cuboid constructed via a prism structure.

PubMed

Endo, Masayuki; Hidaka, Kumi; Sugiyama, Hiroshi

2011-04-07

A cuboid structure was constructed using a DNA origami design based on a square prism structure. The structure was characterized by atomic force microscopy (AFM) and dynamic light scattering. The real-time opening event of the cuboid was directly observed by high-speed AFM.

Detection of Silver and TiO2 Nanoparticles using Light Scatter by Flow Cytometry and Darkfield Microscopy

EPA Science Inventory

Titanium Dioxide (Ti02) and Silver (Ag) nanoparticles are used in many domestic applications, including sunscreens and paints. Evaluation of the potential hazard of manmade nanomaterials has been hampered by a limited ability to detect and measure nanoparticles in cells. In the p...

Detection and isolation of cell-derived microparticles are compromised by protein complexes resulting from shared biophysical parameters.

PubMed

György, Bence; Módos, Károly; Pállinger, Eva; Pálóczi, Krisztina; Pásztói, Mária; Misják, Petra; Deli, Mária A; Sipos, Aron; Szalai, Anikó; Voszka, István; Polgár, Anna; Tóth, Kálmán; Csete, Mária; Nagy, György; Gay, Steffen; Falus, András; Kittel, Agnes; Buzás, Edit I

2011-01-27

Numerous diseases, recently reported to associate with elevated microvesicle/microparticle (MP) counts, have also long been known to be characterized by accelerated immune complex (IC) formation. The goal of this study was to investigate the potential overlap between parameters of protein complexes (eg, ICs or avidin-biotin complexes) and MPs, which might perturb detection and/or isolation of MPs. In this work, after comprehensive characterization of MPs by electron microscopy, atomic force microscopy, dynamic light-scattering analysis, and flow cytometry, for the first time, we drive attention to the fact that protein complexes, especially insoluble ICs, overlap in biophysical properties (size, light scattering, and sedimentation) with MPs. This, in turn, affects MP quantification by flow cytometry and purification by differential centrifugation, especially in diseases in which IC formation is common, including not only autoimmune diseases, but also hematologic disorders, infections, and cancer. These data may necessitate reevaluation of certain published data on patient-derived MPs and contribute to correct the clinical laboratory assessment of the presence and biologic functions of MPs in health and disease.

ZnO nanopowder induced light scattering for improved visualization of emission sites in carbon nanotube films and arrays

NASA Astrophysics Data System (ADS)

Meško, Marcel; Ou, Qiongrong; Matsuda, Takafumi; Ishikawa, Tomokazu; Veis, Martin; Antoš, Roman; Ogino, Akihisa; Nagatsu, Masaaki

2009-06-01

We report on ZnO nanopowder induced light scattering for improved visualization of emission sites in carbon nanotube films and arrays. We observed a significant reduction of the internal multiple light scattering phenomena, which are characteristic for ZnO micropowders. The microsized grains of the commercially available ZnO:Zn (P 15) were reduced to the nanometre scale by pulsed laser ablation at an oxygen ambient pressure of 10 kPa. Our investigations show no crystalline change and no shift of the broad green emission peak at 500 nm for the ZnO nanopowder. For the application in field emission displays, we demonstrate the possibility of achieving cathodoluminescence with a fine pitch size of 100 µm of the patterned pixels without requiring additional electron beam focusing and without a black matrix. Moreover, the presented results show the feasibility of employing ZnO nanopowder as a detection material for the phosphorus screen method, which is able to localize emission sites of carbon nanotube films and arrays with an accuracy comparable to scanning anode field emission microscopy.

Wide-field optical detection of nanoparticles using on-chip microscopy and self-assembled nanolenses

NASA Astrophysics Data System (ADS)

Mudanyali, Onur; McLeod, Euan; Luo, Wei; Greenbaum, Alon; Coskun, Ahmet F.; Hennequin, Yves; Allier, Cédric P.; Ozcan, Aydogan

2013-03-01

The direct observation of nanoscale objects is a challenging task for optical microscopy because the scattering from an individual nanoparticle is typically weak at optical wavelengths. Electron microscopy therefore remains one of the gold standard visualization methods for nanoparticles, despite its high cost, limited throughput and restricted field-of-view. Here, we describe a high-throughput, on-chip detection scheme that uses biocompatible wetting films to self-assemble aspheric liquid nanolenses around individual nanoparticles to enhance the contrast between the scattered and background light. We model the effect of the nanolens as a spatial phase mask centred on the particle and show that the holographic diffraction pattern of this effective phase mask allows detection of sub-100 nm particles across a large field-of-view of >20 mm2. As a proof-of-concept demonstration, we report on-chip detection of individual polystyrene nanoparticles, adenoviruses and influenza A (H1N1) viral particles.

Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

DOE PAGES

Ophus, Colin; Ciston, Jim; Pierce, Jordan; ...

2016-02-29

The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, makingmore » it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Ultimately, simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.« less

Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry.

PubMed

Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R; Chess, Jordan; McMorran, Benjamin J; Czarnik, Cory; Rose, Harald H; Ercius, Peter

2016-02-29

The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.

Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

PubMed Central

Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

2016-01-01

The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals. PMID:26923483

Wide-field optical detection of nanoparticles using on-chip microscopy and self-assembled nanolenses

PubMed Central

Mudanyali, Onur; McLeod, Euan; Luo, Wei; Greenbaum, Alon; Coskun, Ahmet F.; Hennequin, Yves; Allier, Cédric P.; Ozcan, Aydogan

2013-01-01

The direct observation of nanoscale objects is a challenging task for optical microscopy because the scattering from an individual nanoparticle is typically weak at optical wavelengths. Electron microscopy therefore remains one of the gold standard visualization methods for nanoparticles, despite its high cost, limited throughput and restricted field-of-view. Here, we describe a high-throughput, on-chip detection scheme that uses biocompatible wetting films to self-assemble aspheric liquid nanolenses around individual nanoparticles to enhance the contrast between the scattered and background light. We model the effect of the nanolens as a spatial phase mask centred on the particle and show that the holographic diffraction pattern of this effective phase mask allows detection of sub-100 nm particles across a large field-of-view of >20 mm2. As a proof-of-concept demonstration, we report on-chip detection of individual polystyrene nanoparticles, adenoviruses and influenza A (H1N1) viral particles. PMID:24358054

Fast wavefront optimization for focusing through biological tissue (Conference Presentation)

NASA Astrophysics Data System (ADS)

Blochet, Baptiste; Bourdieu, Laurent; Gigan, Sylvain

2017-02-01

The propagation of light in biological tissues is rapidly dominated by multiple scattering: ballistic light is exponentially attenuated, which limits the penetration depth of conventional microscopy techniques. For coherent light, the recombination of the different scattered paths creates a complex interference: speckle. Recently, different wavefront shaping techniques have been developed to coherently manipulate the speckle. It opens the possibility to focus light through complex media and ultimately to image in them, provided however that the medium can be considered as stationary. We have studied the possibility to focus in and through time-varying biological tissues. Their intrinsic temporal dynamics creates a fast decorrelation of the speckle pattern. Therefore, focusing through biological tissues requires fast wavefront shaping devices, sensors and algorithms. We have investigated the use of a MEMS-based spatial light modulator (SLM) and a fast photodetector, combined with FPGA electronics to implement a closed-loop optimization. Our optimization process is just limited by the temporal dynamics of the SLM (200µs) and the computation time (45µs), thus corresponding to a rate of 4 kHz. To our knowledge, it's the fastest closed loop optimization using phase modulators. We have studied the focusing through colloidal solutions of TiO2 particles in glycerol, allowing tunable temporal stability, and scattering properties similar to biological tissues. We have shown that our set-up fulfills the required characteristics (speed, enhancement) to focus through biological tissues. We are currently investigating the focusing through acute rat brain slices and the memory effect in dynamic scattering media.

Quantitative Assessment of Fat Levels in Caenorhabditis elegans Using Dark Field Microscopy

PubMed Central

Fouad, Anthony D.; Pu, Shelley H.; Teng, Shelly; Mark, Julian R.; Fu, Moyu; Zhang, Kevin; Huang, Jonathan; Raizen, David M.; Fang-Yen, Christopher

2017-01-01

The roundworm Caenorhabditis elegans is widely used as a model for studying conserved pathways for fat storage, aging, and metabolism. The most broadly used methods for imaging fat in C. elegans require fixing and staining the animal. Here, we show that dark field images acquired through an ordinary light microscope can be used to estimate fat levels in worms. We define a metric based on the amount of light scattered per area, and show that this light scattering metric is strongly correlated with worm fat levels as measured by Oil Red O (ORO) staining across a wide variety of genetic backgrounds and feeding conditions. Dark field imaging requires no exogenous agents or chemical fixation, making it compatible with live worm imaging. Using our method, we track fat storage with high temporal resolution in developing larvae, and show that fat storage in the intestine increases in at least one burst during development. PMID:28404661

High-extinction virtually imaged phased array-based Brillouin spectroscopy of turbid biological media

NASA Astrophysics Data System (ADS)

Fiore, Antonio; Zhang, Jitao; Shao, Peng; Yun, Seok Hyun; Scarcelli, Giuliano

2016-05-01

Brillouin microscopy has recently emerged as a powerful technique to characterize the mechanical properties of biological tissue, cell, and biomaterials. However, the potential of Brillouin microscopy is currently limited to transparent samples, because Brillouin spectrometers do not have sufficient spectral extinction to reject the predominant non-Brillouin scattered light of turbid media. To overcome this issue, we combined a multi-pass Fabry-Perot interferometer with a two-stage virtually imaged phased array spectrometer. The Fabry-Perot etalon acts as an ultra-narrow band-pass filter for Brillouin light with high spectral extinction and low loss. We report background-free Brillouin spectra from Intralipid solutions and up to 100 μm deep within chicken muscle tissue.

High-refractive index of acrylate embedding resin clarifies mouse brain tissue

NASA Astrophysics Data System (ADS)

Zhou, Hongfu; Xiong, Yumiao; Wang, Yu; Wang, Xiaojun; Li, Pei; Gang, Yadong; Liu, Xiuli; Zeng, Shaoqun

2017-11-01

Biological tissue transparency combined with light-sheet fluorescence microscopy is a useful method for studying the neural structure of biological tissues. The development of light-sheet fluorescence microscopy also promotes progress in biological tissue clearing methods. The current clarifying methods mostly use liquid reagent to denature protein or remove lipids first, to eliminate or reduce the scattering index or refractive index of the biological tissue. However, denaturing protein and removing lipids require complex procedures or an extended time period. Therefore, here we have developed acrylate resin with a high refractive index, which causes clearing of biological tissue directly after polymerization. This method can improve endogenous fluorescence retention by adjusting the pH value of the resin monomer.

Globular bodies: a primary cause of the opacity in senile and diabetic posterior cortical subcapsular cataracts?

PubMed

Creighton, M O; Trevithick, J R; Mousa, G Y; Percy, D H; McKinna, A J; Dyson, C; Maisel, H; Bradley, R

1978-07-01

We examined 9 cataracts from maturity onset diabetics and 4 senile posterior subcapsular cataracts by scanning electron microscopy, transmission electron microscopy, immunofluorescence for crystallin proteins and actin, histochemical methods and x-ray diffraction. The cataractous regions contained spherical globules up to 20 mu in diameter, often in a fibrous matrix. Some were extracellular Morgagnian globules, apparently formed by blebbing from the cell surface; others appeared to have been formed intracellularly. The area of globular degeneration was usually 300 mu deep, but had deeper fusiform extensions. Morphological changes in the cell cytoplasm varied according to their depth in the cataract. Electron microscopy showed intracellular and extracellular globules, many of them were bounded by lipid bilayer membranes. Immunofluorescent staining showed that all the globules contained gamma-crystallin; some contained alpha- and beta-crystallins and actin. All the globules contained higher concentrations of cysteine or cystine than the surrounding lens tissue but they did not react to stains for carbohydrate or calcium. X-ray diffraction studies showed that crystalline calcium salts were absent. Globules and cavities averaged 45% of the total area in cross section. Assuming an area of cataract to be 300 micron thick and that globules 1 mu in diameter scattered, while 2--20 mu in diameter reflected light, we calculated that light passing through such a thickness would be reduced by 65%. Thus the globules could account for most of the opacity of the cataractous area. Presumably the fibrous degeneration of the cells causes enough light scattering to account for the remainder of the reduction. Cataract patients complain of decreased visual acuity, a golden halo around objects, and difficulties when driving while facing oncoming traffic at night. These probably result from light scattering. In our previous experiments, globular bodies containing gamma-crystallin were found in cells grown in tissue culture, and blebs with increased acitn content similar to Morgagnian globules were formed in tissue culture by treating differentiated rat lens cells of stage 2 by cytochalasin D (which impaired microfilament function). These results suggest the possibility of simulating in tissue culture the morphological alterations seen in the cataractous cell.

Ultraviolet refractometry using field-based light scattering spectroscopy

PubMed Central

Fu, Dan; Choi, Wonshik; Sung, Yongjin; Oh, Seungeun; Yaqoob, Zahid; Park, YongKeun; Dasari, Ramachandra R.; Feld, Michael S.

2010-01-01

Accurate refractive index measurement in the deep ultraviolet (UV) range is important for the separate quantification of biomolecules such as proteins and DNA in biology. This task is demanding and has not been fully exploited so far. Here we report a new method of measuring refractive index using field-based light scattering spectroscopy, which is applicable to any wavelength range and suitable for both solutions and homogenous objects with well-defined shape such as microspheres. The angular scattering distribution of single microspheres immersed in homogeneous media is measured over the wavelength range 260 to 315 nm using quantitative phase microscopy. By least square fitting the observed scattering distribution with Mie scattering theory, the refractive index of either the sphere or the immersion medium can be determined provided that one is known a priori. Using this method, we have measured the refractive index dispersion of SiO2 spheres and bovine serum albumin (BSA) solutions in the deep UV region. Specific refractive index increments of BSA are also extracted. Typical accuracy of the present refractive index technique is ≤0.003. The precision of refractive index measurements is ≤0.002 and that of specific refractive index increment determination is ≤0.01 mL/g. PMID:20372622

Using Stage- and Slit-Scanning to Improve Contrast and Optical Sectioning in Dual-View Inverted Light Sheet Microscopy (diSPIM)

PubMed Central

KUMAR, ABHISHEK; CHRISTENSEN, RYAN; GUO, MIN; CHANDRIS, PANOS; DUNCAN, WILLIAM; WU, YICONG; SANTELLA, ANTHONY; MOYLE, MARK; WINTER, PETER W.; COLÓN-RAMOS, DANIEL; BAO, ZHIRONG; SHROFF, HARI

2017-01-01

Dual-view inverted selective plane illumination microscopy (diSPIM) enables high-speed, long-term, fourdimensional (4D) imaging with isotropic spatial resolution. It is also compatible with conventional sample mounting on glass coverslips. However, broadening of the light sheet at distances far from the beam waist and sample-induced scattering degrades diSPIM contrast and optical sectioning. We describe two simple improvements that address both issues and entail no additional hardware modifications to the base diSPIM. First, we demonstrate improved diSPIM sectioning by keeping the light sheet and detection optics stationary, and scanning the sample through the stationary light sheet (rather than scanning the broadening light sheet and detection plane through the stationary sample, as in conventional diSPIM). This stage-scanning approach allows a thinner sheet to be used when imaging laterally extended samples, such as fixed microtubules or motile mitochondria in cell monolayers, and produces finer contrast than does conventional diSPIM. We also used stage-scanning diSPIM to obtain high-quality, 4D nuclear datasets derived from an uncompressed nematode embryo, and performed lineaging analysis to track 97% of cells until twitching. Second, we describe the improvement of contrast in thick, scattering specimens by synchronizing light-sheet synthesis with the rolling, electronic shutter of our scientific complementary metal-oxide-semiconductor (sCMOS) detector. This maneuver forms a virtual confocal slit in the detection path, partially removing out-of-focus light. We demonstrate the applicability of our combined stage- and slit-scanning-methods by imaging pollen grains and nuclear and neuronal structures in live nematode embryos. All acquisition and analysis code is freely available online. PMID:27638693

Scaffolded DNA origami of a DNA tetrahedron molecular container.

PubMed

Ke, Yonggang; Sharma, Jaswinder; Liu, Minghui; Jahn, Kasper; Liu, Yan; Yan, Hao

2009-06-01

We describe a strategy of scaffolded DNA origami to design and construct 3D molecular cages of tetrahedron geometry with inside volume closed by triangular faces. Each edge of the triangular face is approximately 54 nm in dimension. The estimated total external volume and the internal cavity of the triangular pyramid are about 1.8 x 10(-23) and 1.5 x 10(-23) m(3), respectively. Correct formation of the tetrahedron DNA cage was verified by gel electrophoresis, atomic force microscopy, transmission electron microscopy, and dynamic light scattering techniques.

Salt-induced aggregation and fusion of dioctadecyldimethylammonium chloride and sodium dihexadecylphosphate vesicles.

PubMed Central

Carmona-Ribeiro, A M; Chaimovich, H

1986-01-01

Small dioctadecyldimethylammonium chloride (DODAC) vesicles prepared by sonication fuse upon addition of NaCl as detected by several methods (electron microscopy, trapped volume determinations, temperature-dependent phase transition curves, and osmometer behavior. In contrast, small sodium dihexadecyl phosphate (DHP) vesicles mainly aggregate upon NaCl addition as shown by electron microscopy and the lack of osmometer behavior. Scatter-derived absorbance changes of small and large DODAC or DHP vesicles as a function of time after salt addition were obtained for a range of NaCl or amphiphile concentration. These changes were interpreted in accordance with a phenomenological model based upon fundamental light-scattering laws and simple geometrical considerations. Short-range hydration repulsion between DODAC (or DHP) vesicles is possibly the main energy barrier for the fusion process. Images FIGURE 2 FIGURE 9 PMID:3779002

Visualization of lipids and proteins at high spatial and temporal resolution via interferometric scattering (iSCAT) microscopy

NASA Astrophysics Data System (ADS)

Spindler, Susann; Ehrig, Jens; König, Katharina; Nowak, Tristan; Piliarik, Marek; Stein, Hannah E.; Taylor, Richard W.; Garanger, Elisabeth; Lecommandoux, Sébastien; Alves, Isabel D.; Sandoghdar, Vahid

2016-07-01

Microscopy based on the interferometric detection of light scattered from nanoparticles (iSCAT) was introduced in our laboratory more than a decade ago. In this work, we present various capabilities of iSCAT for biological studies by discussing a selection of our recent results. In particular, we show tracking of lipid molecules in supported lipid bilayers (SLBs), tracking of gold nanoparticles with diameters as small as 5 nm and at frame rates close to 1 MHz, 3D tracking of Tat peptide-coated nanoparticles on giant unilamellar vesicles (GUVs), imaging the formation of lipid bilayers, sensing single unlabelled proteins and tracking their motion under electric fields, as well as challenges of studying live cell membranes. These studies set the ground for future quantitative research on dynamic biophysical processes at the nanometer scale.

Composite particles formed by complexation of poly(methacrylic acid) - stabilized magnetic fluid with chitosan: Magnetic material for bioapplications.

PubMed

Safarik, Ivo; Stepanek, Miroslav; Uchman, Mariusz; Slouf, Miroslav; Baldikova, Eva; Nydlova, Leona; Pospiskova, Kristyna; Safarikova, Mirka

2016-10-01

A simple procedure for the synthesis of magnetic fluid (ferrofluid) stabilized by poly(methacrylic acid) has been developed. This ferrofluid was used to prepare a novel type of magnetically responsive chitosan-based composite material. Both ferrofluid and magnetic chitosan composite were characterized by a combination of microscopy (optical microscopy, TEM, SEM), scattering (static and dynamic light scattering, SANS) and spectroscopy (FTIR) techniques. Magnetic chitosan was found to be a perspective material for various bioapplications, especially as a magnetic carrier for immobilization of enzymes and cells. Lipase from Candida rugosa was covalently attached after cross-linking and activation of chitosan using glutaraldehyde. Baker's yeast cells (Saccharomyces cerevisiae) were incorporated into the chitosan composite during its preparation; both biocatalysts were active after reaction with appropriate substrates. Copyright © 2016 Elsevier B.V. All rights reserved.

Nanoscale chromatin structure characterization for optical applications: a transmission electron microscopy study (Conference Presentation)

NASA Astrophysics Data System (ADS)

Li, Yue; Cherkezyan, Lusik; Zhang, Di; Almassalha, Luay; Roth, Eric; Chandler, John; Bleher, Reiner; Subramanian, Hariharan; Dravid, Vinayak P.; Backman, Vadim

2017-02-01

Structural and biological origins of light scattering in cells and tissue are still poorly understood. We demonstrate how this problem might be addressed through the use of transmission electron microscopy (TEM). For biological samples, TEM image intensity is proportional to mass-density, and thus proportional to refractive index (RI). By calculating the autocorrelation function (ACF) of TEM image intensity of a thin-section of cells, we essentially maintain the nanoscale ACF of the 3D cellular RI distribution, given that the RI distribution is statistically isotropic. Using this nanoscale 3D RI ACF, we can simulate light scattering through biological samples, and thus guiding many optical techniques to quantify specific structures. In this work, we chose to use Partial Wave Spectroscopy (PWS) microscopy as a one of the nanoscale-sensitive optical techniques. Hela cells were prepared using standard protocol to preserve nanoscale ultrastructure, and a 50-nm slice was sectioned for TEM imaging at 6 nm resolution. The ACF was calculated for chromatin, and the PWS mean sigma was calculated by summing over the power spectral density in the visible light frequency of a random medium generated to match the ACF. A 1-µm slice adjacent to the 50-nm slice was sectioned for PWS measurement to guarantee identical chromatin structure. For 33 cells, we compared the calculated PWS mean sigma from TEM and the value measured directly, and obtained a strong correlation of 0.69. This example indicates the great potential of using TEM measured RI distribution to better understand the quantification of cellular nanostructure by optical methods.

A Simple low-cost device enables four epi-illumination techniques on standard light microscopes.

PubMed

Ishmukhametov, Robert R; Russell, Aidan N; Wheeler, Richard J; Nord, Ashley L; Berry, Richard M

2016-02-08

Back-scattering darkfield (BSDF), epi-fluorescence (EF), interference reflection contrast (IRC), and darkfield surface reflection (DFSR) are advanced but expensive light microscopy techniques with limited availability. Here we show a simple optical design that combines these four techniques in a simple low-cost miniature epi-illuminator, which inserts into the differential interference-contrast (DIC) slider bay of a commercial microscope, without further additions required. We demonstrate with this device: 1) BSDF-based detection of Malarial parasites inside unstained human erythrocytes; 2) EF imaging with and without dichroic components, including detection of DAPI-stained Leishmania parasite without using excitation or emission filters; 3) RIC of black lipid membranes and other thin films, and 4) DFSR of patterned opaque and transparent surfaces. We believe that our design can expand the functionality of commercial bright field microscopes, provide easy field detection of parasites and be of interest to many users of light microscopy.

A Simple low-cost device enables four epi-illumination techniques on standard light microscopes

NASA Astrophysics Data System (ADS)

Ishmukhametov, Robert R.; Russell, Aidan N.; Wheeler, Richard J.; Nord, Ashley L.; Berry, Richard M.

2016-02-01

Back-scattering darkfield (BSDF), epi-fluorescence (EF), interference reflection contrast (IRC), and darkfield surface reflection (DFSR) are advanced but expensive light microscopy techniques with limited availability. Here we show a simple optical design that combines these four techniques in a simple low-cost miniature epi-illuminator, which inserts into the differential interference-contrast (DIC) slider bay of a commercial microscope, without further additions required. We demonstrate with this device: 1) BSDF-based detection of Malarial parasites inside unstained human erythrocytes; 2) EF imaging with and without dichroic components, including detection of DAPI-stained Leishmania parasite without using excitation or emission filters; 3) RIC of black lipid membranes and other thin films, and 4) DFSR of patterned opaque and transparent surfaces. We believe that our design can expand the functionality of commercial bright field microscopes, provide easy field detection of parasites and be of interest to many users of light microscopy.

Diffraction data of core-shell nanoparticles from an X-ray free electron laser

DOE PAGES

Li, Xuanxuan; Chiu, Chun -Ya; Wang, Hsiang -Ju; ...

2017-04-11

X-ray free-electron lasers provide novel opportunities to conduct single particle analysis on nanoscale particles. Coherent diffractive imaging experiments were performed at the Linac Coherent Light Source (LCLS), SLAC National Laboratory, exposing single inorganic core-shell nanoparticles to femtosecond hard-X-ray pulses. Each facetted nanoparticle consisted of a crystalline gold core and a differently shaped palladium shell. Scattered intensities were observed up to about 7 nm resolution. Analysis of the scattering patterns revealed the size distribution of the samples, which is consistent with that obtained from direct real-space imaging by electron microscopy. Furthermore, scattering patterns resulting from single particles were selected and compiledmore » into a dataset which can be valuable for algorithm developments in single particle scattering research.« less

Quantitative Assessment of Ultrastructure and Light Scatter in Mouse Corneal Debridement Wounds

PubMed Central

Boote, Craig; Du, Yiqin; Morgan, Sian; Harris, Jonathan; Kamma-Lorger, Christina S.; Hayes, Sally; Lathrop, Kira L.; Roh, Danny S.; Burrow, Michael K.; Hiller, Jennifer; Terrill, Nicholas J.; Funderburgh, James L.; Meek, Keith M.

2012-01-01

Purpose. The mouse has become an important wound healing model with which to study corneal fibrosis, a frequent complication of refractive surgery. The aim of the current study was to quantify changes in stromal ultrastructure and light scatter that characterize fibrosis in mouse corneal debridement wounds. Methods. Epithelial debridement wounds, with and without removal of basement membrane, were produced in C57BL/6 mice. Corneal opacity was measured using optical coherence tomography, and collagen diameter and matrix order were quantified by x-ray scattering. Electron microscopy was used to visualize proteoglycans. Quantitative PCR (Q-PCR) measured mRNA transcript levels for several quiescent and fibrotic markers. Results. Epithelial debridement without basement membrane disruption produced a significant increase in matrix disorder at 8 weeks, but minimal corneal opacity. In contrast, basement membrane penetration led to increases in light scatter, matrix disorder, and collagen diameter, accompanied by the appearance of abnormally large proteoglycans in the subepithelial stroma. This group also demonstrated upregulation of several quiescent and fibrotic markers 2 to 4 weeks after wounding. Conclusions. Fibrotic corneal wound healing in mice involves extensive changes to collagen and proteoglycan ultrastructure, consistent with deposition of opaque scar tissue. Epithelial basement membrane penetration is a deciding factor determining the degree of ultrastructural changes and resulting opacity. PMID:22467580

Electric-field induced surface instabilities of soft dielectrics and their effects on optical transmittance and scattering

NASA Astrophysics Data System (ADS)

Shian, Samuel; Kjeer, Peter; Clarke, David R.

2018-03-01

When a voltage is applied to a percolative, mechanically compliant mat of carbon nanotubes (CNTs) on a smooth elastomer bilayer attached to an ITO coated glass substrate, the in-line optical transmittance decreases with increasing voltage. Two regimes of behavior have been identified based on optical scattering, bright field optical microscopy, and confocal optical microscopy. In the low field regime, the electric field produces a spatially inhomogeneous surface deformation of the elastomer that causes local variations in optical refraction and modulates the light transmittance. The spatial variation is associated with the distribution of the CNTs over the surface. At higher fields, above a threshold voltage, an array of pits in the surface form by a nucleation and growth mechanism and these also scatter light. The formation of pits, and creases, in the thickness of the elastomer, is due to a previously identified electro-mechanical surface instability. When the applied voltage is decreased from its maximum, the transmittance returns to its original value although there is a transmittance hysteresis and a complicated time response. When the applied voltage exceeds the threshold voltage, there can be remnant optical contrast associated with creasing of the elastomer and the recovery time appears to be dependent on local jamming of CNTs in areas where the pits formed. A potential application of this work as an electrically tunable privacy window or camouflaging devices is demonstrated.

Three-dimensional scanning near field optical microscopy (3D-SNOM) imaging of random arrays of copper nanoparticles: implications for plasmonic solar cell enhancement.

PubMed

Ezugwu, Sabastine; Ye, Hanyang; Fanchini, Giovanni

2015-01-07

In order to investigate the suitability of random arrays of nanoparticles for plasmonic enhancement in the visible-near infrared range, we introduced three-dimensional scanning near-field optical microscopy (3D-SNOM) imaging as a useful technique to probe the intensity of near-field radiation scattered by random systems of nanoparticles at heights up to several hundred nm from their surface. We demonstrated our technique using random arrays of copper nanoparticles (Cu-NPs) at different particle diameter and concentration. Bright regions in the 3D-SNOM images, corresponding to constructive interference of forward-scattered plasmonic waves, were obtained at heights Δz ≥ 220 nm from the surface for random arrays of Cu-NPs of ∼ 60-100 nm in diameter. These heights are too large to use Cu-NPs in contact of the active layer for light harvesting in thin organic solar cells, which are typically no thicker than 200 nm. Using a 200 nm transparent spacer between the system of Cu-NPs and the solar cell active layer, we demonstrate that forward-scattered light can be conveyed in 200 nm thin film solar cells. This architecture increases the solar cell photoconversion efficiency by a factor of 3. Our 3D-SNOM technique is general enough to be suitable for a large number of other applications in nanoplasmonics.

Visual Understanding of Light Absorption and Waveguiding in Standing Nanowires with 3D Fluorescence Confocal Microscopy

PubMed Central

2017-01-01

Semiconductor nanowires are promising building blocks for next-generation photonics. Indirect proofs of large absorption cross sections have been reported in nanostructures with subwavelength diameters, an effect that is even more prominent in vertically standing nanowires. In this work we provide a three-dimensional map of the light around vertical GaAs nanowires standing on a substrate by using fluorescence confocal microscopy, where the strong long-range disruption of the light path along the nanowire is illustrated. We find that the actual long-distance perturbation is much larger in size than calculated extinction cross sections. While the size of the perturbation remains similar, the intensity of the interaction changes dramatically over the visible spectrum. Numerical simulations allow us to distinguish the effects of scattering and absorption in the nanowire leading to these phenomena. This work provides a visual understanding of light absorption in semiconductor nanowire structures, which is of high interest for solar energy conversion applications. PMID:28966933

Lensfree microscopy on a cellphone

PubMed Central

Tseng, Derek; Mudanyali, Onur; Oztoprak, Cetin; Isikman, Serhan O.; Sencan, Ikbal; Yaglidere, Oguzhan; Ozcan, Aydogan

2010-01-01

We demonstrate lensfree digital microscopy on a cellphone. This compact and light-weight holographic microscope installed on a cellphone does not utilize any lenses, lasers or other bulky optical components and it may offer a cost-effective tool for telemedicine applications to address various global health challenges. Weighing ~38 grams (<1.4 ounces), this lensfree imaging platform can be mechanically attached to the camera unit of a cellphone where the samples are loaded from the side, and are vertically illuminated by a simple light-emitting diode (LED). This incoherent LED light is then scattered from each micro-object to coherently interfere with the background light, creating the lensfree hologram of each object on the detector array of the cellphone. These holographic signatures captured by the cellphone permit reconstruction of microscopic images of the objects through rapid digital processing. We report the performance of this lensfree cellphone microscope by imaging various sized micro-particles, as well as red blood cells, white blood cells, platelets and a waterborne parasite (Giardia lamblia). PMID:20445943

Visual Understanding of Light Absorption and Waveguiding in Standing Nanowires with 3D Fluorescence Confocal Microscopy.

PubMed

Frederiksen, Rune; Tutuncuoglu, Gozde; Matteini, Federico; Martinez, Karen L; Fontcuberta I Morral, Anna; Alarcon-Llado, Esther

2017-09-20

Semiconductor nanowires are promising building blocks for next-generation photonics. Indirect proofs of large absorption cross sections have been reported in nanostructures with subwavelength diameters, an effect that is even more prominent in vertically standing nanowires. In this work we provide a three-dimensional map of the light around vertical GaAs nanowires standing on a substrate by using fluorescence confocal microscopy, where the strong long-range disruption of the light path along the nanowire is illustrated. We find that the actual long-distance perturbation is much larger in size than calculated extinction cross sections. While the size of the perturbation remains similar, the intensity of the interaction changes dramatically over the visible spectrum. Numerical simulations allow us to distinguish the effects of scattering and absorption in the nanowire leading to these phenomena. This work provides a visual understanding of light absorption in semiconductor nanowire structures, which is of high interest for solar energy conversion applications.

Enhanced light element imaging in atomic resolution scanning transmission electron microscopy.

PubMed

Findlay, S D; Kohno, Y; Cardamone, L A; Ikuhara, Y; Shibata, N

2014-01-01

We show that an imaging mode based on taking the difference between signals recorded from the bright field (forward scattering region) in atomic resolution scanning transmission electron microscopy provides an enhancement of the detectability of light elements over existing techniques. In some instances this is an enhancement of the visibility of the light element columns relative to heavy element columns. In all cases explored it is an enhancement in the signal-to-noise ratio of the image at the light column site. The image formation mechanisms are explained and the technique is compared with earlier approaches. Experimental data, supported by simulation, are presented for imaging the oxygen columns in LaAlO₃. Case studies looking at imaging hydrogen columns in YH₂ and lithium columns in Al₃Li are also explored through simulation, particularly with respect to the dependence on defocus, probe-forming aperture angle and detector collection aperture angles. © 2013 Elsevier B.V. All rights reserved.

Efficiency of Launching Highly Confined Polaritons by Infrared Light Incident on a Hyperbolic Material.

PubMed

Dai, Siyuan; Ma, Qiong; Yang, Yafang; Rosenfeld, Jeremy; Goldflam, Michael D; McLeod, Alex; Sun, Zhiyuan; Andersen, Trond I; Fei, Zhe; Liu, Mengkun; Shao, Yinming; Watanabe, Kenji; Taniguchi, Takashi; Thiemens, Mark; Keilmann, Fritz; Jarillo-Herrero, Pablo; Fogler, Michael M; Basov, D N

2017-09-13

We investigated phonon-polaritons in hexagonal boron nitride-a naturally hyperbolic van der Waals material-by means of the scattering-type scanning near-field optical microscopy. Real-space nanoimages we have obtained detail how the polaritons are launched when the light incident on a thin hexagonal boron nitride slab is scattered by various intrinsic and extrinsic inhomogeneities, including sample edges, metallic nanodisks deposited on its top surface, random defects, and surface impurities. The scanned tip of the near-field microscope is itself a polariton launcher whose efficiency proves to be superior to all the other types of polariton launchers we studied. Our work may inform future development of polaritonic nanodevices as well as fundamental studies of collective modes in van der Waals materials.

Super-resolution photoacoustic microscopy using joint sparsity

NASA Astrophysics Data System (ADS)

Burgholzer, P.; Haltmeier, M.; Berer, T.; Leiss-Holzinger, E.; Murray, T. W.

2017-07-01

We present an imaging method that uses the random optical speckle patterns that naturally emerge as light propagates through strongly scattering media as a structured illumination source for photoacoustic imaging. Our approach, termed blind structured illumination photoacoustic microscopy (BSIPAM), was inspired by recent work in fluorescence microscopy where super-resolution imaging was demonstrated using multiple unknown speckle illumination patterns. We extend this concept to the multiple scattering domain using photoacoustics (PA), with the speckle pattern serving to generate ultrasound. The optical speckle pattern that emerges as light propagates through diffuse media provides structured illumination to an object placed behind a scattering wall. The photoacoustic signal produced by such illumination is detected using a focused ultrasound transducer. We demonstrate through both simulation and experiment, that by acquiring multiple photoacoustic images, each produced by a different random and unknown speckle pattern, an image of an absorbing object can be reconstructed with a spatial resolution far exceeding that of the ultrasound transducer. We experimentally and numerically demonstrate a gain in resolution of more than a factor of two by using multiple speckle illuminations. The variations in the photoacoustic signals generated with random speckle patterns are utilized in BSIPAM using a novel reconstruction algorithm. Exploiting joint sparsity, this algorithm is capable of reconstructing the absorbing structure from measured PA signals with a resolution close to the speckle size. Another way to excite random excitation for photoacoustic imaging are small absorbing particles, including contrast agents, which flow through small vessels. For such a set-up, the joint-sparsity is generated by the fact that all the particles move in the same vessels. Structured illumination in that case is not necessary.

Harmonic demodulation and minimum enhancement factors in field-enhanced near-field optical microscopy.

PubMed

Scarpettini, A F; Bragas, A V

2015-01-01

Field-enhanced scanning optical microscopy relies on the design and fabrication of plasmonic probes which had to provide optical and chemical contrast at the nanoscale. In order to do so, the scattering containing the near-field information recorded in a field-enhanced scanning optical microscopy experiment, has to surpass the background light, always present due to multiple interferences between the macroscopic probe and sample. In this work, we show that when the probe-sample distance is modulated with very low amplitude, the higher the harmonic demodulation is, the better the ratio between the near-field signal and the interferometric background results. The choice of working at a given n harmonic is dictated by the experiment when the signal at the n + 1 harmonic goes below the experimental noise. We demonstrate that the optical contrast comes from the nth derivative of the near-field scattering, amplified by the interferometric background. By modelling the far and near field we calculate the probe-sample approach curves, which fit very well the experimental ones. After taking a great amount of experimental data for different probes and samples, we conclude with a table of the minimum enhancement factors needed to have optical contrast with field-enhanced scanning optical microscopy. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

Visualizing individual microtubules by bright field microscopy

NASA Astrophysics Data System (ADS)

Gutiérrez-Medina, Braulio; Block, Steven M.

2010-11-01

Microtubules are slender (˜25 nm diameter), filamentous polymers involved in cellular structure and organization. Individual microtubules have been visualized via fluorescence imaging of dye-labeled tubulin subunits and by video-enhanced, differential interference-contrast microscopy of unlabeled polymers using sensitive CCD cameras. We demonstrate the imaging of unstained microtubules using a microscope with conventional bright field optics in conjunction with a webcam-type camera and a light-emitting diode illuminator. The light scattered by microtubules is image-processed to remove the background, reduce noise, and enhance contrast. The setup is based on a commercial microscope with a minimal set of inexpensive components, suitable for implementation in a student laboratory. We show how this approach can be used in a demonstration motility assay, tracking the gliding motions of microtubules driven by the motor protein kinesin.

Atomic oxygen effects on thin film space coatings studied by spectroscopic ellipsometry, atomic force microscopy, and laser light scattering

NASA Technical Reports Server (NTRS)

Synowicki, R. A.; Hale, Jeffrey S.; Woollam, John A.

1992-01-01

The University of Nebraska is currently evaluating Low Earth Orbit (LEO) simulation techniques as well as a variety of thin film protective coatings to withstand atomic oxygen (AO) degradation. Both oxygen plasma ashers and an electron cyclotron resonance (ECR) source are being used for LEO simulation. Thin film coatings are characterized by optical techniques including Variable Angle Spectroscopic Ellipsometry, Optical spectrophotometry, and laser light scatterometry. Atomic Force Microscopy (AFM) is also used to characterize surface morphology. Results on diamondlike carbon (DLC) films show that DLC degrades with simulated AO exposure at a rate comparable to Kapton polyimide. Since DLC is not as susceptible to environmental factors such as moisture absorption, it could potentially provide more accurate measurements of AO fluence on short space flights.

High-refractive index of acrylate embedding resin clarifies mouse brain tissue.

PubMed

Zhou, Hongfu; Xiong, Yumiao; Wang, Yu; Wang, Xiaojun; Li, Pei; Gang, Yadong; Liu, Xiuli; Zeng, Shaoqun

2017-11-01

Biological tissue transparency combined with light-sheet fluorescence microscopy is a useful method for studying the neural structure of biological tissues. The development of light-sheet fluorescence microscopy also promotes progress in biological tissue clearing methods. The current clarifying methods mostly use liquid reagent to denature protein or remove lipids first, to eliminate or reduce the scattering index or refractive index of the biological tissue. However, denaturing protein and removing lipids require complex procedures or an extended time period. Therefore, here we have developed acrylate resin with a high refractive index, which causes clearing of biological tissue directly after polymerization. This method can improve endogenous fluorescence retention by adjusting the pH value of the resin monomer. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

4D (x-y-z-t) imaging of thick biological samples by means of Two-Photon inverted Selective Plane Illumination Microscopy (2PE-iSPIM)

PubMed Central

Lavagnino, Zeno; Sancataldo, Giuseppe; d’Amora, Marta; Follert, Philipp; De Pietri Tonelli, Davide; Diaspro, Alberto; Cella Zanacchi, Francesca

2016-01-01

In the last decade light sheet fluorescence microscopy techniques, such as selective plane illumination microscopy (SPIM), has become a well established method for developmental biology. However, conventional SPIM architectures hardly permit imaging of certain tissues since the common sample mounting procedure, based on gel embedding, could interfere with the sample morphology. In this work we propose an inverted selective plane microscopy system (iSPIM), based on non-linear excitation, suitable for 3D tissue imaging. First, the iSPIM architecture provides flexibility on the sample mounting, getting rid of the gel-based mounting typical of conventional SPIM, permitting 3D imaging of hippocampal slices from mouse brain. Moreover, all the advantages brought by two photon excitation (2PE) in terms of reduction of scattering effects and contrast improvement are exploited, demonstrating an improved image quality and contrast compared to single photon excitation. The system proposed represents an optimal platform for tissue imaging and it smooths the way to the applicability of light sheet microscopy to a wider range of samples including those that have to be mounted on non-transparent surfaces. PMID:27033347

Biophysical characterization of influenza virus subpopulations using field flow fractionation and multiangle light scattering: correlation of particle counts, size distribution and infectivity.

PubMed

Wei, Ziping; McEvoy, Matt; Razinkov, Vladimir; Polozova, Alla; Li, Elizabeth; Casas-Finet, Jose; Tous, Guillermo I; Balu, Palani; Pan, Alfred A; Mehta, Harshvardhan; Schenerman, Mark A

2007-09-01

Adequate biophysical characterization of influenza virions is important for vaccine development. The influenza virus vaccines are produced from the allantoic fluid of developing chicken embryos. The process of viral replication produces a heterogeneous mixture of infectious and non-infectious viral particles with varying states of aggregation. The study of the relative distribution and behavior of different subpopulations and their inter-correlation can assist in the development of a robust process for a live virus vaccine. This report describes a field flow fractionation and multiangle light scattering (FFF-MALS) method optimized for the analysis of size distribution and total particle counts. The FFF-MALS method was compared with several other methods such as transmission electron microscopy (TEM), atomic force microscopy (AFM), size exclusion chromatography followed by MALS (SEC-MALS), quantitative reverse transcription polymerase chain reaction (RT Q-PCR), median tissue culture dose (TCID(50)), and the fluorescent focus assay (FFA). The correlation between the various methods for determining total particle counts, infectivity and size distribution is reported. The pros and cons of each of the analytical methods are discussed.

Optimizing the performance of dual-axis confocal microscopes via Monte-Carlo scattering simulations and diffraction theory.

PubMed

Chen, Ye; Liu, Jonathan T C

2013-06-01

Dual-axis confocal (DAC) microscopy has been found to exhibit superior rejection of out-of-focus and multiply scattered background light compared to conventional single-axis confocal microscopy. DAC microscopes rely on the use of separated illumination and collection beam paths that focus and intersect at a single focal volume (voxel) within tissue. While it is generally recognized that the resolution and contrast of a DAC microscope depends on both the crossing angle of the DAC beams, 2θ, and the focusing numerical aperture of the individual beams, α, a detailed study to investigate these dependencies has not been performed. Contrast and resolution are considered as two main criteria to assess the performance of a point-scanned DAC microscope (DAC-PS) and a line-scanned DAC microscope (DAC-LS) as a function of θ and α. The contrast and resolution of these designs are evaluated by Monte-Carlo scattering simulations and diffraction theory calculations, respectively. These results can be used for guiding the optimal designs of DAC-PS and DAC-LS microscopes.

Analysis of the complex formation of heparin with protamine by light scattering and analytical ultracentrifugation: implications for blood coagulation management.

PubMed

Maurer, Jürgen; Haselbach, Stephanie; Klein, Oliver; Baykut, Doan; Vogel, Vitali; Mäntele, Werner

2011-02-02

Heparin, a linear glycosaminoglycan, is used in different forms in anticoagulation treatment. Protamine, a highly positive charged peptide containing about 32 amino acids, acts as an antagonist for heparin to restore normal blood coagulation. The complex formation of protamine with heparin was analyzed by a combination of analytical ultracentrifugation and light scattering. Titration of heparin with protamine in blood plasma preparations results in a drastic increase of turbidity, indicating the formation of nanoscale particles. A similar increase of turbidity was observed in physiological saline solution with or without human serum albumin (HSA). Particle size analysis by analytical ultracentrifugation revealed a particle radius of approximately 30 nm for unfractionated heparin and of approximately 60 nm for low molecular weight heparin upon complexation with excess protamine, in agreement with atomic force microscopy data. In the absence of HSA, larger and more heterogeneous particles were observed. The particles obtained were found to be stable for hours. The particle formation kinetics was analyzed by light scattering at different scattering angles and was found to be complete within several minutes. The time course of particle formation suggests a condensation reaction, with sigmoidal traces for low heparin concentrations and quasi-first-order reaction for high heparin concentrations. Under all conditions, the final scattering intensity reached after several minutes was found to be proportional to the amount of heparin in the blood plasma or buffer solution, provided that excess protamine was available and no multiple scattering occurred. On the basis of a direct relation between particle concentration and the heparin concentration present before protaminization, a light scattering assay was developed which permits the quantitative analysis of the heparin concentration in blood plasma and which could complement or even replace the activated clotting time test, which is currently the most commonly used method for blood coagulation management.

Confocal multispot microscope for fast and deep imaging in semicleared tissues

NASA Astrophysics Data System (ADS)

Adam, Marie-Pierre; Müllenbroich, Marie Caroline; Di Giovanna, Antonino Paolo; Alfieri, Domenico; Silvestri, Ludovico; Sacconi, Leonardo; Pavone, Francesco Saverio

2018-02-01

Although perfectly transparent specimens are imaged faster with light-sheet microscopy, less transparent samples are often imaged with two-photon microscopy leveraging its robustness to scattering; however, at the price of increased acquisition times. Clearing methods that are capable of rendering strongly scattering samples such as brain tissue perfectly transparent specimens are often complex, costly, and time intensive, even though for many applications a slightly lower level of tissue transparency is sufficient and easily achieved with simpler and faster methods. Here, we present a microscope type that has been geared toward the imaging of semicleared tissue by combining multispot two-photon excitation with rolling shutter wide-field detection to image deep and fast inside semicleared mouse brain. We present a theoretical and experimental evaluation of the point spread function and contrast as a function of shutter size. Finally, we demonstrate microscope performance in fixed brain slices by imaging dendritic spines up to 400-μm deep.

Coherent anti-Stokes Raman scattering microscopy of single nanodiamonds

NASA Astrophysics Data System (ADS)

Pope, Iestyn; Payne, Lukas; Zoriniants, George; Thomas, Evan; Williams, Oliver; Watson, Peter; Langbein, Wolfgang; Borri, Paola

2014-11-01

Nanoparticles have attracted enormous attention for biomedical applications as optical labels, drug-delivery vehicles and contrast agents in vivo. In the quest for superior photostability and biocompatibility, nanodiamonds are considered one of the best choices due to their unique structural, chemical, mechanical and optical properties. So far, mainly fluorescent nanodiamonds have been utilized for cell imaging. However, their use is limited by the efficiency and costs in reliably producing fluorescent defect centres with stable optical properties. Here, we show that single non-fluorescing nanodiamonds exhibit strong coherent anti-Stokes Raman scattering (CARS) at the sp3 vibrational resonance of diamond. Using correlative light and electron microscopy, the relationship between CARS signal strength and nanodiamond size is quantified. The calibrated CARS signal in turn enables the analysis of the number and size of nanodiamonds internalized in living cells in situ, which opens the exciting prospect of following complex cellular trafficking pathways quantitatively.

Coherent anti-Stokes Raman scattering microscopy of single nanodiamonds

PubMed Central

Pope, Iestyn; Payne, Lukas; Zoriniants, George; Thomas, Evan; Williams, Oliver; Watson, Peter; Langbein, Wolfgang; Borri, Paola

2016-01-01

Nanoparticles have attracted enormous attention for biomedical applications as optical labels, drug delivery vehicles, and contrast agents in vivo. In the quest for superior photostability and bio-compatibility, nanodiamonds (NDs) are considered one of the best choices due to their unique structural, chemical, mechanical, and optical properties. So far, mainly fluorescent NDs have been utilized for cell imaging. However, their use is limited by the efficiency and costs in reliably producing fluorescent defect centers with stable optical properties. Here, we show that single non-fluorescing NDs exhibit strong coherent anti-Stokes Raman scattering (CARS) at the sp3 vibrational resonance of diamond. Using correlative light and electron microscopy, the relationship between CARS signal strength and ND size is quantified. The calibrated CARS signal in turn enables the analysis of the number and size of NDs internalized in living cells in situ, which opens the exciting prospect of following complex cellular trafficking pathways quantitatively. PMID:25305746

Coherent anti-Stokes Raman scattering microscopy of single nanodiamonds.

PubMed

Pope, Iestyn; Payne, Lukas; Zoriniants, George; Thomas, Evan; Williams, Oliver; Watson, Peter; Langbein, Wolfgang; Borri, Paola

2014-11-01

Nanoparticles have attracted enormous attention for biomedical applications as optical labels, drug-delivery vehicles and contrast agents in vivo. In the quest for superior photostability and biocompatibility, nanodiamonds are considered one of the best choices due to their unique structural, chemical, mechanical and optical properties. So far, mainly fluorescent nanodiamonds have been utilized for cell imaging. However, their use is limited by the efficiency and costs in reliably producing fluorescent defect centres with stable optical properties. Here, we show that single non-fluorescing nanodiamonds exhibit strong coherent anti-Stokes Raman scattering (CARS) at the sp(3) vibrational resonance of diamond. Using correlative light and electron microscopy, the relationship between CARS signal strength and nanodiamond size is quantified. The calibrated CARS signal in turn enables the analysis of the number and size of nanodiamonds internalized in living cells in situ, which opens the exciting prospect of following complex cellular trafficking pathways quantitatively.

Wave optics theory and 3-D deconvolution for the light field microscope

PubMed Central

Broxton, Michael; Grosenick, Logan; Yang, Samuel; Cohen, Noy; Andalman, Aaron; Deisseroth, Karl; Levoy, Marc

2013-01-01

Light field microscopy is a new technique for high-speed volumetric imaging of weakly scattering or fluorescent specimens. It employs an array of microlenses to trade off spatial resolution against angular resolution, thereby allowing a 4-D light field to be captured using a single photographic exposure without the need for scanning. The recorded light field can then be used to computationally reconstruct a full volume. In this paper, we present an optical model for light field microscopy based on wave optics, instead of previously reported ray optics models. We also present a 3-D deconvolution method for light field microscopy that is able to reconstruct volumes at higher spatial resolution, and with better optical sectioning, than previously reported. To accomplish this, we take advantage of the dense spatio-angular sampling provided by a microlens array at axial positions away from the native object plane. This dense sampling permits us to decode aliasing present in the light field to reconstruct high-frequency information. We formulate our method as an inverse problem for reconstructing the 3-D volume, which we solve using a GPU-accelerated iterative algorithm. Theoretical limits on the depth-dependent lateral resolution of the reconstructed volumes are derived. We show that these limits are in good agreement with experimental results on a standard USAF 1951 resolution target. Finally, we present 3-D reconstructions of pollen grains that demonstrate the improvements in fidelity made possible by our method. PMID:24150383

Development of fiber lasers and devices for coherent Raman scattering microscopy

NASA Astrophysics Data System (ADS)

Lamb, Erin Stranford

As ultrafast laser technology has found expanding application in machining, spectroscopy, microscopy, surgery, and numerous other areas, the desire for inexpensive and robust laser sources has grown. Until recently, nonlinear effects in fiber systems due to the tight confinement of the light in the core have limited their performance. However, with advances in managing nonlinearity through pulse propagation physics and the use of large core fibers, the performance of fiber lasers can compete with that of their solid-state counterparts. As specific applications, such as coherent Raman scattering microscopy, emerge that stand to benefit from fiber technology, new performance challenges in areas such as laser noise are anticipated. This thesis studies nonlinear pulse propagation in fiber lasers and fiber parametric devices. Applications of dissipative solitons and self-similar pulse propagation to low-repetition rate oscillators that have the potential to simplify short-pulse amplification schemes will be examined. The rest of this thesis focuses on topics relevant to fiber laser development for coherent Raman scattering microscopy sources. Coherent pulse division and recombination inside the laser cavity will be introduced as an energy-scaling mechanism and demonstrated for a fiber soliton laser. The relative intensity noise properties of mode-locked fiber lasers, with a particular emphasis on normal dispersion lasers, will be explored in simulation and experiment. A fiber optical parametric oscillator will be studied in detail for low noise frequency conversion of picosecond pulses, and its utility for coherent Raman imaging will be demonstrated. Spectral compression of femtosecond pulses is used to generate picosecond pulses to pump this device, and this technique provides a route to future noise reduction in the system. Furthermore, this device forms a multimodal source capable of providing the picosecond pulses for coherent Raman scattering microscopy and the high energy femtosecond pulses for other multiphoton imaging techniques. Finally, ideas for future extensions of this work will be discussed.

Fast method of cross-talk effect reduction in biomedical imaging (Conference Presentation)

NASA Astrophysics Data System (ADS)

Nowakowski, Maciej; Kolenderska, Sylwia M.; Borycki, Dawid; Wojtkowski, Maciej

2016-03-01

Optical imaging of biological samples or living tissue structures requires light delivery to a region of interest and then collection of scattered light or fluorescent light in order to reconstruct an image of the object. When the coherent illumination light enters bulky biological object, each of scattering center (single molecule, group of molecules or other sample feature) acts as a secondary light source. As a result, scattered spherical waves from these secondary sources interact with each other, generating cross-talk noise between optical channels (eigenmodes). The cross-talk effect have serious impact on the performance of the imaging systems. In particular it reduces an ability of optical system to transfer high spatial frequencies thereby reducing its resolution. In this work we present a fast method to eliminate all unwanted waves combination, that overlap at image plane, suppressing recovery of high spatial frequencies by using the spatio-temporal optical coherence manipulation (STOC, [1]). In this method a number of phase mask is introduced to illuminating beam by spatial light modulator in a time of single image acquisition. We use a digital mirror device (DMD) in order to rapid cross-talk noise reduction (up to 22kHz modulation frequency) when imaging living biological cells in vivo by using full-field microscopy setup with double pass arrangement. This, to our best knowledge, has never been shown before. [1] D. Borycki, M. Nowakowski, and M. Wojtkowski, Opt. Lett. 38, 4817 (2013).

Optimization of nanoparticle structure for improved conversion efficiency of dye solar cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohamed, Norani Muti, E-mail: noranimuti-mohamed@petronas.com.my; Zaine, Siti Nur Azella, E-mail: ct.azella@gmail.com.my

2014-10-24

Heavy dye loading and the ability to contain the light within the thin layer (typically ∼12 μm) are the requirement needed for the photoelectrode material in order to enhance the harvesting efficiency of dye solar cell. This can be realized by optimizing the particle size with desirable crystal structure. The paper reports the investigation on the dependency of the dye loading and light scattering on the properties of nanostructured photoelectrode materials by comparing 4 different samples of TiO{sub 2} in the form of nanoparticles and micron-sized TiO{sub 2} aggregates which composed of nanocrystallites. Their properties were evaluated by using scanningmore » electron microscopy, X-ray diffraction and UVVis spectroscopy while the performance of the fabricated test cells were measured using universal photovoltaic test system (UPTS) under 1000 W/cm{sup 2} intensity of radiation. Nano sized particles provide large surface area which allow for greater dye adsorption but have no ability to retain the incident light in the TiO{sub 2} film. In contrast, micron-sized particles in the form of aggregates can generate light scattering allowing the travelling distance of the light to be extended and increasing the interaction between the photons and dye molecules adsorb on TiO{sub 2}nanocrystallites. This resulted in an improvement in the conversion efficiency of the aggregates that demonstrates the close relation between light scattering effect and the structure of the photolectrode film.« less

Boxcar detection for high-frequency modulation in stimulated Raman scattering microscopy

NASA Astrophysics Data System (ADS)

Fimpel, P.; Riek, C.; Ebner, L.; Leitenstorfer, A.; Brida, D.; Zumbusch, A.

2018-04-01

Stimulated Raman scattering (SRS) microscopy is an important non-linear optical technique for the investigation of unlabeled samples. The SRS signal manifests itself as a small intensity exchange between the laser pulses involved in coherent excitation of Raman modes. Usually, high-frequency modulation is applied in one pulse train, and the signal is then detected on the other pulse train via lock-in amplification. While allowing shot-noise limited detection sensitivity, lock-in detection, which corresponds to filtering the signal in the frequency domain, is not the most efficient way of using the excitation light. In this manuscript, we show that boxcar averaging, which is equivalent to temporal filtering, is better suited for the detection of low-duty-cycle signals as encountered in SRS microscopy. We demonstrate that by employing suitable gating windows, the signal-to-noise ratios achievable with lock-in detection can be realized in shorter time with boxcar averaging. Therefore, high-quality images are recorded at a faster rate and lower irradiance which is an important factor, e.g., for minimizing degradation of biological samples.

Polarization recovery through scattering media.

PubMed

de Aguiar, Hilton B; Gigan, Sylvain; Brasselet, Sophie

2017-09-01

The control and use of light polarization in optical sciences and engineering are widespread. Despite remarkable developments in polarization-resolved imaging for life sciences, their transposition to strongly scattering media is currently not possible, because of the inherent depolarization effects arising from multiple scattering. We show an unprecedented phenomenon that opens new possibilities for polarization-resolved microscopy in strongly scattering media: polarization recovery via broadband wavefront shaping. We demonstrate focusing and recovery of the original injected polarization state without using any polarizing optics at the detection. To enable molecular-level structural imaging, an arbitrary rotation of the input polarization does not degrade the quality of the focus. We further exploit the robustness of polarization recovery for structural imaging of biological tissues through scattering media. We retrieve molecular-level organization information of collagen fibers by polarization-resolved second harmonic generation, a topic of wide interest for diagnosis in biomedical optics. Ultimately, the observation of this new phenomenon paves the way for extending current polarization-based methods to strongly scattering environments.

Axonal inclusions in the crab Hemigrapsus nudus.

PubMed

Smith, R S

1978-10-01

Light microscopic examination of living giant axons from the walking legs of Hemigrapsus nudus revealed intra-axonal inclusions which were usually several tens of micrometers long and about 5 micron wide. The inclusions were filled with small light-scattering particles. The inclusions were shown, by thin section electron microscopy, to be composed largely 68% by volume) of mitochondria. Each inclusion was surrounded by membrane bounded spaces which are presumed to represent a part of the smooth endoplasmic reticulum. Similar inclusions were not found in the leg axons of a variety of other decapod crustaceans.

Investigation of light scattering characteristics of individual leukocytes using three-dimensional refractive index maps

NASA Astrophysics Data System (ADS)

Sung, Kung-Bin; Lin, Yang-Hsien; Lin, Fong-jheng; Hsieh, Chao-Mao; Wu, Shang-Ju

2017-04-01

Three-dimensional (3D) refractive-index (RI) microscopy is an emerging technique suitable for live-cell imaging due to its label-free and fast 3D imaging capabilities. We have developed a common-path system to acquire 3D RI microscopic images of cells with excellent speed and stability. After obtaining 3D RI distributions of individual leukocytes, we used a 3D finite-difference time-domain tool to study light scattering properties. Backscattering spectra of lymphocytes, monocytes and neutrophils are different from each other. Backscattering spectra of lymphocytes matched well with those of homogeneous spheres as predicted by Mie theory while backscattering spectra of neutrophils are significantly more intense than those of the other two types. This suggests the possibility of classifying the three types of leukocytes based on backscattering.

Improving high resolution retinal image quality using speckle illumination HiLo imaging

PubMed Central

Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

2014-01-01

Retinal image quality from flood illumination adaptive optics (AO) ophthalmoscopes is adversely affected by out-of-focus light scatter due to the lack of confocality. This effect is more pronounced in small eyes, such as that of rodents, because the requisite high optical power confers a large dioptric thickness to the retina. A recently-developed structured illumination microscopy (SIM) technique called HiLo imaging has been shown to reduce the effect of out-of-focus light scatter in flood illumination microscopes and produce pseudo-confocal images with significantly improved image quality. In this work, we adopted the HiLo technique to a flood AO ophthalmoscope and performed AO imaging in both (physical) model and live rat eyes. The improvement in image quality from HiLo imaging is shown both qualitatively and quantitatively by using spatial spectral analysis. PMID:25136486

Improving high resolution retinal image quality using speckle illumination HiLo imaging.

PubMed

Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

2014-08-01

Retinal image quality from flood illumination adaptive optics (AO) ophthalmoscopes is adversely affected by out-of-focus light scatter due to the lack of confocality. This effect is more pronounced in small eyes, such as that of rodents, because the requisite high optical power confers a large dioptric thickness to the retina. A recently-developed structured illumination microscopy (SIM) technique called HiLo imaging has been shown to reduce the effect of out-of-focus light scatter in flood illumination microscopes and produce pseudo-confocal images with significantly improved image quality. In this work, we adopted the HiLo technique to a flood AO ophthalmoscope and performed AO imaging in both (physical) model and live rat eyes. The improvement in image quality from HiLo imaging is shown both qualitatively and quantitatively by using spatial spectral analysis.

Förster resonance energy transfer (FRET)-based picosecond lifetime reference for instrument response evaluation

NASA Astrophysics Data System (ADS)

Luchowski, R.; Kapusta, P.; Szabelski, M.; Sarkar, P.; Borejdo, J.; Gryczynski, Z.; Gryczynski, I.

2009-09-01

Förster resonance energy transfer (FRET) can be utilized to achieve ultrashort fluorescence responses in time-domain fluorometry. In a poly(vinyl) alcohol matrix, the presence of 60 mM Rhodamine 800 acceptor shortens the fluorescence lifetime of a pyridine 1 donor to about 20 ps. Such a fast fluorescence response is very similar to the instrument response function (IRF) obtained using scattered excitation light. A solid fluorescent sample (e.g a film) with picosecond lifetime is ideal for IRF measurements and particularly useful for time-resolved microscopy. Avalanche photodiode detectors, commonly used in this field, feature color- dependent-timing responses. We demonstrate that recording the fluorescence decay of the proposed FRET-based reference sample yields a better IRF approximation than the conventional light-scattering method and therefore avoids systematic errors in decay curve analysis.

Application of asymmetric flow-field flow fractionation to the characterization of colloidal dispersions undergoing aggregation.

PubMed

Lattuada, Marco; Olivo, Carlos; Gauer, Cornelius; Storti, Giuseppe; Morbidelli, Massimo

2010-05-18

The characterization of complex colloidal dispersions is a relevant and challenging problem in colloidal science. In this work, we show how asymmetric flow-field flow fractionation (AF4) coupled to static light scattering can be used for this purpose. As an example of complex colloidal dispersions, we have chosen two systems undergoing aggregation. The first one is a conventional polystyrene latex undergoing reaction-limited aggregation, which leads to the formation of fractal clusters with well-known structure. The second one is a dispersion of elastomeric colloidal particles made of a polymer with a low glass transition temperature, which undergoes coalescence upon aggregation. Samples are withdrawn during aggregation at fixed times, fractionated with AF4 using a two-angle static light scattering unit as a detector. We have shown that from the analysis of the ratio between the intensities of the scattered light at the two angles the cluster size distribution can be recovered, without any need for calibration based on standard elution times, provided that the geometry and scattering properties of particles and clusters are known. The nonfractionated samples have been characterized also by conventional static and dynamic light scattering to determine their average radius of gyration and hydrodynamic radius. The size distribution of coalescing particles has been investigated also through image analysis of cryo-scanning electron microscopy (SEM) pictures. The average radius of gyration and the average hydrodynamic radius of the nonfractionated samples have been calculated and successfully compared to the values obtained from the size distributions measured by AF4. In addition, the data obtained are also in good agreement with calculations made with population balance equations.

Prediction of Prostate Cancer Recurrence Using Quantitative Phase Imaging

NASA Astrophysics Data System (ADS)

Sridharan, Shamira; Macias, Virgilia; Tangella, Krishnarao; Kajdacsy-Balla, André; Popescu, Gabriel

2015-05-01

The risk of biochemical recurrence of prostate cancer among individuals who undergo radical prostatectomy for treatment is around 25%. Current clinical methods often fail at successfully predicting recurrence among patients at intermediate risk for recurrence. We used a label-free method, spatial light interference microscopy, to perform localized measurements of light scattering in prostatectomy tissue microarrays. We show, for the first time to our knowledge, that anisotropy of light scattering in the stroma immediately adjoining cancerous glands can be used to identify patients at higher risk for recurrence. The data show that lower value of anisotropy corresponds to a higher risk for recurrence, meaning that the stroma adjoining the glands of recurrent patients is more fractionated than in non-recurrent patients. Our method outperformed the widely accepted clinical tool CAPRA-S in the cases we interrogated irrespective of Gleason grade, prostate-specific antigen (PSA) levels and pathological tumor-node-metastasis (pTNM) stage. These results suggest that QPI shows promise in assisting pathologists to improve prediction of prostate cancer recurrence.

Quantitative readout of optically encoded gold nanorods using an ordinary dark-field microscope.

PubMed

Mercatelli, Raffaella; Ratto, Fulvio; Centi, Sonia; Soria, Silvia; Romano, Giovanni; Matteini, Paolo; Quercioli, Franco; Pini, Roberto; Fusi, Franco

2013-10-21

In this paper we report on a new use for dark-field microscopy in order to retrieve two-dimensional maps of optical parameters of a thin sample such as a cryptograph, a histological section, or a cell monolayer. In particular, we discuss the construction of quantitative charts of light absorbance and scattering coefficients of a polyvinyl alcohol film that was embedded with gold nanorods and then etched using a focused mode-locked Ti:Sapphire oscillator. Individual pulses from this laser excite plasmonic oscillations of the gold nanorods, thus triggering plastic deformations of the particles and their environment, which are confined within a few hundred nm of the light focus. In turn, these deformations modify the light absorbance and scattering landscape, which can be measured with optical resolution in a dark-field microscope equipped with an objective of tuneable numerical aperture. This technique may prove to be valuable for various applications, such as the fast readout of optically encoded data or to model functional interactions between light and biological tissue at the level of cellular organelles, including the photothermolysis of cancer.

Three-dimensional automated nanoparticle tracking using Mie scattering in an optical microscope.

PubMed

Gineste, J-M; Macko, P; Patterson, E A; Whelan, M P

2011-08-01

The forward scattering of light in a conventional inverted optical microscope by nanoparticles ranging in diameter from 10 to 50nm has been used to automatically and quantitatively identify and track their location in three-dimensions with a temporal resolution of 200ms. The standard deviation of the location of nominally stationary 50-nm-diameter nanoparticles was found to be about 50nm along the light path and about 5nm in the plane perpendicular to the light path. The method is based on oscillating the microscope objective along the light path using a piezo actuator and acquiring images with the condenser aperture closed to a minimum to enhance the effects of diffraction. Data processing in the time and spatial domains allowed the location of particles to be obtained automatically so that the technique has potential applications both in the processing of nanoparticles and in their use in a variety of fields including nanobiotechnology, pharmaceuticals and food processing where a simple optical microscope maybe preferred for a variety of reasons. © 2011 The Authors Journal of Microscopy © 2011 Royal Microscopical Society.

Effect of void shape in Czochralski-Si wafers on the intensity of laser-scattering

NASA Astrophysics Data System (ADS)

Takahashi, J.; Kawakami, K.; Nakai, K.

2001-06-01

The shape effect of anisotropic-shaped microvoid defects in Czochralski-grown silicon wafers on the intensity of laser scattering has been investigated. The size and shape of the defects were examined by means of transmission electron microscopy. Octahedral voids in conventional (nitrogen-undoped) wafers showed an almost isotropic scattering property under the incident condition of a p-polarization beam. On the other hand, parallelepiped-plate-shaped voids in nitrogen-doped wafers showed an anisotropic scattering property on both p- and s-polarized components of scattered light, depending strongly on the incident laser direction. The measured results were explained not by scattering calculation using Born approximation but by calculation based on Rayleigh scattering. It was found that the s component is explained by an inclination of a dipole moment induced on a defect from the scattering plane. Furthermore, using numerical electromagnetic analysis it was shown that the asymmetric behavior of the s component on the parallelepiped-plate voids is ascribed to the parallelepiped shape effect. These results suggest that correction of the scattering intensity is necessary to evaluate the size and volume of anisotropic-shaped defects from the scattered intensity.

Selective imaging of saturated and unsaturated lipids by wide-field CARS-microscopy.

PubMed

Heinrich, Christoph; Hofer, Alexander; Ritsch, Andreas; Ciardi, Christian; Bernet, Stefan; Ritsch-Marte, Monika

2008-02-18

Wide-field Coherent Anti-Stokes Raman Scattering (CARS) microscopy is employed to identify saturated and unsaturated fatty acids in micro-emulsions and cells, using the ratio between the strong -C-H CARS signal at 2850 cm(-1) and the weak signal of the =C-H vibration around 3015 cm(-1) for distinction. Quantitative CARS imaging at the =C-H resonance is challenging, since it yields only a low CARS signal, and small differences on the order of 5% in the concentration of polyunsaturated fatty lipids have to be detected. For this purpose we draw advantage of the high signal-to-noise ratio of wide-field CARS microscopy that is achieved by an excitation geometry involving a "sheet-of-light"-type illumination.

Materials characterisation by angle-resolved scanning transmission electron microscopy.

PubMed

Müller-Caspary, Knut; Oppermann, Oliver; Grieb, Tim; Krause, Florian F; Rosenauer, Andreas; Schowalter, Marco; Mehrtens, Thorsten; Beyer, Andreas; Volz, Kerstin; Potapov, Pavel

2016-11-16

Solid-state properties such as strain or chemical composition often leave characteristic fingerprints in the angular dependence of electron scattering. Scanning transmission electron microscopy (STEM) is dedicated to probe scattered intensity with atomic resolution, but it drastically lacks angular resolution. Here we report both a setup to exploit the explicit angular dependence of scattered intensity and applications of angle-resolved STEM to semiconductor nanostructures. Our method is applied to measure nitrogen content and specimen thickness in a GaN x As 1-x layer independently at atomic resolution by evaluating two dedicated angular intervals. We demonstrate contrast formation due to strain and composition in a Si- based metal-oxide semiconductor field effect transistor (MOSFET) with Ge x Si 1-x stressors as a function of the angles used for imaging. To shed light on the validity of current theoretical approaches this data is compared with theory, namely the Rutherford approach and contemporary multislice simulations. Inconsistency is found for the Rutherford model in the whole angular range of 16-255 mrad. Contrary, the multislice simulations are applicable for angles larger than 35 mrad whereas a significant mismatch is observed at lower angles. This limitation of established simulations is discussed particularly on the basis of inelastic scattering.

Optical properties of mouse brain tissue after optical clearing with FocusClear™

NASA Astrophysics Data System (ADS)

Moy, Austin J.; Capulong, Bernard V.; Saager, Rolf B.; Wiersma, Matthew P.; Lo, Patrick C.; Durkin, Anthony J.; Choi, Bernard

2015-09-01

Fluorescence microscopy is commonly used to investigate disease progression in biological tissues. Biological tissues, however, are strongly scattering in the visible wavelengths, limiting the application of fluorescence microscopy to superficial (<200 μm) regions. Optical clearing, which involves incubation of the tissue in a chemical bath, reduces the optical scattering in tissue, resulting in increased tissue transparency and optical imaging depth. The goal of this study was to determine the time- and wavelength-resolved dynamics of the optical scattering properties of rodent brain after optical clearing with FocusClear™. Light transmittance and reflectance of 1-mm mouse brain sections were measured using an integrating sphere before and after optical clearing and the inverse adding doubling algorithm used to determine tissue optical scattering. The degree of optical clearing was quantified by calculating the optical clearing potential (OCP), and the effects of differing OCP were demonstrated using the optical histology method, which combines tissue optical clearing with optical imaging to visualize the microvasculature. We observed increased tissue transparency with longer optical clearing time and an analogous increase in OCP. Furthermore, OCP did not vary substantially between 400 and 1000 nm for increasing optical clearing durations, suggesting that optical histology can improve ex vivo visualization of several fluorescent probes.

Optical monitoring of protein crystal growth

NASA Technical Reports Server (NTRS)

Choudry, A.

1988-01-01

The possibility of using various optical techniques for detecting the onset of nucleation in protein crystal growth was investigated. Direct microscopy, general metrologic techniques, light scattering, ultraviolet absorption, and interferometry are addressed along with techniques for determining pH value. The necessity for collecting basic data on the optical properties of the growth solution as a prerequisite to the evaluation of monitoring techniques is pointed out.

Engineered Defects for Investigation of Laser-Induced Damage of Fused Silica at 355nm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamza, A V; Siekhaus, W J; Rubenchik, A M

2001-12-18

Embedded gold and mechanical deformation in silica were used to investigate initiation of laser-induced damage at 3.55-nm (7.6 ns). The nanoparticle-covered surfaces were coated with between 0 and 500 nm of SiO{sub 2} by e-beam deposition. The threshold for observable damage and initiation site morphology for these ''engineered'' surfaces was determined. The gold nanoparticle coated surfaces with 500nm SiO{sub 2} coating exhibited pinpoint damage threshold of <0.7 J/cm{sup 2} determined by light scattering and Nomarski microscopy. The gold nanoparticle coated surfaces with the 100nm SiO{sub 2} coatings exhibited what nominally appeared to be film exfoliation damage threshold of 19 J/cm{supmore » 2} via light scattering and Nomarski microscopy. With atomic force microscopy pinholes could be detected at fluences greater than 7 J/cm{sup 2} and blisters at fluences greater than 3 J/cm{sup 2} on the 100 nm-coated surfaces. A series of mechanical indents and scratches were made in the fused silica substrates using a nano-indentor. Plastic deformation without cracking led to damage thresholds of -25 J/cm{sup 2}, whereas indents and scratches with cracking led to damage thresholds of only {approx}5 J/cm{sup 2}. Particularly illuminating was the deterministic damage of scratches at the deepest end of the scratch, as if the scratch acted as a waveguide.« less

Isotope effect in heavy/light water suspensions of optically active gold nanoparticles

NASA Astrophysics Data System (ADS)

Kutsenko, V. Y.; Artykulnyi, O. P.; Petrenko, V. I.; Avdeev, M. V.; Marchenko, O. A.; Bulavin, L. A.; Snegir, S. V.

2018-04-01

Aqueous suspensions of optically active gold nanoparticles coated with trisodium citrate were synthesized in light (H2O) water and mixture of light and heavy (H2O/D2O) water using the modified Turkevich protocol. The objective of the paper was to verify sensitivity of neutron scattering methods (in particular, neutron reflectometry) to the potential isotope H/D substitution in the stabilizing organic shell around particles in colloidal solutions. First, the isotope effect was studied with respect to the changes in the structural properties of metal particles (size, shape, crystalline morphology) in solutions by electron microscopy including high-resolution transmission electron microscopy from dried systems. The structural factors determining the variation in the adsorption spectra in addition to the change in the optical properties of surrounding medium were discussed. Then, neutron reflectometry was applied to the layered nanoparticles anchored on a silicon wafer via 3-aminopropyltriethoxysilane molecules to reveal the presence of deuterated water molecules in the shell presumably formed by citrate molecules around the metallic core.

Light-responsive micelles of spiropyran initiated hyperbranched polyglycerol for smart drug delivery.

PubMed

Son, Suhyun; Shin, Eeseul; Kim, Byeong-Su

2014-02-10

Light-responsive polymeric micelles have emerged as site-specific and time-controlled systems for advanced drug delivery. Spiropyran (SP), a well-known photochromic molecule, was used to initiate the ring-opening multibranching polymerization of glycidol to afford a series of hyperbranched polyglycerols (SP-hb-PG). The micelle assembly and disassembly were induced by an external light source owing to the reversible photoisomerization of hydrophobic SP to hydrophilic merocyanine (MC). Transmission electron microscopy, atomic force microscopy, UV/vis spectroscopy, and dynamic light scattering demonstrated the successful assembly and disassembly of SP-hb-PG micelles. In addition, the critical micelle concentration (CMC) was determined through the fluorescence analysis of pyrene to confirm the amphiphilicity of respective SP-hb-PGn (n = 15, 29, and 36) micelles, with CMC values ranging from 13 to 20 mg/L, which is correlated to the length of the polar polyglycerol backbone. Moreover, the superior biocompatibility of the prepared SP-hb-PG was evaluated using WI-38 cells and HeLa cells, suggesting the prospective applicability of the micelles in smart drug delivery systems.

Imaging of Lipids in Microalgae with Coherent Anti-Stokes Raman Scattering Microscopy1[OPEN

PubMed Central

Cavonius, Lillie; Fink, Helen; Kiskis, Juris; Albers, Eva; Undeland, Ingrid; Enejder, Annika

2015-01-01

Microalgae have great prospects as a sustainable resource of lipids for refinement into nutraceuticals and biodiesel, which increases the need for detailed insights into their intracellular lipid synthesis/storage mechanisms. As an alternative strategy to solvent- and label-based lipid quantification techniques, we introduce time-gated coherent anti-Stokes Raman scattering (CARS) microscopy for monitoring lipid contents in living algae, despite strong autofluorescence from the chloroplasts, at approximately picogram and subcellular levels by probing inherent molecular vibrations. Intracellular lipid droplet synthesis was followed in Phaeodactylum tricornutum algae grown under (1) light/nutrient-replete (control [Ctrl]), (2) light-limited (LL), and (3) nitrogen-starved (NS) conditions. Good correlation (r2 = 0.924) was found between lipid volume data yielded by CARS microscopy and total fatty acid content obtained from gas chromatography-mass spectrometry analysis. In Ctrl and LL cells, micron-sized lipid droplets were found to increase in number throughout the growth phases, particularly in the stationary phase. During more excessive lipid accumulation, as observed in NS cells, promising commercial harvest as biofuels and nutritional lipids, several micron-sized droplets were present already initially during cultivation, which then fused into a single giant droplet toward stationary phase alongside with new droplets emerging. CARS microspectroscopy further indicated lower lipid fluidity in NS cells than in Ctrl and LL cells, potentially due to higher fatty acid saturation. This agreed with the fatty acid profiles gathered by gas chromatography-mass spectrometry. CARS microscopy could thus provide quantitative and semiqualitative data at the single-cell level along with important insights into lipid-accumulating mechanisms, here revealing two different modes for normal and excessive lipid accumulation. PMID:25583924

Optical, Physical and Chemical Properties of Tar Balls Observed During the Yosemite Aerosol Characterization Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hand, Jenny L.; Malm, W. C.; Laskin, Alexander

2005-11-09

The Yosemite Aerosol Characterization Study of summer 2002 (YACS) occurred during an active fire season in the western U. S., and provided an opportunity to investigate many unresolved issues related to the radiative effects of biomass burning aerosols. Single particle analysis was performed on field collected aerosol samples using an array of electron microscopy techniques. Amorphous carbon spheres, or “tar balls”, were present in samples collected during episodes of high particle light scattering coefficients that occurred during the peak of a smoke/haze event. The highest concentrations of light-absorbing carbon from a dual-wavelength aethalometer (λ = 370 and 880 nm) occurredmore » during periods when the particles were predominantly tar balls, indicating they do absorb light in the UV and near-IR range of the solar spectrum. Closure experiments of mass concentrations and light scattering coefficients during periods dominated by tar balls did not require any distinct assumptions of organic carbon molecular weight correction factors, density, or refractive index compared to periods dominated by other types of organic carbon aerosols. Measurements of the hygroscopic behavior of tar balls using an environmental SEM indicate that tar balls do not exhibit deliquescence, but do uptake some water at high (~83 %) relative humidity. The ability of tar balls to efficiently scatter and absorb light, and to absorb water has important implications for their role in regional haze and climate fence.« less

Vegetable Oil-Loaded Nanocapsules: Innovative Alternative for Incorporating Drugs for Parenteral Administration.

PubMed

Venturinil, C G; Bruinsmann, A; Oliveira, C P; Contri, R V; Pohlmann, A R; Guterres, S S

2016-02-01

An innovative nanocapsule formulation for parenteral administration using selected vegetable oils (mango, jojoba, pequi, oat, annatto, calendula, and chamomile) was developed that has the potential to encapsulate various drugs. The vegetable oil-loaded nanocapsules were prepared by interfacial deposition and compared with capric/caprylic triglyceride-loaded lipid core nanocapsules. The major objective was to investigate the effect of vegetable oils on particle size distribution and physical stability and to determine the hemolytic potential of the nanocapsules, considering their applicability for intravenous administration. Taking into account the importance of accurately determining particle size for the selected route of administration, different size characterization techniques were employed, such as Laser Diffraction, Dynamic Light Scattering, Multiple Light Scattering, Nanoparticle Tracking Analysis, and Transmission Electronic Microscopy. Laser diffraction studies indicated that the mean particle size of all nanocapsules was below 300 nm. For smaller particles, the laser diffraction and multiple light scattering data were in agreement (D[3,2]-130 nm). Dynamic light scattering and nanoparticle tracking analysis, two powerful techniques that complement each other, exhibited size values between 180 and 259 nm for all nanoparticles. Stability studies demonstrated a tendency of particle creaming for jojoba-nanocapsules and sedimentation for the other nanoparticles; however, no size variation occurred over 30 days. The hemolysis test proved the hemocompatibility of all nanosystems, irrespective of the type of oil. Although all developed nanocapsules presented the potential for parenteral administration, jojoba oil-loaded nanocapsules were selected as the most promising nanoformulation due to their low average size and high particle size homogeneity.

Bioorthogonal Chemical Imaging for Biomedicine

NASA Astrophysics Data System (ADS)

Min, Wei

2017-06-01

Innovations in light microscopy have tremendously revolutionized the way researchers study biological systems with subcellular resolution. Although fluorescence microscopy is currently the method of choice for cellular imaging, it faces fundamental limitations for studying the vast number of small biomolecules. This is because relatively bulky fluorescent labels could introduce considerable perturbation to or even completely alter the native functions of vital small biomolecules. Hence, despite their immense functional importance, these small biomolecules remain largely undetectable by fluorescence microscopy. To address this challenge, we have developed a bioorthogonal chemical imaging platform. By coupling stimulated Raman scattering (SRS) microscopy, an emerging nonlinear Raman microscopy technique, with tiny and Raman-active vibrational probes (e.g., alkynes, nitriles and stable isotopes including 2H and 13C), bioorthogonal chemical imaging exhibits superb sensitivity, specificity, multiplicity and biocompatibility for imaging small biomolecules in live systems including tissues and organisms. Exciting biomedical applications such as imaging fatty acid metabolism related to lipotoxicity, glucose uptake and metabolism, drug trafficking, protein synthesis, DNA replication, protein degradation, RNA synthesis and tumor metabolism will be presented. This bioorthogonal chemical imaging platform is compatible with live-cell biology, thus allowing real-time imaging of small-molecule dynamics. Moreover, further chemical and spectroscopic strategies allow for multicolor bioorthogonal chemical imaging, a valuable technique in the era of "omics". We envision that the coupling of SRS microscopy with vibrational probes would do for small biomolecules what fluorescence microscopy of fluorophores has done for larger molecular species, bringing small molecules under the illumination of modern light microscopy.

You can't measure what you can't see - detectors for microscopies

NASA Astrophysics Data System (ADS)

Denes, Peter

For centuries, the human eye has been the imaging detector of choice thanks to its high sensitivity, wide dynamic range, and direct connection to a built-in data recording and analysis system. The eye, however, is limited to visible light, which excludes microscopies with electrons and X-rays, and the built-in recording system stores archival information at very low rates. The former limitation has been overcome by ``indirect'' detectors, which convert probe particles to visible light, and the latter by a variety of recording techniques, from photographic film to semiconductor-based imagers. Semiconductor imagers have been used for decades as ``direct'' detectors in particle physics, and almost as long for hard X-rays. For soft X-ray microscopy, the challenge has been the small signal levels - plus getting the X-rays into the detector itself, given how quickly they are absorbed in inert layers. For electron microscopy, the challenge has been reconciling detector spatial resolution and pixel count with the large multiple scattering of electrons with energies used for microscopy. Further, a high recording rate (``movies'' rather than ``snapshots'') enables time-resolved studies, time-dependent corrections, shot-by-shot experiments and scanning techniques - at the expense of creating large data volumes. This talk will discuss solutions to these challenges, as well as an outlook towards future developments.

Dynamic light scattering for the characterization and counting of extracellular vesicles: a powerful noninvasive tool

NASA Astrophysics Data System (ADS)

Palmieri, Valentina; Lucchetti, Donatella; Gatto, Ilaria; Maiorana, Alessandro; Marcantoni, Margherita; Maulucci, Giuseppe; Papi, Massimiliano; Pola, Roberto; De Spirito, Marco; Sgambato, Alessandro

2014-09-01

Extracellular vesicles (EVs) are cell-to-cell shuttles that have recently drawn interest both as drug delivery platforms and disease biomarkers. Despite the increasingly recognized relevance of these vesicles, their detection, and characterization still have several technical drawbacks. In this paper, we accurately assess the size distribution and concentration of EVs by using a high-throughput non-perturbative technique such as Dynamic Light Scattering (DLS). The vesicle radii distribution, as further confirmed by Atomic Force Microscopy experiments, ranges from 10 to 80 nm and appears very asymmetric towards larger radii with a main peak at roughly 30 nm. By combining DLS and Bradford assay, we also demonstrate the feasibility of recovering the concentration and its distribution of proteins contained inside vesicles. The sensitivity of our approach allows to detect protein concentrations as low as 0.01 mg/ml.

Controlled Synthesis and Fluorescence Tracking of Highly Uniform Poly(N-isopropylacrylamide) Microgels.

PubMed

Virtanen, Otto L J; Purohit, Ashvini; Brugnoni, Monia; Wöll, Dominik; Richtering, Walter

2016-09-08

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this work, we use single particle tracking of fluorescently labeled PNIPAM microgels as a showcase for tuning microgel size by a rapid non-stirred precipitation polymerization procedure. This approach is well suited for prototyping new reaction compositions and conditions or for applications that do not require large amounts of product. Microgel synthesis, particle size and structure determination by dynamic and static light scattering are detailed in the protocol. It is shown that the addition of functional comonomers can have a large influence on the particle nucleation and structure. Single particle tracking by wide-field fluorescence microscopy allows for an investigation of the diffusion of labeled tracer microgels in a concentrated matrix of non-labeled microgels, a system not easily investigated by other methods such as dynamic light scattering.

Adapalene microemulsion for transfollicular drug delivery.

PubMed

Bhatia, Gaurav; Zhou, Yingcong; Banga, Ajay K

2013-08-01

The aim of this study was to develop a microemulsion formulation of adapalene for transfollicular delivery. A pseudoternary phase diagram was developed for microemulsion consisting of oleic acid as oil phase, tween 20 as surfactant, Transcutol® as cosurfactant, and deionized water. Differential tape stripping and confocal laser scanning microscopy were performed to determine the penetration of microemulsion through hair follicles. Transmission electron microscopy, dynamic light scattering, polarizing light microscopy, and differential scanning calorimetry were performed to characterize the microstructures of microemulsion. The pH and viscosity of the microemulsions were also determined. Permeation studies were carried out in vitro on porcine ear skin over a period of 24 h using Franz diffusion cells. The drug penetration in the hair follicles increased from 0.109 ± 0.03 to 0.292 ± 0.094 μg, as the microstructure of microemulsion shifted from oil-in-water to bi-continuous, with increase in water content of microemulsion. Confocal laser scanning microscopy images suggested that hair follicles provided the path for transfollicular permeation of adapalene microemulsion. These results suggest that microemulsion penetrated through hair follicles and are promising for transfollicular drug delivery. Copyright © 2013 Wiley Periodicals, Inc.

Broadband near-field mid-infrared spectroscopy and application to phonon resonances in quartz.

PubMed

Ishikawa, Michio; Katsura, Makoto; Nakashima, Satoru; Ikemoto, Yuka; Okamura, Hidekazu

2012-05-07

Infrared (IR) spectroscopy is a versatile analytical method and nano-scale spatial resolution could be achieved by scattering type near-field optical microscopy (s-SNOM). The spectral bandwidth was, however, limited to approximately 300 cm(-1) with a laser light source. In the present study, the development of a broadband mid-IR near-field spectroscopy with a ceramic light source is demonstrated. A much wider bandwidth (at least 3000 to 1000 cm(-1)) is achieved with a ceramic light source. The experimental data on quartz Si-O phonon resonance bands are well reproduced by theoretical simulations indicating the validity of the present broadband near-field IR spectroscopy.

In vivo flow cytometry for blood cell analysis using differential epi-detection of forward scattered light

NASA Astrophysics Data System (ADS)

Paudel, Hari P.; Jung, Yookyung; Raphael, Anthony; Alt, Clemens; Wu, Juwell; Runnels, Judith; Lin, Charles P.

2018-02-01

The present standard of blood cell analysis is an invasive procedure requiring the extraction of patient's blood, followed by ex-vivo analysis using a flow cytometer or a hemocytometer. We are developing a noninvasive optical technique that alleviates the need for blood extraction. For in-vivo blood analysis we need a high speed, high resolution and high contrast label-free imaging technique. In this proceeding report, we reported a label-free method based on differential epi-detection of forward scattered light, a method inspired by Jerome Mertz's oblique back-illumination microscopy (OBM) (Ford et al, Nat. Meth. 9(12) 2012). The differential epi-detection of forward light gives phase contrast image at diffraction-limited resolution. Unlike reflection confocal microscopy (RCM), which detects only sharp refractive index variation and suffers from speckle noise, this technique is suitable for detection of subtle variation of refractive index in biological tissue and it provides the shape and the size of cells. A custom built high speed electronic detection circuit board produces a real-time differential signal which yields image contrast based on phase gradient in the sample. We recorded blood flow in-vivo at 17.2k lines per second in line scan mode, or 30 frames per second (full frame), or 120 frame per second (quarter frame) in frame scan mode. The image contrast and speed of line scan data recording show the potential of the system for noninvasive blood cell analysis.

Characterization of Propylene Glycol-Mitigated Freeze/Thaw Agglomeration of a Frozen Liquid nOMV Vaccine Formulation by Static Light Scattering and Micro-Flow Imaging.

PubMed

Mensch, Christopher D; Davis, Harrison B; Blue, Jeffrey T

2015-01-01

The purpose of this work was to investigate the susceptibility of an aluminum adjuvant and an aluminum-adjuvanted native outer membrane vesicle (nOMV) vaccine formulation to freeze/thaw-induced agglomeration using static light scattering and micro-flow Imaging analysis; and to evaluate the use of propylene glycol as a vaccine formulation excipient by which freeze/thaw-induced agglomeration of a nOMV vaccine formulation could be mitigated. Our results indicate that including 7% v/v propylene glycol in an nOMV containing aluminum adjuvanted vaccine formulation, mitigates freeze/thaw-induced agglomeration. We evaluated the effect of freeze-thawing on an aluminum adjuvant and an aluminum adjuvanted native outer membrane vesicle (nOMV) vaccine formulation. Specifically, we characterized the freeze/thaw-induced agglomeration through the use of static light scattering, micro-flow imaging, and cryo-electron microscopy analysis. Further, we evaluated the use of 0-9% v/v propylene glycol as an excipient which could be included in the formulation for the purpose of mitigating the agglomeration induced by freeze/thaw. The results indicate that using 7% v/v propylene glycol as a formulation excipient is effective at mitigating agglomeration of the nOMV vaccine formulation, otherwise induced by freeze-thawing. © PDA, Inc. 2015.

Creation and study of triterpenoid nanoparticles and radioprotective substance genistein.

PubMed

Nguyen, H Q; Chupin, V V; Prokhorov, D I; Chikunov, I E; Kovtun, V Yu; Tarumov, R A; Grebenyuk, A N; Shvets, V I

2015-01-01

This work is devoted to the study and obtaining of new radioprotective agents based on natural flavonoid genistein and spherical amorphous nanoparticles (SANPs) produced from a mixture of birch bark triterpenoids. The physicochemical characteristics of the nanoparticles were studied by electron microscopy, dynamic light scattering, and UV-VIS spectroscopy. The radioprotective efficacy of the nanodrug in vivo and the possibility of its use as a radioprotective agent was shown.

Tip-enhanced near-field optical microscopy

PubMed Central

Mauser, Nina; Hartschuh, Achim

2013-01-01

Tip-enhanced near-field optical microscopy (TENOM) is a scanning probe technique capable of providing a broad range of spectroscopic information on single objects and structured surfaces at nanometer spatial resolution and with highest detection sensitivity. In this review, we first illustrate the physical principle of TENOM that utilizes the antenna function of a sharp probe to efficiently couple light to excitations on nanometer length scales. We then discuss the antenna-induced enhancement of different optical sample responses including Raman scattering, fluorescence, generation of photocurrent and electroluminescence. Different experimental realizations are presented and several recent examples that demonstrate the capabilities of the technique are reviewed. PMID:24100541

Combined SERS and Raman analysis for the identification of red pigments in cross-sections from historic oil paintings.

PubMed

Frano, Kristen A; Mayhew, Hannah E; Svoboda, Shelley A; Wustholz, Kristin L

2014-12-21

The analysis of paint cross-sections can reveal a remarkable amount of information about the layers and materials in a painting without visibly altering the artwork. Although a variety of analytical approaches are used to detect inorganic pigments as well as organic binders, proteins, and lipids in cross-sections, they do not provide for the unambiguous identification of natural, organic colorants. Here, we develop a novel combined surface-enhanced Raman scattering (SERS), light microscopy, and normal Raman scattering (NRS) approach for the identification of red organic and inorganic pigments in paint cross-sections obtained from historic 18th and 19th century oil paintings. In particular, Ag nanoparticles are directly applied to localized areas of paint cross-sections mounted in polyester resin for SERS analysis of the organic pigments. This combined extractionless non-hydrolysis SERS and NRS approach provides for the definitive identification of carmine lake, madder lake, and vermilion in multiple paint layers. To our knowledge, this study represents the first in situ identification of natural, organic pigments within paint cross-sections from oil paintings. Furthermore, the combination of SERS and normal Raman, with light microscopy provides conservators with a more comprehensive understanding of a painting from a single sample and without the need for sample pretreatment.

Virus Characterization by FFF-MALS Assay

NASA Astrophysics Data System (ADS)

Razinkov, Vladimer

2009-03-01

Adequate biophysical characterization of influenza virions is important for vaccine development. The influenza virus vaccines are produced from the allantoic fluid of developing chicken embryos. The process of viral replication produces a heterogeneous mixture of infectious and non-infectious viral particles with varying states of aggregation. The study of the relative distribution and behavior of different subpopulations and their inter-correlation can assist in the development of a robust process for a live virus vaccine. This report describes a field flow fractionation and multiangle light scattering (FFF-MALS) method optimized for the analysis of size distribution and total particle counts. A method using a combination of asymmetric flow field-flow fractionation (AFFFF) and multiangle light scattering (MALS) techniques has been shown to improve the estimation of virus particle counts and the amount of aggregated virus in laboratory samples. The FFF-MALS method was compared with several other methods such as transmission electron microscopy (TEM), atomic force microscopy (AFM), size exclusion chromatography followed by MALS (SEC-MALS), quantitative reverse transcription polymerase chain reaction (RT Q-PCR), median tissue culture dose (TCID(50)), and the fluorescent focus assay (FFA). The correlation between the various methods for determining total particle counts, infectivity and size distribution is reported. The pros and cons of each of the analytical methods are discussed.

Coherent scatter-controlled phase-change grating structures in silicon using femtosecond laser pulses.

PubMed

Fuentes-Edfuf, Yasser; Garcia-Lechuga, Mario; Puerto, Daniel; Florian, Camilo; Garcia-Leis, Adianez; Sanchez-Cortes, Santiago; Solis, Javier; Siegel, Jan

2017-07-04

Periodic structures of alternating amorphous-crystalline fringes have been fabricated in silicon using repetitive femtosecond laser exposure (800 nm wavelength and 120 fs duration). The method is based on the interference of the incident laser light with far- and near-field scattered light, leading to local melting at the interference maxima, as demonstrated by femtosecond microscopy. Exploiting this strategy, lines of highly regular amorphous fringes can be written. The fringes have been characterized in detail using optical microscopy combined modelling, which enables a determination of the three-dimensional shape of individual fringes. 2D micro-Raman spectroscopy reveals that the space between amorphous fringes remains crystalline. We demonstrate that the fringe period can be tuned over a range of 410 nm - 13 µm by changing the angle of incidence and inverting the beam scan direction. Fine control over the lateral dimensions, thickness, surface depression and optical contrast of the fringes is obtained via adjustment of pulse number, fluence and spot size. Large-area, highly homogeneous gratings composed of amorphous fringes with micrometer width and millimeter length can readily be fabricated. The here presented fabrication technique is expected to have applications in the fields of optics, nanoelectronics, and mechatronics and should be applicable to other materials.

New histopathologic and ultrastructural findings in Reis-Bücklers corneal dystrophy caused by the Arg124Leu mutation of TGFBI gene.

PubMed

Qiu, Wen-Ya; Zheng, Li-Bin; Pan, Fei; Wang, Bei-Bei; Yao, Yu-Feng

2016-09-02

Reis-Bücklers corneal dystrophy (RBCD) was consistently reported as a corneal dystrophy only affected Bowman's layer and superficial corneal stroma, and superficial keratectomy was a recommendation surgery for treatment in literatures. The study reported new histopathological and ultrastructural findings in RBCD caused by the Arg124Leu mutation of transforming growth factor induced (TGFBI) gene in a four-generation Chinese pedigree. Subjects including eight patients and seven unaffected family members received slit-lamp biomicroscopy and photography. DNA was obtained from all subjects, and exons 4 and 11 to 14 of TGFBI gene were analyzed by polymerase chain reaction and the products were sequenced. Anterior segment optical coherence tomography (AS OCT) and in vivo confocal microscopy were conducted for ten eyes of five patients. Based on the results of AS OCT and in vivo confocal microscopy, deep anterior lamellar keratoplasty (DLKP) using cryopreserved donor cornea was applied for four eyes of four patients. Four lamellar dystrophic corneal buttons were studied by light and transmission electron microscopy, and TGFBI immunohistochemistry. Eight patients had typical clinical manifestations of RBCD presenting recurrent painful corneal erosion starting in their early first decades, along with age-dependent progressive geographic corneal opacities. TGFBI sequencing revealed a heterozygous mutation, Arg124Leu in all eight patients. Anterior segment optical coherence tomography and in vivo confocal microscopy showed the dystrophic deposits involved not only in subepithelial and superficial stroma, but also in mid- or posterior stroma in four examined advanced eyes. Light microscopy showed Bowman's layer was absent, replaced by abnormal deposits stain bright red with Masson's trichrome. In superficial cornea, the deposits stacked and produced three to five continuous bands parallel to the corneal collagen lamellae. In mid- to posterior stroma, numerous granular or dot- like aggregates were heavily scattered, and most of them presented around the nuclei of stromal keratocytes. Transmission electron microscopy revealed the multiple electron-dense rod-shaped deposits aggregated and formed a characteristic pattern of three to five continuous bands in superficial cornea, which were similar to those seen under light microscopy. In mid- to posterior stroma, clusters of rod-shaped bodies were scattered extracellular or intracellular of the stromal keratocytes between the stromal lamellae suggesting the close relationship between mutated proteins and keratocyte. The study offer evidences indicating DLKP is a viable treatment option for advanced RBCD to avoid recurrence, and the mutated TGFBIp in dystrophic corneas are of keratocytes origin.

Gaussian vs. Bessel light-sheets: performance analysis in live large sample imaging

NASA Astrophysics Data System (ADS)

Reidt, Sascha L.; Correia, Ricardo B. C.; Donnachie, Mark; Weijer, Cornelis J.; MacDonald, Michael P.

2017-08-01

Lightsheet fluorescence microscopy (LSFM) has rapidly progressed in the past decade from an emerging technology into an established methodology. This progress has largely been driven by its suitability to developmental biology, where it is able to give excellent spatial-temporal resolution over relatively large fields of view with good contrast and low phototoxicity. In many respects it is superseding confocal microscopy. However, it is no magic bullet and still struggles to image deeply in more highly scattering samples. Many solutions to this challenge have been presented, including, Airy and Bessel illumination, 2-photon operation and deconvolution techniques. In this work, we show a comparison between a simple but effective Gaussian beam illumination and Bessel illumination for imaging in chicken embryos. Whilst Bessel illumination is shown to be of benefit when a greater depth of field is required, it is not possible to see any benefits for imaging into the highly scattering tissue of the chick embryo.

Cryogenic coherent X-ray diffraction imaging of biological samples at SACLA: a correlative approach with cryo-electron and light microscopy.

PubMed

Takayama, Yuki; Yonekura, Koji

2016-03-01

Coherent X-ray diffraction imaging at cryogenic temperature (cryo-CXDI) allows the analysis of internal structures of unstained, non-crystalline, whole biological samples in micrometre to sub-micrometre dimensions. Targets include cells and cell organelles. This approach involves preparing frozen-hydrated samples under controlled humidity, transferring the samples to a cryo-stage inside a vacuum chamber of a diffractometer, and then exposing the samples to coherent X-rays. Since 2012, cryo-coherent diffraction imaging (CDI) experiments have been carried out with the X-ray free-electron laser (XFEL) at the SPring-8 Ångstrom Compact free-electron LAser (SACLA) facility in Japan. Complementary use of cryo-electron microscopy and/or light microscopy is highly beneficial for both pre-checking samples and studying the integrity or nature of the sample. This article reports the authors' experience in cryo-XFEL-CDI of biological cells and organelles at SACLA, and describes an attempt towards reliable and higher-resolution reconstructions, including signal enhancement with strong scatterers and Patterson-search phasing.

Deep Tissue Fluorescent Imaging in Scattering Specimens Using Confocal Microscopy

PubMed Central

Clendenon, Sherry G.; Young, Pamela A.; Ferkowicz, Michael; Phillips, Carrie; Dunn, Kenneth W.

2015-01-01

In scattering specimens, multiphoton excitation and nondescanned detection improve imaging depth by a factor of 2 or more over confocal microscopy; however, imaging depth is still limited by scattering. We applied the concept of clearing to deep tissue imaging of highly scattering specimens. Clearing is a remarkably effective approach to improving image quality at depth using either confocal or multiphoton microscopy. Tissue clearing appears to eliminate the need for multiphoton excitation for deep tissue imaging. PMID:21729357

Selective suppression of CARS signal with three-beam competing stimulated Raman scattering processes.

PubMed

Choi, Dae Sik; Rao, B Jayachander; Kim, Doyeon; Shim, Sang-Hee; Rhee, Hanju; Cho, Minhaeng

2018-06-14

Coherent Raman scattering spectroscopy and microscopy are useful methods for studying the chemical and biological structures of molecules with Raman-active modes. In particular, coherent anti-Stokes Raman scattering (CARS) microscopy, which is a label-free method capable of imaging structures by displaying the vibrational contrast of the molecules, has been widely used. However, the lack of a technique for switching-off the CARS signal has prevented the development of the super-resolution Raman imaging method. Here, we demonstrate that a selective suppression of the CARS signal is possible by using a three-beam double stimulated Raman scattering (SRS) scheme; the three beams are the pump, Stokes, and depletion lights in order of frequency. Both pump-Stokes and pump-depletion beam pairs can generate SRS processes by tuning their beat frequencies to match two different vibrational modes, then two CARS signals induced by pump-Stokes-pump and pump-depletion-pump interactions can be generated, where the two CARS signals are coupled with each other because they both involve interactions with the common pump beam. Herein, we show that as the intensity of the depletion beam is increased, one can selectively suppress the pump-Stokes-pump CARS signal because the pump-depletion SRS depletes the pump photons. A detailed theoretical description of the coupled differential equations for the three incident fields and the generated CARS signal fields is presented. Taking benzene as a molecular system, we obtained a maximum CARS suppression efficiency of about 97% with our experimental scheme, where the ring breathing mode of the benzene is associated with pump-Stokes-pump CARS, while the C-H stretching mode is associated with the competing pump-depletion SRS process. We anticipate that this selective switching-off scheme will be of use in developing super-resolution label-free CARS microscopy.

Investigation of the optical response of photonic crystal nanocavities in ferroelectric oxide thin film

NASA Astrophysics Data System (ADS)

Lin, Pao Tai; Russin, William A.; Joshi-Imre, Alexandra; Ocola, Leonidas E.; Wessels, B. W.

2015-10-01

The optical properties of BaTiO3 two dimensional photonic crystal (PhC) nanocavities were investigated. Two types of nanocavities consisting of dopants and vacancies with PhC periodicities ranging from 200 to 550 nm were evaluated. The images from laser scanning confocal microscopy show the optical scattering of the PhC cavities is highly wavelength dependent. An optical intensity reversal is observed when the wavelength of probe light shifts by 29 nm. Meanwhile, intensity contrast between the nanocavity and its adjacent PhCs is enhanced as the PhC periodicity becomes shorter than the probe wavelength. To determine the photonic band structures fluorescence from dye covered PhCs were imaged and analyzed. A strong enhancement of fluorescence is observed for the PhC with a period of 200 nm. Upon comparison to the 2D finite difference time domain calculations, the enhancement is attributed to strong light localization within the PhC nanocavity. As a result, the in-plane lightwave propagation is prohibited that results in an increase in the vertical light scattering.

Photochemical mineralization of europium, titanium, and iron oxyhydroxide nanoparticles in the ferritin protein cage.

PubMed

Klem, Michael T; Mosolf, Jesse; Young, Mark; Douglas, Trevor

2008-04-07

The Fe storage protein ferritin was used as a size-constrained reaction vessel for the photoreduction and reoxidation of complexed Eu, Fe, and Ti precursors for the formation of oxyhydroxide nanoparticles. The resultant materials were characterized by dynamic light scattering, gel electrophoresis, UV-vis spectroscopy, and transmission electron microscopy. The photoreduction and reoxidation process is inspired by biological sequestration mechanisms observed in some marine siderophore systems.

Nanoplasmonic imaging of latent fingerprints and identification of cocaine.

PubMed

Li, Kun; Qin, Weiwei; Li, Fan; Zhao, Xingchun; Jiang, Bowei; Wang, Kun; Deng, Suhui; Fan, Chunhai; Li, Di

2013-10-25

Search for traces: Aptamer-bound Au nanoparticles (Au NPs) were used to provide high-resolution dark-field microscopy images of latent fingerprints (LFPs) with level 2 and level 3 details. Furthermore, the cocaine-induced aggregation of Au NPs results in a true green-to-red color change of the scattered light, providing a quasi-quantative method to identify cocaine loadings in LFPs. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Competitive Self-Assembly Manifests Supramolecular Darwinism in Soft-Oxometalates

NASA Astrophysics Data System (ADS)

Das, Santu; Kumar, Saurabh; Mallick, Apabrita; Roy, Soumyajit

2015-09-01

Topological transformation manifested in inorganic materials shows manifold possibilities. In our present work, we show a clear topological transformation in a soft-oxometalate (SOM) system which was formed from its polyoxometalate (POM) precursor [PMo12@Mo72Fe30]. This topological transformation was observed due to time dependent competitive self-assembly of two different length scale soft-oxometalate moieties formed from this two-component host-guest reaction. We characterized different morphologies by scanning electron microscopy, electron dispersive scattering spectroscopy, dynamic light scattering, horizontal attenuated total reflection-infrared spectroscopy and Raman spectroscopy. The predominant structure is selected by its size in a sort of supramolecular Darwinian competition in this process and is described here.

Plasmonics and SERS activity of post-transition metal nanoparticles

NASA Astrophysics Data System (ADS)

Bezerra, A. G.; Machado, T. N.; Woiski, T. D.; Turchetti, D. A.; Lenz, J. A.; Akcelrud, L.; Schreiner, W. H.

2018-05-01

Nanoparticles of the post-transition metals, In, Sn, Pb, and Bi, and of the metalloid Sb were produced by laser ablation synthesis in solution (LASiS) and tested for localized surface plasmon resonances (LSPR) and surface-enhanced Raman scattering (SERS). The nanoparticles were characterized by UV-Vis optical absorption, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Several organic and biological molecules were tested, and SERS activity was demonstrated for all tested nanoparticles and molecules. The Raman enhancement factor for each nanoparticle class and molecule was experimentally determined. The search for new plasmonic nanostructures is important mainly for life sciences-related applications and this study expands the range of SERS active systems.

Effect of interparticle interactions on size determination of zirconia and silica based systems – A comparison of SAXS, DLS, BET, XRD and TEM

PubMed Central

Pabisch, Silvia; Feichtenschlager, Bernhard; Kickelbick, Guido; Peterlik, Herwig

2012-01-01

The aim of this work is a systematic comparison of size characterisation methods for two completely different model systems of oxide nanoparticles, i.e. amorphous spherical silica and anisotropic facet-shaped crystalline zirconia. Size and/or size distribution were determined in a wide range from 5 to 70 nm using small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), nitrogen sorption (BET), X-ray diffraction (XRD) and transmission electron microscopy (TEM). A nearly perfect coincidence was observed only for SAXS and TEM for both types of particles. For zirconia nanoparticles considerable differences between different measurement methods were observed. PMID:22347721

Green light for quantitative live-cell imaging in plants.

PubMed

Grossmann, Guido; Krebs, Melanie; Maizel, Alexis; Stahl, Yvonne; Vermeer, Joop E M; Ott, Thomas

2018-01-29

Plants exhibit an intriguing morphological and physiological plasticity that enables them to thrive in a wide range of environments. To understand the cell biological basis of this unparalleled competence, a number of methodologies have been adapted or developed over the last decades that allow minimal or non-invasive live-cell imaging in the context of tissues. Combined with the ease to generate transgenic reporter lines in specific genetic backgrounds or accessions, we are witnessing a blooming in plant cell biology. However, the imaging of plant cells entails a number of specific challenges, such as high levels of autofluorescence, light scattering that is caused by cell walls and their sensitivity to environmental conditions. Quantitative live-cell imaging in plants therefore requires adapting or developing imaging techniques, as well as mounting and incubation systems, such as micro-fluidics. Here, we discuss some of these obstacles, and review a number of selected state-of-the-art techniques, such as two-photon imaging, light sheet microscopy and variable angle epifluorescence microscopy that allow high performance and minimal invasive live-cell imaging in plants. © 2018. Published by The Company of Biologists Ltd.

Stripe artifact elimination based on nonsubsampled contourlet transform for light sheet fluorescence microscopy

NASA Astrophysics Data System (ADS)

Liang, Xiao; Zang, Yali; Dong, Di; Zhang, Liwen; Fang, Mengjie; Yang, Xin; Arranz, Alicia; Ripoll, Jorge; Hui, Hui; Tian, Jie

2016-10-01

Stripe artifacts, caused by high-absorption or high-scattering structures in the illumination light path, are a common drawback in both unidirectional and multidirectional light sheet fluorescence microscopy (LSFM), significantly deteriorating image quality. To circumvent this problem, we present an effective multidirectional stripe remover (MDSR) method based on nonsubsampled contourlet transform (NSCT), which can be used for both unidirectional and multidirectional LSFM. In MDSR, a fast Fourier transform (FFT) filter is designed in the NSCT domain to shrink the stripe components and eliminate the noise. Benefiting from the properties of being multiscale and multidirectional, MDSR succeeds in eliminating stripe artifacts in both unidirectional and multidirectional LSFM. To validate the method, MDSR has been tested on images from a custom-made unidirectional LSFM system and a commercial multidirectional LSFM system, clearly demonstrating that MDSR effectively removes most of the stripe artifacts. Moreover, we performed a comparative experiment with the variational stationary noise remover and the wavelet-FFT methods and quantitatively analyzed the results with a peak signal-to-noise ratio, showing an improved noise removal when using the MDSR method.

Size and surface effects on the magnetism of magnetite and maghemite nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikiforov, V. N., E-mail: pppnvn@yandex.ru; Ignatenko, A. N.; Irkhin, V. Yu.

2017-02-15

The size effects of magnetite and maghemite nanoparticles on their magnetic properties (magnetic moment, Curie temperature, blocking temperature, etc.) have been investigated. Magnetic separation and centrifugation of an aqueous solution of nanoparticles were used for their separation into fractions; their sizes were measured by atomic force microscopy, dynamic light scattering, and electron microscopy. A change in the size leads to a change in the Curie temperature and magnetic moment per formula unit. Both native nanoparticles and those covered with a bioresorbable layer have been considered. The magnetic properties have been calculated by the Monte Carlo method for the classical Heisenbergmore » model with various bulk and surface magnetic moments.« less

Interaction of Water-Soluble CdTe Quantum Dots with Bovine Serum Albumin

PubMed Central

2011-01-01

Semiconductor nanoparticles (quantum dots) are promising fluorescent markers, but it is very little known about interaction of quantum dots with biological molecules. In this study, interaction of CdTe quantum dots coated with thioglycolic acid (TGA) with bovine serum albumin was investigated. Steady state spectroscopy, atomic force microscopy, electron microscopy and dynamic light scattering methods were used. It was explored how bovine serum albumin affects stability and spectral properties of quantum dots in aqueous media. CdTe–TGA quantum dots in aqueous solution appeared to be not stable and precipitated. Interaction with bovine serum albumin significantly enhanced stability and photoluminescence quantum yield of quantum dots and prevented quantum dots from aggregating. PMID:27502633

Ultra-fast 3D scanning and holographic illumination in non-linear microscopy using acousto-optic deflectors

NASA Astrophysics Data System (ADS)

Akemann, Walther; Ventalon, Cathie; Léger, Jean-François; Mathieu, Benjamin; Dieudonné, Stéphane; Blochet, Baptiste; Gigan, Sylvain; Bourdieu, Laurent

2017-04-01

Decoding of information in the brain requires the imaging of large neuronal networks using e.g. two-photon microscopy (TPM). Fast control of the focus in 3D can be achieved with phase shaping of the light beam using acoustooptic deflectors (AODs). However, beam shaping using AODs is not straightforward because of non-stationary of acousto-optic diffraction. Here, we demonstrated a new stable AOD-based phase modulator, which operates at a rate of up to about hundred kHz. It provides opportunity for 3D scanning in TPM with the possibility to correct aberrations independently for every focus position or to achieve refocusing of scattered photons in rapidly decorrelating tissues.

The development of optical microscopy techniques for the advancement of single-particle studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchuk, Kyle

2013-05-15

Single particle orientation and rotational tracking (SPORT) has recently become a powerful optical microscopy tool that can expose many molecular motions. Unfortunately, there is not yet a single microscopy technique that can decipher all particle motions in all environmental conditions, thus there are limitations to current technologies. Within, the two powerful microscopy tools of total internal reflection and interferometry are advanced to determine the position, orientation, and optical properties of metallic nanoparticles in a variety of environments. Total internal reflection is an optical phenomenon that has been applied to microscopy to produce either fluorescent or scattered light. The non-invasive far-fieldmore » imaging technique is coupled with a near-field illumination scheme that allows for better axial resolution than confocal microscopy and epi-fluorescence microscopy. By controlling the incident illumination angle using total internal reflection fluorescence (TIRF) microscopy, a new type of imaging probe called “non-blinking” quantum dots (NBQDs) were super-localized in the axial direction to sub-10-nm precision. These particles were also used to study the rotational motion of microtubules being propelled by the motor protein kinesin across the substrate surface. The same instrument was modified to function under total internal reflection scattering (TIRS) microscopy to study metallic anisotropic nanoparticles and their dynamic interactions with synthetic lipid bilayers. Utilizing two illumination lasers with opposite polarization directions at wavelengths corresponding to the short and long axis surface plasmon resonance (SPR) of the nanoparticles, both the in-plane and out-of-plane movements of many particles could be tracked simultaneously. When combined with Gaussian point spread function (PSF) fitting for particle super-localization, the binding status and rotational movement could be resolved without degeneracy. TIRS microscopy was also used to find the 3D orientation of stationary metallic anisotropic nanoparticles utilizing only long-axis SPR enhancement. The polarization direction of the illuminating light was rotated causing the relative intensity of p-polarized and s-polarized light within the evanescent field to change. The interaction of the evanescent field with the particles is dependent on the orientation of the particle producing an intensity curve. This curve and the in-plane angle can be compared with simulations to accurately determine the 3D orientation. Differential interference contrast (DIC) microscopy is another non-invasive far-field technique based upon interferometry that does not rely on staining or other contrast enhancing techniques. In addition, high numerical aperture condensers and objectives can be used to give a very narrow depth of field allowing for the optical tomography of samples, which makes it an ideal candidate to study biological systems. DIC microscopy has also proven itself in determining the orientation of gold nanorods in both engineered environments and within cells. Many types of nanoparticles and nanostructures have been synthesized using lithographic techniques on silicon wafer substrates. Traditionally, reflective mode DIC microscopes have been developed and applied to the topographical study of reflective substrates and the imaging of chips on silicon wafers. Herein, a laser-illuminated reflected-mode DIC was developed for studying nanoparticles on reflective surfaces.« less

The development of optical microscopy techniques for the advancement of single-particle studies

NASA Astrophysics Data System (ADS)

Marchuk, Kyle

Single particle orientation and rotational tracking (SPORT) has recently become a powerful optical microscopy tool that can expose many molecular motions. Unfortunately, there is not yet a single microscopy technique that can decipher all particle motions in all environmental conditions, thus there are limitations to current technologies. Within, the two powerful microscopy tools of total internal reflection and interferometry are advanced to determine the position, orientation, and optical properties of metallic nanoparticles in a variety of environments. Total internal reflection is an optical phenomenon that has been applied to microscopy to produce either fluorescent or scattered light. The non-invasive far-field imaging technique is coupled with a near-field illumination scheme that allows for better axial resolution than confocal microscopy and epi-fluorescence microscopy. By controlling the incident illumination angle using total internal reflection fluorescence (TIRF) microscopy, a new type of imaging probe called "non-blinking" quantum dots (NBQDs) were super-localized in the axial direction to sub-10-nm precision. These particles were also used to study the rotational motion of microtubules being propelled by the motor protein kinesin across the substrate surface. The same instrument was modified to function under total internal reflection scattering (TIRS) microscopy to study metallic anisotropic nanoparticles and their dynamic interactions with synthetic lipid bilayers. Utilizing two illumination lasers with opposite polarization directions at wavelengths corresponding to the short and long axis surface plasmon resonance (SPR) of the nanoparticles, both the in-plane and out-of-plane movements of many particles could be tracked simultaneously. When combined with Gaussian point spread function (PSF) fitting for particle super-localization, the binding status and rotational movement could be resolved without degeneracy. TIRS microscopy was also used to find the 3D orientation of stationary metallic anisotropic nanoparticles utilizing only long-axis SPR enhancement. The polarization direction of the illuminating light was rotated causing the relative intensity of p-polarized and s-polarized light within the evanescent field to change. The interaction of the evanescent field with the particles is dependent on the orientation of the particle producing an intensity curve. This curve and the in-plane angle can be compared with simulations to accurately determine the 3D orientation. Differential interference contrast (DIC) microscopy is another non-invasive far-field technique based upon interferometry that does not rely on staining or other contrast enhancing techniques. In addition, high numerical aperture condensers and objectives can be used to give a very narrow depth of field allowing for the optical tomography of samples, which makes it an ideal candidate to study biological systems. DIC microscopy has also proven itself in determining the orientation of gold nanorods in both engineered environments and within cells. Many types of nanoparticles and nanostructures have been synthesized using lithographic techniques on silicon wafer substrates. Traditionally, reflective mode DIC microscopes have been developed and applied to the topographical study of reflective substrates and the imaging of chips on silicon wafers. Herein, a laser-illuminated reflected-mode DIC was developed for studying nanoparticles on reflective surfaces.

Encapsulation efficiency of CdSe/ZnS quantum dots by liposomes determined by thermal lens microscopy

PubMed Central

Batalla, Jessica; Cabrera, Humberto; San Martín-Martínez, Eduardo; Korte, Dorota; Calderón, Antonio; Marín, Ernesto

2015-01-01

In this study the encapsulation of core shell carboxyl CdSe/ZnS quantum dots (QDs) by phospholipids liposome complexes is presented. It makes the quantum dots water soluble and photo-stable. Fluorescence self-quenching of the QDs inside the liposomes was observed. Therefore, the thermal lens microscopy (TLM) was found to be an useful tool for measuring the encapsulation efficiency of the QDs by the liposomes, for which an optimum value of 36% was determined. The obtained limit of detection (LOD) for determining QDs concentration by TLM was 0.13 nM. Moreover, the encapsulated QDs showed no prominent cytotoxicity toward Breast cancer cells line MDA-MB-231. This study was supported by UV-visible spectroscopy, high resolution transmission electron microscopy (HRTEM) and dynamic light scattering measurements (DLS). PMID:26504640

Scatter sensitive microscopic techniques to identify contrasting mucosal structures in ultrahigh-resolution optical coherence tomograms of mouse colon

NASA Astrophysics Data System (ADS)

Tumlinson, Alexandre R.; Hariri, Lida P.; Drexler, Wolfgang; Barton, Jennifer K.

2008-02-01

Optical coherence tomography, optical coherence microscopy, reflectance confocal microscopy, and darkfield microscopy all derive contrast from the intensity of endogenous tissue scatter. We have imaged excised mouse colon tissue with these complimentary technologies to make conclusions about structural origins of scatter in the mouse colonic mucosa observed with endoscopic OCT. We find hyperintense scattering both from the cytoplasm of epithelial cells and from the boundary between epithelia and the lamina propria. We find almost no scatter from the portion of epithelial cells containing the nucleus. These observations substantiate explanations for the appearance of colonic crypts and the luminal surface.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilbur, Jeffrey D.; Gomez, Enrique D.; Ellsworth, Mark W.

A procedure for creating samples that can be repeatedly cycled between weakly aligned and strongly aligned states is described. Poly(styrene-b-isoprene) block copolymer samples were first shear-aligned and then cross-linked using a high energy electron beam. Samples with more than 1.0 cross-links per chain on average showed almost complete recovery of their initial alignment state even after 20 cycles of heating above the order–disorder transition temperature of the un-cross-linked block copolymer. Samples with 1.1 cross-links per chain, which showed over 90% loss of alignment on heating and almost 100% recovery of alignment on cooling, provided the best example of a reversiblemore » aligned-to-unaligned transition. Samples with lower cross-linking densities exhibited irreversible loss of alignment upon heating, while those with higher cross-linking densities exhibited less than 90% loss of alignment upon heating. Alignment was quantified by a technique that we call two color depolarized light scattering (TCDLS), an extension of the traditional depolarized light scattering experiment used to determine the state of order in block copolymers. Qualitative confirmation of our interpretation of TCDLS data was obtained by small-angle X-ray scattering and transmission electron microscopy.« less

A review of exosome separation techniques and characterization of B16-F10 mouse melanoma exosomes with AF4-UV-MALS-DLS-TEM.

PubMed

Petersen, Kevin E; Manangon, Eliana; Hood, Joshua L; Wickline, Samuel A; Fernandez, Diego P; Johnson, William P; Gale, Bruce K

2014-12-01

Exosomes participate in cancer metastasis, but studying them presents unique challenges as a result of their small size and purification difficulties. Asymmetrical field flow fractionation with in-line ultraviolet absorbance, dynamic light scattering, and multi-angle light scattering was applied to the size separation and characterization of non-labeled B16-F10 exosomes from an aggressive mouse melanoma cell culture line. Fractions were collected and further analyzed using batch mode dynamic light scattering, transmission electron microscopy and compared with known size standards. Fractogram peak positions and computed radii show good agreement between samples and across fractions. Ultraviolet absorbance fractograms in combination with transmission electron micrographs were able to resolve subtle heterogeneity of vesicle retention times between separate batches of B16-F10 exosomes collected several weeks apart. Further, asymmetrical field flow fractionation also effectively separated B16-F10 exosomes into vesicle subpopulations by size. Overall, the flow field flow fractionation instrument combined with multiple detectors was able to rapidly characterize and separate exosomes to a degree not previously demonstrated. These approaches have the potential to facilitate a greater understanding of exosome function by subtype, as well as ultimately allow for "label-free" isolation of large scale clinical exosomes for the purpose of developing future exosome-based diagnostics and therapeutics.

A review of exosome separation techniques and characterization of B16-F10 mouse melanoma exosomes with AF4-UV-MALS-DLS-TEM

PubMed Central

Manangon, Eliana; Hood, Joshua L.; Wickline, Samuel A.; Fernandez, Diego P.; Johnson, William P.; Gale, Bruce K.

2015-01-01

Exosomes participate in cancer metastasis, but studying them presents unique challenges as a result of their small size and purification difficulties. Asymmetrical field flow fractionation with in-line ultraviolet absorbance, dynamic light scattering, and multi-angle light scattering was applied to the size separation and characterization of non-labeled B16-F10 exosomes from an aggressive mouse melanoma cell culture line. Fractions were collected and further analyzed using batch mode dynamic light scattering, transmission electron microscopy and compared with known size standards. Fractogram peak positions and computed radii show good agreement between samples and across fractions. Ultraviolet absorbance fractograms in combination with transmission electron micrographs were able to resolve subtle heterogeneity of vesicle retention times between separate batches of B16-F10 exosomes collected several weeks apart. Further, asymmetrical field flow fractionation also effectively separated B16-F10 exosomes into vesicle subpopulations by size. Overall, the flow field flow fractionation instrument combined with multiple detectors was able to rapidly characterize and separate exosomes to a degree not previously demonstrated. These approaches have the potential to facilitate a greater understanding of exosome function by subtype, as well as ultimately allow for “label-free” isolation of large scale clinical exosomes for the purpose of developing future exosome-based diagnostics and therapeutics. PMID:25084738

The Use of Cellulose Nanocrystals for Potential Application in Topical Delivery of Hydroquinone.

PubMed

Taheri, Azade; Mohammadi, Mina

2015-07-01

Nanotechnology-based drug delivery systems can enhance drug permeation through the skin and improve the drug stability. The biodegradability and biocompatibility of cellulose nanocrystals have made these nanoparticles good candidates to use in biomedical applications. The hyperpigmentation is a common skin disorder that could be caused by number of reasons such as sun exposure and pregnancy. Hydroquinone could inhibit the production of melanin and eliminate the discolorations of skin. This study is aimed at introducing cellulose nanocrystals as suitable carriers for drug delivery to skin. Prepared cellulose nanocrystals were characterized by dynamic light scattering and atomic force microscopy. The size of cellulose nanocrystals determined using dynamic light scattering was 301 ± 10 nm. Hydroquinone-cellulose nanocrystal complex was prepared by incubating of hydroquinone solution in cellulose nanocrystals suspension. The size of hydroquinone-cellulose nanocrystal complex determined using dynamic light scattering was 310 ± 10 nm. The hydroquinone content of the hydroquinone-cellulose complex was determined using UV/vis spectroscopy. Hydroquinone was bound to cellulose nanocrystals representing 79.3 ± 2% maximum binding efficiency when 1.1 mg hydroquinone was added to 1 mL of cellulose nanocrystals suspension (2 mg cellulose nanocrystal). The hydroquinone-cellulose nanocrystal complex showed an approximately sustained release profile of hydroquinone. Approximately, 80% of bound hydroquinone released in 4 h. © 2014 John Wiley & Sons A/S.

Broadband near-field infrared spectroscopy with a high temperature plasma light source.

PubMed

Lahneman, D J; Huffman, T J; Xu, Peng; Wang, S L; Grogan, T; Qazilbash, M M

2017-08-21

Scattering-type scanning near-field optical microscopy (S-SNOM) has enormous potential as a spectroscopy tool in the infrared spectral range where it can probe phonon resonances and carrier dynamics at the nanometer lengths scales. However, its applicability is limited by the lack of practical and affordable table-top light sources emitting intense broadband infrared radiation in the 100 cm -1 to 2,500 cm -1 spectral range. This paper introduces a high temperature plasma light source that is both ultra-broadband and has much more radiant power in the infrared spectral range than conventional, table-top thermal light sources such as the globar. We implement this plasma lamp in our near-field optical spectroscopy set up and demonstrate its capability as a broadband infrared nano-spectroscopy light source by obtaining near-field infrared amplitude and phase spectra of the phonon resonances of SiO 2 and SrTiO 3 .

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alenaizi, R.; Radiman, S.; Mohamed, F.

The morphology of vesicles system with defined particle size and shape is one of interest in our technical applications. Here we have used dynamic light scattering technique and transmission electron microscopy for structural characterization of N-dimethylglycine Betaine with 5-cholesten-3β-ol vesicles in aqueous solutions. An isotropic one phase region is found in the very diluted regions depending on Betaine/Cholesterol ratio. The isotropic region was stable for more than 3 months at room temperature, with monodispersed unilamellar vesicles ∼ 300nm.

Morphologic and proteomic characterization of exosomes released by cultured extravillous trophoblast cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atay, Safinur; Gercel-Taylor, Cicek; Kesimer, Mehmet

Exosomes represent an important intercellular communication vehicle, mediating events essential for the decidual microenvironment. While we have demonstrated exosome induction of pro-inflammatory cytokines, to date, no extensive characterization of trophoblast-derived exosomes has been provided. Our objective was to provide a morphologic and proteomic characterization of these exosomes. Exosomes were isolated from the conditioned media of Swan71 human trophoblast cells by ultrafiltration and ultracentrifugation. These were analyzed for density (sucrose density gradient centrifugation), morphology (electron microscopy), size (dynamic light scattering) and protein composition (Ion Trap mass spectrometry and western immunoblotting). Based on density gradient centrifugation, microvesicles from Sw71 cells exhibit amore » density between 1.134 and 1.173 g/ml. Electron microscopy demonstrated that microvesicles from Sw71 cells exhibit the characteristic cup-shaped morphology of exosomes. Dynamic light scattering showed a bell-shaped curve, indicating a homogeneous population with a mean size of 165 nm {+-} 0.5 nm. Ion Trap mass spectrometry demonstrated the presence of exosome marker proteins (including CD81, Alix, cytoskeleton related proteins, and Rab family). The MS results were confirmed by western immunoblotting. Based on morphology, density, size and protein composition, we defined the release of exosomes from extravillous trophoblast cells and provide their first extensive characterization. This characterization is essential in furthering our understanding of 'normal' early pregnancy.« less

The bundling of actin with polyethylene glycol 8000 in the presence and absence of gelsolin.

PubMed Central

Goverman, J; Schick, L A; Newman, J

1996-01-01

Actin filament and bundle formation occur in the cytosol under conditions of very high total macromolecular concentration. In this study we have utilized the inert molecule polyethylene glycol 8000 (PEG) as a means of simulating crowded conditions in vitro. Column-purified Ca-actin was polymerized in the absence and presence of gelsolin (to regulate mean filament lengths between 50 and 5000 mers) and PEG (2-8%) using various concentrations of KCl and/or 2 mM divalent cations. Bundling was characterized by the scattered light intensity and mean diffusion coefficients obtained from dynamic light scattering, as well as by fluorescence and phase-contrast microscopy. The minimum concentration of KCl required for bundling decreases both with increasing concentration of PEG at a fixed mean filament length, and with decreasing filament length at a fixed concentration of PEG. In the absence of divalent cation, bundling is reversible on dilution, as determined by intensity levels, diffusion coefficients, and microscopy. However, with either 2 mM Mg2+ or Ca2+ added, bundling is irreversible under conditions of higher PEG concentrations or longer filaments, indicating that osmotic pressure effects cannot fully explain actin bundling with PEG. Weaker divalent cation-binding sites on actin as well as disulfide bonds appear to be involved in the irreversible bundling. Images FIGURE 7 PMID:8874022

Synthesis of surfactant-coated cobalt ferrite nanoparticles for adsorptive removal of acid blue 45 dye

NASA Astrophysics Data System (ADS)

Waheed Mushtaq, Muhammad; Kanwal, Farah; Imran, Muhammad; Ameen, Naila; Batool, Madeeha; Batool, Aisha; Bashir, Shahid; Mustansar Abbas, Syed; Rehman, Ata ur; Riaz, Saira; Naseem, Shahzad; Ullah, Zaka

2018-03-01

Cobalt ferrite (CoFe2O4) nanoparticles (NPs) are synthesized by wet chemical coprecipitation method using metal chlorides as precursors and potassium hydroxide (KOH) as a precipitant. The tergitol-1x (T-1x) and didecyldimethyl ammonium bromide (DDAB) are used as capping agents and their effect is investigated on particle size, size distribution and morphology of cobalt ferrite nanoparticles (CFNPs). The Fourier transform infrared spectroscopy confirms the synthesis of CFNPs and formation of metal-oxygen (M-O) bond. The spinel phase structure, morphology, polydispersity and magnetic properties of ferrite nanoparticles are investigated by x-ray diffraction, scanning electron microscopy, dynamic light scattering and vibrating sample magnetometry analyses, respectively. The addition of capping agents effects the secondary growth of CFNPs and reduces their particle size, as is investigated by dynamic light scattering and atomic force microscopy. The results evidence that the DDAB is more promising surfactant to control the particle size (∼13 nm), polydispersity and aggregation of CFNPs. The synthesized CFNPs, CFNPs/T-1x and CFNPs/DDAB are used to study their adsorption potential for removal of acid blue 45 dye, and a maximum adsorptive removal of 92.25% is recorded by 0.1 g of CFNPs/DDAB at pH 2.5 and temperature 20 ± 1 °C. The results show that the dye is physically adsorbed by magnetic NPs and follows the Langmuir isotherm model.

Characterization of Gd loaded chitosan-TPP nanohydrogels by a multi-technique approach combining dynamic light scattering (DLS), asymetrical flow-field-flow-fractionation (AF4) and atomic force microscopy (AFM) and design of positive contrast agents for molecular resonance imaging (MRI)

NASA Astrophysics Data System (ADS)

Rigaux, G.; Gheran, C. V.; Callewaert, M.; Cadiou, C.; Voicu, S. N.; Dinischiotu, A.; Andry, M. C.; Vander Elst, L.; Laurent, S.; Muller, R. N.; Berquand, A.; Molinari, M.; Huclier-Markai, S.; Chuburu, F.

2017-02-01

Chitosan CS—tripolyphosphate TPP/hyaluronic acid HA nanohydrogels loaded with gadolinium chelates (GdDOTA ⊂ CS-TPP/HA NGs) synthesized by ionic gelation were designed for lymph node (LN) MRI. In order to be efficiently drained to LNs, nanogels (NGs) needed to exhibit a diameter ϕ < 100 nm. For that, formulation parameters were tuned, using (i) CS of two different molecular weights (51 and 37 kDa) and (ii) variable CS/TPP ratio (2 < CS/TPP < 8). Characterization of NG size distribution by dynamic light scattering (DLS) and asymetrical flow-field-flow-fractionation (AF4) showed discrepancies since DLS diameters were consistently above 200 nm while AF4 showed individual nano-objects with ϕ < 100 nm. Such a difference could be correlated to the presence of aggregates inherent to ionic gelation. This point was clarified by atomic force microscopy (AFM) in liquid mode which highlighted the main presence of individual nano-objects in nanosuspensions. Thus, combination of DLS, AF4 and AFM provided a more precise characterization of GdDOTA ⊂ CS-TPP/HA nanohydrogels which, in turn, allowed to select formulations leading to NGs of suitable mean sizes showing good MRI efficiency and negligible toxicity.

Engineered silica nanoparticles as additives in lubricant oils

PubMed Central

López, Teresa Díaz-Faes; González, Alfonso Fernández; Del Reguero, Ángel; Matos, María; Díaz-García, Marta E; Badía-Laíño, Rosana

2015-01-01

Silica nanoparticles (SiO2 NPs) synthesized by the sol–gel approach were engineered for size and surface properties by grafting hydrophobic chains to prevent their aggregation and facilitate their contact with the phase boundary, thus improving their dispersibility in lubricant base oils. The surface modification was performed by covalent binding of long chain alkyl functionalities using lauric acid and decanoyl chloride to the SiO2 NP surface. The hybrid SiO2 NPs were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, simultaneous differential thermal analysis, nuclear magnetic resonance and dynamic light scattering, while their dispersion in two base oils was studied by static multiple light scattering at low (0.01% w/v) and high (0.50%w/v) concentrations. The nature of the functional layer and the functionalization degree seemed to be directly involved in the stability of the suspensions. The potential use of the functional SiO2 NPs as lubricant additives in base oils, specially designed for being used in hydraulic circuits, has been outlined by analyzing the tribological properties of the dispersions. The dendritic structure of the external layer played a key role in the tribological characteristics of the material by reducing the friction coefficient and wear. These nanoparticles reduce drastically the waste of energy in friction processes and are more environmentally friendly than other additives. PMID:27877840

Reflectance of topologically disordered photonic-crystal films

NASA Astrophysics Data System (ADS)

Vigneron, Jean-Pol; Lousse, Virginie M.; Biro, Laszlo P.; Vertesy, Zofia; Balint, Zolt

2005-04-01

Periodicity implies the creation of discretely diffracted beams while various departures from periodicity lead to broadened scattering angles. This effect is investigated for disturbed lattices exhibiting randomly varying periods. In the Born approximation, the diffused reflection is shown to be related to a pair correlation function constructed from the distribution of the film scattering power. The technique is first applied to a natural photonic crystal found on the ventral side of the wings of the butterfly Cyanophrys remus, where scanning electron microscopy reveals the formation of polycrystalline photonic structures. Second, the disorder in the distribution of the cross-ribs on the scales another butterfly, Lycaena virgaureae, is investigated. The irregular arrangement of scatterers found in chitin structure of this insect produces light reflection in the long-wavelength part of the visible range, with a quite unusual broad directionality. The use of the pair correlation function allows to propose estimates of the diffusive spreading in these very different systems.

Scattered electrons in microscopy and microanalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ottensmeyer, F.P.

The use of scattered electrons alone for direct imaging of biological specimens makes it possible to obtain structural information at atomic and near-atomic spatial resolutions of 0.3 to 0.5 nanometer. While this is not as good as the resolution possible with x-ray crystallography, such an approach provides structural information rapidly on individual macromolecules that have not been, and possibly cannot be, crystallized. Analysis of the spectrum of energies of scattered electrons and imaging of the latter with characteristic energy bands within the spectrum produces a powerful new technique of atomic microanalysis. This technique, which has a spatial resolution of aboutmore » 0.5 nanometer and a minimum detection sensitivity of about 50 atoms of phosphorus, is especially useful for light atom analysis and appears to have applications in molecular biology, cell biology, histology, pathology, botany, and many other fields.« less

Scattered electrons in microscopy and microanalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ottensmeyer, F.P.

The use of scattered electrons alone for direct imaging of biological specimens makes it possible to obtain structural information at atomic and near-atomic spatial resolutions of 0.3 to 0.5 nanometer. While this is not as good as the resolution possible with x-ray crystallography, such an approach provides structural information rapidly on individual macromolecules that have not been, and possibly cannot be, crystallized. Analysis of the spectrum of energies of scattered electrons and imaging of the latter with characteristic energy bands within the spectrum produce a powerful new technique of atomic microanalysis. This technique, which has a spatial resolution of aboutmore » 0.5 nanometer and a minimum detection sensitivity of about 50 atoms of phosphorus, is especially useful for light atom analysis and appears to have applications in molecular biology, cell biology, histology, pathology, botany, and many other fields.« less

Polymer-coated surface enhanced Raman scattering (SERS) gold nanoparticles for multiplexed labeling of chronic lymphocytic leukemia cells

NASA Astrophysics Data System (ADS)

MacLaughlin, Christina M.; Parker, Edward P. K.; Walker, Gilbert C.; Wang, Chen

2012-01-01

The ease and flexibility of functionalization and inherent light scattering properties of plasmonic nanoparticles make them suitable contrast agents for measurement of cell surface markers. Immunophenotyping of lymphoproliferative disorders is traditionally undertaken using fluorescence detection methods which have a number of limitations. Herein, surface-enhanced Raman scattering (SERS) gold nanoparticles conjugated to monoclonal antibodies are used for the selective targeting of CD molecules on the surface of chronic lymphocytic leukemia (CLL) cells. Raman-active reporters were physisorbed on to the surface of 60 nm spherical Au nanoparticles, the particles were coated with 5kDa polyethylene glycol (PEG) including functionalities for conjugation to monoclonal IgG1 antibodies. A novel method for quantifying the number of antibodies bound to SERS probes on an individual basis as opposed to obtaining averages from solution was demonstrated using metal dots in transmission electron microscopy (TEM). The specificity of the interaction between SERS probes and surface CD molecules of CLL cells was assessed using Raman spectroscopy and dark field microscopy. An in-depth study of SERS probe targeting to B lymphocyte marker CD20 was undertaken, and proof-of-concept targeting using different SERS nanoparticle dyes specific for cell surface CD19, CD45 and CD5 demonstrated using SERS spectroscopy.

Modeling of Fibrin Gels Based on Confocal Microscopy and Light-Scattering Data

PubMed Central

Magatti, Davide; Molteni, Matteo; Cardinali, Barbara; Rocco, Mattia; Ferri, Fabio

2013-01-01

Fibrin gels are biological networks that play a fundamental role in blood coagulation and other patho/physiological processes, such as thrombosis and cancer. Electron and confocal microscopies show a collection of fibers that are relatively monodisperse in diameter, not uniformly distributed, and connected at nodal points with a branching order of ∼3–4. Although in the confocal images the hydrated fibers appear to be quite straight (mass fractal dimension Dm = 1), for the overall system 1

The study of membrane formation via phase inversion method by cloud point and light scattering experiment

NASA Astrophysics Data System (ADS)

Arahman, Nasrul; Maimun, Teuku; Mukramah, Syawaliah

2017-01-01

The composition of polymer solution and the methods of membrane preparation determine the solidification process of membrane. The formation of membrane structure prepared via non-solvent induced phase separation (NIPS) method is mostly determined by phase separation process between polymer, solvent, and non-solvent. This paper discusses the phase separation process of polymer solution containing Polyethersulfone (PES), N-methylpirrolidone (NMP), and surfactant Tetronic 1307 (Tet). Cloud point experiment is conducted to determine the amount of non-solvent needed on induced phase separation. Amount of water required as a non-solvent decreases by the addition of surfactant Tet. Kinetics of phase separation for such system is studied by the light scattering measurement. With the addition of Tet., the delayed phase separation is observed and the structure growth rate decreases. Moreover, the morphology of fabricated membrane from those polymer systems is analyzed by scanning electron microscopy (SEM). The images of both systems show the formation of finger-like macrovoids through the cross-section.

Growth of textured thin Au coatings on iron oxide nanoparticles with near infrared absorbance

PubMed Central

Ma, L L; Borwankar, A U; Willsey, B W; Yoon, K Y; Tam, J O; Sokolov, K V; Feldman, M D; Milner, T E; Johnston, K P

2013-01-01

A homologous series of Au-coated iron oxide nanoparticles, with hydrodynamic diameters smaller than 60 nm was synthesized with very low Auto-iron mass ratios as low as 0.15. The hydrodynamic diameter was determined by dynamic light scattering and the composition by atomic absorption spectroscopy and energy dispersive x-ray spectroscopy (EDS). Unusually low Au precursor supersaturation levels were utilized to nucleate and grow Au coatings on iron oxide relative to formation of pure Au nanoparticles. This approach produced unusually thin coatings, by lowering autocatalytic growth of Au on Au, as shown by transmission electron microscopy (TEM). Nearly all of the nanoparticles were attracted by a magnet indicating a minimal amount of pure Au particles The coatings were sufficiently thin to shift the surface plasmon resonance (SPR) to the near infrared (NIR), with large extinction coefficients., despite the small particle hydrodynamic diameters, observed from dynamic light scattering to be less than 60 nm. PMID:23238021

Optical Sensors Using Stimulated Brillouin Scattering

NASA Technical Reports Server (NTRS)

Christensen, Caleb A (Inventor); Zavriyev, Anton (Inventor)

2017-01-01

A method for enhancing a sensitivity of an optical sensor having an optical cavity counter-propagates beams of pump light within the optical cavity to produce scattered light based on Stimulated Brillouin Scattering (SBS). The properties of the pump light are selected to generate fast-light conditions for the scattered light, such that the scattered light includes counter-propagating beams of fast light. The method prevents the pump light from resonating within the optical cavity, while allowing the scattered light to resonate within the optical cavity. At least portions of the scattered light are interfered outside of the optical cavity to produce a beat note for a measurement of the optical sensor. The disclosed method is particularly applicable to optical gyroscopes.

Polymeric capsule-cushioned leukocyte cell membrane vesicles as a biomimetic delivery platform

NASA Astrophysics Data System (ADS)

Gao, Changyong; Wu, Zhiguang; Lin, Zhihua; Lin, Xiankun; He, Qiang

2016-02-01

We report a biomimetic delivery of microsized capsule-cushioned leukocyte membrane vesicles (CLMVs) through the conversion of freshly reassembled leukocyte membrane vesicles (LMVs), including membrane lipids and membrane-bound proteins onto the surface of layer-by-layer assembled polymeric multilayer microcapsules. The leukocyte membrane coating was verified by using electron microscopy, a quartz crystal microbalance, dynamic light scattering, and confocal laser scanning microscopy. The resulting CLMVs have the ability to effectively evade clearance by the immune system and thus prolong the circulation time in mice. Moreover, we also show that the right-side-out leukocyte membrane coating can distinctly improve the accumulation of capsules in tumor sites through the molecular recognition of membrane-bound proteins of CLMVs with those of tumor cells in vitro and in vivo. The natural cell membrane camouflaged polymeric multilayer capsules with the immunosuppressive and tumor-recognition functionalities of natural leukocytes provide a new biomimetic delivery platform for disease therapy.We report a biomimetic delivery of microsized capsule-cushioned leukocyte membrane vesicles (CLMVs) through the conversion of freshly reassembled leukocyte membrane vesicles (LMVs), including membrane lipids and membrane-bound proteins onto the surface of layer-by-layer assembled polymeric multilayer microcapsules. The leukocyte membrane coating was verified by using electron microscopy, a quartz crystal microbalance, dynamic light scattering, and confocal laser scanning microscopy. The resulting CLMVs have the ability to effectively evade clearance by the immune system and thus prolong the circulation time in mice. Moreover, we also show that the right-side-out leukocyte membrane coating can distinctly improve the accumulation of capsules in tumor sites through the molecular recognition of membrane-bound proteins of CLMVs with those of tumor cells in vitro and in vivo. The natural cell membrane camouflaged polymeric multilayer capsules with the immunosuppressive and tumor-recognition functionalities of natural leukocytes provide a new biomimetic delivery platform for disease therapy. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08407e

Complementary Imaging of Silver Nanoparticle Interactions with Green Algae: Dark-Field Microscopy, Electron Microscopy, and Nanoscale Secondary Ion Mass Spectrometry.

PubMed

Sekine, Ryo; Moore, Katie L; Matzke, Marianne; Vallotton, Pascal; Jiang, Haibo; Hughes, Gareth M; Kirby, Jason K; Donner, Erica; Grovenor, Chris R M; Svendsen, Claus; Lombi, Enzo

2017-11-28

Increasing consumer use of engineered nanomaterials has led to significantly increased efforts to understand their potential impact on the environment and living organisms. Currently, no individual technique can provide all the necessary information such as their size, distribution, and chemistry in complex biological systems. Consequently, there is a need to develop complementary instrumental imaging approaches that provide enhanced understanding of these "bio-nano" interactions to overcome the limitations of individual techniques. Here we used a multimodal imaging approach incorporating dark-field light microscopy, high-resolution electron microscopy, and nanoscale secondary ion mass spectrometry (NanoSIMS). The aim was to gain insight into the bio-nano interactions of surface-functionalized silver nanoparticles (Ag-NPs) with the green algae Raphidocelis subcapitata, by combining the fidelity, spatial resolution, and elemental identification offered by the three techniques, respectively. Each technique revealed that Ag-NPs interact with the green algae with a dependence on the size (10 nm vs 60 nm) and surface functionality (tannic acid vs branched polyethylenimine, bPEI) of the NPs. Dark-field light microscopy revealed the presence of strong light scatterers on the algal cell surface, and SEM imaging confirmed their nanoparticulate nature and localization at nanoscale resolution. NanoSIMS imaging confirmed their chemical identity as Ag, with the majority of signal concentrated at the cell surface. Furthermore, SEM and NanoSIMS provided evidence of 10 nm bPEI Ag-NP internalization at higher concentrations (40 μg/L), correlating with the highest toxicity observed from these NPs. This multimodal approach thus demonstrated an effective approach to complement dose-response studies in nano-(eco)-toxicological investigations.

Studying post-etching silicon crystal defects on 300mm wafer by automatic defect review AFM

NASA Astrophysics Data System (ADS)

Zandiatashbar, Ardavan; Taylor, Patrick A.; Kim, Byong; Yoo, Young-kook; Lee, Keibock; Jo, Ahjin; Lee, Ju Suk; Cho, Sang-Joon; Park, Sang-il

2016-03-01

Single crystal silicon wafers are the fundamental elements of semiconductor manufacturing industry. The wafers produced by Czochralski (CZ) process are very high quality single crystalline materials with known defects that are formed during the crystal growth or modified by further processing. While defects can be unfavorable for yield for some manufactured electrical devices, a group of defects like oxide precipitates can have both positive and negative impacts on the final device. The spatial distribution of these defects may be found by scattering techniques. However, due to limitations of scattering (i.e. light wavelength), many crystal defects are either poorly classified or not detected. Therefore a high throughput and accurate characterization of their shape and dimension is essential for reviewing the defects and proper classification. While scanning electron microscopy (SEM) can provide high resolution twodimensional images, atomic force microscopy (AFM) is essential for obtaining three-dimensional information of the defects of interest (DOI) as it is known to provide the highest vertical resolution among all techniques [1]. However AFM's low throughput, limited tip life, and laborious efforts for locating the DOI have been the limitations of this technique for defect review for 300 mm wafers. To address these limitations of AFM, automatic defect review AFM has been introduced recently [2], and is utilized in this work for studying DOI on 300 mm silicon wafer. In this work, we carefully etched a 300 mm silicon wafer with a gaseous acid in a reducing atmosphere at a temperature and for a sufficient duration to decorate and grow the crystal defects to a size capable of being detected as light scattering defects [3]. The etched defects form a shallow structure and their distribution and relative size are inspected by laser light scattering (LLS). However, several groups of defects couldn't be properly sized by the LLS due to the very shallow depth and low light scattering. Likewise, SEM cannot be used effectively for post-inspection defect review and classification of these very shallow types of defects. To verify and obtain accurate shape and three-dimensional information of those defects, automatic defect review AFM (ADR AFM) is utilized for accurate locating and imaging of DOI. In ADR AFM, non-contact mode imaging is used for non-destructive characterization and preserving tip sharpness for data repeatability and reproducibility. Locating DOI and imaging are performed automatically with a throughput of many defects per hour. Topography images of DOI has been collected and compared with SEM images. The ADR AFM has been shown as a non-destructive metrology tool for defect review and obtaining three-dimensional topography information.

Nonlinear plasmonic imaging techniques and their biological applications

NASA Astrophysics Data System (ADS)

Deka, Gitanjal; Sun, Chi-Kuang; Fujita, Katsumasa; Chu, Shi-Wei

2017-01-01

Nonlinear optics, when combined with microscopy, is known to provide advantages including novel contrast, deep tissue observation, and minimal invasiveness. In addition, special nonlinearities, such as switch on/off and saturation, can enhance the spatial resolution below the diffraction limit, revolutionizing the field of optical microscopy. These nonlinear imaging techniques are extremely useful for biological studies on various scales from molecules to cells to tissues. Nevertheless, in most cases, nonlinear optical interaction requires strong illumination, typically at least gigawatts per square centimeter intensity. Such strong illumination can cause significant phototoxicity or even photodamage to fragile biological samples. Therefore, it is highly desirable to find mechanisms that allow the reduction of illumination intensity. Surface plasmon, which is the collective oscillation of electrons in metal under light excitation, is capable of significantly enhancing the local field around the metal nanostructures and thus boosting up the efficiency of nonlinear optical interactions of the surrounding materials or of the metal itself. In this mini-review, we discuss the recent progress of plasmonics in nonlinear optical microscopy with a special focus on biological applications. The advancement of nonlinear imaging modalities (including incoherent/coherent Raman scattering, two/three-photon luminescence, and second/third harmonic generations that have been amalgamated with plasmonics), as well as the novel subdiffraction limit imaging techniques based on nonlinear behaviors of plasmonic scattering, is addressed.

Ocular forward light scattering and corneal backward light scattering in patients with dry eye.

PubMed

Koh, Shizuka; Maeda, Naoyuki; Ikeda, Chikako; Asonuma, Sanae; Mitamura, Hayato; Oie, Yoshinori; Soma, Takeshi; Tsujikawa, Motokazu; Kawasaki, Satoshi; Nishida, Kohji

2014-09-18

To evaluate ocular forward light scattering and corneal backward light scattering in patients with dry eye. Thirty-five eyes in 35 patients with dry eye and 20 eyes of 20 healthy control subjects were enrolled. The 35 dry eyes were classified into two groups according to whether superficial punctate keratopathy in the central 6-mm corneal zone (cSPK) was present or not. Ocular forward light scattering was quantified with a straylight meter. Corneal backward light scattering from the anterior, middle, and posterior corneal parts was assessed with a corneal densitometry program using the Scheimpflug imaging system. Both dry eye groups had significantly higher intraocular forward light scattering than the control group (both P<0.05). The dry eye group with cSPK had significantly higher values in anterior and total corneal backward light scattering than the other two groups. Moderate positive correlations were observed between the cSPK score and corneal backward light scattering from the anterior cornea (R=0.60, P<0.001) and corneal backward light scattering from the total cornea (R=0.54, P<0.001); however, no correlation was found between cSPK score and ocular forward light scattering (R=0.01, P=0.932). Ocular forward light scattering and corneal backward light scattering from the anterior cornea were greater in dry eyes than in normal eyes. Increased corneal backward light scattering in dry eye at least partially results from cSPK overlying the optical zone. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Silver nanoparticles (AgNPs) as a contrast agent for imaging of animal tissue using swept-source optical coherence tomography (SSOCT)

NASA Astrophysics Data System (ADS)

Mondal, Indranil; Raj, Shipra; Roy, Poulomi; Poddar, Raju

2018-01-01

We present noninvasive three-dimensional depth-resolved imaging of animal tissue with a swept-source optical coherence tomography system at 1064 nm center wavelength and silver nanoparticles (AgNPs) as a potential contrast agent. A swept-source laser light source is used to enable an imaging rate of 100 kHz (100 000 A-scans s-1). Swept-source optical coherence tomography is a new variant of the optical coherence tomography (OCT) technique, offering unique advantages in terms of sensitivity, reduction of motion artifacts, etc. To enhance the contrast of an OCT image, AgNPs are utilized as an exogeneous contrast agent. AgNPs are synthesized using a modified Tollens method and characterization is done by UV-vis spectroscopy, dynamic light scattering, scanning electron microscopy and energy dispersive x-ray spectroscopy. In vitro imaging of chicken breast tissue, with and without the application of AgNPs, is performed. The effect of AgNPs is studied with different exposure times. A mathematical model is also built to calculate changes in the local scattering coefficient of tissue from OCT images. A quantitative estimation of scattering coefficient and contrast is performed for tissues with and without application of AgNPs. Significant improvement in contrast and increase in scattering coefficient with time is observed.

Hierarchical structure and dynamics of oligocarbonate-functionalized PEG block copolymer gels

NASA Astrophysics Data System (ADS)

Prabhu, Vivek; Wei, Guangmin; Ali, Samim; Venkataraman, Shrinivas; Yang, Yi Yan; Hedrick, James

Hierarchical, self-assembled block copolymers in aqueous solutions provide advanced materials for biomaterial applications. Recent advancements in the synthesis of aliphatic polycarbonates have shown nontraditional micellar and hierarchical structures driven by the supramolecular assembly of the carbonate block functionality that includes cholesterol, vitamin D, and fluorene. This presentation shall describe the supramolecular assembly structure and dynamics observed by static and dynamic light scattering, small-angle neutron scattering and transmission electron microscopy in a model pi-pi stacking driven fluorene system. The combination of real-space and reciprocal space methods to develop appropriate models that quantify the structure from the micelle to transient gel network will be discussed. 1) Biomedical Research Council, Agency for Science, Technology and Research, Singapore, 2) NIST Materials Genome Initiative.

In vivo chemical and structural analysis of plant cuticular waxes using stimulated Raman scattering microscopy.

PubMed

Littlejohn, George R; Mansfield, Jessica C; Parker, David; Lind, Rob; Perfect, Sarah; Seymour, Mark; Smirnoff, Nicholas; Love, John; Moger, Julian

2015-05-01

The cuticle is a ubiquitous, predominantly waxy layer on the aerial parts of higher plants that fulfils a number of essential physiological roles, including regulating evapotranspiration, light reflection, and heat tolerance, control of development, and providing an essential barrier between the organism and environmental agents such as chemicals or some pathogens. The structure and composition of the cuticle are closely associated but are typically investigated separately using a combination of structural imaging and biochemical analysis of extracted waxes. Recently, techniques that combine stain-free imaging and biochemical analysis, including Fourier transform infrared spectroscopy microscopy and coherent anti-Stokes Raman spectroscopy microscopy, have been used to investigate the cuticle, but the detection sensitivity is severely limited by the background signals from plant pigments. We present a new method for label-free, in vivo structural and biochemical analysis of plant cuticles based on stimulated Raman scattering (SRS) microscopy. As a proof of principle, we used SRS microscopy to analyze the cuticles from a variety of plants at different times in development. We demonstrate that the SRS virtually eliminates the background interference compared with coherent anti-Stokes Raman spectroscopy imaging and results in label-free, chemically specific confocal images of cuticle architecture with simultaneous characterization of cuticle composition. This innovative use of the SRS spectroscopy may find applications in agrochemical research and development or in studies of wax deposition during leaf development and, as such, represents an important step in the study of higher plant cuticles. © 2015 American Society of Plant Biologists. All Rights Reserved.

Proximate bases of silver color in anhinga (Anhinga anhinga) feathers.

PubMed

Shawkey, Matthew D; Maia, Rafael; D'Alba, Liliana

2011-11-01

Colors of living organisms are produced by selective light absorption from pigments and/or by light scattering from highly ordered nanostructures (i.e., structural color). While the physical bases of metallic colors of arthropods and fish are fairly well-known, those of birds are not. Here we examine structurally based silver color and its production in feathers of the waterbird species Anhinga. This achromatic color is distinguished from grey by high specular reflectance, from white by low diffuse reflectance, and from both by high gloss. Light and electron microscopy revealed three modifications of feathers likely leading to silver color. First, proximal barbules were highly elongated and contained glossy black color at their base and white color at their pennulum. Second, this glossy black portion contained a single outer layer of keratin weakly bounded by melanosomes. Finally, the white portion contained a disordered amorphous matrix of keratin and air. Optical analyzes suggest that these structures produce, respectively, glossy black color through thin-film interference and white color through incoherent light scattering. Silver color likely results from the combined reflectance of these adjacent structures. This represents a distinct mechanism for attaining silver colors that may have been partially derived through selection for display, thermoregulation or decreased hydrophobicity. Copyright © 2011 Wiley-Liss, Inc.

Visible light optical coherence microscopy imaging of the mouse cortex with femtoliter volume resolution

NASA Astrophysics Data System (ADS)

Merkle, Conrad W.; Chong, Shau Poh; Kho, Aaron M.; Zhu, Jun; Kholiqov, Oybek; Dubra, Alfredo; Srinivasan, Vivek J.

2018-02-01

Most flying-spot Optical Coherence Tomography (OCT) and Optical Coherence Microscopy (OCM) systems use a symmetric confocal geometry, where the detection path retraces the illumination path starting from and ending with the spatial mode of a single mode optical fiber. Here, we describe a visible light OCM instrument that breaks this symmetry to improve transverse resolution without sacrificing collection efficiency in scattering tissue. This was achieved by overfilling a 0.3 numerical aperture (NA) water immersion objective on the illumination path, while maintaining a conventional Gaussian mode detection path (1/e2 intensity diameter 0.82 Airy disks), enabling 1.1 μm full-width at half-maximum (FWHM) transverse resolution. At the same time, a 0.9 μm FWHM axial resolution in tissue, achieved by a broadband visible light source, enabled femtoliter volume resolution. We characterized this instrument according to paraxial coherent microscopy theory, and then used it to image the meningeal layers, intravascular red blood cell-free layer, and myelinated axons in the mouse neocortex in vivo through the thinned skull. Finally, by introducing a 0.8 NA water immersion objective, we improved the lateral resolution to 0.44 μm FWHM, which provided a volumetric resolution of 0.2 fL, revealing cell bodies in cortical layer I of the mouse brain with OCM for the first time.

Nanophotonic force microscopy: characterizing particle-surface interactions using near-field photonics.

PubMed

Schein, Perry; Kang, Pilgyu; O'Dell, Dakota; Erickson, David

2015-02-11

Direct measurements of particle-surface interactions are important for characterizing the stability and behavior of colloidal and nanoparticle suspensions. Current techniques are limited in their ability to measure pico-Newton scale interaction forces on submicrometer particles due to signal detection limits and thermal noise. Here we present a new technique for making measurements in this regime, which we refer to as nanophotonic force microscopy. Using a photonic crystal resonator, we generate a strongly localized region of exponentially decaying, near-field light that allows us to confine small particles close to a surface. From the statistical distribution of the light intensity scattered by the particle we are able to map out the potential well of the trap and directly quantify the repulsive force between the nanoparticle and the surface. As shown in this Letter, our technique is not limited by thermal noise, and therefore, we are able to resolve interaction forces smaller than 1 pN on dielectric particles as small as 100 nm in diameter.

X-ray micro-modulated luminescence tomography (XMLT)

PubMed Central

Cong, Wenxiang; Liu, Fenglin; Wang, Chao; Wang, Ge

2014-01-01

Imaging depth of optical microscopy has been fundamentally limited to millimeter or sub-millimeter due to strong scattering of light in a biological sample. X-ray microscopy can resolve spatial details of few microns deep inside a sample but contrast resolution is inadequate to depict heterogeneous features at cellular or sub-cellular levels. To enhance and enrich biological contrast at large imaging depth, various nanoparticles are introduced and become essential to basic research and molecular medicine. Nanoparticles can be functionalized as imaging probes, similar to fluorescent and bioluminescent proteins. LiGa5O8:Cr3+ nanoparticles were recently synthesized to facilitate luminescence energy storage with x-ray pre-excitation and subsequently stimulated luminescence emission by visible/near-infrared (NIR) light. In this paper, we propose an x-ray micro-modulated luminescence tomography (XMLT, or MLT to be more general) approach to quantify a nanophosphor distribution in a thick biological sample with high resolution. Our numerical simulation studies demonstrate the feasibility of the proposed approach. PMID:24663898

Low cost label-free live cell imaging for biological samples

NASA Astrophysics Data System (ADS)

Seniya, C.; Towers, C. E.; Towers, D. P.

2017-02-01

This paper reports the progress to develop a practical phase measuring microscope offering new capabilities in terms of phase measurement accuracy and quantification of cell:cell interactions over the longer term. A novel, low cost phase interference microscope for imaging live cells (label-free) is described. The method combines the Zernike phase contrast approach with a dual mirror design to enable phase modulation between the scattered and un-scattered optical fields. Two designs are proposed and demonstrated, one of which retains the common path nature of Zernike's original microscopy concept. In both setups the phase shift is simple to control via a piezoelectric driven mirror in the back focal plane of the imaging system. The approach is significantly cheaper to implement than those based on spatial light modulators (SLM) at approximately 20% of the cost. A quantitative assessment of the performance of a set of phase shifting algorithms is also presented, specifically with regard to broad bandwidth illumination in phase contrast microscopy. The simulation results show that the phase measurement accuracy is strongly dependent on the algorithm selected and the optical path difference in the sample.

Polypyrrole coated phase-change contrast agents for sono-photoacoustic imaging (Conference Presentation)

NASA Astrophysics Data System (ADS)

Li, David S.; Yoon, Soon Joon; Matula, Thomas J.; O'Donnell, Matthew; Pozzo, Lilo D.

2017-03-01

A new light and sound sensitive nanoemulsion contrast agent is presented. The agents feature a low boiling point liquid perfluorocarbon core and a broad light spectrum absorbing polypyrrole (PPy) polymer shell. The PPy coated nanoemulsions can reversibly convert from liquid to gas phase upon cavitation of the liquid perfluorocarbon core. Cavitation can be initiated using a sufficiently high intensity acoustic pulse or from heat generation due to light absorption from a laser pulse. The emulsions can be made between 150 and 350 nm in diameter and PPy has a broad optical absorption covering both the visible spectrum and extending into the near-infrared spectrum (peak absorption 1053 nm). The size, structure, and optical absorption properties of the PPy coated nanoemulsions were characterized and compared to PPy nanoparticles (no liquid core) using dynamic light scattering, ultraviolet-visible spectrophotometry, transmission electron microscopy, and small angle X-ray scattering. The cavitation threshold and signal intensity were measured as a function of both acoustic pressure and laser fluence. Overlapping simultaneous transmission of an acoustic and laser pulse can significantly reduce the activation energy of the contrast agents to levels lower than optical or acoustic activation alone. We also demonstrate that simultaneous light and sound cavitation of the agents can be used in a new sono-photoacoustic imaging method, which enables greater sensitivity than traditional photoacoustic imaging.

Quasiparticle interference in ZrSiS: Strongly band-selective scattering depending on impurity lattice site

NASA Astrophysics Data System (ADS)

Butler, Christopher J.; Wu, Yu-Mi; Hsing, Cheng-Rong; Tseng, Yi; Sankar, Raman; Wei, Ching-Ming; Chou, Fang-Cheng; Lin, Minn-Tsong

2017-11-01

Scanning tunneling microscopy visualizations of quasiparticle interference (QPI) enable powerful insights into the k -space properties of superconducting, topological, Rashba, and other exotic electronic phases, but their reliance on impurities acting as scattering centers is rarely scrutinized. Here, we investigate QPI at the vacuum-cleaved (001) surface of the Dirac semimetal ZrSiS. We find that interference patterns around impurities located on the Zr and S lattice sites appear very different, and can be ascribed to selective scattering of different subsets of the predominantly Zr 4 d -derived band structure, namely, the m =0 and ±1 components. We show that the selectivity of scattering channels requires an explanation beyond the different bands' orbital characteristics and their respective charge density distributions over Zr and S lattice sites. Importantly, this result shows that the usual assumption of generic scattering centers allowing observations of quasiparticle interference to shed light indiscriminately and isotropically upon the q space of scattering events does not hold, and that the scope and interpretation of QPI observations can therefore be be strongly contingent on the material defect chemistry. This finding promises to spur new investigations into the quasiparticle scattering process itself, to inform future interpretations of quasiparticle interference observations, and ultimately to aid the understanding and engineering of quantum electronic transport properties.

Milligram-per-second femtosecond laser production of Se nanoparticle inks and ink-jet printing of nanophotonic 2D-patterns

NASA Astrophysics Data System (ADS)

Ionin, Andrey; Ivanova, Anastasia; Khmel'nitskii, Roman; Klevkov, Yury; Kudryashov, Sergey; Mel'nik, Nikolay; Nastulyavichus, Alena; Rudenko, Andrey; Saraeva, Irina; Smirnov, Nikita; Zayarny, Dmitry; Baranov, Anatoly; Kirilenko, Demid; Brunkov, Pavel; Shakhmin, Alexander

2018-04-01

Milligram-per-second production of selenium nanoparticles in water sols was realized through 7-W, 2 MHz-rate femtosecond laser ablation of a crystalline trigonal selenium pellet. High-yield particle formation mechanism and ultimate mass-removal yield were elucidated by optical profilometry and scanning electron microscopy characterization of the corresponding crater depths and topographies. Deposited selenium particles were inspected by scanning and transmission electron microscopy, while their hydrosols (nanoinks) were characterized by optical transmission, Raman and dynamic light scattering spectroscopy. 2D patterns and coatings were ink-jet printed on thin supported silver films and their bare silica glass substrates, as well as on IR-transparent CaF2 substrates, and characterized by electron microscopy, energy-dispersive x-ray spectroscopy, and broadband (vis-mid IR) transmission spectroscopy, exhibiting crystalline selenium nanoparticles with high refractive index as promising all-dielectric sensing building nanoblocks in nanophotonics.

Fourier Transform Infrared (FTIR) Spectroscopy, Ultraviolet Resonance Raman (UVRR) Spectroscopy, and Atomic Force Microscopy (AFM) for Study of the Kinetics of Formation and Structural Characterization of Tau Fibrils.

PubMed

Ramachandran, Gayathri

2017-01-01

Kinetic studies of tau fibril formation in vitro most commonly employ spectroscopic probes such as thioflavinT fluorescence and laser light scattering or negative stain transmission electron microscopy. Here, I describe the use of Fourier transform infrared (FTIR) spectroscopy, ultraviolet resonance Raman (UVRR) spectroscopy, and atomic force microscopy (AFM) as complementary probes for studies of tau aggregation. The sensitivity of vibrational spectroscopic techniques (FTIR and UVRR) to secondary structure content allows for measurement of conformational changes that occur when the intrinsically disordered protein tau transforms into cross-β-core containing fibrils. AFM imaging serves as a gentle probe of structures populated over the time course of tau fibrillization. Together, these assays help further elucidate the structural and mechanistic complexity inherent in tau fibril formation.

Improvement of axial excitation confinement in temporal focusing-based multiphoton microscopy via spatially modulated illumination

NASA Astrophysics Data System (ADS)

Chang, Chia-Yuan; Chen, Shean-Jen

2017-02-01

Conventional temporal focusing-based multiphoton excitation microscopy (TFMPEM) can offer widefield optical sectioning with an axial excitation confinement (AEC) of a few microns. Herein, a developed TFMPEM with a digital micromirror device (DMD), acting as the blazed grating for light spatial dispersion and simultaneous patterned illumination, has been extended to implement spatially modulated illumination at structured frequency and orientation. By implementing the spatially modulated illumination, the beam coverage at the back-focal aperture of the objective lens can be increased. As a result, the AEC can be condensed from 3.0 μm to 1.5 μm in full width at half maximum for a 2-fold enhancement. Furthermore, by using HiLo microscopy with two structured illuminations at the same spatial frequency but different orientation, biotissue images according to the structured illumination with condensed AEC is obviously superior in contrast and scattering suppression.

Calcium phosphate nanoparticles as versatile carrier for small and large molecules across cell membranes

NASA Astrophysics Data System (ADS)

Sokolova, Viktoriya; Rotan, Olga; Klesing, Jan; Nalbant, Perihan; Buer, Jan; Knuschke, Torben; Westendorf, Astrid M.; Epple, Matthias

2012-06-01

The successful transport of molecules across the cell membrane is a key point in biology and medicine. In most cases, molecules alone cannot penetrate the cell membrane, therefore an efficient carrier is needed. Calcium phosphate nanoparticles (diameter: 100-250 nm, depending on the functionalization) were loaded with fluorescent oligonucleotides, peptide, proteins, antibodies, polymers or porphyrins and characterized by dynamic light scattering, nanoparticle tracking analysis and scanning electron microscopy. Any excess of molecules was removed by ultracentrifugation, and the dissolved molecules at the same concentration were used as control. The uptake of such fluorescence-labeled nanoparticles into HeLa cells was monitored by fluorescence microscopy and confocal laser scanning microscopy. Calcium phosphate nanoparticles were able to transport all molecules across the cell membrane, whereas the dissolved molecules alone were taken up only to a very small extent or even not at all.

Enabling the detection of UV signal in multimodal nonlinear microscopy with catalogue lens components.

PubMed

Vogel, Martin; Wingert, Axel; Fink, Rainer H A; Hagl, Christian; Ganikhanov, Feruz; Pfeffer, Christian P

2015-10-01

Using an optical system made from fused silica catalogue optical components, third-order nonlinear microscopy has been enabled on conventional Ti:sapphire laser-based multiphoton microscopy setups. The optical system is designed using two lens groups with straightforward adaptation to other microscope stands when one of the lens groups is exchanged. Within the theoretical design, the optical system collects and transmits light with wavelengths between the near ultraviolet and the near infrared from an object field of at least 1 mm in diameter within a resulting numerical aperture of up to 0.56. The numerical aperture can be controlled with a variable aperture stop between the two lens groups of the condenser. We demonstrate this new detection capability in third harmonic generation imaging experiments at the harmonic wavelength of ∼300 nm and in multimodal nonlinear optical imaging experiments using third-order sum frequency generation and coherent anti-Stokes Raman scattering microscopy so that the wavelengths of the detected signals range from ∼300 nm to ∼660 nm. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Ribbon phase in a phase-separated lyotropic lamellar-sponge mixture under shear flow

NASA Astrophysics Data System (ADS)

Cristobal, G.; Rouch, J.; Panizza, P.; Narayanan, T.

2001-07-01

We report the effect of shear flow on a phase-separated system composed of lyotropic lamellar (Lα) and sponge (L3) phases in a mixture of brine, surfactant, and cosurfactant. Optical microscopy, small-angle light, and x-ray scattering measurements are consistent with the existence of a steady state made of multilamellar ribbonlike structures aligned in the flow direction. At high shear rates, these ribbonlike structures become unstable and break up into monodisperse droplets resulting in a shear-thickening transition.

Single Polymer Chain Elongation by Atomic Force Microscopy.

DTIC Science & Technology

1998-01-01

are designated by PS for polystyrene and P2VP or PVP for poly-2-vinyl-pyridine. Molecular weights of the individual blocks are given after the...In the case of PS - P2VP the difference in interfacial tensions of the two blocks with water are too close to distinguish. Using block copolymers with...Stanford University, 1987. (20) Static light scattering reveals that the CMC of PS - P2VP solutions in toluene is approximately 65ug/ml,19 and as such

Ru(II)-based metallosurfactant forming inverted aggregates.

PubMed

Domínguez-Gutiérrez, David; Surtchev, Marko; Eiser, Erika; Elsevier, Cornelis J

2006-02-01

Knowing the advantages of incorporating a transition metal into interfaces, we report on the first inverted aggregates formed using metallosurfactants. The metallosurfactant possesses four long linear tails that account for the shielding of the polar headgroup in apolar solvents. The nature of the so-formed aggregates changes dramatically from inverted vesicles (toluene) to inverted micelles (hexane). The size of the aggregates was determined using dynamic light scattering. Atomic force microscopy allowed us to study the dry structure of the vesicles on a glass surface.

Nonvolatile RRAM cells from polymeric composites embedding recycled SiC powders.

PubMed

De Girolamo Del Mauro, Anna; Nenna, Giuseppe; Miscioscia, Riccardo; Freda, Cesare; Portofino, Sabrina; Galvagno, Sergio; Minarini, Carla

2014-10-21

Silicon carbide powders have been synthesized from tires utilizing a patented recycling process. Dynamic light scattering, Raman spectroscopy, SEM microscopy, and X-ray diffraction have been carried out to gather knowledge about powders and the final composite structure. The obtained powder has been proven to induce resistive switching in a PMMA polymer-based composite device. Memory effect has been detected in two-terminal devices having coplanar contacts and quantified by read-write-erase measurements in terms of level separation and persistence.

Morphological and Spectral Characteristics of Hybrid Nanosystems Based on Mono- and Bimetallic Platinum Nanoparticles and Silver

NASA Astrophysics Data System (ADS)

Valueva, S. V.; Vylegzhanina, M. E.; Sukhanova, T. E.

2018-02-01

Morphological and spectral characteristics of hybrid nanosystems (NSes) based on mono- and bimetallic silver and platinum nanoparticles (NPs) stabilized by a cationic polyelectrolyte (CP), poly- N,N,N,N-trimethylmethacryloyloxyethylammonium methylsulfate, are determined via static/dynamic light scattering, UV spectroscopy, and atomic force microscopy. The formation of dense spherical polymolecular nanostructures is established. The possibility of controlling the morphological and spectral characteristics of the NS is shown by varying the nature and composition of NPs.

Electrospun Conjugated Polymer/Fullerene Hybrid Fibers: Photoactive Blends, Conductivity through Tunneling-AFM, Light Scattering, and Perspective for Their Use in Bulk-Heterojunction Organic Solar Cells

DOE PAGES

Yang, Zhenhua; Moffa, Maria; Liu, Ying; ...

2018-01-25

Hybrid conjugated polymer/fullerene filaments based on MEH-PPV/PVP/PCBM were prepared by electrospinning, and their properties were assessed by scanning electron, atomic and lateral-force, tunneling, and confocal microscopies, as well as by attenuated-total-reflection Fourier transform infrared spectroscopy, photoluminescence quantum yield, and spatially resolved fluorescence. Highlighted features include the ribbon shape of the realized fibers and the persistence of a network serving as a template for heterogeneous active layers in solar cell devices. A set of favorable characteristics is evidenced in this way in terms of homogeneous charge-transport behavior and formation of effective interfaces for diffusion and dissociation of photogenerated excitons. The interactionmore » of the organic filaments with light, exhibiting specific light-scattering properties of the nanofibrous mat, might also contribute to spreading incident radiation across the active layers, thus potentially enhancing photovoltaic performance. Finally, this method might be applied to other electron donor–electron acceptor material systems for the fabrication of solar cell devices enhanced by nanofibrillar morphologies embedding conjugated polymers and fullerene compounds.« less

Electrospun Conjugated Polymer/Fullerene Hybrid Fibers: Photoactive Blends, Conductivity through Tunneling-AFM, Light Scattering, and Perspective for Their Use in Bulk-Heterojunction Organic Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Zhenhua; Moffa, Maria; Liu, Ying

Hybrid conjugated polymer/fullerene filaments based on MEH-PPV/PVP/PCBM were prepared by electrospinning, and their properties were assessed by scanning electron, atomic and lateral-force, tunneling, and confocal microscopies, as well as by attenuated-total-reflection Fourier transform infrared spectroscopy, photoluminescence quantum yield, and spatially resolved fluorescence. Highlighted features include the ribbon shape of the realized fibers and the persistence of a network serving as a template for heterogeneous active layers in solar cell devices. A set of favorable characteristics is evidenced in this way in terms of homogeneous charge-transport behavior and formation of effective interfaces for diffusion and dissociation of photogenerated excitons. The interactionmore » of the organic filaments with light, exhibiting specific light-scattering properties of the nanofibrous mat, might also contribute to spreading incident radiation across the active layers, thus potentially enhancing photovoltaic performance. Finally, this method might be applied to other electron donor–electron acceptor material systems for the fabrication of solar cell devices enhanced by nanofibrillar morphologies embedding conjugated polymers and fullerene compounds.« less

Fluorescent Imaging of Single Nanoparticles and Viruses on a Smart Phone

PubMed Central

Wei, Qingshan; Qi, Hangfei; Luo, Wei; Tseng, Derek; Ki, So Jung; Wan, Zhe; Göröcs, Zoltán; Bentolila, Laurent A.; Wu, Ting-Ting; Sun, Ren; Ozcan, Aydogan

2014-01-01

Optical imaging of nanoscale objects, whether it is based on scattering or fluorescence, is a challenging task due to reduced detection signal-to-noise ratio and contrast at subwavelength dimensions. Here, we report a field-portable fluorescence microscopy platform installed on a smart phone for imaging of individual nanoparticles as well as viruses using a lightweight and compact opto-mechanical attachment to the existing camera module of the cell phone. This hand-held fluorescent imaging device utilizes (i) a compact 450 nm laser diode that creates oblique excitation on the sample plane with an incidence angle of ~75°, (ii) a long-pass thin-film interference filter to reject the scattered excitation light, (iii) an external lens creating 2× optical magnification, and (iv) a translation stage for focus adjustment. We tested the imaging performance of this smart-phone-enabled microscopy platform by detecting isolated 100 nm fluorescent particles as well as individual human cytomegaloviruses that are fluorescently labeled. The size of each detected nano-object on the cell phone platform was validated using scanning electron microscopy images of the same samples. This field-portable fluorescence microscopy attachment to the cell phone, weighing only ~186 g, could be used for specific and sensitive imaging of subwavelength objects including various bacteria and viruses and, therefore, could provide a valuable platform for the practice of nanotechnology in field settings and for conducting viral load measurements and other biomedical tests even in remote and resource-limited environments. PMID:24016065

Efficiency enhancement in dye sensitized solar cells using dual function mesoporous silica as scatterer and back recombination inhibitor

NASA Astrophysics Data System (ADS)

Tanvi; Mahajan, Aman; Bedi, R. K.; Kumar, Subodh; Saxena, Vibha; Aswal, D. K.

2016-08-01

In the present work, we report the usage of mesoporous silica for improving light harvesting as well as for suppression of back recombination without affecting the extent of dye loading on TiO2 films. Synthesized mesoporous SiO2 was characterized by X-ray photoelectron spectroscopy, X-ray diffraction, Brunauer Emmett and Teller measurement, Scanning electron microscopy and Transmission electron microscopy. DSSCs were fabricated by incorporating different wt% of mesoporous SiO2 in TiO2 paste. An improvement of 50% was observed for devices fabricated using 0.75 wt% of mesoporous SiO2. The mechanism behind the improvement was investigated using electrochemical impedance spectroscopy and UV-Vis spectroscopy.

One-step, low-temperature fabrication of CdS quantum dots by watermelon rind: a green approach

PubMed Central

Lakshmipathy, Rajasekhar; Sarada, Nallani Chakravarthula; Chidambaram, K; Pasha, Sk Khadeer

2015-01-01

We investigated the one-step synthesis of CdS nanoparticles via green synthesis that used aqueous extract of watermelon rind as a capping and stabilizing agent. Preliminary phytochemical analysis depicted the presence of carbohydrates which can act as capping and stabilizing agents. Synthesized CdS nanoparticles were characterized using UV-visible, Fourier transform infrared spectroscopy, X-ray diffraction, EDX, dynamic light scattering, transmission electron microscopy, and atomic force microscopy techniques. The CdS nanoparticles were found to be size- and shape-controlled and were stable even after 3 months of synthesis. The results suggest that watermelon rind, an agro-waste, can be used for synthesis of CdS nanoparticles without any addition of stabilizing and capping agents. PMID:26491319

Nanoparticle conversion to biofilms: in vitro demonstration using serum-derived mineralo-organic nanoparticles.

PubMed

Wong, Tsui-Yin; Peng, Hsin-Hsin; Wu, Cheng-Yeu; Martel, Jan; Ojcius, David M; Hsu, Fu-Yung; Young, John D

2015-01-01

Mineralo-organic nanoparticles (NPs) detected in biological fluids have been described as precursors of physiological and pathological calcifications in the body. Our main objective was to examine the early stages of mineral NP formation in body fluids. A nanomaterial approach based on atomic force microscopy, dynamic light scattering, electron microscopy and spectroscopy was used. The mineral particles, which contain the serum proteins albumin and fetuin-A, initially precipitate in the form of round amorphous NPs that gradually grow in size, aggregate and coalesce to form crystalline mineral films similar to the structures observed in calcified human arteries. Our study reveals the early stages of particle formation and provides a platform to analyze the role(s) of mineralo-organic NPs in human tissues.

Preparation of silver nanoparticles loaded graphene oxide nanosheets for antibacterial activity

NASA Astrophysics Data System (ADS)

T, T. T., Vi; Lue, S. J.

2016-11-01

A simple, facile method to fabricate successfully silver nanoparticle (AgNPs) decorated on graphene oxide (GO) layers via grafted thiol groups. Samples were prepared with different concentrations of AgNO3. Resulting AgNPs were quasi-spherical in shape and attached on the layers of GO. Physical properties were confirmed by X-ray diffraction (XRD), zeta potential, dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectra, thermogravimetric analyzer (TGA), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM). Antimicrobial test was effectively showed using MRSA (Staphylococcus areus). The GO-Ag NPs with appropriate Ag NPs content of 0.2 M AgNO3 exhibited the strongest antibacterial activity at 48.77% inhibition after 4 hours incubation.

Fast imaging of live organisms with sculpted light sheets

NASA Astrophysics Data System (ADS)

Chmielewski, Aleksander K.; Kyrsting, Anders; Mahou, Pierre; Wayland, Matthew T.; Muresan, Leila; Evers, Jan Felix; Kaminski, Clemens F.

2015-04-01

Light-sheet microscopy is an increasingly popular technique in the life sciences due to its fast 3D imaging capability of fluorescent samples with low photo toxicity compared to confocal methods. In this work we present a new, fast, flexible and simple to implement method to optimize the illumination light-sheet to the requirement at hand. A telescope composed of two electrically tuneable lenses enables us to define thickness and position of the light-sheet independently but accurately within milliseconds, and therefore optimize image quality of the features of interest interactively. We demonstrated the practical benefit of this technique by 1) assembling large field of views from tiled single exposure each with individually optimized illumination settings; 2) sculpting the light-sheet to trace complex sample shapes within single exposures. This technique proved compatible with confocal line scanning detection, further improving image contrast and resolution. Finally, we determined the effect of light-sheet optimization in the context of scattering tissue, devising procedures for balancing image quality, field of view and acquisition speed.

A novel full-angle scanning light scattering profiler to quantitatively evaluate forward and backward light scattering from intraocular lenses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, Bennett N., E-mail: bennett.walker@fda.hhs.gov; Office of Device Evaluation, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, Maryland 20993; James, Robert H.

Glare, glistenings, optical defects, dysphotopsia, and poor image quality are a few of the known deficiencies of intraocular lenses (IOLs). All of these optical phenomena are related to light scatter. However, the specific direction that light scatters makes a critical difference between debilitating glare and a slightly noticeable decrease in image quality. Consequently, quantifying the magnitude and direction of scattered light is essential to appropriately evaluate the safety and efficacy of IOLs. In this study, we introduce a full-angle scanning light scattering profiler (SLSP) as a novel approach capable of quantitatively evaluating the light scattering from IOLs with a nearlymore » 360° view. The SLSP method can simulate in situ conditions by controlling the parameters of the light source including angle of incidence. This testing strategy will provide a more effective nonclinical approach for the evaluation of IOL light scatter.« less

Angle-resolved light scattering of individual rod-shaped bacteria based on Fourier transform light scattering

NASA Astrophysics Data System (ADS)

Jo, Youngju; Jung, Jaehwang; Lee, Jee Woong; Shin, Della; Park, Hyunjoo; Nam, Ki Tae; Park, Ji-Ho; Park, Yongkeun

2014-05-01

Two-dimensional angle-resolved light scattering maps of individual rod-shaped bacteria are measured at the single-cell level. Using quantitative phase imaging and Fourier transform light scattering techniques, the light scattering patterns of individual bacteria in four rod-shaped species (Bacillus subtilis, Lactobacillus casei, Synechococcus elongatus, and Escherichia coli) are measured with unprecedented sensitivity in a broad angular range from -70° to 70°. The measured light scattering patterns are analyzed along the two principal axes of rod-shaped bacteria in order to systematically investigate the species-specific characteristics of anisotropic light scattering. In addition, the cellular dry mass of individual bacteria is calculated and used to demonstrate that the cell-to-cell variations in light scattering within bacterial species is related to the cellular dry mass and growth.

Light transport in turbid media with non-scattering, low-scattering and high absorption heterogeneities based on hybrid simplified spherical harmonics with radiosity model

PubMed Central

Yang, Defu; Chen, Xueli; Peng, Zhen; Wang, Xiaorui; Ripoll, Jorge; Wang, Jing; Liang, Jimin

2013-01-01

Modeling light propagation in the whole body is essential and necessary for optical imaging. However, non-scattering, low-scattering and high absorption regions commonly exist in biological tissues, which lead to inaccuracy of the existing light transport models. In this paper, a novel hybrid light transport model that couples the simplified spherical harmonics approximation (SPN) with the radiosity theory (HSRM) was presented, to accurately describe light transport in turbid media with non-scattering, low-scattering and high absorption heterogeneities. In the model, the radiosity theory was used to characterize the light transport in non-scattering regions and the SPN was employed to handle the scattering problems, including subsets of low-scattering and high absorption. A Neumann source constructed by the light transport in the non-scattering region and formed at the interface between the non-scattering and scattering regions was superposed into the original light source, to couple the SPN with the radiosity theory. The accuracy and effectiveness of the HSRM was first verified with both regular and digital mouse model based simulations and a physical phantom based experiment. The feasibility and applicability of the HSRM was then investigated by a broad range of optical properties. Lastly, the influence of depth of the light source on the model was also discussed. Primary results showed that the proposed model provided high performance for light transport in turbid media with non-scattering, low-scattering and high absorption heterogeneities. PMID:24156077

Light transport in turbid media with non-scattering, low-scattering and high absorption heterogeneities based on hybrid simplified spherical harmonics with radiosity model.

PubMed

Yang, Defu; Chen, Xueli; Peng, Zhen; Wang, Xiaorui; Ripoll, Jorge; Wang, Jing; Liang, Jimin

2013-01-01

Modeling light propagation in the whole body is essential and necessary for optical imaging. However, non-scattering, low-scattering and high absorption regions commonly exist in biological tissues, which lead to inaccuracy of the existing light transport models. In this paper, a novel hybrid light transport model that couples the simplified spherical harmonics approximation (SPN) with the radiosity theory (HSRM) was presented, to accurately describe light transport in turbid media with non-scattering, low-scattering and high absorption heterogeneities. In the model, the radiosity theory was used to characterize the light transport in non-scattering regions and the SPN was employed to handle the scattering problems, including subsets of low-scattering and high absorption. A Neumann source constructed by the light transport in the non-scattering region and formed at the interface between the non-scattering and scattering regions was superposed into the original light source, to couple the SPN with the radiosity theory. The accuracy and effectiveness of the HSRM was first verified with both regular and digital mouse model based simulations and a physical phantom based experiment. The feasibility and applicability of the HSRM was then investigated by a broad range of optical properties. Lastly, the influence of depth of the light source on the model was also discussed. Primary results showed that the proposed model provided high performance for light transport in turbid media with non-scattering, low-scattering and high absorption heterogeneities.

Dual-view inverted selective plane illumination microscopy (diSPIM) with improved background rejection for accurate 3D digital pathology

NASA Astrophysics Data System (ADS)

Hu, Bihe; Bolus, Daniel; Brown, J. Quincy

2018-02-01

Current gold-standard histopathology for cancerous biopsies is destructive, time consuming, and limited to 2D slices, which do not faithfully represent true 3D tumor micro-morphology. Light sheet microscopy has emerged as a powerful tool for 3D imaging of cancer biospecimens. Here, we utilize the versatile dual-view inverted selective plane illumination microscopy (diSPIM) to render digital histological images of cancer biopsies. Dual-view architecture enabled more isotropic resolution in X, Y, and Z; and different imaging modes, such as adding electronic confocal slit detection (eCSD) or structured illumination (SI), can be used to improve degraded image quality caused by background signal of large, scattering samples. To obtain traditional H&E-like images, we used DRAQ5 and eosin (D&E) staining, with 488nm and 647nm laser illumination, and multi-band filter sets. Here, phantom beads and a D&E stained buccal cell sample have been used to verify our dual-view method. We also show that via dual view imaging and deconvolution, more isotropic resolution has been achieved for optical cleared human prostate sample, providing more accurate quantitation of 3D tumor architecture than was possible with single-view SPIM methods. We demonstrate that the optimized diSPIM delivers more precise analysis of 3D cancer microarchitecture in human prostate biopsy than simpler light sheet microscopy arrangements.

Structured polarized light microscopy (SPLM) for mapping collagen fiber orientation of ocular tissues

NASA Astrophysics Data System (ADS)

Yang, Bin; Brazile, Bryn; Jan, Ning-Jiun; Voorhees, Andrew P.; Sigal, Ian A.

2018-02-01

Glaucoma is a disease characterized by progressive and irreversible vision loss leading to blindness. This vision loss is believed to be largely determined by the biomechanics of the optic nerve head region. Optic nerve head biomechanics, in turn, is determined by the properties of the constituent collagen. However, it is challenging to visualize and quantify collagen morphology and orientation in situ, and therefore often studies of the region collagen have used histological sections. Here we describe SPLM, a novel imaging technique that combines structured light illumination and polarized light microscopy (PLM) to enable collagen fiber visualization and fiber orientation mapping without requiring tissue sectioning. We developed a custom automated SPLM imaging system based on an upright microscope and a digital micromirror device (DMD) projector. The high spatial frequency patterns were used to achieve effective background suppression. Enhanced scattering sensitivity with SPLM resulted in images with highly improved visibility of collagen structures, even of tissues covered by pigment. SPLM produced improved fiber orientation maps from superficial layers compared to depth-averaged orientation from regular PLM. SPLM imaging provides valuable information of collagen fiber morphology and orientation in situ thus strengthening the study of ocular collagen fiber biomechanics and glaucoma.

Gelation Kinetics and Network Structure of Cellulose Nanocrystals in Aqueous Solution.

PubMed

Peddireddy, Karthik R; Capron, Isabelle; Nicolai, Taco; Benyahia, Lazhar

2016-10-10

Cellulose nanocrystals (CNC) are rod-like biosourced nanoparticles that are widely used in a range of applications. Charged CNC was obtained by acid extraction from cotton and dispersed in aqueous solution using ultrasound and characterized by light scattering. Aggregation and gelation of CNC induced by addition of NaCl was investigated by light scattering as a function of the NaCl concentration (30-70 mM), the CNC concentration (0.5-5 g/L), and the temperature (10-60 °C). Formation of fractal aggregates was observed that grow with time until they percolate and form a weak system spanning network. The aggregation rate and gel time were found to decrease very steeply with increasing NaCl concentration and more weakly with increasing CNC concentration. A decrease of the gel time was also observed with increasing temperature for T > 20 °C. The structure of the CNC networks was studied using confocal laser scanning microscopy and light scattering. The local structure of the networks was fractal and reflected that of the constituting aggregates. The gels were homogeneous on length scales larger than the correlation length, which decreased with increasing CNC concentration. The CNC gels flowed when tilted for C < 12 g/L and sedimentation was observed macroscopically for C < 4 g/L due to the collapse of the CNC network under gravity. The speed and extent of sedimentation was investigated as a function of the ionic strength and the CNC concentration. Gelled CNC could be completely redispersed by applying ultrasound.

3D multiplexed immunoplasmonics microscopy

NASA Astrophysics Data System (ADS)

Bergeron, Éric; Patskovsky, Sergiy; Rioux, David; Meunier, Michel

2016-07-01

Selective labelling, identification and spatial distribution of cell surface biomarkers can provide important clinical information, such as distinction between healthy and diseased cells, evolution of a disease and selection of the optimal patient-specific treatment. Immunofluorescence is the gold standard for efficient detection of biomarkers expressed by cells. However, antibodies (Abs) conjugated to fluorescent dyes remain limited by their photobleaching, high sensitivity to the environment, low light intensity, and wide absorption and emission spectra. Immunoplasmonics is a novel microscopy method based on the visualization of Abs-functionalized plasmonic nanoparticles (fNPs) targeting cell surface biomarkers. Tunable fNPs should provide higher multiplexing capacity than immunofluorescence since NPs are photostable over time, strongly scatter light at their plasmon peak wavelengths and can be easily functionalized. In this article, we experimentally demonstrate accurate multiplexed detection based on the immunoplasmonics approach. First, we achieve the selective labelling of three targeted cell surface biomarkers (cluster of differentiation 44 (CD44), epidermal growth factor receptor (EGFR) and voltage-gated K+ channel subunit KV1.1) on human cancer CD44+ EGFR+ KV1.1+ MDA-MB-231 cells and reference CD44- EGFR- KV1.1+ 661W cells. The labelling efficiency with three stable specific immunoplasmonics labels (functionalized silver nanospheres (CD44-AgNSs), gold (Au) NSs (EGFR-AuNSs) and Au nanorods (KV1.1-AuNRs)) detected by reflected light microscopy (RLM) is similar to the one with immunofluorescence. Second, we introduce an improved method for 3D localization and spectral identification of fNPs based on fast z-scanning by RLM with three spectral filters corresponding to the plasmon peak wavelengths of the immunoplasmonics labels in the cellular environment (500 nm for 80 nm AgNSs, 580 nm for 100 nm AuNSs and 700 nm for 40 nm × 92 nm AuNRs). Third, the developed technology is simple and compatible with standard epi-fluorescence microscopes used in biological and clinical laboratories. Thus, 3D multiplexed immunoplasmonics microscopy is ready for clinical applications as a cost-efficient alternative to immunofluorescence.Selective labelling, identification and spatial distribution of cell surface biomarkers can provide important clinical information, such as distinction between healthy and diseased cells, evolution of a disease and selection of the optimal patient-specific treatment. Immunofluorescence is the gold standard for efficient detection of biomarkers expressed by cells. However, antibodies (Abs) conjugated to fluorescent dyes remain limited by their photobleaching, high sensitivity to the environment, low light intensity, and wide absorption and emission spectra. Immunoplasmonics is a novel microscopy method based on the visualization of Abs-functionalized plasmonic nanoparticles (fNPs) targeting cell surface biomarkers. Tunable fNPs should provide higher multiplexing capacity than immunofluorescence since NPs are photostable over time, strongly scatter light at their plasmon peak wavelengths and can be easily functionalized. In this article, we experimentally demonstrate accurate multiplexed detection based on the immunoplasmonics approach. First, we achieve the selective labelling of three targeted cell surface biomarkers (cluster of differentiation 44 (CD44), epidermal growth factor receptor (EGFR) and voltage-gated K+ channel subunit KV1.1) on human cancer CD44+ EGFR+ KV1.1+ MDA-MB-231 cells and reference CD44- EGFR- KV1.1+ 661W cells. The labelling efficiency with three stable specific immunoplasmonics labels (functionalized silver nanospheres (CD44-AgNSs), gold (Au) NSs (EGFR-AuNSs) and Au nanorods (KV1.1-AuNRs)) detected by reflected light microscopy (RLM) is similar to the one with immunofluorescence. Second, we introduce an improved method for 3D localization and spectral identification of fNPs based on fast z-scanning by RLM with three spectral filters corresponding to the plasmon peak wavelengths of the immunoplasmonics labels in the cellular environment (500 nm for 80 nm AgNSs, 580 nm for 100 nm AuNSs and 700 nm for 40 nm × 92 nm AuNRs). Third, the developed technology is simple and compatible with standard epi-fluorescence microscopes used in biological and clinical laboratories. Thus, 3D multiplexed immunoplasmonics microscopy is ready for clinical applications as a cost-efficient alternative to immunofluorescence. Electronic supplementary information (ESI) available: Characterization of functionalized nanoparticles by UV-visible-NIR spectroscopy, standard dark field microscopy and reflected light microscopy. Immunofluorescence of cells. See DOI: 10.1039/c6nr01257d

Eliminating Unwanted Far-Field Excitation in Objective-Type TIRF. Part II. Combined Evanescent-Wave Excitation and Supercritical-Angle Fluorescence Detection Improves Optical Sectioning

PubMed Central

Brunstein, Maia; Hérault, Karine; Oheim, Martin

2014-01-01

Azimuthal beam scanning makes evanescent-wave (EW) excitation isotropic, thereby producing total internal reflection fluorescence (TIRF) images that are evenly lit. However, beam spinning does not fundamentally address the problem of propagating excitation light that is contaminating objective-type TIRF. Far-field excitation depends more on the specific objective than on cell scattering. As a consequence, the excitation impurities in objective-type TIRF are only weakly affected by changes of azimuthal or polar beam angle. These are the main results of the first part of this study (Eliminating unwanted far-field excitation in objective-type TIRF. Pt.1. Identifying sources of nonevanescent excitation light). This second part focuses on exactly where up beam in the illumination system stray light is generated that gives rise to nonevanescent components in TIRF. Using dark-field imaging of scattered excitation light we pinpoint the objective, intermediate lenses and, particularly, the beam scanner as the major sources of stray excitation. We study how adhesion-molecule coating and astrocytes or BON cells grown on the coverslip surface modify the dark-field signal. On flat and weakly scattering cells, most background comes from stray reflections produced far from the sample plane, in the beam scanner and the objective lens. On thick, optically dense cells roughly half of the scatter is generated by the sample itself. We finally show that combining objective-type EW excitation with supercritical-angle fluorescence (SAF) detection efficiently rejects the fluorescence originating from deeper sample regions. We demonstrate that SAF improves the surface selectivity of TIRF, even at shallow penetration depths. The coplanar microscopy scheme presented here merges the benefits of beam spinning EW excitation and SAF detection and provides the conditions for quantitative wide-field imaging of fluorophore dynamics at or near the plasma membrane. PMID:24606929

Development of In-situ Resonant Soft X-ray Scattering for Soft Materials at Advanced Light Source

NASA Astrophysics Data System (ADS)

Wang, Cheng; Hexemer, Alexander; Young, Anthony; Padmore, Howard

2014-03-01

Resonant Soft X-ray Scattering was developed at ALS over the past a few years. It combines soft x-ray spectroscopy with x-ray scattering and offers statistical information for 3D chemical morphology over a large sample area. Its unique chemical sensitivity, large accessible size scale, polarization control and high coherence make it a powerful tool for mesoscale chemical/morphological structure characterization for many classes of materials. However, in order to study sciences in naturally occurring conditions, we need to overcome the sample limitations set by the low penetration depth of soft x-rays and requirement of high vacuum. Adapting to the evolving environmental cell designs utilized increasingly in the Electron Microscopy community, we will report our development of customize design liquid/gas environmental cells that will enable soft x-ray scattering experiments on biological, electro-chemical, self-assembly, and hierarchical functional systems in both static and dynamic fashion. Initial RSoXS result of solar fuel membrane assembly/fuel-cell membrane structure in wet cell will be presented.

Mass-specific scattering coefficient for natural minerogenic particle populations: particle size distribution effect and closure analyses.

PubMed

Peng, Feng; Effler, Steve W

2012-05-01

The relationship between the particulate scattering coefficient (b(p)) and the concentration of suspended particulate matter (SPM), as represented by the mass-specific scattering coefficient of particulates (b(p)*=b(p)/SPM), depends on particle size distribution (PSD). This dependence is quantified for minerogenic particle populations in this paper through calculations of b(p)* for common minerals as idealized populations (monodispersed spheres); contemporaneous measurements of b(p), SPM, and light-scattering attributes of mineral particles with scanning electron microscopy interfaced with automated image and x-ray analyses (SAX), for a connected stream-reservoir system where minerogenic particles dominate b(p); and estimates of b(p) and its size dependency (through SAX results-driven Mie theory calculations), particle volume concentration, and b(p)*. Modest changes in minerogenic PSDs are shown to result in substantial variations in b(p)*. Good closure of the SAX-based estimates of b(p) and particle volume concentration with bulk measurements is demonstrated. Converging relationships between b(p)* and particle size, developed from three approaches, were well described by power law expressions.

Particle formation in SiOx film deposition by low frequency plasma enhanced chemical vapor deposition

NASA Astrophysics Data System (ADS)

Yamaguchi, Tomoyo; Sakamoto, Naoshi; Shimozuma, Mitsuo; Yoshino, Masaki; Tagashira, Hiroaki

1998-01-01

Dust particle formation dynamics in the process of SiOx film deposition from a SiH4 and N2O gas mixture by a low frequency plasma enhanced chemical vapor deposition have been investigated using scanning electron microscopy and laser light scattering. The deposited films are confirmed to be SiOx from the measurements of Auger electron spectroscopy, x-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. It is observed by scanning electron microscopy that particles are deposited on Si substrate at the plasma power frequency f=5 kHz and above both with and without substrate heating (400 °C), while no particle is deposited below f=1 kHz. Moreover, the laser light scattering indicates that particles are generated at the plasma power frequency of f=3 kHz and above in the gas phase, and that they are not generated in the gas phase at below f=3 kHz. Properties (the refractive index, resistivity, and Vickers hardness) of the films with particles are inferior to those of the films without particles. This article has revealed experimentally the effect of plasma power frequency on SiOx particle formation and makes a contribution to the explication of the particle formation mechanism. We suggest that high-quality film deposition with the low frequency plasma enhanced chemical vapor deposition method is attained at f=1 kHz or less without substrate heating.

Unveiling the stimulatory effects of tartrazine on human and bovine serum albumin fibrillogenesis: Spectroscopic and microscopic study

NASA Astrophysics Data System (ADS)

Al-Shabib, Nasser Abdulatif; Khan, Javed Masood; Alsenaidy, Mohammad A.; Alsenaidy, Abdulrahman M.; Khan, Mohd Shahnawaz; Husain, Fohad Mabood; Khan, Mohammad Rashid; Naseem, Mohammad; Sen, Priyankar; Alam, Parvez; Khan, Rizwan Hasan

2018-02-01

Amyloid fibrils are playing key role in the pathogenesis of various neurodegenerative diseases. Generally anionic molecules are known to induce amyloid fibril in several proteins. In this work, we have studied the effect of anionic food additive dye i.e., tartrazine (TZ) on the amyloid fibril formation of human serum albumins (HSA) and bovine serum albumin (BSA) at pHs 7.4 and 3.5. We have employed various biophysical methods like, turbidity measurements, Rayleigh Light Scattering (RLS), Dynamic Light Scattering (DLS), intrinsic fluorescence, Congo red assay, far-UV CD, transmission electron microscopy (TEM) and atomic force microscopy (AFM) to decipher the mechanism of TZ-induce amyloid fibril formation in both the serum albumins at pHs 7.4 and 3.5. The obtained results suggest that both the albumins forms amyloid-like aggregates in the presence of 1.0 to 15.0 mM of TZ at pH 3.5, but no amyloid fibril were seen at pH 7.4. The possible cause of TZ-induced amyloid fibril formation is electrostatic and hydrophobic interaction because sulfate group of TZ may have interacted electrostatically with positively charged amino acids of the albumins at pH 3.5 and increased protein-protein and protein-TZ interactions leading to amyloid fibril formation. The TEM, RLS and DLS results are suggesting that BSA forms bigger size amyloids compared to HSA, may be due to high surface hydrophobicity of BSA.

Organic electroluminescent devices having improved light extraction

DOEpatents

Shiang, Joseph John [Niskayuna, NY

2007-07-17

Organic electroluminescent devices having improved light extraction include a light-scattering medium disposed adjacent thereto. The light-scattering medium has a light scattering anisotropy parameter g in the range from greater than zero to about 0.99, and a scatterance parameter S less than about 0.22 or greater than about 3.

Structural characterization of casein micelles: shape changes during film formation.

PubMed

Gebhardt, R; Vendrely, C; Kulozik, U

2011-11-09

The objective of this study was to determine the effect of size-fractionation by centrifugation on the film structure of casein micelles. Fractionated casein micelles in solution were asymmetrically distributed with a small distribution width as measured by dynamic light scattering. Films prepared from the size-fractionated samples showed a smooth surface in optical microscopy images and a homogeneous microstructure in atomic force micrographs. The nano- and microstructure of casein films was probed by micro-beam grazing incidence small angle x-ray scattering (μGISAXS). Compared to the solution measurements, the sizes determined in the film were larger and broadly distributed. The measured GISAXS patterns clearly deviate from those simulated for a sphere and suggest a deformation of the casein micelles in the film. © 2011 IOP Publishing Ltd

[Development of non-invasive clinical examination methods for the anterior segment of the eye and their clinical significance].

PubMed

Sawa, Mitsuru

2011-03-01

1. Slit-lamp microscopy is a principal ophthalmic clinical method, because it provides microscopic findings of the anterior segment of the eye noninvasively. Its findings, however, are qualitative and there are large inter-observer variations in their evaluation. Furthermore, slit-lamp microscopy provides morphological findings, but a functional evaluation is difficult. We developed two novel methods that establish a qualitative methodology of the slit-lamp microscope and the pathophysiology of the anterior segment of the eye. One is the flare-cell photometer to evaluate flare and cells in the aqueous humor of the eye and the other is an immunohistochemical examination method using tear fluid to evaluate ocular surface disorders. The comprehensive evaluation of these studies is herein overviewed. 2. INNOVATION OF THE FLARE-CELL PHOTOMETER AND ITS CLINICAL SIGNIFICANCE: The breakdown of the blood-aqueous barrier (BAB) causes an increase in protein (flare) and leakage of blood cells (cell) into the aqueous humor of the eye and the severity of BAB breakdown has a positive correlation with the intensity of flare and cells. The flare and cells in the aqueous can be observed qualitatively by slit-lamp microscopy. These findings are primarily distinguished in optics by light scattering. Therefore, detection of the intensity of light scattering due to flare and cells can evaluate the BAB function. The flare-cell photometer comprises 3 novel components: a laser beam system as an incident light, a photomultiplier to detect scattered light intensity and a computer-assisted system to operate the whole system and analyze detected scattered light signals due to flare and cells. The instrument enables us to quantitatively analyze the flare and cells non-invasively and accurately with a wide dynamic measurement range, resulting in a repeated examination of each individual case. It also enables the evaluation of inflammation in the aqueous not only postoperatively but also in endogenous uveitis, evaluation of the effects of anti-inflammatory drugs on BAB and evaluation of aqueous humor dynamics. Furthermore, repeating the examination can minimize inter-individual variations and reduce the number of animals in animal experiments. 3. Sampling of tears can be performed noninvasively, but the obtainable volume is limited. Therefore, a determination of targeting biomarkers and a development of their micro-volume analysis methods play a crucial role in pathophysiological studies of the ocular surface. Targeting biomarkers should be determined according to the various specified bioactive substances such as eosinophil cationic protein (ECP), cytokines and others. A number of microvolume analysis methods, such as chemiluminescent enzyme immunoassay, immunochromatography, micro-array system and polymerase chain reaction method are used. Objective disorders in the studies include allergic conjunctivitis and infectious diseases such as herpetic keratitis. Quantitative evaluation methods for ECP concentration, antigen-specific secretory IgA in allergic diseases and herpetic keratitis, herpes simplex virus-DNA and cytokine and chemokine profile in tear fluid sampled by filter paper method were investigated. We developed a clinically applicable quantitative immunochemical method for ECP concentration in tear fluid. The results revealed that tear fluid analysis using the above mentioned methods is a clinically useful to investigate the pathophysiology of the ocular surface. 4. Laser flare-cell photometer and tear fluid analysis are potent clinical quantitative methods to investigate the pathophysiology of the anterior segment of the eye.

Apparatus for measuring particle properties

DOEpatents

Rader, Daniel J.; Castaneda, Jaime N.; Grasser, Thomas W.; Brockmann, John E.

1998-01-01

An apparatus for determining particle properties from detected light scattered by the particles. The apparatus uses a light beam with novel intensity characteristics to discriminate between particles that pass through the beam and those that pass through an edge of the beam. The apparatus can also discriminate between light scattered by one particle and light scattered by multiple particles. The particle's size can be determined from the intensity of the light scattered. The particle's velocity can be determined from the elapsed time between various intensities of the light scattered.

Hyperspectral imaging with laser-scanning sum-frequency generation microscopy

PubMed Central

Hanninen, Adam; Shu, Ming Wai; Potma, Eric O.

2017-01-01

Vibrationally sensitive sum-frequency generation (SFG) microscopy is a chemically selective imaging technique sensitive to non-centrosymmetric molecular arrangements in biological samples. The routine use of SFG microscopy has been hampered by the difficulty of integrating the required mid-infrared excitation light into a conventional, laser-scanning nonlinear optical (NLO) microscope. In this work, we describe minor modifications to a regular laser-scanning microscope to accommodate SFG microscopy as an imaging modality. We achieve vibrationally sensitive SFG imaging of biological samples with sub-μm resolution at image acquisition rates of 1 frame/s, almost two orders of magnitude faster than attained with previous point-scanning SFG microscopes. Using the fast scanning capability, we demonstrate hyperspectral SFG imaging in the CH-stretching vibrational range and point out its use in the study of molecular orientation and arrangement in biologically relevant samples. We also show multimodal imaging by combining SFG microscopy with second-harmonic generation (SHG) and coherent anti-Stokes Raman scattering (CARS) on the same imaging platfrom. This development underlines that SFG microscopy is a unique modality with a spatial resolution and image acquisition time comparable to that of other NLO imaging techniques, making point-scanning SFG microscopy a valuable member of the NLO imaging family. PMID:28966861

Scatter Measurements Made With Ultraviolet Light

NASA Astrophysics Data System (ADS)

Anthon, Erik W.

1985-09-01

The quality of optical surfaces is generally evaluated by how much light (normally visible light) is scattered by the surface. Most optical glasses and many coating materials are completely opaque to ultraviolet light (253.7 nm). Ultraviolet light tends to scatter much more than visible light. Scatter measurements made with ultraviolet light are therefore very sensitive and the scatter from second surfaces and from the interior (bulk) of the optical material is eliminated by the opacity. A novel scattermeter that operates with ultraviolet light has been developed. The construction and operation of this scattermeter will be described. Cleaning soon becomes the limiting factor when measuring the surfaces with very low level of scatter. Sensitivity to repeated cleaning has been investigated. Different surfaces are compared and uniformity of surfaces is measured by mapping a surface area with an x-y stage. Polished glass surfaces generally have much higher scatter than natural glass surfaces (fire polished, drawn or floated surfaces). Very low scatter levels have been found on thin drawn glass.

Red-luminescent europium (III) doped silica nanoshells: synthesis, characterization, and their interaction with HeLa cells

NASA Astrophysics Data System (ADS)

Yang, Jian; Sandoval, Sergio; Alfaro, Jesus G.; Aschemeyer, Sharraya; Liberman, Alex; Martin, David T.; Makale, Milan; Kummel, Andrew C.; Trogler, William C.

2011-06-01

A simple method to fabricate Eu3+ doped silica nanoshells particles with 100 and 200 nm diameters is reported. Amino polystyrene beads were used as templates, and an 8 to 10 nm thick silica gel coating was formed by the sol-gel reaction. After removing the template by calcination, porous dehydrated silica gel nanoshells of uniform size were obtained. The Eu3+ doped silica nanoshells exhibited a red emission at 615 nm on UV excitation. The porous structure of the silica shell wall was characterized by transmission electron microscopy measurements, while particle size and zeta potentials of the particles suspended in aqueous solution were characterized by dynamic light scattering. Two-photon microscopy was used to image the nanoshells after assimilation by HeLa cancer cells.

Cations Modulate Actin Bundle Mechanics, Assembly Dynamics, and Structure.

PubMed

Castaneda, Nicholas; Zheng, Tianyu; Rivera-Jacquez, Hector J; Lee, Hyun-Ju; Hyun, Jaekyung; Balaeff, Alexander; Huo, Qun; Kang, Hyeran

2018-04-12

Actin bundles are key factors in the mechanical support and dynamic reorganization of the cytoskeleton. High concentrations of multivalent counterions promote bundle formation through electrostatic attraction between actin filaments that are negatively charged polyelectrolytes. In this study, we evaluate how physiologically relevant divalent cations affect the mechanical, dynamic, and structural properties of actin bundles. Using a combination of total internal reflection fluorescence microscopy, transmission electron microscopy, and dynamic light scattering, we demonstrate that divalent cations modulate bundle stiffness, length distribution, and lateral growth. Molecular dynamics simulations of an all-atom model of the actin bundle reveal specific actin residues coordinate cation-binding sites that promote the bundle formation. Our work suggests that specific cation interactions may play a fundamental role in the assembly, structure, and mechanical properties of actin bundles.

Image formation of thick three-dimensional objects in differential-interference-contrast microscopy.

PubMed

Trattner, Sigal; Kashdan, Eugene; Feigin, Micha; Sochen, Nir

2014-05-01

The differential-interference-contrast (DIC) microscope is of widespread use in life sciences as it enables noninvasive visualization of transparent objects. The goal of this work is to model the image formation process of thick three-dimensional objects in DIC microscopy. The model is based on the principles of electromagnetic wave propagation and scattering. It simulates light propagation through the components of the DIC microscope to the image plane using a combined geometrical and physical optics approach and replicates the DIC image of the illuminated object. The model is evaluated by comparing simulated images of three-dimensional spherical objects with the recorded images of polystyrene microspheres. Our computer simulations confirm that the model captures the major DIC image characteristics of the simulated object, and it is sensitive to the defocusing effects.

Extremely strong self-assembly of a bimetallic salen complex visualized at the single-molecule level.

PubMed

Salassa, Giovanni; Coenen, Michiel J J; Wezenberg, Sander J; Hendriksen, Bas L M; Speller, Sylvia; Elemans, Johannes A A W; Kleij, Arjan W

2012-04-25

A bis-Zn(salphen) structure shows extremely strong self-assembly both in solution as well as at the solid-liquid interface as evidenced by scanning tunneling microscopy, competitive UV-vis and fluorescence titrations, dynamic light scattering, and transmission electron microscopy. Density functional theory analysis on the Zn(2) complex rationalizes the very high stability of the self-assembled structures provoked by unusual oligomeric (Zn-O)(n) coordination motifs within the assembly. This coordination mode is strikingly different when compared with mononuclear Zn(salphen) analogues that form dimeric structures having a typical Zn(2)O(2) central unit. The high stability of the multinuclear structure therefore holds great promise for the development of stable self-assembled monolayers with potential for new opto-electronic materials.

Synthesis of poly(3-hydroxybutyrate) nanospheres and deposition thereof into porous thin film

NASA Astrophysics Data System (ADS)

Abid, S.; Raza, Z. A.; Rehman, A.

2016-10-01

Polymeric nanostructures have gained importance in medical science as drug delivery carriers due to their biocompatibility and biodegradability. Polyhydroxybutyrate (PHB) is one of the natural biodegradable polymers used to deliver drugs in the form of nano/microcapsules. In this study, solvent evaporation method has been used for the synthesis of PHB nanospheres using poly(vinyl) alcohol (PVA) both as emulsifier and stabilizer. The produced PHB nanospheres were analyzed using dynamic light scattering and scanning electron microscopy. The size of nanospheres decreased whereas the zeta potential increased on increasing the concentration of emulsifier. The PHB nanospheres were then deposited into porous thin film on a glass surface and characterized against bulk PHB film by using atomic force microscopy, contact angle measurement and x-ray diffraction.

Reversible Stabilization of Vesicles: Redox-Responsive Polymer Nanocontainers for Intracellular Delivery.

PubMed

de Vries, Wilke C; Grill, David; Tesch, Matthias; Ricker, Andrea; Nüsse, Harald; Klingauf, Jürgen; Studer, Armido; Gerke, Volker; Ravoo, Bart Jan

2017-08-01

We present the self-assembly of redox-responsive polymer nanocontainers comprising a cyclodextrin vesicle core and a thin reductively cleavable polymer shell anchored via host-guest recognition on the vesicle surface. The nanocontainers are of uniform size, show high stability, and selectively respond to a mild reductive trigger as revealed by dynamic light scattering, transmission electron microscopy, atomic force microscopy, a quantitative thiol assay, and fluorescence spectroscopy. Live cell imaging experiments demonstrate a specific redox-responsive release and cytoplasmic delivery of encapsulated hydrophilic payloads, such as the pH-probe pyranine, and the fungal toxin phalloidin. Our results show the high potential of these stimulus-responsive nanocontainers for cell biological applications requiring a controlled delivery. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical phase conjugation (OPC)-assisted isotropic focusing.

PubMed

Jang, Mooseok; Sentenac, Anne; Yang, Changhuei

2013-04-08

Isotropic optical focusing - the focusing of light with axial confinement that matches its lateral confinement, is important for a broad range of applications. Conventionally, such focusing is achieved by overlapping the focused beams from a pair of opposite-facing microscope objective lenses. However the exacting requirements for the alignment of the objective lenses and the method's relative intolerance to sample turbidity have significantly limited its utility. In this paper, we present an optical phase conjugation (OPC)-assisted isotropic focusing method that can address both challenges. We exploit the time-reversal nature of OPC playback to naturally guarantee the overlap of the two focused beams even when the objective lenses are significantly misaligned (up to 140 microns transversely and 80 microns axially demonstrated). The scattering correction capability of OPC also enabled us to accomplish isotropic focusing through thick scattering samples (demonstrated with samples of ~7 scattering mean free paths). This method can potentially improve 4Pi microscopy and 3D microstructure patterning.

Degradation of Methylammonium Lead Iodide Perovskite Structures through Light and Electron Beam Driven Ion Migration

PubMed Central

2016-01-01

Organometal halide perovskites show promising features for cost-effective application in photovoltaics. The material instability remains a major obstacle to broad application because of the poorly understood degradation pathways. Here, we apply simultaneous luminescence and electron microscopy on perovskites for the first time, allowing us to monitor in situ morphology evolution and optical properties upon perovskite degradation. Interestingly, morphology, photoluminescence (PL), and cathodoluminescence of perovskite samples evolve differently upon degradation driven by electron beam (e-beam) or by light. A transversal electric current generated by a scanning electron beam leads to dramatic changes in PL and tunes the energy band gaps continuously alongside film thinning. In contrast, light-induced degradation results in material decomposition to scattered particles and shows little PL spectral shifts. The differences in degradation can be ascribed to different electric currents that drive ion migration. Moreover, solution-processed perovskite cuboids show heterogeneity in stability which is likely related to crystallinity and morphology. Our results reveal the essential role of ion migration in perovskite degradation and provide potential avenues to rationally enhance the stability of perovskite materials by reducing ion migration while improving morphology and crystallinity. It is worth noting that even moderate e-beam currents (86 pA) and acceleration voltages (10 kV) readily induce significant perovskite degradation and alter their optical properties. Therefore, attention has to be paid while characterizing such materials using scanning electron microscopy or transmission electron microscopy techniques. PMID:26804213

Exploring the feasibility of focusing CW light through a scattering medium into closely spaced twin peaks via numerical solutions of Maxwell’s equations

NASA Astrophysics Data System (ADS)

Tseng, Snow H.; Chang, Shih-Hui

2018-04-01

Here we present a numerical simulation to analyze the effect of scattering on focusing light into closely-spaced twin peaks. The pseudospectral time-domain (PSTD) is implemented to model continuous-wave (CW) light propagation through a scattering medium. Simulations show that CW light can propagate through a scattering medium and focus into closely-spaced twin peaks. CW light of various wavelengths focusing into twin peaks with sub-diffraction spacing is simulated. In advance, light propagation through scattering media of various number densities is simulated to decipher the dependence of CW light focusing phenomenon on the scattering medium. The reported simulations demonstrate the feasibility of focusing CW light into twin peaks with sub-diffraction dimensions. More importantly, based upon numerical solutions of Maxwell’s equations, research findings show that the sub-diffraction focusing phenomenon can be achieved with scarce or densely-packed scattering media.

Asymmetric flow field-flow fractionation (AF4) for the quantification of nanoparticle release from tablets during dissolution testing.

PubMed

Engel, A; Plöger, M; Mulac, D; Langer, K

2014-01-30

Nanoparticles composed of poly(DL-lactide-co-glycolide) (PLGA) represent promising colloidal drug carriers for improved drug targeting. Although most research activities are focused on intravenous application of these carriers the peroral administration is described to improve bioavailability of poorly soluble drugs. Based on these insights the manuscript describes a model tablet formulation for PLGA-nanoparticles and especially its analytical characterisation with regard to a nanosized drug carrier. Besides physico-chemical tablet characterisation according to pharmacopoeias the main goal of the study was the development of a suitable analytical method for the quantification of nanoparticle release from tablets. An analytical flow field-flow fractionation (AF4) method was established and validated which enables determination of nanoparticle content in solid dosage forms as well as quantification of particle release during dissolution testing. For particle detection a multi-angle light scattering (MALS) detector was coupled to the AF4-system. After dissolution testing, the presence of unaltered PLGA-nanoparticles was successfully proved by dynamic light scattering and scanning electron microscopy. Copyright © 2013 Elsevier B.V. All rights reserved.

Interactions between antimicrobial polynorbornenes and phospholipid vesicles monitored by light scattering and microcalorimetry.

PubMed

Gabriel, Gregory J; Pool, Joanna G; Som, Abhigyan; Dabkowski, Jeffrey M; Coughlin, E Bryan; Muthukumar, M; Tew, Gregory N

2008-11-04

Antimicrobial polynorbornenes composed of facially amphiphilic monomers have been previously reported to accurately emulate the antimicrobial activity of natural host-defense peptides (HDPs). The lethal mechanism of most HDPs involves binding to the membrane surface of bacteria leading to compromised phospholipid bilayers. In this paper, the interactions between biomimetic vesicle membranes and these cationic antimicrobial polynorbornenes are reported. Vesicle dye-leakage experiments were consistent with previous biological assays and corroborated a mode of action involving membrane disruption. Dynamic light scattering (DLS) showed that these antimicrobial polymers cause extensive aggregation of vesicles without complete bilayer disintegration as observed with surfactants that efficiently solubilize the membrane. Fluorescence microscopy on vesicles and bacterial cells also showed polymer-induced aggregation of both synthetic vesicles and bacterial cells. Isothermal titration calorimetry (ITC) afforded free energy of binding values (Delta G) and polymer to lipid binding ratios, plus revealed that the interaction is entropically favorable (Delta S>0, Delta H>0). It was observed that the strength of vesicle binding was similar between the active polymers while the binding stoichiometries were dramatically different.

Biological elements carry out optical tasks in coherent imaging systems

NASA Astrophysics Data System (ADS)

Ferraro, P.; Bianco, V.; Paturzo, M.; Miccio, L.; Memmolo, P.; Merola, F.; Marchesano, V.

2016-03-01

We show how biological elements, like live bacteria species and Red Blood Cells (RBCs) can accomplish optical functionalities in DH systems. Turbid media allow coherent microscopy despite the strong light scattering these provoke, acting on light just as moving diffusers. Furthermore, a turbid medium can have positive effects on a coherent imaging system, providing resolution enhancement and mimicking the action of noise decorrelation devices, thus yielding an image quality significantly higher than the quality achievable through a transparent medium in similar recording conditions. Besides, suspended RBCs are demonstrated to behave as controllable liquid micro-lenses, opening new possibilities in biophotonics for endoscopy imaging purposes, as well as telemedicine for point-of-care diagnostics in developing countries and low-resource settings.

Apparatus for measuring particle properties

DOEpatents

Rader, D.J.; Castaneda, J.N.; Grasser, T.W.; Brockmann, J.E.

1998-08-11

An apparatus is described for determining particle properties from detected light scattered by the particles. The apparatus uses a light beam with novel intensity characteristics to discriminate between particles that pass through the beam and those that pass through an edge of the beam. The apparatus can also discriminate between light scattered by one particle and light scattered by multiple particles. The particle`s size can be determined from the intensity of the light scattered. The particle`s velocity can be determined from the elapsed time between various intensities of the light scattered. 11 figs.

Evaluation of paraxial forward scattering from intraocular lens with increased surface light scattering using goniophotometry and Hartmann-Shack wavefront aberrometry.

PubMed

Minami, Keiichiro; Maruyama, Yoko; Mihashi, Toshifumi; Miyata, Kazunori; Oshika, Tetsuro

2017-03-01

To evaluate the influence of increases in light scattering on intraocular lens (IOL) surfaces on paraxial forward scattering using goniophotometry and Hartmann-Shack wavefront aberrometry. Surface light scattering was reproduced experimentally by acceleratedly aging 4 intraocular lenses by 0, 3, 5, and 10 years each. Light scattering from both IOL surfaces was measured using Scheimpflug photography. The paraxial forward scattering from the aged IOLs was measured using a goniophotometer with a halogen light source (wavelength: 350-850 nm) and telecentric optics, and changes in the maximum intensity and full width at 10% of maximum intensity (FW10%) were evaluated. The influences on the retina image were examined using a Hartmann-Shack aberrometer (wavelength: 840 nm). The contrast and difference from the point spread function of the central centroids were evaluated. The mean surface light scattering from both IOL surfaces ranged from 30.0 to 118.3 computer compatible tape (CCT) and increased with each aging year. Evaluations using the goniophotometer and the Hartmann-Shack aberrometer showed no significant change in the paraxial forward scattering with the aging year (P > .45, Kruskal-Wallis test), and no association with the surface light scattering intensity was found (P > .75, Spearman rank correlation). This experimental study using aged IOLs demonstrated that surface light scattering does not influence paraxial forward scattering.

Synthesis and characterization of PEG-P(MAA-SS-VCL) nanoparticles

NASA Astrophysics Data System (ADS)

Yu, L. L.; Yang, K.; Mu, R. H.; Zhang, N.; Su, L.

2016-07-01

The PEG-P(MAA-SS-VCL) nanoparticles were obtained using disulfide containing dimethacrylate (SS) as cross-linking agent, using polyethylene glycol methyl acrylate (PEGMA), N-Vinyl-ε-caprolactam (VCL), and methacrylic acid (MAA) as monomers via homogeneous polymerization in aqueous. The PEG-P(MAA-SS-VCL) nanoparticles were characterized by FT-IR and TGA. The particle size and morphology variation in different environments were detected by dynamic light scattering (DLS) and scanning electron microscopy (SEM). It is the very method that PEG-P(MAA-SS-VCL) nanoparticles can be obtained in this study.

Holographic Characterization of Colloidal Fractal Aggregates

NASA Astrophysics Data System (ADS)

Wang, Chen; Cheong, Fook Chiong; Ruffner, David B.; Zhong, Xiao; Ward, Michael D.; Grier, David G.

In-line holographic microscopy images of micrometer-scale fractal aggregates can be interpreted with the Lorenz-Mie theory of light scattering and an effective-sphere model to obtain each aggregate's size and the population-averaged fractal dimension. We demonstrate this technique experimentally using model fractal clusters of polystyrene nanoparticles and fractal protein aggregates composed of bovine serum albumin and bovine pancreas insulin. This technique can characterize several thousand aggregates in ten minutes and naturally distinguishes aggregates from contaminants such as silicone oil droplets. Work supported by the SBIR program of the NSF.

Structure, transport and photoconductance of PbS quantum dot monolayers functionalized with a copper phthalocyanine derivative.

PubMed

André, A; Theurer, C; Lauth, J; Maiti, S; Hodas, M; Samadi Khoshkhoo, M; Kinge, S; Meixner, A J; Schreiber, F; Siebbeles, L D A; Braun, K; Scheele, M

2017-01-31

We simultaneously surface-functionalize PbS nanocrystals with Cu 4,4',4'',4'''-tetraaminophthalocyanine and assemble this hybrid material into macroscopic monolayers. Electron microscopy and X-ray scattering reveal a granular mesocrystalline structure with strong coherence between the atomic lattice and the superlattice of nanocrystals within each domain. Terahertz spectroscopy and field-effect transistor measurements indicate efficient coupling of holes throughout the hybrid thin film, in conjunction with a pronounced photoresponse. We demonstrate the potential of this material for optoelectronic applications by fabricating a light-effect transistor.

Confocal three dimensional tracking of a single nanoparticle with concurrent spectroscopic readouts

NASA Astrophysics Data System (ADS)

Cang, Hu; Wong, Chung M.; Xu, C. Shan; Rizvi, Abbas H.; Yang, Haw

2006-05-01

We present an apparatus that noninvasively tracks a moving nanoparticle in three dimensions while providing concurrent sequential spectroscopic measurements. The design, based on confocal microscopy, uses a near-infrared laser and a dark-field condenser for illumination of a gold nanoparticle. By monitoring the scattered light from the nanoparticle and using a piezoelectric stage, the system was able to continuously bring the diffusive particle in a glycerol/water solution back to the focal volume with spatial resolution and response time of less than 210nm and a millisecond, respectively.

Bio-sensing with butterfly wings: naturally occurring nano-structures for SERS-based malaria parasite detection.

PubMed

Garrett, Natalie L; Sekine, Ryo; Dixon, Matthew W A; Tilley, Leann; Bambery, Keith R; Wood, Bayden R

2015-09-07

Surface enhanced Raman scattering (SERS) is a powerful tool with great potential to provide improved bio-sensing capabilities. The current 'gold-standard' method for diagnosis of malaria involves visual inspection of blood smears using light microscopy, which is time consuming and can prevent early diagnosis of the disease. We present a novel surface-enhanced Raman spectroscopy substrate based on gold-coated butterfly wings, which enabled detection of malarial hemozoin pigment within lysed blood samples containing 0.005% and 0.0005% infected red blood cells.

Laser Light Scattering with Multiple Scattering Suppression Used to Measure Particle Sizes

NASA Technical Reports Server (NTRS)

Meyer, William V.; Tin, Padetha; Lock, James A.; Cannell, David S.; Smart, Anthony E.; Taylor, Thomas W.

1999-01-01

Laser light scattering is the technique of choice for noninvasively sizing particles in a fluid. The members of the Advanced Technology Development (ATD) project in laser light scattering at the NASA Lewis Research Center have invented, tested, and recently enhanced a simple and elegant way to extend the concentration range of this standard laboratory particle-sizing technique by several orders of magnitude. With this technique, particles from 3 nm to 3 mm can be measured in a solution. Recently, laser light scattering evolved to successfully size particles in both clear solutions and concentrated milky-white solutions. The enhanced technique uses the property of light that causes it to form tall interference patterns at right angles to the scattering plane (perpendicular to the laser beam) when it is scattered from a narrow laser beam. Such multiple-scattered light forms a broad fuzzy halo around the focused beam, which, in turn, forms short interference patterns. By placing two fiber optics on top of each other and perpendicular to the laser beam (see the drawing), and then cross-correlating the signals they produce, only the tall interference patterns formed by singly scattered light are detected. To restate this, unless the two fiber optics see the same interference pattern, the scattered light is not incorporated into the signal. With this technique, only singly scattered light is seen (multiple-scattered light is rejected) because only singly scattered light has an interference pattern tall enough to span both of the fiber-optic pickups. This technique is simple to use, easy to align, and works at any angle. Placing a vertical slit in front of the signal collection fibers enhanced this approach. The slit serves as an optical mask, and it significantly shortens the time needed to collect good data by selectively masking out much of the unwanted light before cross-correlation is applied.

Nonlinear adaptive optics: aberration correction in three photon fluorescence microscopy for mouse brain imaging

NASA Astrophysics Data System (ADS)

Sinefeld, David; Paudel, Hari P.; Wang, Tianyu; Wang, Mengran; Ouzounov, Dimitre G.; Bifano, Thomas G.; Xu, Chris

2017-02-01

Multiphoton fluorescence microscopy is a well-established technique for deep-tissue imaging with subcellular resolution. Three-photon microscopy (3PM) when combined with long wavelength excitation was shown to allow deeper imaging than two-photon microscopy (2PM) in biological tissues, such as mouse brain, because out-of-focus background light can be further reduced due to the higher order nonlinear excitation. As was demonstrated in 2PM systems, imaging depth and resolution can be improved by aberration correction using adaptive optics (AO) techniques which are based on shaping the scanning beam using a spatial light modulator (SLM). In this way, it is possible to compensate for tissue low order aberration and to some extent, to compensate for tissue scattering. Here, we present a 3PM AO microscopy system for brain imaging. Soliton self-frequency shift is used to create a femtosecond source at 1675 nm and a microelectromechanical (MEMS) SLM serves as the wavefront shaping device. We perturb the 1020 segment SLM using a modified nonlinear version of three-point phase shifting interferometry. The nonlinearity of the fluorescence signal used for feedback ensures that the signal is increasing when the spot size decreases, allowing compensation of phase errors in an iterative optimization process without direct phase measurement. We compare the performance for different orders of nonlinear feedback, showing an exponential growth in signal improvement as the nonlinear order increases. We demonstrate the impact of the method by applying the 3PM AO system for in-vivo mouse brain imaging, showing improvement in signal at 1-mm depth inside the brain.

Brillouin microscopy: assessing ocular tissue biomechanics.

PubMed

Yun, Seok Hyun; Chernyak, Dimitri

2018-07-01

Assessment of corneal biomechanics has been an unmet clinical need in ophthalmology for many years. Many researchers and clinicians have identified corneal biomechanics as source of variability in refractive procedures and one of the main factors in keratoconus. However, it has been difficult to accurately characterize corneal biomechanics in patients. The recent development of Brillouin light scattering microscopy heightens the promise of bringing biomechanics into the clinic. The aim of this review is to overview the progress and discuss prospective applications of this new technology. Brillouin microscopy uses a low-power near-infrared laser beam to determine longitudinal modulus or mechanical compressibility of tissue by analyzing the return signal spectrum. Human clinical studies have demonstrated significant difference in the elastic properties of normal corneas versus corneas diagnosed with mild and severe keratoconus. Clinical data have also shown biomechanical changes after corneal cross-linking treatment of keratoconus patients. Brillouin measurements of the crystalline lens and sclera have also been demonstrated. Brillouin microscopy is a promising technology under commercial development at present. The technique enables physicians to characterize the biomechanical properties of ocular tissues.

Super Resolution Imaging of Genetically Labeled Synapses in Drosophila Brain Tissue

PubMed Central

Spühler, Isabelle A.; Conley, Gaurasundar M.; Scheffold, Frank; Sprecher, Simon G.

2016-01-01

Understanding synaptic connectivity and plasticity within brain circuits and their relationship to learning and behavior is a fundamental quest in neuroscience. Visualizing the fine details of synapses using optical microscopy remains however a major technical challenge. Super resolution microscopy opens the possibility to reveal molecular features of synapses beyond the diffraction limit. With direct stochastic optical reconstruction microscopy, dSTORM, we image synaptic proteins in the brain tissue of the fruit fly, Drosophila melanogaster. Super resolution imaging of brain tissue harbors difficulties due to light scattering and the density of signals. In order to reduce out of focus signal, we take advantage of the genetic tools available in the Drosophila and have fluorescently tagged synaptic proteins expressed in only a small number of neurons. These neurons form synapses within the calyx of the mushroom body, a distinct brain region involved in associative memory formation. Our results show that super resolution microscopy, in combination with genetically labeled synaptic proteins, is a powerful tool to investigate synapses in a quantitative fashion providing an entry point for studies on synaptic plasticity during learning and memory formation. PMID:27303270

Super Resolution Imaging of Genetically Labeled Synapses in Drosophila Brain Tissue.

PubMed

Spühler, Isabelle A; Conley, Gaurasundar M; Scheffold, Frank; Sprecher, Simon G

2016-01-01

Understanding synaptic connectivity and plasticity within brain circuits and their relationship to learning and behavior is a fundamental quest in neuroscience. Visualizing the fine details of synapses using optical microscopy remains however a major technical challenge. Super resolution microscopy opens the possibility to reveal molecular features of synapses beyond the diffraction limit. With direct stochastic optical reconstruction microscopy, dSTORM, we image synaptic proteins in the brain tissue of the fruit fly, Drosophila melanogaster. Super resolution imaging of brain tissue harbors difficulties due to light scattering and the density of signals. In order to reduce out of focus signal, we take advantage of the genetic tools available in the Drosophila and have fluorescently tagged synaptic proteins expressed in only a small number of neurons. These neurons form synapses within the calyx of the mushroom body, a distinct brain region involved in associative memory formation. Our results show that super resolution microscopy, in combination with genetically labeled synaptic proteins, is a powerful tool to investigate synapses in a quantitative fashion providing an entry point for studies on synaptic plasticity during learning and memory formation.

Bandgap Inhomogeneity of a PbSe Quantum Dot Ensemble from Two-Dimensional Spectroscopy and Comparison to Size Inhomogeneity from Electron Microscopy

DOE PAGES

Park, Samuel D.; Baranov, Dmitry; Ryu, Jisu; ...

2017-01-03

Femtosecond two-dimensional Fourier transform spectroscopy is used to determine the static bandgap inhomogeneity of a colloidal quantum dot ensemble. The excited states of quantum dots absorb light, so their absorptive two-dimensional (2D) spectra will typically have positive and negative peaks. We show that the absorption bandgap inhomogeneity is robustly determined by the slope of the nodal line separating positive and negative peaks in the 2D spectrum around the bandgap transition; this nodal line slope is independent of excited state parameters not known from the absorption and emission spectra. The absorption bandgap inhomogeneity is compared to a size and shape distributionmore » determined by electron microscopy. The electron microscopy images are analyzed using new 2D histograms that correlate major and minor image projections to reveal elongated nanocrystals, a conclusion supported by grazing incidence small-angle X-ray scattering and high-resolution transmission electron microscopy. Lastly, the absorption bandgap inhomogeneity quantitatively agrees with the bandgap variations calculated from the size and shape distribution, placing upper bounds on any surface contributions.« less

Bacterial Identification Using Light Scattering Measurements: a Preliminary Report

NASA Technical Reports Server (NTRS)

Wilkins, J. R.

1971-01-01

The light scattering properties of single bacterial cells were examined as a possible means of identification. Three species were studied with streptococcus faecalis exhibiting a unique pattern; the light-scattering traces for staphylococcus aureus and escherichia coli were quite similar although differences existed. Based on preliminary investigations, the light scattering approach appeared promising with additional research needed to include a wide variety of bacterial species, computer capability to handle and analyze data, and expansion of light scattering theory to include bacterial cells.

Scattering theory of stochastic electromagnetic light waves.

PubMed

Wang, Tao; Zhao, Daomu

2010-07-15

We generalize scattering theory to stochastic electromagnetic light waves. It is shown that when a stochastic electromagnetic light wave is scattered from a medium, the properties of the scattered field can be characterized by a 3 x 3 cross-spectral density matrix. An example of scattering of a spatially coherent electromagnetic light wave from a deterministic medium is discussed. Some interesting phenomena emerge, including the changes of the spectral degree of coherence and of the spectral degree of polarization of the scattered field.

Resolution enhancement in deep-tissue nanoparticle imaging based on plasmonic saturated excitation microscopy

NASA Astrophysics Data System (ADS)

Deka, Gitanjal; Nishida, Kentaro; Mochizuki, Kentaro; Ding, Hou-Xian; Fujita, Katsumasa; Chu, Shi-Wei

2018-03-01

Recently, many resolution enhancing techniques are demonstrated, but most of them are severely limited for deep tissue applications. For example, wide-field based localization techniques lack the ability of optical sectioning, and structured light based techniques are susceptible to beam distortion due to scattering/aberration. Saturated excitation (SAX) microscopy, which relies on temporal modulation that is less affected when penetrating into tissues, should be the best candidate for deep-tissue resolution enhancement. Nevertheless, although fluorescence saturation has been successfully adopted in SAX, it is limited by photobleaching, and its practical resolution enhancement is less than two-fold. Recently, we demonstrated plasmonic SAX which provides bleaching-free imaging with three-fold resolution enhancement. Here we show that the three-fold resolution enhancement is sustained throughout the whole working distance of an objective, i.e., 200 μm, which is the deepest super-resolution record to our knowledge, and is expected to extend into deeper tissues. In addition, SAX offers the advantage of background-free imaging by rejecting unwanted scattering background from biological tissues. This study provides an inspirational direction toward deep-tissue super-resolution imaging and has the potential in tumor monitoring and beyond.

Photovoltaic Performance Characterization of Textured Silicon Solar Cells Using Luminescent Down-Shifting Eu-Doped Phosphor Particles of Various Dimensions.

PubMed

Ho, Wen-Jeng; Deng, Yu-Jie; Liu, Jheng-Jie; Feng, Sheng-Kai; Lin, Jian-Cheng

2017-01-01

This paper reports on efforts to enhance the photovoltaic performance of textured silicon solar cells through the application of a layer of Eu-doped silicate phosphor with particles of various dimensions using the spin-on film technique. We examined the surface profile and dimensions of the Eu-doped phosphors in the silicate layer using optical microscopy with J-image software. Optical reflectance, photoluminescence, and external quantum efficiency were used to characterize the luminescent downshifting (LDS) and light scattering of the Eu-doped silicate phosphor layer. Current density-voltage curves under AM 1.5G simulation were used to confirm the contribution of LDS and light scattering produced by phosphor particles of various dimensions. Experiment results reveal that smaller phosphor particles have a more pronounced effect on LDS and a slight shading of incident light. The application of small Eu-doped phosphor particles increased the conversion efficiency by 9.2% (from 12.56% to 13.86%), far exceeding the 5.6% improvement (from 12.54% to 13.32%) achieved by applying a 250 nm layer of SiO₂ and the 4.5% improvement (from 12.37% to 12.98%) observed in cells with large Eu-doped phosphor particles.

Photovoltaic Performance Characterization of Textured Silicon Solar Cells Using Luminescent Down-Shifting Eu-Doped Phosphor Particles of Various Dimensions

PubMed Central

Ho, Wen-Jeng; Deng, Yu-Jie; Liu, Jheng-Jie; Feng, Sheng-Kai; Lin, Jian-Cheng

2017-01-01

This paper reports on efforts to enhance the photovoltaic performance of textured silicon solar cells through the application of a layer of Eu-doped silicate phosphor with particles of various dimensions using the spin-on film technique. We examined the surface profile and dimensions of the Eu-doped phosphors in the silicate layer using optical microscopy with J-image software. Optical reflectance, photoluminescence, and external quantum efficiency were used to characterize the luminescent downshifting (LDS) and light scattering of the Eu-doped silicate phosphor layer. Current density-voltage curves under AM 1.5G simulation were used to confirm the contribution of LDS and light scattering produced by phosphor particles of various dimensions. Experiment results reveal that smaller phosphor particles have a more pronounced effect on LDS and a slight shading of incident light. The application of small Eu-doped phosphor particles increased the conversion efficiency by 9.2% (from 12.56% to 13.86%), far exceeding the 5.6% improvement (from 12.54% to 13.32%) achieved by applying a 250 nm layer of SiO2 and the 4.5% improvement (from 12.37% to 12.98%) observed in cells with large Eu-doped phosphor particles. PMID:28772384

Raman spectroscopy for cancer detection and characterization in metastasis models

NASA Astrophysics Data System (ADS)

Koga, Shigehiro; Oshima, Yusuke; Sato, Mitsunori; Ishimaru, Kei; Yoshida, Motohira; Yamamoto, Yuji; Matsuno, Yusuke; Watanabe, Yuji

2017-02-01

Raman spectroscopy provides a wealth of diagnostic information to the surgeon with in situ cancer detection and label-free histopathology in clinical practice. Raman spectroscopy is a developing optical technique which can analyze biological tissues with light scattering. The difference in frequencies between the incident light and the scattering light are called Raman shifts, which correspond to the vibrational energy of the molecular bonds. Raman spectrum gives information about the molecular structure and composition in biological specimens. We had been previously reported that Raman spectroscopy could distinguish various histological types of human lung cancer cells from normal cells in vitro. However, to identify and detect cancer diagnostic biomarkers in vivo on Raman spectroscopy is still challenging, because malignancy can be characterized not only by the cancer cells but also by the environmental factors including immune cells, stroma cells, secretion vesicles and extracellular matrix. Here we investigate morphological and molecular dynamics in both cancer cells and their environment in xenograft models and spontaneous metastasis models using Raman spectroscopy combined with fluorescence microscopy and photoluminescence imaging. We are also constructing a custom-designed Raman spectral imaging system for both in vitro and in vivo assay of tumor tissues to reveal the metastasis process and to evaluate therapeutic effects of anti-cancer drugs and their drug delivery toward the clinical application of the technique.

[Comparison of surface light scattering of acrylic intraocular lenses made by lathe-cutting and cast-molding methods--long-term observation and experimental study].

PubMed

Nishihara, Hitoshi; Ayaki, Masahiko; Watanabe, Tomiko; Ohnishi, Takeo; Kageyama, Toshiyuki; Yaguchi, Shigeo

2004-03-01

To compare the long-term clinical and experimental results of soft acrylic intraocular lenses(IOLs) manufactured by the lathe-cut(LC) method and by the cast-molding(CM) method. This was a retrospective study of 20 patients(22 eyes) who were examined in a 5- and 7-year follow-up study. Sixteen eyes were implanted with polyacrylic IOLs manufactured by the LC method and 6 eyes were implanted with polyacrylic IOLs manufactured by the CM method. Postoperative measurements included best corrected visual acuity, contrast sensitivity, biomicroscopic examination, and Scheimpflug slit-lamp images to evaluate surface light scattering. Scanning electron microscopy and three-dimensional surface analysis were conducted. At 7 years, the mean visual acuity was 1.08 +/- 0.24 (mean +/- standard deviation) in the LC group and 1.22 +/- 0.27 in the CM group. Surface light-seatter was 12.0 +/- 4.0 computer compatible tapes(CCT) in the LC group and 37.4 +/- 5.4 CCT in the CM group. Mean surface roughness was 0.70 +/- 0.07 nm in the LC group and 6.16 +/- 0.97 nm in the CM group. Acrylic IOLs manufactured by the LC method are more stable in long-termuse.

Anisotropic light scattering of individual sickle red blood cells.

PubMed

Kim, Youngchan; Higgins, John M; Dasari, Ramachandra R; Suresh, Subra; Park, YongKeun

2012-04-01

We present the anisotropic light scattering of individual red blood cells (RBCs) from a patient with sickle cell disease (SCD). To measure light scattering spectra along two independent axes of elongated-shaped sickle RBCs with arbitrary orientation, we introduce the anisotropic Fourier transform light scattering (aFTLS) technique and measured both the static and dynamic anisotropic light scattering. We observed strong anisotropy in light scattering patterns of elongated-shaped sickle RBCs along its major axes using static aFTLS. Dynamic aFTLS analysis reveals the significantly altered biophysical properties in individual sickle RBCs. These results provide evidence that effective viscosity and elasticity of sickle RBCs are significantly different from those of the healthy RBCs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alekseev, A E; Potapov, V T; Gorshkov, B G

We report the results of studying statistical properties of the intensity of partially polarised coherent light backscattered by a single mode optical fibre. An expression is derived for the deviation of the backscattered light intensity depending on the scattering region length, the degree of the light source coherence and the degree of scattered light polarisation. It is shown that the backscattered light in a fibre scattered-light interferometer is partially polarised with the polarisation degree P = 1/3 in the case of external perturbations of the interferometer fibre. (scattering of light)

A study of the polarization of light scattered by vegetation. M.S. Thesis

NASA Technical Reports Server (NTRS)

Woessner, P. N.

1985-01-01

This study was undertaken in order to better understand the factors that govern the polarization of light scattered from vegetation and soils. The intensity and polarization of light scattered by clover and grass in vivo and soil were measured at a number of different angles of incidence and reflectance. Both individual leaves and natural patches of leaves were measured. The light transmitted through the leaves was found to be negatively polarized. The light scattered from the upper leaf surface was found to be positively polarized in a manner which could be accounted for qualitatively but not quantitatively by the Fresnel reflection coefficients modified by a shadowing function of the form cos sup2 (g/2), where g is the phase angle. Findings indicate that the polarization of light scattered by vegetation is a more complex process than previously thought, and that besides the surface-scattered component of light, the volume-scattered and multiply-scattered components also contribute significantly to the polarization.

Coherent imaging with incoherent light in digital holographic microscopy

NASA Astrophysics Data System (ADS)

Chmelik, Radim

2012-01-01

Digital holographic microscope (DHM) allows for imaging with a quantitative phase contrast. In this way it becomes an important instrument, a completely non-invasive tool for a contrast intravital observation of living cells and a cell drymass density distribution measurement. A serious drawback of current DHMs is highly coherent illumination which makes the lateral resolution worse and impairs the image quality by a coherence noise and a parasitic interference. An uncompromising solution to this problem can be found in the Leith concept of incoherent holography. An off-axis hologram can be formed with arbitrary degree of light coherence in systems equipped with an achromatic interferometer and thus the resolution and the image quality typical for an incoherent-light wide-field microscopy can be achieved. In addition, advanced imaging modes based on limited coherence can be utilized. The typical example is a coherence-gating effect which provides a finite axial resolution and makes DHM image similar to that of a confocal microscope. These possibilities were described theoretically using the formalism of three-dimensional coherent transfer functions and proved experimentally by the coherence-controlled holographic microscope which is DHM based on the Leith achromatic interferometer. Quantitative-phase-contrast imaging is demonstrated with incoherent light by the living cancer cells observation and their motility evaluation. The coherence-gating effect was proved by imaging of model samples through a scattering layer and living cells inside an opalescent medium.

Narrowly peaked forward light scattering on particulate media: II. Angular spreading of light scattered by polystyrene microspheres

NASA Astrophysics Data System (ADS)

Turcu, Ioan; Bratfalean, Radu; Neamtu, Silvia

2008-07-01

The adequacy of the effective phase function (EPF) used to describe the light scattered at small angles was tested on aqueous suspensions of polystyrene microspheres. Angular resolved light scattering measurements were performed on two types of latex suspension, which contained polystyrene spheres of 3 µm and 5 µm diameters, respectively. The experimental data were fitted with two EPF approximants. If the polystyrene spheres are at least 3 µm in diameter the quasi-ballistic light scattering process can be described relatively well by the EPF in a small angular range centered in the forward direction. The forward light scattering by macroscopic samples containing microspheres can be modeled relatively well if the true Mie single particle scattering phase function is replaced by a simpler Henyey-Greenstein dependence having the same width at half-height as the first scattering lobe.

A study on independently using static and dynamic light scattering methods to determine the coagulation rate

NASA Astrophysics Data System (ADS)

Zhou, Hongwei; Xu, Shenghua; Mi, Li; Sun, Zhiwei; Qin, Yanming

2014-09-01

Absolute coagulation rate constants were determined by independently, instead of simultaneously, using static and dynamic light scattering with the requested optical factors calculated by T-matrix method. The aggregating suspensions of latex particles with diameters of 500, 700, and 900 nm, that are all beyond validity limit of the traditional Rayleigh-Debye-Gans approximation, were adopted. The results from independent static and dynamic light scattering measurements were compared with those by simultaneously using static and dynamic light scattering; and three of them show good consistency. We found, theoretically and experimentally, that for independent static light scattering measurements there are blind scattering angles at that the scattering measurements become impossible and the number of blind angles increases rapidly with particle size. For independent dynamic light scattering measurements, however, there is no such a blind angle at all. A possible explanation of the observed phenomena is also presented.

Instrumentation on Multi-Scaled Scattering of Bio-Macromolecular Solutions

PubMed Central

Chu, Benjamin; Fang, Dufei; Mao, Yimin

2015-01-01

The design, construction and initial tests on a combined laser light scattering and synchrotron X-ray scattering instrument can cover studies of length scales from atomic sizes in Angstroms to microns and dynamics from microseconds to seconds are presented. In addition to static light scattering (SLS), dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and wide angle X-ray diffraction (WAXD), the light scattering instrument is being developed to carry out studies in mildly turbid solutions, in the presence of multiple scattering. Three-dimensional photon cross correlation function (3D-PCCF) measurements have been introduced to couple with synchrotron X-ray scattering to study the structure, size and dynamics of macromolecules in solution. PMID:25946340

Multimodal Spectral Imaging of Cells Using a Transmission Diffraction Grating on a Light Microscope

PubMed Central

Isailovic, Dragan; Xu, Yang; Copus, Tyler; Saraswat, Suraj; Nauli, Surya M.

2011-01-01

A multimodal methodology for spectral imaging of cells is presented. The spectral imaging setup uses a transmission diffraction grating on a light microscope to concurrently record spectral images of cells and cellular organelles by fluorescence, darkfield, brightfield, and differential interference contrast (DIC) spectral microscopy. Initially, the setup was applied for fluorescence spectral imaging of yeast and mammalian cells labeled with multiple fluorophores. Fluorescence signals originating from fluorescently labeled biomolecules in cells were collected through triple or single filter cubes, separated by the grating, and imaged using a charge-coupled device (CCD) camera. Cellular components such as nuclei, cytoskeleton, and mitochondria were spatially separated by the fluorescence spectra of the fluorophores present in them, providing detailed multi-colored spectral images of cells. Additionally, the grating-based spectral microscope enabled measurement of scattering and absorption spectra of unlabeled cells and stained tissue sections using darkfield and brightfield or DIC spectral microscopy, respectively. The presented spectral imaging methodology provides a readily affordable approach for multimodal spectral characterization of biological cells and other specimens. PMID:21639978

Three dimensional HiLo-based structured illumination for a digital scanned laser sheet microscopy (DSLM) in thick tissue imaging

PubMed Central

Bhattacharya, Dipanjan; Singh, Vijay Raj; Zhi, Chen; So, Peter T. C.; Matsudaira, Paul; Barbastathis, George

2012-01-01

Laser sheet based microscopy has become widely accepted as an effective active illumination method for real time three-dimensional (3D) imaging of biological tissue samples. The light sheet geometry, where the camera is oriented perpendicular to the sheet itself, provides an effective method of eliminating some of the scattered light and minimizing the sample exposure to radiation. However, residual background noise still remains, limiting the contrast and visibility of potentially interesting features in the samples. In this article, we investigate additional structuring of the illumination for improved background rejection, and propose a new technique, “3D HiLo” where we combine two HiLo images processed from orthogonal directions to improve the condition of the 3D reconstruction. We present a comparative study of conventional structured illumination based demodulation methods, namely 3Phase and HiLo with a newly implemented 3D HiLo approach and demonstrate that the latter yields superior signal-to-background ratio in both lateral and axial dimensions, while simultaneously suppressing image processing artifacts. PMID:23262684

Three dimensional HiLo-based structured illumination for a digital scanned laser sheet microscopy (DSLM) in thick tissue imaging.

PubMed

Bhattacharya, Dipanjan; Singh, Vijay Raj; Zhi, Chen; So, Peter T C; Matsudaira, Paul; Barbastathis, George

2012-12-03

Laser sheet based microscopy has become widely accepted as an effective active illumination method for real time three-dimensional (3D) imaging of biological tissue samples. The light sheet geometry, where the camera is oriented perpendicular to the sheet itself, provides an effective method of eliminating some of the scattered light and minimizing the sample exposure to radiation. However, residual background noise still remains, limiting the contrast and visibility of potentially interesting features in the samples. In this article, we investigate additional structuring of the illumination for improved background rejection, and propose a new technique, "3D HiLo" where we combine two HiLo images processed from orthogonal directions to improve the condition of the 3D reconstruction. We present a comparative study of conventional structured illumination based demodulation methods, namely 3Phase and HiLo with a newly implemented 3D HiLo approach and demonstrate that the latter yields superior signal-to-background ratio in both lateral and axial dimensions, while simultaneously suppressing image processing artifacts.

Dual-slit confocal light sheet microscopy for in vivo whole-brain imaging of zebrafish

PubMed Central

Yang, Zhe; Mei, Li; Xia, Fei; Luo, Qingming; Fu, Ling; Gong, Hui

2015-01-01

In vivo functional imaging at single-neuron resolution is an important approach to visualize biological processes in neuroscience. Light sheet microscopy (LSM) is a cutting edge in vivo imaging technique that provides micron-scale spatial resolution at high frame rate. Due to the scattering and absorption of tissue, however, conventional LSM is inadequate to resolve cells because of the attenuated signal to noise ratio (SNR). Using dual-beam illumination and confocal dual-slit detection, here a dual-slit confocal LSM is demonstrated to obtain the SNR enhanced images with frame rate twice as high as line confocal LSM method. Through theoretical calculations and experiments, the correlation between the slit’s width and SNR was determined to optimize the image quality. In vivo whole brain structural imaging stacks and the functional imaging sequences of single slice were obtained for analysis of calcium activities at single-cell resolution. A two-fold increase in imaging speed of conventional confocal LSM makes it possible to capture the sequence of the neurons’ activities and help reveal the potential functional connections in the whole zebrafish’s brain. PMID:26137381

Multi-peaks scattering of light in glasses

NASA Astrophysics Data System (ADS)

Smirnov, V. A.; Vostrikova, L. I.

2018-04-01

Investigations of the multi-peaks scattering of the laser light on the micro-scale susceptibility gratings with small periodicities photo-induced in the various glass materials are presented. The observed pictures of the multi-peaks scattering of light in oxide samples show that the efficiencies of the processes of scattering can vary for the different chemical compositions. Experimental results are in agreement with the proposed theory of light scattering.

Diffusing Wave Spectroscopy Used to Study Foams

NASA Technical Reports Server (NTRS)

Zimmerli, Gregory A.; Durian, Douglas J.

2000-01-01

The white appearance of familiar objects such as clouds, snow, milk, or foam is due to the random scattering of light by the sample. As we all know, pure water is clear and easily passes a beam of light. However, tiny water droplets, such as those in a cloud, scatter light because the air and water droplet have different indexes of refraction. When many droplets, or scattering sites, are present, the incident light is scattered in random directions and the sample takes on a milky white appearance. In a glass of milk, the scattering is due to small colloidal particles. The white appearance of shaving cream, or foam, is due to the scattering of light at the water-bubble interface. Diffusing wave spectroscopy (DWS) is a laser light-scattering technique used to noninvasively probe the particle dynamics in systems that strongly scatter light. The technique takes advantage of the diffuse nature of light, which is reflected or transmitted from samples such as foams, dense colloidal suspensions (such as paint and milk), emulsions, liquid crystals, sandpiles, and even biological tissues.

CO2-switchable fluorescence of a dendritic polymer and its applications

NASA Astrophysics Data System (ADS)

Gao, Chunmei; Lü, Shaoyu; Liu, Mingzhu; Wu, Can; Xiong, Yun

2015-12-01

The synthesis and properties of CO2 responsive and fluorescent dendritic polymers, poly(amido amine)/Pluronic F127 (PAMAM/F127), are reported in this paper. The morphologies and sizes of PAMAM/F127 dendritic polymers were investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). PAMAM/F127 dendritic polymers showed unimolecular micelle morphologies at low concentrations, and changed to multimolecular micelles at higher concentrations. Additionally, fluorescence spectra and confocal laser scanning microscopy images showed that PAMAM/F127 dendritic polymers exhibited a fluorescent enhancement response to the presence of CO2. Apart from that, the release behavior of PAMAM/F127 gels under simulated body fluids was investigated by choosing curcumin as the hydrophobic drug. The results indicated that PAMAM/F127 dendritic polymers can be used to improve the solubility of curcumin, and the drug released faster in the presence of CO2. Such CO2 responsive fluorescent dendritic polymers are potentially applicable in cellular imaging or drug controlled release.The synthesis and properties of CO2 responsive and fluorescent dendritic polymers, poly(amido amine)/Pluronic F127 (PAMAM/F127), are reported in this paper. The morphologies and sizes of PAMAM/F127 dendritic polymers were investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). PAMAM/F127 dendritic polymers showed unimolecular micelle morphologies at low concentrations, and changed to multimolecular micelles at higher concentrations. Additionally, fluorescence spectra and confocal laser scanning microscopy images showed that PAMAM/F127 dendritic polymers exhibited a fluorescent enhancement response to the presence of CO2. Apart from that, the release behavior of PAMAM/F127 gels under simulated body fluids was investigated by choosing curcumin as the hydrophobic drug. The results indicated that PAMAM/F127 dendritic polymers can be used to improve the solubility of curcumin, and the drug released faster in the presence of CO2. Such CO2 responsive fluorescent dendritic polymers are potentially applicable in cellular imaging or drug controlled release. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06729d

3D imaging of cleared human skin biopsies using light-sheet microscopy: A new way to visualize in-depth skin structure.

PubMed

Abadie, S; Jardet, C; Colombelli, J; Chaput, B; David, A; Grolleau, J-L; Bedos, P; Lobjois, V; Descargues, P; Rouquette, J

2018-05-01

Human skin is composed of the superimposition of tissue layers of various thicknesses and components. Histological staining of skin sections is the benchmark approach to analyse the organization and integrity of human skin biopsies; however, this approach does not allow 3D tissue visualization. Alternatively, confocal or two-photon microscopy is an effective approach to perform fluorescent-based 3D imaging. However, owing to light scattering, these methods display limited light penetration in depth. The objectives of this study were therefore to combine optical clearing and light-sheet fluorescence microscopy (LSFM) to perform in-depth optical sectioning of 5 mm-thick human skin biopsies and generate 3D images of entire human skin biopsies. A benzyl alcohol and benzyl benzoate solution was used to successfully optically clear entire formalin fixed human skin biopsies, making them transparent. In-depth optical sectioning was performed with LSFM on the basis of tissue-autofluorescence observations. 3D image analysis of optical sections generated with LSFM was performed by using the Amira ® software. This new approach allowed us to observe in situ the different layers and compartments of human skin, such as the stratum corneum, the dermis and epidermal appendages. With this approach, we easily performed 3D reconstruction to visualise an entire human skin biopsy. Finally, we demonstrated that this method is useful to visualise and quantify histological anomalies, such as epidermal hyperplasia. The combination of optical clearing and LSFM has new applications in dermatology and dermatological research by allowing 3D visualization and analysis of whole human skin biopsies. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Comparative study of ex vivo probe-based confocal laser endomicroscopy and light microscopy in lung cancer diagnostics.

PubMed

Sorokina, Anastasia; Danilevskaya, Olesya; Averyanov, Alexander; Zabozlaev, Fedor; Sazonov, Dmitry; Yarmus, Lonny; Lee, Hans J

2014-08-01

Probe-based confocal laser endoscopy (pCLE) allows for real-time non-invasive histological imaging via bronchoscopy. Interpreting CLE images and correlating with traditional histopathology remains challenging. We performed an ex vivo study to evaluate the correlation between light microscopy findings and pCLE imaging of primary lung carcinoma. Post-lobectomy specimens for lung cancer nodules were examined ex vivo by pCLE. The examined areas were marked with brilliant green dye, and the surrounding tissues were stained by methylene blue dye. Lung tissue segments were resected and histopathological specimens were generated with 50-μm thickness from the marked areas and stained with haematoxylin and eosin. Pathologists and pulmonologists reviewed the images for correlating features. Eighteen lobectomy specimens from 18 different patients were collected. Three primary features were observed in all samples using pCLE in the cancer surroundings: alveolar dystelectasis with thickening of alveolar walls, alveolar edema and a large amount of macrophages. The stromal and parenchymal components of the studied subtypes of non-small-cell lung cancer differed from each other. The stromal component for all nine adenocarcinoma specimens had a highly fluorescent field penetrated by dark hollows. All six squamous cell carcinoma specimens had the stromal component appeared as 'biparously' branching, highly fluorescent fibres. No stromal component was observed in any small-cell carcinoma specimen, and at low power field, the cellular component was dominant with an observed light scattering pattern. pCLE can identify lung carcinoma in ex vivo samples. Certain light microscopy features of lung carcinoma can be visualized with pCLE. © 2014 Asian Pacific Society of Respirology.

Surfactant-mediated amyloidogenesis behavior of stem bromelain; a biophysical insight.

PubMed

Zaman, Masihuz; Zakariya, Syed Mohammad; Nusrat, Saima; Khan, Mohsin Vahid; Qadeer, Atiyatul; Ajmal, Mohammad Rehan; Khan, Rizwan Hasan

2017-05-01

Neurodegenerative disorders are mainly associated with amyloid fibril formation of different proteins. Stem bromelain (SB), a cysteine protease, is known to exist as a molten globule state at pH 10.0. It passes through the identical surrounding (pH 10.0) in the gut epithelium of intestine upon oral administration. Protein-surfactant complexes are widely employed as drug carriers, so the nature of surfactant toward protein is of great interest. The present work describes the effect of cationic surfactants (CTAB & DTAB) and their hydrophobic behavior toward amyloidogenesis behavior of SB at pH 10.0. Multiple approaches including light scattering, far UV-CD, turbidity measurements, and dye binding assay (ThT, Congo red and ANS) were performed to measure the aggregation propensity of SB. Further, we monitored the hydrodynamic radii of aggregates formed using dynamic light scattering technique. Structure of fibrils was also visualized through fluorescence microscopy as well as TEM. At pH 10.0, low concentration of CTAB (0-200 μM) induced amyloid formation in SB as evident from a prominent increase in turbidity and light scattering, gain in β-sheet content, and enhanced ThT fluorescence intensity. However, further increase in CTAB concentration suppressed the fibrillation phenomenon. In contrast, DTAB did not induce fibril formation at any concentration used (0-500 μM) due to lower hydrophobicity. Net negative charge developed on protein at high pH (10.0) might have facilitated amyloid formation at low concentration of cationic surfactant (CTAB) due to electrostatic and hydrophobic interactions.

Spectral interferometric microscopy reveals absorption by individual optical nanoantennas from extinction phase

PubMed Central

Gennaro, Sylvain D.; Sonnefraud, Yannick; Verellen, Niels; Van Dorpe, Pol; Moshchalkov, Victor V.; Maier, Stefan A.; Oulton, Rupert F.

2014-01-01

Optical antennas transform light from freely propagating waves into highly localized excitations that interact strongly with matter. Unlike their radio frequency counterparts, optical antennas are nanoscopic and high frequency, making amplitude and phase measurements challenging and leaving some information hidden. Here we report a novel spectral interferometric microscopy technique to expose the amplitude and phase response of individual optical antennas across an octave of the visible to near-infrared spectrum. Although it is a far-field technique, we show that knowledge of the extinction phase allows quantitative estimation of nanoantenna absorption, which is a near-field quantity. To verify our method we characterize gold ring-disk dimers exhibiting Fano interference. Our results reveal that Fano interference only cancels a bright mode’s scattering, leaving residual extinction dominated by absorption. Spectral interference microscopy has the potential for real-time and single-shot phase and amplitude investigations of isolated quantum and classical antennas with applications across the physical and life sciences. PMID:24781663

Determining the size of nanoparticles in the example of magnetic iron oxide core-shell systems

NASA Astrophysics Data System (ADS)

Jarzębski, Maciej; Kościński, Mikołaj; Białopiotrowicz, Tomasz

2017-08-01

The size of nanoparticles is one of the most important factors for their possible applications. Various techniques for the nanoparticle size characterization are available. In this paper selected techniques will be considered base on the prepared core-shell magnetite nanoparticles. Magnetite is one of the most investigated and developed magnetic material. It shows interesting magnetic properties which can be used for biomedical applications, such as drug delivery, hypothermia and also as a contrast agent. To reduce the toxic effects of Fe3O4, magnetic core was covered by dextran and gelatin. Moreover, the shell was doped by fluorescent dye for confocal microscopy investigation. The main investigation focused on the methods for particles size determination of modified magnetite nanoparticles prepared with different techniques. The size distribution were obtained by nanoparticle tracking analysis, dynamic light scattering and transmission electron microscopy. Furthermore, fluorescent correlation spectroscopy (FCS) and confocal microscopy were used to compare the results for particle size determination of core-shell systems.

Green synthesis and characterization of alginate nanoparticles and its role as a biosorbent for Cr(VI) ions

NASA Astrophysics Data System (ADS)

Geetha, P.; Latha, M. S.; Pillai, Saumya S.; Deepa, B.; Santhosh Kumar, K.; Koshy, Mathew

2016-02-01

Green synthesis of nanoparticles has attained considerable attention in recent years because of its myriad of applications including drug delivery, tissue engineering and water purification. In the present study, alginate nanoparticles stabilized by honey were prepared by cross-linking aqueous solution of alginate with calcium ions. Honey mediated synthesis has been reported earlier for the production of metal nanoparticles. However no literature is available on the use of this technique for polymeric nanoparticles. Highly stable nanoparticles of 10-100 nm size were generated by this technique. The synthesised nanoparticles were characterized by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, dynamic light scattering and Fourier transform infrared spectroscopic techniques. Potential of using these nanoparticles for heavy metal removal was studied by using Cr(VI) from aqueous solution, where a maximum removal efficiency of 93.5% was obtained. This method was also successfully employed for the production of other polymeric nanoparticles like casein, chitosan and albumin.

Characterization of contaminant removal by an optical strip material

NASA Astrophysics Data System (ADS)

Hamilton, James P.; Frigo, S. P.; Caroll, Brenden J.; Assoufidyen, L.; Lewis, Matthew S.; Cook, Russell E.; de Carlo, F.

2001-03-01

Department of Chemistry and Engineering Physics, University of Wisconsin-Platteville, Platteville, WI 53818 Advanced Photon Source, X-Ray Facilities Division, Argonne National Laboratory, Advanced Photon Source, User Program Division, Argonne National Laboratory, *Electron Microscopy Center, Materials Science Division, Argonne National Laboratory, Argonne National Laboratory, 9700 S. Cass Ave., Argonne IL 60439-4856 USA A novel optical strip coating material, Opticlean, has been shown to safely remove fingerprints, particles and contamination from a variety of optical surfaces including coated glass, Si and first surface mirrors. Contaminant removal was monitored by Nomarski, Atomic Force and Scanning Electron Microscopy. Sub-micron features on diffraction gratings and silicon wafers were also cleaned without leaving light scattering particles on the surface. **This work was supported in part by the U.S. Department of Energy, Basic Energy Sciences-Materials Sciences, under contract no. W-31-109-ENG-38. The authors acknowledge the support and facilities provided by the Advanced Photon Source and the Electron Microscopy Center at Argonne National Laboratory.

Noninvasive label-free monitoring of cosmetics and pharmaceuticals in human skin using nonlinear optical microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Osseiran, Sam; Wang, Hequn; Evans, Conor L.

2017-02-01

Over the past decade, nonlinear optical microscopy has seen a dramatic rise in its use in research settings due to its noninvasiveness, enhanced penetration depth, intrinsic optical sectioning, and the ability to probe chemical compounds with molecular specificity without exogenous contrast agents. Nonlinear optical techniques including two-photon excitation fluorescence (2PEF), fluorescence lifetime imaging microscopy (FLIM), second harmonic generation (SHG), coherent anti-Stokes and stimulated Raman scattering (CARS and SRS, respectively), as well as transient and sum frequency absorption (TA and SFA, respectively), have been widely used to explore the physiology and microanatomy of skin. Recently, these modalities have shed light on dermal processes that could not have otherwise been observed, including the spatiotemporal monitoring of cosmetics and pharmaceuticals. However, a challenge quickly arises when studying such chemicals in a dermatological context: many exogenous compounds have optical signatures that can interfere with the signals that would otherwise be acquired from intact skin. For example, oily solvents exhibit strong signals when probing CH2 vibrations with CARS/SRS; chemical sun filters appear bright in 2PEF microscopy; and darkly colored compounds readily absorb light across a broad spectrum, producing strong TA/SFA signals. Thus, this discussion will first focus on the molecular contrast in skin that can be probed using the aforementioned nonlinear optical techniques. This will be followed by an overview of strategies that take advantage of the exogenous compounds' optical signatures to probe spatiotemporal dynamics while preserving endogenous information from skin.

Specific physical and chemical properties of two modifications of poly(N-vinylcaprolcatam)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chihacheva, I. P.; Timaeva, O. I.; Kuz’micheva, G. M., E-mail: galina-kuzmicheva@list.ru

2016-05-15

Two modifications of poly(N-vinylcaprolactam)—PVCL25 and PVCL40 (drying of a PVCL solution at 25 and 40°C, respectively)—as powdered films and their solutions were systematically investigated for the first time. Powders were studied by X-ray diffraction, IR spectroscopy, scanning electron microscopy, low-temperature krypton adsorption, and differential scanning calorimetry. Solutions were studied by smallangle X-ray scattering and dynamic light scattering. It was demonstrated that powders of PVCL25 and PVCL40 differ in the characteristics of the sub- and microstructure and in the water content and the solutions differ in the particle size. The relationships between the characteristics of the systems in the solid andmore » liquid state and between the hydrodynamic diameter of PVCL particles in solution and their coagulation time were found.« less

Pupil-segmentation-based adaptive optics for microscopy

NASA Astrophysics Data System (ADS)

Ji, Na; Milkie, Daniel E.; Betzig, Eric

2011-03-01

Inhomogeneous optical properties of biological samples make it difficult to obtain diffraction-limited resolution in depth. Correcting the sample-induced optical aberrations needs adaptive optics (AO). However, the direct wavefront-sensing approach commonly used in astronomy is not suitable for most biological samples due to their strong scattering of light. We developed an image-based AO approach that is insensitive to sample scattering. By comparing images of the sample taken with different segments of the pupil illuminated, local tilt in the wavefront is measured from image shift. The aberrated wavefront is then obtained either by measuring the local phase directly using interference or with phase reconstruction algorithms similar to those used in astronomical AO. We implemented this pupil-segmentation-based approach in a two-photon fluorescence microscope and demonstrated that diffraction-limited resolution can be recovered from nonbiological and biological samples.

Two-Photon Infrared Resonance Can Enhance Coherent Raman Scattering

NASA Astrophysics Data System (ADS)

Traverso, Andrew J.; Hokr, Brett; Yi, Zhenhuan; Yuan, Luqi; Yamaguchi, Shoichi; Scully, Marlan O.; Yakovlev, Vladislav V.

2018-02-01

In this Letter we present a new technique for attaining efficient low-background coherent Raman scattering where the Raman coherence is mediated by a tunable infrared laser in two-photon resonance with a chosen vibrational transition. In addition to the traditional benefits of conventional coherent Raman schemes, this approach offers a number of advantages including potentially higher emission intensity, reduction of nonresonant four-wave mixing background, preferential excitation of the anti-Stokes field, and simplified phase matching conditions. In particular, this is demonstrated in gaseous methane along the ν1 (A1) and ν3 (T2) vibrational levels using an infrared field tuned between 1400 and 1600 cm-1 and a 532-nm pump field. This approach has broad applications, from coherent light generation to spectroscopic remote sensing and chemically specific imaging in microscopy.

Coherent Raman scattering microscopy for label-free imaging of live amphioxus

NASA Astrophysics Data System (ADS)

Yu, Zhilong; Chen, Tao; Zhang, Xiannian; Shen, Jie; Chen, Junyuan; Huang, Yanyi

2012-03-01

The existence of notochord distinguishes chordates from other phyla. Amphioxus is the only animal that keeps notochord during the whole life. Notochord is a unique organ for amphioxus, with its vertically arranged muscular notochordal plates, which is different from notochords in embryos of other chordates. We use stimulated Raman scattering (SRS) microscopy as a non-invasive technique to image the chemical components in amphioxus notochord. SRS provides chemical specificity as spontaneous Raman does and offers a higher sensitivity for fast acquisition. Unlike coherent anti- Stokes Raman scattering (CARS) microscopy, SRS microscopy doesn't have non-resonant background and can better differentiate different components in the specimen. We verify that the notochord is a protein-rich organ, which agrees well with the result of conventional staining methods. Detailed structures in notochordal plates and notochordal sheath are revealed by SRS microscopy with diffraction limited resolution. Our experiment shows that SRS microscopy is an excellent imaging tool for biochemical research with its intrinsic chemical selectivity, high spatiotemporal resolution and native 3D optical sectioning ability.

Wide field fluorescence epi-microscopy behind a scattering medium enabled by speckle correlations

NASA Astrophysics Data System (ADS)

Hofer, Matthias; Soeller, Christian; Brasselet, Sophie; Bertolotti, Jacopo

2018-04-01

Fluorescence microscopy is widely used in biological imaging, however scattering from tissues strongly limits its applicability to a shallow depth. In this work we adapt a methodology inspired from stellar speckle interferometry, and exploit the optical memory effect to enable fluorescence microscopy through a turbid layer. We demonstrate efficient reconstruction of micrometer-size fluorescent objects behind a scattering medium in epi-microscopy, and study the specificities of this imaging modality (magnification, field of view, resolution) as compared to traditional microscopy. Using a modified phase retrieval algorithm to reconstruct fluorescent objects from speckle images, we demonstrate robust reconstructions even in relatively low signal to noise conditions. This modality is particularly appropriate for imaging in biological media, which are known to exhibit relatively large optical memory ranges compatible with tens of micrometers size field of views, and large spectral bandwidths compatible with emission fluorescence spectra of tens of nanometers widths.

Amphiphilic Imbalance and Stabilization of Block Copolymer Micelles on-Demand through Combinational Photo-Cleavage and Photo-Crosslinking.

PubMed

Zhang, Xuan; Wang, Youpeng; Li, Guo; Liu, Zhaotie; Liu, Zhongwen; Jiang, Jinqiang

2017-01-01

An amphiphilic block copolymer of poly(ethylene oxide)-b-poly((N-methacryloxy phthalimide)-co-(7-(4-vinyl-benzyloxyl)-4-methylcoumarin)) (PEO 45 -b-P(MAPI 36 -co-VBC 4 )) is designed to improve the micellar stability during the photo-triggered release of hydrophobic cargoes. Analysis of absorption and emission spectra, solution transmittance, dynamic light scattering, and transmission electron microscopy supports that polymer micelles of PEO 45 -b-P(MAPI 36 -co-VBC 4 ) upon the combinational irradiation of 365 and 254 nm light can be solubilized through the photolysis of phthalimide esters and simultaneously crosslinked via the partially reversible photo-dimerization of coumarins. The photo-triggered release experiment shows that the leakage of doxorubicin molecules from crosslinked micelles can be predictably regulated by controlling the irradiation time of 365 and 254 nm light. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical memory effect from polarized Laguerre-Gaussian light beam in light-scattering turbid media

NASA Astrophysics Data System (ADS)

Shumyatsky, Pavel; Milione, Giovanni; Alfano, Robert R.

2014-06-01

Propagation effects of polarized Laguerre-Gaussian light with different orbital angular momentum (L) in turbid media are described. The optical memory effect in scattering media consisting of small and large size (compared to the wavelength) scatterers is investigated for scattered polarized light. Imaging using polarized laser modes with a varying orbital strength L-parameter was performed. The backscattered image quality (contrast) was enhanced by more than an order of magnitude using circularly polarized light when the concentration of scatterers was close to invisibility of the object.

Stimulated concentration (diffusion) light scattering on nanoparticles in a liquid suspension

NASA Astrophysics Data System (ADS)

Burkhanov, I. S.; Krivokhizha, S. V.; Chaikov, L. L.

2016-06-01

A nonlinear growth of the light scattering intensity has been observed and the frequency shift of the spectral line of scattered light has been measured in light backscattered in suspensions of diamond and latex nanoparticles in water. The shift corresponds to the HWHM of the line of spontaneous scattering on particles. We may conclude that there exists stimulated concentration (diffusion) light scattering on variations of the particle concentration, which is also called the stimulated Mie scattering. In a fibre probe scheme, the growth of the shift of the scattered spectral line is observed with an increase in the exciting beam power. The variation of the frequency shift with an increase in the exciting power is explained by convection in liquid.

Frequency mismatch in stimulated scattering processes: An important factor for the transverse distribution of scattered light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong, Tao; Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, Sichuan 621900; Zheng, Jian, E-mail: jzheng@ustc.edu.cn

2016-06-15

A 2D cylindrically symmetric model with inclusion of both diffraction and self-focus effects is developed to deal with the stimulated scattering processes of a single hotspot. The calculated results show that the transverse distribution of the scattered light is sensitive to the longitudinal profiles of the plasma parameters. The analysis of the evolution of the scattered light indicates that it is the frequency mismatch of coupling due to the inhomogeneity of plasmas that determines the transverse distribution of the scattered light.

Intraocular light scatter, reflections, fluorescence and absorption: what we see in the slit lamp.

PubMed

van den Berg, Thomas J T P

2018-01-01

Much knowledge has been collected over the past 20 years about light scattering in the eye- in particular in the eye lens- and its visual effect, called straylight. It is the purpose of this review to discuss how these insights can be applied to understanding the slit lamp image. The slit lamp image mainly results from back scattering, whereas the effects on vision result mainly from forward scatter. Forward scatter originates from particles of about wavelength size distributed throughout the lens. Most of the slit lamp image originates from small particle scatter (Rayleigh scatter). For a population of middle aged lenses it will be shown that both these scatter components remove around 10% of the light from the direct beam. For slit lamp observation close to the reflection angles, zones of discontinuity (Wasserspalten) at anterior and posterior parts of the lens show up as rough surface reflections. All these light scatter effects increase with age, but the correlations with age, and also between the different components, are weak. For retro-illumination imaging it will be argued that the density or opacity seen in areas of cortical or posterior subcapsular cataract show up because of light scattering, not because of light loss. NOTES: (1) Light scatter must not be confused with aberrations. Light penetrating the eye is divided into two parts: a relatively small part is scattered, and removed from the direct beam. Most of the light is not scattered, but continues as the direct beam. This non-scattered part is the basis for functional imaging, but its quality is under the control of aberrations. Aberrations deflect light mainly over small angles (<1°), whereas light scatter is important because of the straylight effects over large angles (>1°), causing problems like glare and hazy vision. (2) The slit lamp image in older lenses and nuclear cataract is strongly influenced by absorption. However, this effect is greatly exaggerated by the light path lengths concerned. This obviates proper judgement of the functional importance of absorption, and hinders the appreciation of the Rayleigh nature of what is seen in the slit lamp image. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

Fiberoptic spectrophotometer

DOEpatents

Tans, Petrus P.; Lashof, Daniel A.

1986-01-01

A device for determining the relative composition of a sample of a gas by comparison of the Raman-scattered light of the sample with that of a known gas comprising: a means for passing a single light source through the unknown and the known gases, choppers to alternate the Raman-scattered light into a common light detection and measuring system, optical fiber networks for spatially mixing the resulting Raman scattered light from each sample and directing the mixed light to selective detectors, and a compiler to record the light intensity of each wavelength of Raman-scattered light as a function of the sample from which it originated.

Polymeric nanoparticles of cholesterol-modified glycol chitosan for doxorubicin delivery: preparation and in-vitro and in-vivo characterization.

PubMed

Yu, Jing-Mou; Li, Yong-Jie; Qiu, Li-Yan; Jin, Yi

2009-06-01

Polymeric nanoparticles have been extensively studied as drug carriers. Chitosan and its derivatives have attracted significant attention in this regard but have limited application because of insolubility in biological solution. In this work, we attempted to utilize cholesterol-modified glycol chitosan (CHGC) self-aggregated nanoparticles to increase aqueous solubility, and to reduce side effects and enhance the antitumour efficacy of the anticancer drug doxorubicin. Methods CHGC nanoparticles were loaded with doxorubicin by a dialysis method, and their characteristics were determined by transmission electron microscopy examination, light-scattering study, in-vitro drug-release study, pharmacokinetic study in rats and in-vivo antitumour activity in mice. The resulting doxorubicin-loaded CHGC nanoparticles (DCNs) formed self-assembled aggregates in aqueous medium. From the observation by transmission electron microscopy, DCNs were almost spherical in shape. The mean diameters of these nanoparticles determined by dynamic light scattering were in the range of 237-336 nm as the doxorubicin-loading content increased from 1.73% to 9.36%. In-vitro data indicated that doxorubicin release from DCNs was much faster in phosphate-buffered saline at pH 5.5 than at pH 6.5 and 7.4, and the release rate was dependent on the loading content of doxorubicin in these nanoparticles. It was observed that DCN-16 (drug loaded content: 9.36%) exhibited prolonged circulation time in rat plasma and showed higher antitumour efficacy against S180-bearing mice than free doxorubicin. These results indicated that CHGC nanoparticles had potential as a carrier for insoluble anticancer drugs in cancer therapy.

Mueller tensor approach for nonlinear optics in turbid media

NASA Astrophysics Data System (ADS)

Ulcickas, James R. W.; Deng, Fengyuan; Ding, Changqin; Simpson, Garth J.

2018-02-01

As plane-polarized light propagates through a turbid medium, scattering alters the phase and polarization differently in different locations. The corresponding depolarization of the beam complicates recovery of the rich information content contained within the polarization-dependence of second harmonic generation (SHG) microscopy. A theoretical framework connecting Jones and Stokes formalisms for describing optical polarization allows prediction of the polarization-dependent SHG produced from "ballistic", but depolarized incident light. Measurements with collagen-rich tissue sections support the predictions of the framework. Partially polarized SHG produced from a depolarized source enabled recovery of local orientation distribution for collagen and local tensor information. Bridging the gap between SHG instigated by fully depolarized light and partially polarized light more common to practical turbid systems, a method for predicting local nonlinear optical susceptibility tensor elements was developed and applied to collagen in thick sections. Recovered values for the tensor element ratio ρ are in good agreement with previous results for thin tissue and literature reports.

Interpretation of light scattering and turbidity measurements in aggregated systems: effect of intra-cluster multiple-light scattering.

PubMed

Soos, Miroslav; Lattuada, Marco; Sefcik, Jan

2009-11-12

In this work we studied the effect of intracluster multiple-light scattering on the scattering properties of a population of fractal aggregates. To do so, experimental data of diffusion-limited aggregation for three polystyrene latexes with similar surface properties but different primary particle diameters (equal to 118, 420, and 810 nm) were obtained by static light scattering and by means of a spectrophotometer. In parallel, a population balance equation (PBE) model, which takes into account the effect of intracluster multiple-light scattering by solving the T-matrix and the mean-field version of T-matrix, was formulated and validated against time evolution of the root mean radius of gyration, , of the zero angle intensity of scattered light, I(0), and of the turbidity, tau. It was found that the mean-field version of the T-matrix theory is able to correctly predict the time evolution of all measured light scattering quantities for all sizes of primary particles without any adjustable parameter. The structure of the aggregates, characterized by fractal dimension, d(f), was independent of the primary particle size and equal to 1.7, which is in agreement with values found in literature. Since the mean-field version of the T-matrix theory used is rather complicated and requires advanced knowledge of cluster structure (i.e., the particle-particle correlation function), a simplified version of the light scattering model was proposed and tested. It was found that within the range of operating conditions investigated, the simplified version of the light scattering model was able to describe with reasonable accuracy the time evolution of all measured light scattering quantities of the cluster mass distribution (CMD) for all three sizes of primary particles and two values of the laser wavelength.

Physical and Optical/Radiative Properties of Arctic Aerosols: Potential Effects on Arctic Climate

NASA Technical Reports Server (NTRS)

Pueschel, R. F.; Kinne, S. A.; Gore, Warren J. (Technical Monitor)

1994-01-01

We have determined the abundance of light-scattering sulfuric acid (H2SO4/H2O) and light-absorbing black carbon aerosol (BCA) in Spring 1992 in the Arctic atmosphere by airborne in situ sampling with impactors, and measured particle sizes and morphologies by scanning electron microscopy. The mass of BCA in the Arctic troposphere is one percent of the total aerosol, reduced to one part in 104 in the stratosphere. A Mie algorithm permits the calculation of the optical properties of the various aerosol components, and an algorithm developed by Ackerman and Toon and modified to serve our needs lets us calculate the optical effects of the black carbon aerosol that is mixed internally with the sulfuric acid aerosol. It follows that the effect of internally-mixed BCA on the aerosol scattering and absorption properties depends on its location within the droplet. BCA concentrated near the droplet surface has a greater effect on absorption of solar radiation than does the same amount of BCA located near its center. Single scatter albedos of the combined system are omega(sub 0)=1.0 in the post-Pinatubo Arctic stratosphere, and as low as 0.94 in the troposphere. The aerosol has the potential to regionally warm the Arctic earth-atmosphere system, because of the high surface albedo of the snow-covered Arctic.

Evaluation of drug delivery to intact and porated skin by coherent Raman scattering and fluorescence microscopies.

PubMed

Belsey, Natalie A; Garrett, Natalie L; Contreras-Rojas, L Rodrigo; Pickup-Gerlaugh, Adam J; Price, Gareth J; Moger, Julian; Guy, Richard H

2014-01-28

Stimulated Raman scattering microscopy was used to assess the permeation of topically applied drugs and formulation excipients into porcine skin. This chemically selective technique generates high-resolution 3D images, from which semi-quantitative information may be elucidated. Ibuprofen, applied as a close-to-saturated solution in propylene glycol, was directly observed to crystallise in/on the skin, as the co-solvent permeated more rapidly, resulting in precipitation of the drug. Coherent Raman scattering microscopy is also an excellent tool, in conjunction with more conventional confocal fluorescence microscopy, with which to image micro/nanoparticle-based formulations. Specifically, the uptake of particles into thermal ablation transport pathways in the skin has been examined. Copyright © 2013 Elsevier B.V. All rights reserved.

Static and dynamic light scattering by red blood cells: A numerical study.

PubMed

Mauer, Johannes; Peltomäki, Matti; Poblete, Simón; Gompper, Gerhard; Fedosov, Dmitry A

2017-01-01

Light scattering is a well-established experimental technique, which gains more and more popularity in the biological field because it offers the means for non-invasive imaging and detection. However, the interpretation of light-scattering signals remains challenging due to the complexity of most biological systems. Here, we investigate static and dynamic scattering properties of red blood cells (RBCs) using two mesoscopic hydrodynamics simulation methods-multi-particle collision dynamics and dissipative particle dynamics. Light scattering is studied for various membrane shear elasticities, bending rigidities, and RBC shapes (e.g., biconcave and stomatocyte). Simulation results from the two simulation methods show good agreement, and demonstrate that the static light scattering of a diffusing RBC is not very sensitive to the changes in membrane properties and moderate alterations in cell shapes. We also compute dynamic light scattering of a diffusing RBC, from which dynamic properties of RBCs such as diffusion coefficients can be accessed. In contrast to static light scattering, the dynamic measurements can be employed to differentiate between the biconcave and stomatocytic RBC shapes and generally allow the differentiation based on the membrane properties. Our simulation results can be used for better understanding of light scattering by RBCs and the development of new non-invasive methods for blood-flow monitoring.

Static and dynamic light scattering by red blood cells: A numerical study

PubMed Central

Mauer, Johannes; Peltomäki, Matti; Poblete, Simón; Gompper, Gerhard

2017-01-01

Light scattering is a well-established experimental technique, which gains more and more popularity in the biological field because it offers the means for non-invasive imaging and detection. However, the interpretation of light-scattering signals remains challenging due to the complexity of most biological systems. Here, we investigate static and dynamic scattering properties of red blood cells (RBCs) using two mesoscopic hydrodynamics simulation methods—multi-particle collision dynamics and dissipative particle dynamics. Light scattering is studied for various membrane shear elasticities, bending rigidities, and RBC shapes (e.g., biconcave and stomatocyte). Simulation results from the two simulation methods show good agreement, and demonstrate that the static light scattering of a diffusing RBC is not very sensitive to the changes in membrane properties and moderate alterations in cell shapes. We also compute dynamic light scattering of a diffusing RBC, from which dynamic properties of RBCs such as diffusion coefficients can be accessed. In contrast to static light scattering, the dynamic measurements can be employed to differentiate between the biconcave and stomatocytic RBC shapes and generally allow the differentiation based on the membrane properties. Our simulation results can be used for better understanding of light scattering by RBCs and the development of new non-invasive methods for blood-flow monitoring. PMID:28472125

Development of wide-angle 2D light scattering static cytometry

NASA Astrophysics Data System (ADS)

Xie, Linyan; Liu, Qiao; Shao, Changshun; Su, Xuantao

2016-10-01

We have recently developed a 2D light scattering static cytometer for cellular analysis in a label-free manner, which measures side scatter (SSC) light in the polar angular range from 79 to 101 degrees. Compared with conventional flow cytometry, our cytometric technique requires no fluorescent labeling of the cells, and static cytometry measurements can be performed without flow control. In this paper we present an improved label-free static cytometer that can obtain 2D light scattering patterns in a wider angular range. By illuminating the static microspheres on chip with a scanning optical fiber, wide-angle 2D light scattering patterns of single standard microspheres with a mean diameter of 3.87 μm are obtained. The 2D patterns of 3.87 μm microspheres contain both large-angle forward scatter (FSC) and SSC light in the polar angular range from 40 to 100 degrees, approximately. Experimental 2D patterns of 3.87 μm microspheres are in good agreement with Mie theory simulated ones. The wide-angle light scattering measurements may provide a better resolution for particle analysis as compared with the SSC measurements. Two dimensional light scattering patterns of HL-60 human acute leukemia cells are obtained by using our static cytometer. Compared with SSC 2D light scattering patterns, wide-angle 2D patterns contain richer information of the HL-60 cells. The obtaining of 2D light scattering patterns in a wide angular range could help to enhance the capabilities of our label-free static cytometry for cell analysis.

The artefacts of radiochromic film dosimetry with flatbed scanners and their causation by light scattering from radiation-induced polymers.

PubMed

Schoenfeld, Andreas A; Poppinga, Daniela; Harder, Dietrich; Doerner, Karl-Joachim; Poppe, Bjoern

2014-07-07

Optical experiments and theoretical considerations have been undertaken in order to understand the causes of the 'orientation effect' and the 'parabola effect', the artefacts impairing the desired light absorption measurement on radiochromic EBT3 films with flatbed scanners. EBT3 films exposed to doses up to 20.9 Gy were scanned with an Epson Expression 10000XL flatbed scanner in landscape and portrait orientation. The horizontally and vertically polarized light components of the scanner were determined, and another Epson Expression 10000XL flatbed scanner was disassembled to examine its optical components. The optical properties of exposed and unexposed EBT3 films were studied with incident polarized and unpolarized white light, and the transmitted red light was investigated for its polarization and scattering properties including the distribution of the scattering angles. Neutral density filters were studied for comparison. Guidance was sought from the theory of light scattering from rod-like macromolecular structures. The drastic dose-dependent variation of the transmitted total light current as function of the orientation of front and rear polarizers, interpreted by light scattering theory, shows that the radiation-induced polymerization of the monomers of EBT3 films produces light scattering oscillators preferably polarized at right angles with the coating direction of the film. The directional distribution of the scattered light is partly anisotropic, with a preferred scattering plane at right angles with the coating direction, indicating light scattering from stacks of coherently vibrating oscillators piled up along the monomer crystals. The polyester carrier film also participates in these effects. The 'orientation' and 'parabola' artefacts due to flatbed scanning of radiochromic films can be explained by the interaction of the polarization-dependent and anisotropic light scattering from exposed and unexposed EBT3 films with the quantitative difference between the scanner's horizontally and vertically polarized light supply and with the limited directional acceptance of the scanner's light recording system.

Laser scatter in clinical applications

NASA Astrophysics Data System (ADS)

Luther, Ed; Geddie, William

2008-02-01

Brightfield Laser Scanning Imaging (BLSI) is available on Laser Scanning Cytometers (LSCs) from CompuCyte Corporation. Briefly, digitation of photodetector outputs is coordinated with the combined motions of a small diameter (typically 2 to 10 microns) laser beam scanning a specimen in the Y direction (directed by a galvanometer-driven scanning mirror) and the microscope stage motion in the X direction. The output measurements are assembled into a two-dimensional array to provide a "non-real" digital image, where each pixel value reports the amount of laser-scattered light that is obtained when the laser beam is centered on that location. Depending on the detector positions, these images are analogous to Differential Interference Contrast or Phase Contrast microscopy. We report the incorporation of the new laser scattering capabilities into the workflow of a high-volume clinical cytology laboratory at University Health Network, Toronto, Canada. The laboratory has been employing LSC technology since 2003 for immunophenotypic fluorescence analysis of approximately 1200 cytological specimens per year, using the Clatch methodology. The new BLSI component allows visualization of cellular morphology at higher resolution levels than is possible with standard brightfield microscopic evaluation of unstained cells. BLSI is incorporated into the triage phase, where evaluation of unstained samples is combined with fluorescence evaluation to obtain specimen background levels. Technical details of the imaging methodology will be presented, as well as illustrative examples from current studies and comparisons to detailed, but obscure, historical studies of cytology specimens based on phase contrast microscopy.

Light intensity modulation by coccoliths of Emiliania huxleyi as a micro-photo-regulator.

PubMed

Mizukawa, Yuri; Miyashita, Yuito; Satoh, Manami; Shiraiwa, Yoshihiro; Iwasaka, Masakazu

2015-09-01

In this study, we present experimental evidence showing that coccoliths have light-scattering anisotropy that contributes to a possible control of solar light exposure in the ocean. Changing the angle between the incident light and an applied magnetic field causes differences in the light-scattering intensities of a suspension of coccoliths isolated from Emiliania huxleyi. The magnetic field effect is induced by the diamagnetic torque force directing the coccolith radial plane perpendicular to the applied magnetic fields at 400 to 500 mT. The developed technique reveals the light-scattering anisotropies in the 3-μm-diameter floating coccoliths by orienting themselves in response to the magnetic fields. The detached coccolith scatters radially the light incident to its radial plane. The experimental results on magnetically oriented coccoliths show that an individual coccolith has a specific direction of light scattering, although the possible physiological effect of the coccolith remains for further study, focusing on the light-scattering anisotropies of coccoliths on living cells.

Light intensity modulation by coccoliths of Emiliania huxleyi as a micro-photo-regulator

NASA Astrophysics Data System (ADS)

Mizukawa, Yuri; Miyashita, Yuito; Satoh, Manami; Shiraiwa, Yoshihiro; Iwasaka, Masakazu

2015-09-01

In this study, we present experimental evidence showing that coccoliths have light-scattering anisotropy that contributes to a possible control of solar light exposure in the ocean. Changing the angle between the incident light and an applied magnetic field causes differences in the light-scattering intensities of a suspension of coccoliths isolated from Emiliania huxleyi. The magnetic field effect is induced by the diamagnetic torque force directing the coccolith radial plane perpendicular to the applied magnetic fields at 400 to 500 mT. The developed technique reveals the light-scattering anisotropies in the 3-μm-diameter floating coccoliths by orienting themselves in response to the magnetic fields. The detached coccolith scatters radially the light incident to its radial plane. The experimental results on magnetically oriented coccoliths show that an individual coccolith has a specific direction of light scattering, although the possible physiological effect of the coccolith remains for further study, focusing on the light-scattering anisotropies of coccoliths on living cells.

Breaking the diffraction barrier using coherent anti-Stokes Raman scattering difference microscopy.

PubMed

Wang, Dong; Liu, Shuanglong; Chen, Yue; Song, Jun; Liu, Wei; Xiong, Maozhen; Wang, Guangsheng; Peng, Xiao; Qu, Junle

2017-05-01

We propose a method to improve the resolution of coherent anti-Stokes Raman scattering microscopy (CARS), and present a theoretical model. The proposed method, coherent anti-Stokes Raman scattering difference microscopy (CARS-D), is based on the intensity difference between two differently acquired images. One being the conventional CARS image, and the other obtained when the sample is illuminated by a doughnut shaped spot. The final super-resolution CARS-D image is constructed by intensity subtraction of these two images. However, there is a subtractive factor between them, and the theoretical model sets this factor to obtain the best imaging effect.

Improved Optics For Quasi-Elastic Light Scattering

NASA Technical Reports Server (NTRS)

Cheung, Harry Michael

1995-01-01

Improved optical train devised for use in light-scattering measurements of quasi-elastic light scattering (QELS) and laser spectroscopy. Measurements performed on solutions, microemulsions, micellular solutions, and colloidal dispersions. Simultaneous measurements of total intensity and fluctuations in total intensity of light scattered from sample at various angles provides data used, in conjunction with diffusion coefficients, to compute sizes of particles in sample.

Study of ZnO nanoparticles: Antibacterial property and light depolarization property using light scattering tool

NASA Astrophysics Data System (ADS)

Roy, Sanchita; Barua, Nilakshi; Buragohain, Alak K.; Ahmed, Gazi A.

2013-03-01

Investigations on treatment of ZnO nanoparticles on Staphylococcus aureus MTCC 737 strain was essentially made by using standard biochemical method. The anti-microbial assay against S. aureus, and time kill assay revealed the anti-bacterial activity of ZnO nanoparticles. We have substantiated this property of ZnO nanoparticles and light depolarization property by using light scattering tool. Light scattering measurements were carried out for ZnO, S. aureus, and ZnO treated S. aureus as a function of scattering angle at 543.5 and 632.8 nm wavelengths. This was done in order to find the scattering profile of the consequent product after the action of ZnO nanoparticles on bacteria by means of light scattering tool. S. aureus treated with ZnO nanoparticles showed closer agreement of the scattering profiles at both the wavelengths, however, the scattering profiles of ZnO nanoparticles and untreated S. aureus significantly varied for the two different laser wavelengths. It was also observed that there was higher intensity of scattering from all S. aureus treated with ZnO particles compared to the untreated ones. In our work, we have studied ZnO nanoparticles and the possibility of observing its anti-bacterial activity by using light scattering tool.

Spectroscopic investigation of the spectroscopic signatures of 2,4-DNT and 2,6-DNT: their interactions with sand particles

NASA Astrophysics Data System (ADS)

Blanco, Alejandro; Mina, Nairmen; Castro, Miguel E.; Castillo-Chara, Jairo; Hernandez-Rivera, Samuel P.

2004-09-01

Raman Spectroscopy is a well established tool for vibrational spectroscopy analysis. Interactions of explosives with different substrates can be measured by using quantitative vibrational signal shift information of scattered Raman light associated with these interactions. A vibrational spectroscopic study has been carried out on 2,4-DNT and 2,6-DNT crystals. Raman Microscopy spectrometers equipped with 514 nm and 785 nm laser excitation lines were used. The samples were recrystallized on different solvents (water, methanol and acetonitrile) and allowed to interact with soil samples. The interaction with sand and soil samples doped with the nitroaromatic compounds showed significant shifts in its peaks. The above information was used to detect DNT in soil using Raman Microscopy. These results will make possible the development of highly sensitive sensors for detection of explosives materials.

Quantitative comparison of self-healing ability between Bessel–Gaussian beam and Airy beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wen, Wei; Chu, Xiuxiang, E-mail: xiuxiangchu@yahoo.com

The self-healing ability during propagation process is one of the most important properties of non-diffracting beams. This ability has crucial advantages to light sheet-based microscopy to reduce scattering artefacts, increase the quality of the image and enhance the resolution of microscopy. Based on similarity between two infinite-dimensional complex vectors in Hilbert space, the ability to a Bessel–Gaussian beam and an Airy beam have been studied and compared. Comparing the evolution of the similarity of Bessel–Gaussian beam with Airy beam under the same conditions, we find that Bessel–Gaussian beam has stronger self-healing ability and is more stable than that of Airymore » beam. To confirm this result, the intensity profiles of Bessel–Gaussian beam and Airy beam with different similarities are numerically calculated and compared.« less

Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuschewski, F.; Ribbeck, H.-G. von; Döring, J.

2016-03-14

Nano-spectroscopy in the terahertz frequency range remains challenging despite recent technological progress in developing both THz emitter sources and near-field optical microscopy (SNOM). Here, we combine scattering-type SNOM with a free-electron laser light source, to tune into the 1.3–8.5 THz range. A significant portion of this range, namely, the frequencies above ∼3 THz, is not covered by previously reported near-field microscopy systems. However, it constitutes an indispensable regime where many elementary processes in solids including collective lattice excitations, charge, and spin transport occur. Our approach of nano-spectroscopy and nano-imaging provides a versatile analysis of nanostructures as small as 50 nm, hence beating themore » optical diffraction limit by λ/4600.« less

Optimal synthesis and characterization of Ag nanofluids by electrical explosion of wires in liquids

PubMed Central

2011-01-01

Silver nanoparticles were produced by electrical explosion of wires in liquids with no additive. In this study, we optimized the fabrication method and examined the effects of manufacturing process parameters. Morphology and size of the Ag nanoparticles were determined using transmission electron microscopy and field-emission scanning electron microscopy. Size and zeta potential were analyzed using dynamic light scattering. A response optimization technique showed that optimal conditions were achieved when capacitance was 30 μF, wire length was 38 mm, liquid volume was 500 mL, and the liquid type was deionized water. The average Ag nanoparticle size in water was 118.9 nm and the zeta potential was -42.5 mV. The critical heat flux of the 0.001-vol.% Ag nanofluid was higher than pure water. PMID:21711757

Plastic protein microarray to investigate the molecular pathways of magnetic nanoparticle-induced nanotoxicity

NASA Astrophysics Data System (ADS)

Liu, Yingshuai; Li, Xuelian; Bao, Shujuan; Lu, Zhisong; Li, Qing; Li, Chang Ming

2013-05-01

Superparamagnetic iron oxide nanoparticles (SPIONs) (about 15 nm) were synthesized via a hydrothermal method and characterized by field emission scanning electron microscopy, transmission electron microscopy, dynamic light scattering, x-ray diffraction, and vibrating sample magnetometer. The molecular pathways of SPIONs-induced nanotoxicity was further investigated by protein microarrays on a plastic substrate from evaluation of cell viability, reactive oxygen species (ROS) generation and cell apoptosis. The experimental results reveal that 50 μg ml-1 or higher levels of SPIONs cause significant loss of cell viability, considerable generation of ROS and cell apoptosis. It is proposed that high level SPIONs could induce cell apoptosis via a mitochondria-mediated intrinsic pathway by activation of caspase 9 and caspase 3, an increase of the Bax/Bcl-2 ratio, and down-regulation of HSP70 and HSP90 survivor factors.

Design of fiber optic probes for laser light scattering

NASA Technical Reports Server (NTRS)

Dhadwal, Harbans S.; Chu, Benjamin

1989-01-01

A quantitative analysis is presented of the role of optical fibers in laser light scattering. Design of a general fiber optic/microlens probe by means of ray tracing is described. Several different geometries employing an optical fiber of the type used in lightwave communications and a graded index microlens are considered. Experimental results using a nonimaging fiber optic detector probe show that due to geometrical limitations of single mode fibers, a probe using a multimode optical fiber has better performance, for both static and dynamic measurements of the scattered light intensity, compared with a probe using a single mode fiber. Fiber optic detector probes are shown to be more efficient at data collection when compared with conventional approaches to measurements of the scattered laser light. Integration of fiber optic detector probes into a fiber optic spectrometer offers considerable miniaturization of conventional light scattering spectrometers, which can be made arbitrarily small. In addition static and dynamic measurements of scattered light can be made within the scattering cell and consequently very close to the scattering center.

Scattering of light by colloidal aluminosilicate particles produces the unusual sky-blue color of Río Celeste (Tenorio volcano complex, Costa Rica).

PubMed

Castellón, Erick; Martínez, María; Madrigal-Carballo, Sergio; Arias, María Laura; Vargas, William E; Chavarría, Max

2013-01-01

Río Celeste (Sky-Blue River) in Tenorio National Park (Costa Rica), a river that derives from the confluence and mixing of two colorless streams--Río Buenavista (Buenavista River) and Quebrada Agria (Sour Creek)--is renowned in Costa Rica because it presents an atypical intense sky-blue color. Although various explanations have been proposed for this unusual hue of Río Celeste, no exhaustive tests have been undertaken; the reasons hence remain unclear. To understand this color phenomenon, we examined the physico-chemical properties of Río Celeste and of the two streams from which it is derived. Chemical analysis of those streams with ion-exchange chromatography (IC) and inductively coupled plasma atomic emission spectroscopy (ICP-OES) made us discard the hypothesis that the origin of the hue is due to colored chemical species. Our tests revealed that the origin of this coloration phenomenon is physical, due to suspended aluminosilicate particles (with diameters distributed around 566 nm according to a lognormal distribution) that produce Mie scattering. The color originates after mixing of two colorless streams because of the enlargement (by aggregation) of suspended aluminosilicate particles in the Río Buenavista stream due to a decrease of pH on mixing with the acidic Quebrada Agria. We postulate a chemical mechanism for this process, supported by experimental evidence of dynamic light scattering (DLS), zeta potential measurements, X-ray diffraction and scanning electron microscopy (SEM) with energy-dispersive spectra (EDS). Theoretical modeling of the Mie scattering yielded a strong coincidence between the observed color and the simulated one.

Super-nonlinear fluorescence microscopy for high-contrast deep tissue imaging

NASA Astrophysics Data System (ADS)

Wei, Lu; Zhu, Xinxin; Chen, Zhixing; Min, Wei

2014-02-01

Two-photon excited fluorescence microscopy (TPFM) offers the highest penetration depth with subcellular resolution in light microscopy, due to its unique advantage of nonlinear excitation. However, a fundamental imaging-depth limit, accompanied by a vanishing signal-to-background contrast, still exists for TPFM when imaging deep into scattering samples. Formally, the focusing depth, at which the in-focus signal and the out-of-focus background are equal to each other, is defined as the fundamental imaging-depth limit. To go beyond this imaging-depth limit of TPFM, we report a new class of super-nonlinear fluorescence microscopy for high-contrast deep tissue imaging, including multiphoton activation and imaging (MPAI) harnessing novel photo-activatable fluorophores, stimulated emission reduced fluorescence (SERF) microscopy by adding a weak laser beam for stimulated emission, and two-photon induced focal saturation imaging with preferential depletion of ground-state fluorophores at focus. The resulting image contrasts all exhibit a higher-order (third- or fourth- order) nonlinear signal dependence on laser intensity than that in the standard TPFM. Both the physical principles and the imaging demonstrations will be provided for each super-nonlinear microscopy. In all these techniques, the created super-nonlinearity significantly enhances the imaging contrast and concurrently extends the imaging depth-limit of TPFM. Conceptually different from conventional multiphoton processes mediated by virtual states, our strategy constitutes a new class of fluorescence microscopy where high-order nonlinearity is mediated by real population transfer.

Engineered surface scatterers in edge-lit slab waveguides to improve light delivery in algae cultivation.

PubMed

Ahsan, Syed Saad; Pereyra, Brandon; Jung, Erica E; Erickson, David

2014-10-20

Most existing photobioreactors do a poor job of distributing light uniformly due to shading effects. One method by which this could be improved is through the use of internal wave-guiding structures incorporating engineered light scattering schemes. By varying the density of these scatterers, one can control the spatial distribution of light inside the reactor enabling better uniformity of illumination. Here, we compare a number of light scattering schemes and evaluate their ability to enhance biomass accumulation. We demonstrate a design for a gradient distribution of surface scatterers with uniform lateral scattering intensity that is superior for algal biomass accumulation, resulting in a 40% increase in the growth rate.

Polar nephelometer for atmospheric particulate studies

NASA Technical Reports Server (NTRS)

Hansen, M. Z.; Evans, W. H.

1980-01-01

A polar nephelometer for use in studying atmospheric aerosols was developed. The nephelometer detects molecular scatter from air and measures scattering from very clean air using pure molecular scattering for calibration. A compact system using a folded light path with an air cooled argon laser for the light source was designed. A small, sensitive detector unit permits easy angular rotation for changing the scattering angle. A narrow detector field of view of + or - 1/4 degree of scattering along with a single wavelength of incident light is used to minimize uncertainties in the scattering theory. The system is automated for data acquisition of the scattering matrix elements over an angular range from 2 degrees to 178 degrees of scattering. Both laser output and detector sensitivity are monitored to normalize the measured light scattering.

Multiple-Fiber-Optic Probe For Light-Scattering Measurements

NASA Technical Reports Server (NTRS)

Dhadwal, Harbans Singh; Ansari, Rafat R.

1996-01-01

Multiple-fiber-optical probe developed for use in measuring light scattered at various angles from specimens of materials. Designed for both static and dynamic light-scattering measurements of colloidal dispersions. Probe compact, rugged unit containing no moving parts and remains stationary during operation. Not restricted to operation in controlled, research-laboratory environment. Positioned inside or outside light-scattering chamber. Provides simultaneous measurements at small angular intervals over range of angles, made to include small scattering angles by orienting probe in appropriate direction.

Focusing of light energy inside a scattering medium by controlling the time-gated multiple light scattering

NASA Astrophysics Data System (ADS)

Jeong, Seungwon; Lee, Ye-Ryoung; Choi, Wonjun; Kang, Sungsam; Hong, Jin Hee; Park, Jin-Sung; Lim, Yong-Sik; Park, Hong-Gyu; Choi, Wonshik

2018-05-01

The efficient delivery of light energy is a prerequisite for the non-invasive imaging and stimulating of target objects embedded deep within a scattering medium. However, the injected waves experience random diffusion by multiple light scattering, and only a small fraction reaches the target object. Here, we present a method to counteract wave diffusion and to focus multiple-scattered waves at the deeply embedded target. To realize this, we experimentally inject light into the reflection eigenchannels of a specific flight time to preferably enhance the intensity of those multiple-scattered waves that have interacted with the target object. For targets that are too deep to be visible by optical imaging, we demonstrate a more than tenfold enhancement in light energy delivery in comparison with ordinary wave diffusion cases. This work will lay a foundation to enhance the working depth of imaging, sensing and light stimulation.

Biological cell classification by multiangle light scattering

DOEpatents

Salzman, G.C.; Crowell, J.M.; Mullaney, P.F.

1975-06-03

The specification is directed to an apparatus and method for detecting light scattering from a biological cell. Light, preferably from a coherent source of radiation, intercepts an individual biological cell in a stream of cells passing through the beam. Light scattered from the cell is detected at a selected number of angles between 0 and 90/sup 0/ to the longitudinal axis of the beam with a circular array of light responsive elements which produce signals representative of the intensity of light incident thereon. Signals from the elements are processed to determine the light-scattering pattern of the cell and therefrom its identity.

Biological imaging with coherent Raman scattering microscopy: a tutorial

PubMed Central

Alfonso-García, Alba; Mittal, Richa; Lee, Eun Seong; Potma, Eric O.

2014-01-01

Abstract. Coherent Raman scattering (CRS) microscopy is gaining acceptance as a valuable addition to the imaging toolset of biological researchers. Optimal use of this label-free imaging technique benefits from a basic understanding of the physical principles and technical merits of the CRS microscope. This tutorial offers qualitative explanations of the principles behind CRS microscopy and provides information about the applicability of this nonlinear optical imaging approach for biological research. PMID:24615671

Fiberoptic spectrophotometer

DOEpatents

Tans, P.P.; Lashof, D.A.

1986-12-23

A device is described for determining the relative composition of a sample of a gas by comparison of the Raman-scattered light of the sample with that of a known gas comprising: a means for passing a single light source through the unknown and the known gases, choppers to alternate the Raman-scattered light into a common light detection and measuring system, optical fiber networks for spatially mixing the resulting Raman scattered light from each sample and directing the mixed light to selective detectors, and a compiler to record the light intensity of each wavelength of Raman-scattered light as a function of the sample from which it originated. 6 figs.

Angular-dependent light scattering from cancer cells in different phases of the cell cycle.

PubMed

Lin, Xiaogang; Wan, Nan; Weng, Lingdong; Zhou, Yong

2017-10-10

Cancer cells in different phases of the cell cycle result in significant differences in light scattering properties. In order to harvest cancer cells in particular phases of the cell cycle, we cultured cancer cells through the process of synchronization. Flow cytometric analysis was applied to check the results of cell synchronization and prepare for light scattering measurements. Angular-dependent light scattering measurements of cancer cells arrested in the G1, S, and G2 phases have been performed. Based on integral calculations for scattering intensities from 5° to 10° and from 110° to 150°, conclusions have been reached. Clearly, the sizes of the cancer cells in different phases of the cell cycle dominated the forward scatter. Accompanying the increase of cell size with the progression of the cell cycle, the forward scattering intensity also increased. Meanwhile, the DNA content of cancer cells in every phase of the cell cycle is responsible for light scattering at large scatter angles. The higher the DNA content of cancer cells was, the greater the positive effect on the high-scattering intensity. As expected, understanding the relationships between the light scattering from cancer cells and cell cycles will aid in the development of cancer diagnoses. Also, it may assist in the guidance of antineoplastic drugs clinically.

Using Light Scattering to Track, Characterize and Manipulate Colloids

NASA Astrophysics Data System (ADS)

van Oostrum, P. D. J.

2011-03-01

A new technique is developed to analyze in-line Digital Holographic Microscopy images, making it possible to characterize, and track colloidal particles in three dimensions at unprecedented accuracy. We took digital snapshots of the interference pattern between the light scattered by micrometer particles and the unaltered portion of a laser beam that was used to illuminate dilute colloidal dispersions on a light microscope in transmission mode. We numerically fit Mie-theory for the light-scattering by micrometer sized particles to these experimental in-line holograms. The fit values give the position in three dimensions with an accuracy of a few nanometers in the lateral directions and several tens of nanometers in the axial direction. The individual particles radii and refractive indices could be determined to within tens of nanometers and a few hundredths respectively. By using a fast CCD camera, we can track particles with millisecond resolution in time which allows us to study dynamical properties such as the hydrodynamic radius and the sedimentation coefficient. The scattering behavior of the particles that we use to track and characterize colloidal particles makes it possible to exert pico-Newton forces on them close to a diffraction limited focus. When these effects are used to confine colloids in space, this technique is called Optical Tweezers. Both by numerical calculations and by experiments, we explore the possibilities of optical tweezers in soft condensed matter research. Using optical tweezers we placed multiple particles in interesting configurations to measure the interaction forces between them. The interaction forces were Yukawa-like screened charge repulsions. Careful timing of the blinking of time-shared optical tweezers and of the recording of holographic snapshots, we were able to measure interaction forces with femto-Newton accuracy from an analysis of (driven) Brownian motion. Forces exerted by external fields such as electric fields and gravity were measured as well. We induced electric dipoles in colloidal particles by applying radio frequency electric fields. Dipole induced strings of particles were formed and made permanent by van der Waals attractions or thermal annealing. Such colloidal strings form colloidal analogues of charged and un-charged (bio-) polymers. The diffusion and bending behavior of such strings was probed using DHM and optical tweezers.

Lung cancer diagnosis with quantitative DIC microscopy and support vector machine

NASA Astrophysics Data System (ADS)

Zheng, Longfei; Cai, Shuangshuang; Zeng, Bixin; Xu, Min

2017-01-01

We report the study of lung squamous cell carcinoma diagnosis using the TI-DIC microscopy and the scattering-phase theorem. The spatially resolved optical properties of tissue are computed from the 2D phase map via the scattering-phase theorem. The scattering coefficient, the reduced scattering coefficient, and the anisotropy factor are all found to increase with the grade of lung cancer. The retrieved optical parameters are shown to distinguish cancer cases from the normal cases with high accuracy. This label-free microscopic approach applicable to fresh tissues may be promising for in situ rapid cancer diagnosis.

Light Scattering by Marine Particles: Modeling with Non-spherical Shapes

DTIC Science & Technology

2009-01-01

1491−1499, 1994. Gordon, H.R. and Tao Du, Light scattering by nonspherical particles: application to coccoliths detached from Emiliania huxleyi...from Emiliania huxleyi, Applied Optics, (2009). van de Hulst, H.C., 1957. Light Scattering by Small Particles, Wiley. Xu, Yu-lin, and Bo A.S...G.C. Boynton, Light scattering by coccoliths detached from Emiliania huxleyi, Applied Optics, (2009). [submitted, in revision] 6 m = 1.05

Determination of morphological parameters of biological cells by analysis of scattered-light distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burger, D.E.

1979-11-01

The extraction of morphological parameters from biological cells by analysis of light-scatter patterns is described. A light-scattering measurement system has been designed and constructed that allows one to visually examine and photographically record biological cells or cell models and measure the light-scatter pattern of an individual cell or cell model. Using a laser or conventional illumination, the imaging system consists of a modified microscope with a 35 mm camera attached to record the cell image or light-scatter pattern. Models of biological cells were fabricated. The dynamic range and angular distributions of light scattered from these models was compared to calculatedmore » distributions. Spectrum analysis techniques applied on the light-scatter data give the sought after morphological cell parameters. These results compared favorably to shape parameters of the fabricated cell models confirming the mathematical model procedure. For nucleated biological material, correct nuclear and cell eccentricity as well as the nuclear and cytoplasmic diameters were determined. A method for comparing the flow equivalent of nuclear and cytoplasmic size to the actual dimensions is shown. This light-scattering experiment provides baseline information for automated cytology. In its present application, it involves correlating average size as measured in flow cytology to the actual dimensions determined from this technique. (ERB)« less

Influence of surface light scattering in hydrophobic acrylic intraocular lenses on laser beam transmittance.

PubMed

Shiraya, Tomoyasu; Kato, Satoshi; Minami, Keiichiro; Miyata, Kazunori

2017-02-01

The aim of this study was to experimentally examine the changes in the transmittances of photocoagulation lasers when surface light scattering increases in AcrySof intraocular lenses (IOLs). SA60AT IOLs (Alcon) were acceleratingly aging for 0, 3, 5, and 10 years to simulate surface light scattering, and the surface light-scattering intensities of both IOL surfaces were measured using a Scheimpflug photographer. The powers of laser beams that passed from a laser photocoagulator through the aged IOLs were measured at 532, 577, and 647 nm. Changes in the laser power and transmittance with the years of aging and the intensities of surface light scattering were examined. Although the intensity of surface light scattering increased with the years of aging, the laser power did not change with the years of aging (P > 0.30, Kruskal-Wallis test). There were no significant changes in the laser transmittance with the years of aging or the laser wavelength (P > 0.30 and 0.57, respectively). The intensity of surface light scattering revealed no significant association with the laser transmittance at any wavelength (P > 0.37, liner regression). The increases in the surface light scattering of the AcrySof IOLs would not influence retinal photocoagulation treatments for up to 10 years after implantation.

Polarized light scattering as a probe for changes in chromosome structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shapiro, Daniel Benjamin

1993-10-01

Measurements and calculations of polarized light scattering are applied to chromosomes. Calculations of the Mueller matrix, which completely describes how the polarization state of light is altered upon scattering, are developed for helical structures related to that of chromosomes. Measurements of the Mueller matrix are presented for octopus sperm heads, and dinoflagellates. Comparisons of theory and experiment are made. A working theory of polarized light scattering from helices is developed. The use of the first Born approximation vs the coupled dipole approximation are investigated. A comparison of continuous, calculated in this work, and discrete models is also discussed. By comparingmore » light scattering measurements with theoretical predictions the average orientation of DNA in an octopus sperm head is determined. Calculations are made for the Mueller matrix of DNA plectonemic helices at UV, visible and X-ray wavelengths. Finally evidence is presented that the chromosomes of dinoflagellates are responsible for observed differential scattering of circularly-polarized light. This differential scattering is found to vary in a manner that is possibly correlated to the cell cycle of the dinoflagellates. It is concluded that by properly choosing the wavelength probe polarized light scattering can provide a useful tool to study chromosome structure.« less

Label-free optical imaging of nonfluorescent molecules by stimulated radiation.

PubMed

Min, Wei

2011-12-01

Imaging contrasts other than fluorescence are highly desirable for label-free detection and interrogation of nonfluorescent molecular species inside live cells, tissues, and organisms. The recently developed stimulated Raman scattering (SRS) and stimulated emission microscopy techniques provide sensitive and specific contrast mechanisms for nonfluorescent species, by employing the light amplification aspect of stimulated radiation. Compared to their spontaneous counterparts, stimulated radiation can enhance the imaging performance significantly, making the previously 'dark' molecules observable. Here we review and summarize the underlying principles of this emerging class of molecular imaging techniques. Copyright © 2011 Elsevier Ltd. All rights reserved.

Can a droplet break up under flow without elongating? Fragmentation of smectic monodisperse droplets

NASA Astrophysics Data System (ADS)

Courbin, L.; Engl, W.; Panizza, P.

2004-06-01

We study the fragmentation under shear flow of smectic monodisperse droplets at high volume fraction. Using small angle light scattering and optical microscopy, we reveal the existence of a break-up mechanism for which the droplets burst into daughter droplets of the same size. Surprisingly, this fragmentation process, which is strain controlled and occurs homogeneously in the cell, does not require any transient elongation of the droplets. Systematic experiments as a function of the initial droplet size and the applied shear rate show that the rupture is triggered by an instability of the inner droplet structure.

Spin-wave wavelength down-conversion at thickness steps

NASA Astrophysics Data System (ADS)

Stigloher, Johannes; Taniguchi, Takuya; Madami, Marco; Decker, Martin; Körner, Helmut S.; Moriyama, Takahiro; Gubbiotti, Gianluca; Ono, Teruo; Back, Christian H.

2018-05-01

We report a systematic experimental study on the refraction and reflection of magnetostatic spin-waves at a thickness step between two Permalloy films of different thickness. The transmitted spin-waves for the transition from a thick film to a thin film have a higher wave vector compared to the incoming waves. Consequently, such systems may find use as passive wavelength transformers in magnonic networks. We investigate the spin-wave transmission behavior by studying the influence of the external magnetic field, incident angle, and thickness ratio of the films using time-resolved scanning Kerr microscopy and micro-focused Brillouin light scattering.

Observation of Dust Stream Formation Produced by Low Current, High Voltage Cathode Spots

NASA Technical Reports Server (NTRS)

Foster, John E.

2004-01-01

Macro-particle acceleration driven by low current, high voltage cathode spots has been investigated. The phenomenon was observed to occur when nanometer and micrometer-sized particles in the presence of a discharge plasma were exposed to a high voltage pulse. The negative voltage pulse initiates the formation of multiple, high voltage, low current cathode spots which provides the mechanism of actual acceleration of the charged dust particles. Dust streams generated by this process were detected using laser scattering techniques. The particle impact craters observed at the surface of downstream witness badges were documented using SEM and light microscopy.

Structure and Dynamics of Interfaces: Drops and Films

NASA Technical Reports Server (NTRS)

Mann, J. Adin, Jr.; Mann, Elizabeth K.; Meyer, William V.; Neumann, A. Wilhelm; Tavana, Hossein

2015-01-01

We aim to acquire measurements of the structure and dynamics of certain liquid-fluid interfaces using an ensemble of techniques in collaboration: (1) Total internal reflection (TIR) Surface light scattering spectroscopy (SLSS), (2) Brewster angle microscopy (BAM), and (3) Drop-shape analysis. SLSS and BAM can be done on a shared interfacial footprint. Results using a 50-50 mixture of pentane-isohexane, which extends the range of NASA's Confined Vapor Bubble (CVB) experiment, yield surface tension results that differ from the expected Langmuir Fit. These results were confirmed using both the SLSS and drop-shape analysis approaches.

Microwave-assisted synthesis and micellization behavior of soy-based copoly(2-oxazoline)s.

PubMed

Hoogenboom, Richard; Leenen, Mark A M; Huang, Haiying; Fustin, Charles-André; Gohy, Jean-François; Schubert, Ulrich S

2006-01-01

Polymers based on renewable resources are promising candidates for replacing common organic polymers, and thus, for reducing oil consumption. In this contribution we report the microwave-assisted synthesis of block and statistical copolymers from 2-ethyl-2-oxazoline and 2-"soy alkyl"-2-oxazoline via a cationic ring-opening polymerization mechanism. The synthesized copolymers were characterized by gel permeation chromatography and 1 H-NMR spectroscopy. The micellization of these amphiphilic copolymers was investigated by dynamic light scattering and atomic force microscopy to examine the effect of hydrophobic block length and monomer distribution on the resulting micellar characteristics.

Gelation of Regenerated Fibroin Solution

NASA Astrophysics Data System (ADS)

Nagarkar, Shailesh; Lele, Ashish; Chassenieux, Christophe; Nicolai, Taco; Durand, Dominique

2008-07-01

Silk fibroin is a high molecular weight multiblock ampiphillic protein known for its ability to form high strength fibers. It is also biocompatible; silk sutures have been traditionally used for many centuries. Recently, there has been much interest in making silk hydrogels for applications ranging from tissue engineering to controlled delivery. Fibroin gels can be formed from aqueous solutions by changing one or more state variables such as pH, temperature and ionic strength. In this work we present our investigations on the gelation of aqueous fibroin solutions derived from Bombyx Mori silk using light scattering, confocal microscopy and rheological techniques.

Rare-earth-doped nanophosphors for multicolor cathodoluminescence nanobioimaging using scanning transmission electron microscopy.

PubMed

Furukawa, Taichi; Fukushima, Shoichiro; Niioka, Hirohiko; Yamamoto, Naoki; Miyake, Jun; Araki, Tsutomu; Hashimoto, Mamoru

2015-05-01

We describe rare-earth-doped nanophosphors (RE-NPs) for biological imaging using cathodoluminescence(CL) microscopy based on scanning transmission electron microscopy (STEM). We report the first demonstration of multicolor CL nanobioimaging using STEM with nanophosphors. The CL spectra of the synthesized nanophosphors (Y2O3∶Eu, Y2O3∶Tb) were sufficiently narrow to be distinguished. From CL images of RE-NPs on an elastic carbon-coated copper grid, the spatial resolution was beyond the diffraction limit of light.Y2O3∶Tb and Y2O3∶Eu RE-NPs showed a remarkable resistance against electron beam exposure even at high acceleration voltage (80 kV) and retained a CL intensity of more than 97% compared with the initial intensity for 1 min. In biological CL imaging with STEM, heavy-metal-stained cell sections containing the RE-NPs were prepared,and both the CL images of RE-NPs and cellular structures, such as mitochondria, were clearly observed from STEM images with high contrast. The cellular CL imaging using RE-NPs also had high spatial resolution even though heavy-metal-stained cells are normally regarded as highly scattering media. Moreover, since theRE-NPs exhibit photoluminescence (PL) excited by UV light, they are useful for multimodal correlative imaging using CL and PL.

Statistical parametric mapping of stimuli-evoked changes in quantitative blood flow using extended-focus optical coherence microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Marchand, Paul J.; Bouwens, Arno; Shamaei, Vincent; Nguyen, David; Extermann, Jerome; Bolmont, Tristan; Lasser, Theo

2016-03-01

Magnetic Resonance Imaging has revolutionised our understanding of brain function through its ability to image human cerebral structures non-invasively over the entire brain. By exploiting the different magnetic properties of oxygenated and deoxygenated blood, functional MRI can indirectly map areas undergoing neural activation. Alongside the development of fMRI, powerful statistical tools have been developed in an effort to shed light on the neural pathways involved in processing of sensory and cognitive information. In spite of the major improvements made in fMRI technology, the obtained spatial resolution of hundreds of microns prevents MRI in resolving and monitoring processes occurring at the cellular level. In this regard, Optical Coherence Microscopy is an ideal instrumentation as it can image at high spatio-temporal resolution. Moreover, by measuring the mean and the width of the Doppler spectra of light scattered by moving particles, OCM allows extracting the axial and lateral velocity components of red blood cells. The ability to assess quantitatively total blood velocity, as opposed to classical axial velocity Doppler OCM, is of paramount importance in brain imaging as a large proportion of cortical vascular is oriented perpendicularly to the optical axis. We combine here quantitative blood flow imaging with extended-focus Optical Coherence Microscopy and Statistical Parametric Mapping tools to generate maps of stimuli-evoked cortical hemodynamics at the capillary level.

Structure-property evolution during polymer crystallization

NASA Astrophysics Data System (ADS)

Arora, Deepak

The main theme of this research is to understand the structure-property evolution during crystallization of a semicrystalline thermoplastic polymer. A combination of techniques including rheology, small angle light scattering, differential scanning calorimetry and optical microscopy are applied to follow the mechanical and optical properties along with crystallinity and the morphology. Isothermal crystallization experiments on isotactic poly-1-butene at early stages of spherulite growth provide quantitative information about nucleation density, volume fraction of spherulites and their crystallinity, and the mechanism of connecting into a sample spanning structure. Optical microscopy near the fluid-to-solid transition suggests that the transition, as determined by time-resolved mechanical spectroscopy, is not caused by packing/jamming of spherulites but by the formation of a percolating network structure. The effect of strain, Weissenberg number (We ) and specific mechanical work (w) on rate of crystallization (nucleation followed by growth) and on growth of anisotropy was studied for shear-induced crystallization of isotactic poly-1-butene. The samples were sheared for a finite strain at the beginning of the experiment and then crystallized without further flow (Janeschitz-Kriegl protocol). Strain requirements to attain steady state/leveling off of the rate of crystallization were found to be much larger than the strain needed to achieve steady state of flow. The large strain and We>1 criteria were also observed for morphological transition from spherulitic growth to oriented growth. An apparatus for small angle light scattering (SALS) and light transmission measurements under shear was built and tested at the University of Massachusetts Amherst. As a new development, the polarization direction can be rotated by a liquid crystal polarization rotator (LCPR) with a short response time of 20 ms. The experiments were controlled and analyzed with a LabVIEW(TM) based code (LabVIEW(TM) 7.1) in real time. The SALS apparatus was custom built for ExxonMobil Research in Clinton NJ.

High-throughput analysis of sub-visible mAb aggregate particles using automated fluorescence microscopy imaging.

PubMed

Paul, Albert Jesuran; Bickel, Fabian; Röhm, Martina; Hospach, Lisa; Halder, Bettina; Rettich, Nina; Handrick, René; Herold, Eva Maria; Kiefer, Hans; Hesse, Friedemann

2017-07-01

Aggregation of therapeutic proteins is a major concern as aggregates lower the yield and can impact the efficacy of the drug as well as the patient's safety. It can occur in all production stages; thus, it is essential to perform a detailed analysis for protein aggregates. Several methods such as size exclusion high-performance liquid chromatography (SE-HPLC), light scattering, turbidity, light obscuration, and microscopy-based approaches are used to analyze aggregates. None of these methods allows determination of all types of higher molecular weight (HMW) species due to a limited size range. Furthermore, quantification and specification of different HMW species are often not possible. Moreover, automation is a perspective challenge coming up with automated robotic laboratory systems. Hence, there is a need for a fast, high-throughput-compatible method, which can detect a broad size range and enable quantification and classification. We describe a novel approach for the detection of aggregates in the size range 1 to 1000 μm combining fluorescent dyes for protein aggregate labelling and automated fluorescence microscope imaging (aFMI). After appropriate selection of the dye and method optimization, our method enabled us to detect various types of HMW species of monoclonal antibodies (mAbs). Using 10 μmol L -1 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonate (Bis-ANS) in combination with aFMI allowed the analysis of mAb aggregates induced by different stresses occurring during downstream processing, storage, and administration. Validation of our results was performed by SE-HPLC, UV-Vis spectroscopy, and dynamic light scattering. With this new approach, we could not only reliably detect different HMW species but also quantify and classify them in an automated approach. Our method achieves high-throughput requirements and the selection of various fluorescent dyes enables a broad range of applications.

Coherent Raman Scattering Microscopy in Biology and Medicine.

PubMed

Zhang, Chi; Zhang, Delong; Cheng, Ji-Xin

2015-01-01

Advancements in coherent Raman scattering (CRS) microscopy have enabled label-free visualization and analysis of functional, endogenous biomolecules in living systems. When compared with spontaneous Raman microscopy, a key advantage of CRS microscopy is the dramatic improvement in imaging speed, which gives rise to real-time vibrational imaging of live biological samples. Using molecular vibrational signatures, recently developed hyperspectral CRS microscopy has improved the readout of chemical information available from CRS images. In this article, we review recent achievements in CRS microscopy, focusing on the theory of the CRS signal-to-noise ratio, imaging speed, technical developments, and applications of CRS imaging in bioscience and clinical settings. In addition, we present possible future directions that the use of this technology may take.

Coherent Raman Scattering Microscopy in Biology and Medicine

PubMed Central

Zhang, Chi; Zhang, Delong; Cheng, Ji-Xin

2016-01-01

Advancements in coherent Raman scattering (CRS) microscopy have enabled label-free visualization and analysis of functional, endogenous biomolecules in living systems. When compared with spontaneous Raman microscopy, a key advantage of CRS microscopy is the dramatic improvement in imaging speed, which gives rise to real-time vibrational imaging of live biological samples. Using molecular vibrational signatures, recently developed hyperspectral CRS microscopy has improved the readout of chemical information available from CRS images. In this article, we review recent achievements in CRS microscopy, focusing on the theory of the CRS signal-to-noise ratio, imaging speed, technical developments, and applications of CRS imaging in bioscience and clinical settings. In addition, we present possible future directions that the use of this technology may take. PMID:26514285

Double-layered liquid crystal light shutter for control of absorption and scattering of the light incident to a transparent display device

NASA Astrophysics Data System (ADS)

Huh, Jae-Won; Yu, Byeong-Hun; Shin, Dong-Myung; Yoon, Tae-Hoon

2015-03-01

Recently, a transparent display has got much attention as one of the next generation display devices. Especially, active studies on a transparent display using organic light-emitting diodes (OLEDs) are in progress. However, since it is not possible to obtain black color using a transparent OLED, it suffers from poor visibility. This inevitable problem can be solved by using a light shutter. Light shutter technology can be divided into two types; light absorption and scattering. However, a light shutter based on light absorption cannot block the background image perfectly and a light shutter based on light scattering cannot provide black color. In this work we demonstrate a light shutter using two liquid crystal (LC) layers, a light absorption layer and a light scattering layer. To realize a light absorption layer and a light scattering layer, we use the planar state of a dye-doped chiral nematic LC (CNLC) cell and the focal-conic state of a long-pitch CNLC cell, respectively. The proposed light shutter device can block the background image perfectly and show black color. We expect that the proposed light shutter can increase the visibility of a transparent display.

Live-cell stimulated Raman scattering imaging of alkyne-tagged biomolecules.

PubMed

Hong, Senlian; Chen, Tao; Zhu, Yuntao; Li, Ang; Huang, Yanyi; Chen, Xing

2014-06-02

Alkynes can be metabolically incorporated into biomolecules including nucleic acids, proteins, lipids, and glycans. In addition to the clickable chemical reactivity, alkynes possess a unique Raman scattering within the Raman-silent region of a cell. Coupling this spectroscopic signature with Raman microscopy yields a new imaging modality beyond fluorescence and label-free microscopies. The bioorthogonal Raman imaging of various biomolecules tagged with an alkyne by a state-of-the-art Raman imaging technique, stimulated Raman scattering (SRS) microscopy, is reported. This imaging method affords non-invasiveness, high sensitivity, and molecular specificity and therefore should find broad applications in live-cell imaging. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Path-length-resolved dynamic light scattering in highly scattering random media: The transition to diffusing wave spectroscopy

NASA Astrophysics Data System (ADS)

Bizheva, Kostadinka K.; Siegel, Andy M.; Boas, David A.

1998-12-01

We used low coherence interferometry to measure Brownian motion within highly scattering random media. A coherence gate was applied to resolve the optical path-length distribution and to separate ballistic from diffusive light. Our experimental analysis provides details on the transition from single scattering to light diffusion and its dependence on the system parameters. We found that the transition to the light diffusion regime occurs at shorter path lengths for media with higher scattering anisotropy or for larger numerical aperture of the focusing optics.

Aquaporin-Based Biomimetic Polymeric Membranes: Approaches and Challenges

PubMed Central

Habel, Joachim; Hansen, Michael; Kynde, Søren; Larsen, Nanna; Midtgaard, Søren Roi; Jensen, Grethe Vestergaard; Bomholt, Julie; Ogbonna, Anayo; Almdal, Kristoffer; Schulz, Alexander; Hélix-Nielsen, Claus

2015-01-01

In recent years, aquaporin biomimetic membranes (ABMs) for water separation have gained considerable interest. Although the first ABMs are commercially available, there are still many challenges associated with further ABM development. Here, we discuss the interplay of the main components of ABMs: aquaporin proteins (AQPs), block copolymers for AQP reconstitution, and polymer-based supporting structures. First, we briefly cover challenges and review recent developments in understanding the interplay between AQP and block copolymers. Second, we review some experimental characterization methods for investigating AQP incorporation including freeze-fracture transmission electron microscopy, fluorescence correlation spectroscopy, stopped-flow light scattering, and small-angle X-ray scattering. Third, we focus on recent efforts in embedding reconstituted AQPs in membrane designs that are based on conventional thin film interfacial polymerization techniques. Finally, we describe some new developments in interfacial polymerization using polyhedral oligomeric silsesquioxane cages for increasing the physical and chemical durability of thin film composite membranes. PMID:26264033

Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging

PubMed Central

Cua, Michelle; Wahl, Daniel J.; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J.; Jian, Yifan; Sarunic, Marinko V.

2016-01-01

Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems. PMID:27599635

Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging.

PubMed

Cua, Michelle; Wahl, Daniel J; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J; Jian, Yifan; Sarunic, Marinko V

2016-09-07

Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems.

Laser light scattering from wood samples soaked in water or in benzyl benzoate

NASA Astrophysics Data System (ADS)

Simonaho, S.-P.; Tolonen, Y.; Rouvinen, J.; Silvennoinen, R.

Laser light scattering from Scots pine (Pinus Sylvesteris L.) wood samples soaked in two different liquids, which were tap water and benzyl benzoate, has been experimentally investigated. Differences in the characteristics of the scattering pattern as function of the soaking time as well as the moisture effect in the orientation of scattering pattern has been experimentally investigated. The wood samples soaked in the test liquids altered the laser light scattering in along and across the grain directions. No correlation between the content of the water in the wood sample and the orientation of laser light scattering pattern was observed.

Light scatter on the surface of AcrySof intraocular lenses: part I. Analysis of lenses retrieved from pseudophakic postmortem human eyes.

PubMed

Yaguchi, Shigeo; Nishihara, Hitoshi; Kambhiranond, Waraporn; Stanley, Daniel; Apple, David J

2008-01-01

To investigate the cause of light scatter measured on the surface of AcrySof intraocular lenses (Alcon Laboratories, Inc., Fort Worth, TX) retrieved from pseudophakic postmortem human eyes. Ten intraocular lenses (Alcon AcrySofModel MA60BM) were retrieved postmortem and analyzed for light scatter before and after removal of surface-bound biofilms. Six of the 10 lenses exhibited light scatter that was clearly above baseline levels. In these 6 lenses, both peak and average pixel density were reduced by approximately 80% after surface cleaning. The current study demonstrates that a coating deposited in vivo on the lens surface is responsible for the light scatter observed when incident light is applied.

Fiber optic light-scattering measurement system for evaluation of embryo viability: light-scattering characteristics from live mouse embryo

NASA Astrophysics Data System (ADS)

Itoh, Harumi; Arai, Tsunenori; Kikuchi, Makoto

1997-06-01

We measured angular distribution of the light scattering from live mouse embryo with 632.8nm in wavelength to evaluate the embryo viability. We aim to measure the mitochondrial density in human embryo which have relation to the embryo viability. We have constructed the light scattering measurement system to detect the mitochondrial density non-invasively. We have employed two optical fibers for the illumination and sensing to change the angle between these fibers. There were two dips on the scattering angular distribution from the embryo. These dips existed on 30 and 85 deg. We calculated the scattering angular pattern by Mie theory to fit the measured scattering estimated scattering size and density. The best fitting was obtained when the particle size and density were 0.9 micrometers and 1010 particles per ml, respectively. These values coincided with the approximated values of mitochondrial in the embryo. The measured light scattering may mainly originated from mitochondria in spite of the existence of the various scattering particles in the embryo. Since our simple scattering measurement may offer the mitochondrial density in the embryo, it might become the practical method of human embryo on in vitro fertilization-embryo transfer.

Size-dependent longitudinal plasmon resonance wavelength and extraordinary scattering properties of Au nanobipyramids.

PubMed

Wang, Wenhao; Yu, Peng; Zhong, Zhiqin; Tong, Xin; Liu, Tianji; Li, Yanbo; Ashalley, Eric; Chen, Huanyang; Wu, Jiang; Wang, Zhiming

2018-08-31

Au nanobipyramids (NBPs) with sharp tips and narrow plasmon linewidths are ideal candidates for plasmonic applications. In this paper, we investigated the influencing factors of longitudinal plasmon resonance wavelength (LPRW) and scattering properties of single Au NBP by simulation. Compared with the volume, we establish the aspect ratio (length/width) as the dominant factor that affects the LPRW of Au NBPs. Plasmonic nanoparticles have been widely used for light-trapping enhancement in photovoltaics. To give a profound understanding of the superior light harvesting properties of Au NBPs, the near-field localization effect and far-field scattering mechanism of Au NBPs were investigated. Under the light injection at LPRW, the tip area shows near-field enhancement and the maximum scattering intensity appears on the side area of the waist owing to the remarkable optical absorption near the tips. Additionally, we confirm the fraction of light scattered into the substrate and angular distribution of the light scattered by the Au NBPs. The fraction of light scattered into the substrate reaches up to 97% from 400-1100 nm and preserves a broadband spectrum. This suggests that the NBP has a predominant forward scattering and reduced backward scattering. The excellent plasmonic scattering properties of Au NBPs are promising in photovoltaic devices and photothermal therapy.

The structural and optical properties of type III human collagen biosynthetic corneal substitutes

PubMed Central

Hayes, Sally; Lewis, Phillip; Islam, M. Mirazul; Doutch, James; Sorensen, Thomas; White, Tomas; Griffith, May; Meek, Keith M.

2015-01-01

The structural and optical properties of clinically biocompatible, cell-free hydrogels comprised of synthetically cross-linked and moulded recombinant human collagen type III (RHCIII) with and without the incorporation of 2-methacryloyloxyethyl phosphorylcholine (MPC) were assessed using transmission electron microscopy (TEM), X-ray scattering, spectroscopy and refractometry. These findings were examined alongside similarly obtained data from 21 human donor corneas. TEM demonstrated the presence of loosely bundled aggregates of fine collagen filaments within both RHCIII and RHCIII-MPC implants, which X-ray scattering showed to lack D-banding and be preferentially aligned in a uniaxial orientation throughout. This arrangement differs from the predominantly biaxial alignment of collagen fibrils that exists in the human cornea. By virtue of their high water content (90%), very fine collagen filaments (2–9 nm) and lack of cells, the collagen hydrogels were found to transmit almost all incident light in the visible spectrum. They also transmitted a large proportion of UV light compared to the cornea which acts as an effective UV filter. Patients implanted with these hydrogels should be cautious about UV exposure prior to regrowth of the epithelium and in-growth of corneal cells into the implants. PMID:26159106

Effect of Monomer Solubility on the Evolution of Copolymer Morphology during Polymerization-Induced Self-Assembly in Aqueous Solution

PubMed Central

2017-01-01

Polymerization-induced self-assembly (PISA) has become a widely used technique for the rational design of diblock copolymer nano-objects in concentrated aqueous solution. Depending on the specific PISA formulation, reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization typically provides straightforward access to either spheres, worms, or vesicles. In contrast, RAFT aqueous emulsion polymerization formulations often lead to just kinetically-trapped spheres. This limitation is currently not understood, and only a few empirical exceptions have been reported in the literature. In the present work, the effect of monomer solubility on copolymer morphology is explored for an aqueous PISA formulation. Using 2-hydroxybutyl methacrylate (aqueous solubility = 20 g dm–3 at 70 °C) instead of benzyl methacrylate (0.40 g dm–3 at 70 °C) for the core-forming block allows access to an unusual “monkey nut” copolymer morphology over a relatively narrow range of target degrees of polymerization when using a poly(methacrylic acid) RAFT agent at pH 5. These new anisotropic nanoparticles have been characterized by transmission electron microscopy, dynamic light scattering, aqueous electrophoresis, shear-induced polarized light imaging (SIPLI), and small-angle X-ray scattering. PMID:28216792

One-step analysis of DNA/chitosan complexes by field-flow fractionation reveals particle size and free chitosan content.

PubMed

Ma, Pei Lian; Buschmann, Michael D; Winnik, Françoise M

2010-03-08

The composition of samples obtained upon complexation of DNA with chitosan was analyzed by asymmetrical flow field flow fractionation (AF4) with online UV-visible, multiangle light scattering (MALS), and dynamic light scattering (DLS) detectors. A chitosan labeled with rhodamine B to facilitate UV-vis detection of the polycation was complexed with DNA under conditions commonly used for transfection (chitosan glucosamine to DNA phosphate molar ratio of 5). AF4 analysis revealed that 73% of the chitosan-rhodamine remained free in the dispersion and that the DNA/chitosan complexes had a broad size distribution ranging from 20 to 160 nm in hydrodynamic radius. The accuracy of the data was assessed by comparison with data from batch-mode DLS and scanning electron microscopy. The AF4 combined with DLS allowed the characterization of small particles that were not detected by conventional batch-mode DLS. The AF4 analysis will prove to be an important tool in the field of gene therapy because it readily provides, in a single measurement, three important physicochemical parameters of the complexes: the amount of unbound polycation, the hydrodynamic size of the complexes, and their size distribution.

Photovoltaic structures having a light scattering interface layer and methods of making the same

DOEpatents

Liu, Xiangxin; Compaan, Alvin D.; Paudel, Naba Raj

2015-10-13

Photovoltaic (PV) cell structures having an integral light scattering interface layer configured to diffuse or scatter light prior to entering a semiconductor material and methods of making the same are described.

Methods and apparatus for transparent display using scattering nanoparticles

DOEpatents

Hsu, Chia Wei; Qiu, Wenjun; Zhen, Bo; Shapira, Ofer; Soljacic, Marin

2017-06-14

Transparent displays enable many useful applications, including heads-up displays for cars and aircraft as well as displays on eyeglasses and glass windows. Unfortunately, transparent displays made of organic light-emitting diodes are typically expensive and opaque. Heads-up displays often require fixed light sources and have limited viewing angles. And transparent displays that use frequency conversion are typically energy inefficient. Conversely, the present transparent displays operate by scattering visible light from resonant nanoparticles with narrowband scattering cross sections and small absorption cross sections. More specifically, projecting an image onto a transparent screen doped with nanoparticles that selectively scatter light at the image wavelength(s) yields an image on the screen visible to an observer. Because the nanoparticles scatter light at only certain wavelengths, the screen is practically transparent under ambient light. Exemplary transparent scattering displays can be simple, inexpensive, scalable to large sizes, viewable over wide angular ranges, energy efficient, and transparent simultaneously.

Light scatter on the surface of AcrySof intraocular lenses: part II. Analysis of lenses following hydrolytic stability testing.

PubMed

Yaguchi, Shigeo; Nishihara, Hitoshi; Kambhiranond, Waraporn; Stanley, Daniel; Apple, David

2008-01-01

To investigate the surface light scatter and optical quality of AcrySof lenses (Alcon Laboratories, Inc., Fort Worth, TX) following simulated aging of 20 years. AcrySof lenses were exposed to exaggerated thermal conditions to simulate up to 20 years of aging and were tested for surface light scatter and optical quality (modulation transfer function). There were no significant differences from baseline for either the surface light scatter or optical quality of the lenses over time. The current study demonstrated that surface light scatter on AcrySof lenses did not increase under conditions simulating 20 years of aging. Because the simulated aging environment contained no protein, this work indirectly supports the finding that surface light scatter is due to the deposition of a biomaterial on the lens surface rather than changes in the material. Optical performance integrity of the test lenses was maintained under severe environmental conditions.

Effective phase function of light scattered at small angles by polydisperse particulate media

NASA Astrophysics Data System (ADS)

Turcu, I.

2008-06-01

Particles with typical dimensions higher than the light wavelength and relative refraction indexes close to one, scatter light mainly in the forward direction where the scattered light intensity has a narrow peak. For particulate media accomplishing these requirements the light scattered at small angles in a far-field detecting set-up can be described analytically by an effective phase function (EPF) even in the multiple scattering regime. The EPF model which was built for monodispersed systems has been extended to polydispersed media. The main ingredients consist in the replacement of the single particle phase function and of the optical thickness with their corresponding averaged values. Using a Gamma particle size distribution (PSD) as a testing model, the effect of polydispersity was systematically investigated. The increase of the average radius or/and of the PSD standard deviation leads to the decrease of the angular spreading of the small angle scattered light.

Methods and apparatus for transparent display using scattering nanoparticles

DOEpatents

Hsu, Chia Wei; Qiu, Wenjun; Zhen, Bo; Shapira, Ofer; Soljacic, Marin

2016-05-10

Transparent displays enable many useful applications, including heads-up displays for cars and aircraft as well as displays on eyeglasses and glass windows. Unfortunately, transparent displays made of organic light-emitting diodes are typically expensive and opaque. Heads-up displays often require fixed light sources and have limited viewing angles. And transparent displays that use frequency conversion are typically energy inefficient. Conversely, the present transparent displays operate by scattering visible light from resonant nanoparticles with narrowband scattering cross sections and small absorption cross sections. More specifically, projecting an image onto a transparent screen doped with nanoparticles that selectively scatter light at the image wavelength(s) yields an image on the screen visible to an observer. Because the nanoparticles scatter light at only certain wavelengths, the screen is practically transparent under ambient light. Exemplary transparent scattering displays can be simple, inexpensive, scalable to large sizes, viewable over wide angular ranges, energy efficient, and transparent simultaneously.

Brillouin light scattering from surface acoustic waves in a subwavelength-diameter optical fibre

PubMed Central

Beugnot, Jean-Charles; Lebrun, Sylvie; Pauliat, Gilles; Maillotte, Hervé; Laude, Vincent; Sylvestre, Thibaut

2014-01-01

Brillouin scattering in optical fibres is a fundamental interaction between light and sound with important implications ranging from optical sensors to slow and fast light. In usual optical fibres, light both excites and feels shear and longitudinal bulk elastic waves, giving rise to forward-guided acoustic wave Brillouin scattering and backward-stimulated Brillouin scattering. In a subwavelength-diameter optical fibre, the situation changes dramatically, as we here report with the first experimental observation of Brillouin light scattering from surface acoustic waves. These Rayleigh-type surface waves travel the wire surface at a specific velocity of 3,400 m s−1 and backscatter the light with a Doppler shift of about 6 GHz. As these acoustic resonances are sensitive to surface defects or features, surface acoustic wave Brillouin scattering opens new opportunities for various sensing applications, but also in other domains such as microwave photonics and nonlinear plasmonics. PMID:25341638

3D widefield light microscope image reconstruction without dyes

NASA Astrophysics Data System (ADS)

Larkin, S.; Larson, J.; Holmes, C.; Vaicik, M.; Turturro, M.; Jurkevich, A.; Sinha, S.; Ezashi, T.; Papavasiliou, G.; Brey, E.; Holmes, T.

2015-03-01

3D image reconstruction using light microscope modalities without exogenous contrast agents is proposed and investigated as an approach to produce 3D images of biological samples for live imaging applications. Multimodality and multispectral imaging, used in concert with this 3D optical sectioning approach is also proposed as a way to further produce contrast that could be specific to components in the sample. The methods avoid usage of contrast agents. Contrast agents, such as fluorescent or absorbing dyes, can be toxic to cells or alter cell behavior. Current modes of producing 3D image sets from a light microscope, such as 3D deconvolution algorithms and confocal microscopy generally require contrast agents. Zernike phase contrast (ZPC), transmitted light brightfield (TLB), darkfield microscopy and others can produce contrast without dyes. Some of these modalities have not previously benefitted from 3D image reconstruction algorithms, however. The 3D image reconstruction algorithm is based on an underlying physical model of scattering potential, expressed as the sample's 3D absorption and phase quantities. The algorithm is based upon optimizing an objective function - the I-divergence - while solving for the 3D absorption and phase quantities. Unlike typical deconvolution algorithms, each microscope modality, such as ZPC or TLB, produces two output image sets instead of one. Contrast in the displayed image and 3D renderings is further enabled by treating the multispectral/multimodal data as a feature set in a mathematical formulation that uses the principal component method of statistics.

Emerging optical nanoscopy techniques

PubMed Central

Montgomery, Paul C; Leong-Hoi, Audrey

2015-01-01

To face the challenges of modern health care, new imaging techniques with subcellular resolution or detection over wide fields are required. Far field optical nanoscopy presents many new solutions, providing high resolution or detection at high speed. We present a new classification scheme to help appreciate the growing number of optical nanoscopy techniques. We underline an important distinction between superresolution techniques that provide improved resolving power and nanodetection techniques for characterizing unresolved nanostructures. Some of the emerging techniques within these two categories are highlighted with applications in biophysics and medicine. Recent techniques employing wider angle imaging by digital holography and scattering lens microscopy allow superresolution to be achieved for subcellular and even in vivo, imaging without labeling. Nanodetection techniques are divided into four subcategories using contrast, phase, deconvolution, and nanomarkers. Contrast enhancement is illustrated by means of a polarized light-based technique and with strobed phase-contrast microscopy to reveal nanostructures. Very high sensitivity phase measurement using interference microscopy is shown to provide nanometric surface roughness measurement or to reveal internal nanometric structures. Finally, the use of nanomarkers is illustrated with stochastic fluorescence microscopy for mapping intracellular structures. We also present some of the future perspectives of optical nanoscopy. PMID:26491270

Quantitative characterization of gold nanoparticles by field-flow fractionation coupled online with light scattering detection and inductively coupled plasma mass spectrometry.

PubMed

Schmidt, Bjørn; Loeschner, Katrin; Hadrup, Niels; Mortensen, Alicja; Sloth, Jens J; Koch, Christian Bender; Larsen, Erik H

2011-04-01

An analytical platform coupling asymmetric flow field-flow fractionation (AF(4)) with multiangle light scattering (MALS), dynamic light scattering (DLS), and inductively coupled plasma mass spectrometry (ICPMS) was established and used for separation and quantitative determination of size and mass concentration of nanoparticles (NPs) in aqueous suspension. Mixtures of three polystyrene (PS) NPs between 20 and 100 nm in diameter and mixtures of three gold (Au) NPs between 10 and 60 nm in diameter were separated by AF(4). The geometric diameters of the separated PS NPs and the hydrodynamic diameters of the Au and PS NPs were determined online by MALS and DLS, respectively. The three separated Au NPs were quantified by ICPMS and recovered at 50-95% of the injected masses, which ranged between approximately 8-80 ng of each nanoparticle size. Au NPs adhering to the membrane in the separation channel was found to be a major cause for incomplete recoveries. The lower limit of detection (LOD) ranged between 0.02 ng Au and 0.4 ng Au, with increasing LOD by increasing nanoparticle diameter. The analytical platform was applied to characterization of Au NPs in livers of rats, which were dosed with 10 nm, 60 nm, or a mixture of 10 and 60 nm nanoparticles by intravenous injection. The homogenized livers were solubilized in tetramethylammonium hydroxide (TMAH), and the recovery of Au NPs from the livers amounted to 86-123% of their total Au content. In spite of successful stabilization with bovine serum albumin even in alkaline medium, separation of the Au NPs by AF(4) was not possible due to association with undissolved remains of the alkali-treated liver tissues as demonstrated by electron microscopy images.

Method and apparatus for aerosol particle absorption spectroscopy

DOEpatents

Campillo, Anthony J.; Lin, Horn-Bond

1983-11-15

A method and apparatus for determining the absorption spectra, and other properties, of aerosol particles. A heating beam source provides a beam of electromagnetic energy which is scanned through the region of the spectrum which is of interest. Particles exposed to the heating beam which have absorption bands within the band width of the heating beam absorb energy from the beam. The particles are also illuminated by light of a wave length such that the light is scattered by the particles. The absorption spectra of the particles can thus be determined from an analysis of the scattered light since the absorption of energy by the particles will affect the way the light is scattered. Preferably the heating beam is modulated to simplify the analysis of the scattered light. In one embodiment the heating beam is intensity modulated so that the scattered light will also be intensity modulated when the particles absorb energy. In another embodiment the heating beam passes through an interferometer and the scattered light reflects the Fourier Transform of the absorption spectra.

Investigation of multimodal forward scatter phenotyping from bacterial colonies

NASA Astrophysics Data System (ADS)

Kim, Huisung

A rapid, label-free, and elastic light scattering (ELS) based bacterial colony phenotyping technology, bacterial rapid detection using optical scattering technology (BARDOT) provides a successful classification of several bacterial genus and species. For a thorough understanding of the phenomena and overcoming the limitations of the previous design, five additional modalities from a bacterial colony: 3D morphology, spatial optical density (OD) distribution, spectral forward scattering pattern, spectral OD, and surface backward reflection pattern are proposed to enhance the classification/identification ratio, and the feasibilities of each modality are verified. For the verification, three different instruments: integrated colony morphology analyzer (ICMA), multi-spectral BARDOT (MS-BARDOT) , and multi-modal BARDOT (MM-BARDOT) are proposed and developed. The ICMA can measure 3D morphology and spatial OD distribution of the colony simultaneously. A commercialized confocal displacement meter is used to measure the profiles of the bacterial colonies, together with a custom built optical density measurement unit to interrogate the biophysics behind the collective behavior of a bacterial colony. The system delivers essential information related to the quantitative growth dynamics (height, diameter, aspect ratio, optical density) of the bacterial colony, as well as, a relationship in between the morphological characteristics of the bacterial colony and its forward scattering pattern. Two different genera: Escherichia coli O157:H7 EDL933, and Staphylococcus aureus ATCC 25923 are selected for the analysis of the spatially resolved growth dynamics, while, Bacillus spp. such as B. subtilis ATCC 6633, B. cereus ATCC 14579, B. thuringiensis DUP6044, B. polymyxa B719W, and B. megaterium DSP 81319, are interrogated since some of the Bacillus spp. provides strikingly different characteristics of ELS patterns, and the origin of the speckle patterns are successfully correlated with the 2-D spatial density map from the ICMA. The MS-BARDOT can measure multispectral elastic-light-scatter patterns of the bacterial colony and its spectral OD to overcome the inherent limits of the single-wavelength BARDOT. A theoretical model for spectral forward scatter patterns from a bacterial colony based on elastic light scatter is presented. The spectral forward scatter patterns are computed by scalar diffraction theory, and compared with experimental results of three discrete wavelengths (405 nm, 635 nm, and 904 nm). Both model and experiment results show an excellent agreement; a longer wavelength induces a wider ring width, a wider ring gap, a smaller pattern size, and smaller numbers of rings. Further analysis using spatial fast Fourier transform (SFFT) shows a good agreement; the spatial frequencies are increasing towards the inward direction, and the slope is inversely proportional to the incoming wavelength. Four major pathogenic bacterial genera (Escherichia coli O157:H7 EDL933, Listeria monocytogenes F4244, Salmonella enterica serovar Enteritidis PT21, and Staphylococcus aureus ATCC 25923) and the seven major Escherichia coli serovar (O26, O45, O103, O111, O121, O145, and O157) with 3-4 strains each are measured and analyzed with the proposed instrument and algorithm. The MM-BARDOT can measure six different modalities: 1) light microscopy, 2) 3D morphology map from confocal microscopy, 3) 3D optical density map, 4) spectral forward scattering pattern, 5) spectral OD, 6) surface backward reflection pattern, and 7) fluorescence of a bacterial colony without moving the specimen. A custom-built confocal microscope with a controller which can be easily attached to an infinity-corrected commercial microscope is designed and built. Since the current BARDOT needs additional information from a bacterial colony to enhance the identification/classification ratio for a lower hierarchy of bacterial taxonomy such as serovar or strain level, the approach can offer a series of coordinates matched and correlated bio-optical characteristics of a colony and enhance the classification accuracy of the previously introduced BARDOT system. Four major pathogenic bacterial genera: Escherichia coli O157:H7 EDL933, Listeria monocytogenes F4244, Salmonella enterica serovar Enteritidis PT21, and Staphylococcus aureus ATCC 25923 are measured and analyzed with the proposed instrument and algorithm. Also, a feasibility test for a smaller colony (up to 500 mum) classification utilizing a surface backward reflection pattern from the measurement is done, and shows a potential as an additional modality for the bacterial phenotyping.

In Situ and In Vivo Molecular Analysis by Coherent Raman Scattering Microscopy

PubMed Central

Liao, Chien-Sheng; Cheng, Ji-Xin

2017-01-01

Coherent Raman scattering (CRS) microscopy is a high-speed vibrational imaging platform with the ability to visualize the chemical content of a living specimen by using molecular vibrational fingerprints. We review technical advances and biological applications of CRS microscopy. The basic theory of CRS and the state-of-the-art instrumentation of a CRS microscope are presented. We further summarize and compare the algorithms that are used to separate the Raman signal from the nonresonant background, to denoise a CRS image, and to decompose a hyperspectral CRS image into concentration maps of principal components. Important applications of single-frequency and hyperspectral CRS microscopy are highlighted. Potential directions of CRS microscopy are discussed. PMID:27306307

Evolution of circular and linear polarization in scattering environments

DOE PAGES

van der Laan, John D.; Wright, Jeremy Benjamin; Scrymgeour, David A.; ...

2015-12-02

This study quantifies the polarization persistence and memory of circularly polarized light in forward-scattering and isotropic (Rayleigh regime) environments; and for the first time, details the evolution of both circularly and linearly polarized states through scattering environments. Circularly polarized light persists through a larger number of scattering events longer than linearly polarized light for all forward-scattering environments; but not for scattering in the Rayleigh regime. Circular polarization’s increased persistence occurs for both forward and backscattered light. The simulated environments model polystyrene microspheres in water with particle diameters of 0.1 μm, 2.0 μm, and 3.0 μm. The evolution of the polarizationmore » states as they scatter throughout the various environments are illustrated on the Poincaré sphere after one, two, and ten scattering events.« less

Light scattering by marine algae: two-layer spherical and nonspherical models

NASA Astrophysics Data System (ADS)

Quirantes, Arturo; Bernard, Stewart

2004-11-01

Light scattering properties of algae-like particles are modeled using the T-matrix for coated scatterers. Two basic geometries have been considered: off-centered coated spheres and centered spheroids. Extinction, scattering and absorption efficiencies, plus scattering in the backward plane, are compared to simpler models like homogeneous (Mie) and coated (Aden-Kerker) models. The anomalous diffraction approximation (ADA), of widespread use in the oceanographic light-scattering community, has also been used as a first approximation, for both homogeneous and coated spheres. T-matrix calculations show that some light scattering values, such as extinction and scattering efficiencies, have little dependence on particle shape, thus reinforcing the view that simpler (Mie, Aden-Kerker) models can be applied to infer refractive index (RI) data from absorption curves. The backscattering efficiency, on the other hand, is quite sensitive to shape. This calls into question the use of light scattering techniques where the phase function plays a pivotal role, and can help explain the observed discrepancy between theoretical and experimental values of the backscattering coefficient in observed in oceanic studies.

Probing neural tissue with airy light-sheet microscopy: investigation of imaging performance at depth within turbid media

NASA Astrophysics Data System (ADS)

Nylk, Jonathan; McCluskey, Kaley; Aggarwal, Sanya; Tello, Javier A.; Dholakia, Kishan

2017-02-01

Light-sheet microscopy (LSM) has received great interest for fluorescent imaging applications in biomedicine as it facilitates three-dimensional visualisation of large sample volumes with high spatiotemporal resolution whilst minimising irradiation of, and photo-damage to the specimen. Despite these advantages, LSM can only visualize superficial layers of turbid tissues, such as mammalian neural tissue. Propagation-invariant light modes have played a key role in the development of high-resolution LSM techniques as they overcome the natural divergence of a Gaussian beam, enabling uniform and thin light-sheets over large distances. Most notably, Bessel and Airy beam-based light-sheet imaging modalities have been demonstrated. In the single-photon excitation regime and in lightly scattering specimens, Airy-LSM has given competitive performance with advanced Bessel-LSM techniques. Airy and Bessel beams share the property of self-healing, the ability of the beam to regenerate its transverse beam profile after propagation around an obstacle. Bessel-LSM techniques have been shown to increase the penetration-depth of the illumination into turbid specimens but this effect has been understudied in biologically relevant tissues, particularly for Airy beams. It is expected that Airy-LSM will give a similar enhancement over Gaussian-LSM. In this paper, we report on the comparison of Airy-LSM and Gaussian-LSM imaging modalities within cleared and non-cleared mouse brain tissue. In particular, we examine image quality versus tissue depth by quantitative spatial Fourier analysis of neural structures in virally transduced fluorescent tissue sections, showing a three-fold enhancement at 50 μm depth into non-cleared tissue with Airy-LSM. Complimentary analysis is performed by resolution measurements in bead-injected tissue sections.

Relative merits and limiting factors for x-ray and electron microscopy of thick, hydrated organic materials

DOE PAGES

Du, Ming; Jacobsen, Chris

2017-10-07

Electron and x-ray microscopes allow one to image the entire, unlabeled structure of hydrated materials at a resolution well beyond what visible light microscopes can achieve. However, both approaches involve ionizing radiation, so that radiation damage must be considered as one of the limits to imaging. Drawing upon earlier work, we describe here a unified approach to estimating the image contrast (and thus the required exposure and corresponding radiation dose) in both x-ray and electron microscopy. This approach accounts for factors such as plural and inelastic scattering, and (in electron microscopy) the use of energy filters to obtain so-called "zeromore » loss" images. As expected, it shows that electron microscopy offers lower dose for specimens thinner than about 1 mu m (such as for studies of macromolecules, viruses, bacteria and archaebacteria, and thin sectioned material), while x-ray microscopy offers superior characteristics for imaging thicker specimen such as whole eukaryotic cells, thick-sectioned tissues, and organs. The required radiation dose scales strongly as a function of the desired spatial resolution, allowing one to understand the limits of live and frozen hydrated specimen imaging. Lastly, we consider the factors limiting x-ray microscopy of thicker materials, suggesting that specimens as thick as a whole mouse brain can be imaged with x-ray microscopes without significant image degradation should appropriate image reconstruction methods be identified.« less

Relative merits and limiting factors for x-ray and electron microscopy of thick, hydrated organic materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Ming; Jacobsen, Chris

Electron and x-ray microscopes allow one to image the entire, unlabeled structure of hydrated materials at a resolution well beyond what visible light microscopes can achieve. However, both approaches involve ionizing radiation, so that radiation damage must be considered as one of the limits to imaging. Drawing upon earlier work, we describe here a unified approach to estimating the image contrast (and thus the required exposure and corresponding radiation dose) in both x-ray and electron microscopy. This approach accounts for factors such as plural and inelastic scattering, and (in electron microscopy) the use of energy filters to obtain so-called "zeromore » loss" images. As expected, it shows that electron microscopy offers lower dose for specimens thinner than about 1 mu m (such as for studies of macromolecules, viruses, bacteria and archaebacteria, and thin sectioned material), while x-ray microscopy offers superior characteristics for imaging thicker specimen such as whole eukaryotic cells, thick-sectioned tissues, and organs. The required radiation dose scales strongly as a function of the desired spatial resolution, allowing one to understand the limits of live and frozen hydrated specimen imaging. Lastly, we consider the factors limiting x-ray microscopy of thicker materials, suggesting that specimens as thick as a whole mouse brain can be imaged with x-ray microscopes without significant image degradation should appropriate image reconstruction methods be identified.« less

A Study of Brownian Motion Using Light Scattering

ERIC Educational Resources Information Center

Clark, Noel A.; Lunacek, Joseph H.

1969-01-01

Describes an apparatus designed to investigate molecular motion by means of light scattering. Light from a He-Ne laser is focused into a cell containing a suspension of polystyrene spheres. The scattered light, collected on the photosurface of a photomultiplier tube, is analyzed. The apparatus won first prize in Demonstration Lecture Apparatus in…

Protein aggregation studied by forward light scattering and light transmission analysis

NASA Astrophysics Data System (ADS)

Penzkofer, A.; Shirdel, J.; Zirak, P.; Breitkreuz, H.; Wolf, E.

2007-12-01

The aggregation of the circadian blue-light photo-receptor cryptochrome from Drosophila melanogaster (dCry) is studied by transmission and forward light scattering measurement in the protein transparent wavelength region. The light scattering in forward direction is caused by Rayleigh scattering which is proportional to the degree of aggregation. The light transmission through the samples in the transparent region is reduced by Mie light scattering in all directions. It depends on the degree of aggregation and the monomer volume fill factor of the aggregates (less total scattering with decreasing monomer volume fill factor of protein globule) allowing a distinction between tightly packed protein aggregation (monomer volume fill factor 1) and loosely packed protein aggregation (monomer volume fill factor less than 1). An increase in aggregation with temperature, concentration, and blue-light exposure is observed. At a temperature of 4 °C and a protein concentration of less than 0.135 mM no dCry aggregation was observed, while at 24 °C and 0.327 mM gelation occurred (loosely packed aggregates occupying the whole solution volume).

Label-free NIR reflectance imaging as a complimentary tool for two-photon fluorescence microscopy: multimodal investigation of stroke (Conference Presentation)

NASA Astrophysics Data System (ADS)

Allegra Mascaro, Anna Letizia; Costantini, Irene; Margoni, Emilia; Iannello, Giulio; Bria, Alessandro; Sacconi, Leonardo; Pavone, Francesco S.

2016-03-01

Two-photon imaging combined with targeted fluorescent indicators is extensively used for visualizing critical features of brain functionality and structural plasticity. Back-scattered photons from the NIR laser provide complimentary information without introducing any exogenous labelling. Here, we describe a versatile approach that, by collecting the reflected NIR light, provides structural details on the myelinated axons and blood vessels in the brain, both in fixed samples and in live animals. Indeed, by combining NIR reflectance and two-photon imaging of a slice of hippocampus from Thy1-GFPm mice, we show the presence of randomly oriented axons intermingled with sparsely fluorescent neuronal processes. The back-scattered photons guide the contextualization of the fluorescence structure within brain atlas thanks to the recognition of characteristic hippocampal structures. Label-free detection of axonal elongations over the layer 2/3 of mouse cortex under a cranial window was also possible in live brain. Finally, blood flow could be measured in vivo, thus validating label free NIR reflectance as a tool for monitoring hemodynamic fluctuations. The prospective versatility of this label-free technique complimentary to two-photon fluorescence microscopy is demonstrated in a mouse model of photothrombotic stroke in which the axonal degeneration and blood flow remodeling can be investigated simultaneously.

Macroscopic and microscopic analysis of the tongue of the common opossum (Didelphis marsupialis).

PubMed

Mançanares, Celina A F; Santos, Amilton C; Piemonte, Maria V; Vasconcelos, Bruno G; Carvalho, Ana F; Miglino, Maria A; Ambrósio, Carlos E; Assis Neto, Antônio C

2012-10-01

We performed a macroscopic and microscopic study of the tongues of common opossums, Didelphis marsupialis, from South America. We studied two males and two females. We collected morphometric data on the tongue with precision calipers. For the light microscopy and scanning electron microscopy analyses, we fixed tissue fragments in 10% formaldehyde and 2.5% glutaraldehyde, respectively. The opossum tongues averaged 5.87 ± 0.20 cm in length, 3.27 ± 0.15 cm in width at the lingual body, and 3.82 ± 0.15 cm in width at the root. The mean thickness of the lingual body was 1.8 ± 0.1 cm, and the thickness of the root was 3.82 ± 0.15 cm. Sharp filiform papillae were scattered across the entire tongue; conical filiform papillae occurred on the lingual body and tongue tip; fungiform papillae were scattered among the filiform papillae on the lingual body and tongue tip; and there were three vallate papillae at the root of the tongue. We found two strands of papillary projections in the tongue root. Despite the low variability observed in the lingual papillae, the morphological data obtained in this study may be related to the opossum's diverse food habits and the extensive geographic distribution of the species throughout America. Copyright © 2012 Wiley Periodicals, Inc.

Thickness dependence of scattering cross-sections in quantitative scanning transmission electron microscopy.

PubMed

Martinez, G T; van den Bos, K H W; Alania, M; Nellist, P D; Van Aert, S

2018-04-01

In quantitative scanning transmission electron microscopy (STEM), scattering cross-sections have been shown to be very sensitive to the number of atoms in a column and its composition. They correspond to the integrated intensity over the atomic column and they outperform other measures. As compared to atomic column peak intensities, which saturate at a given thickness, scattering cross-sections increase monotonically. A study of the electron wave propagation is presented to explain the sensitivity of the scattering cross-sections. Based on the multislice algorithm, we analyse the wave propagation inside the crystal and its link to the scattered signal for the different probe positions contained in the scattering cross-section for detector collection in the low-, middle- and high-angle regimes. The influence to the signal from scattering of neighbouring columns is also discussed. Copyright © 2018 Elsevier B.V. All rights reserved.

Diatomite silica nanoparticles for drug delivery

NASA Astrophysics Data System (ADS)

Ruggiero, Immacolata; Terracciano, Monica; Martucci, Nicola M.; De Stefano, Luca; Migliaccio, Nunzia; Tatè, Rosarita; Rendina, Ivo; Arcari, Paolo; Lamberti, Annalisa; Rea, Ilaria

2014-07-01

Diatomite is a natural fossil material of sedimentary origin, constituted by fragments of diatom siliceous skeletons. In this preliminary work, the properties of diatomite nanoparticles as potential system for the delivery of drugs in cancer cells were exploited. A purification procedure, based on thermal treatments in strong acid solutions, was used to remove inorganic and organic impurities from diatomite and to make them a safe material for medical applications. The micrometric diatomite powder was reduced in nanoparticles by mechanical crushing, sonication, and filtering. Morphological analysis performed by dynamic light scattering and transmission electron microscopy reveals a particles size included between 100 and 300 nm. Diatomite nanoparticles were functionalized by 3-aminopropyltriethoxysilane and labeled by tetramethylrhodamine isothiocyanate. Different concentrations of chemically modified nanoparticles were incubated with cancer cells and confocal microscopy was performed. Imaging analysis showed an efficient cellular uptake and homogeneous distribution of nanoparticles in cytoplasm and nucleus, thus suggesting their potentiality as nanocarriers for drug delivery.

Novel of core-shell AlOOH/Cu nanostructures: Synthesis, characterization, antimicrobial activity and in vitro toxicity in Neuro-2a cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakina, O. V., E-mail: ovbakina@ispms.tsc.ru; Fomenko, A. N., E-mail: alserova@ispms.tsc.ru; Korovin, M. S., E-mail: msk@ispms.tsc.ru

Core-shell micro/nanostructures were fabricated by the reaction of Al/Cu bimetallic nanoparticles with water. Al/Cu nanoparticles have been obtained using the method of simultaneous electrical explosion of a pair of the corresponding metal wires in an argon atmosphere. The nanoparticles are chemically active and interact with water at 60°C to form core-shell micro/nanostructures. The obtained products were characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy and dynamic light scattering and the nitrogen adsorption method. The antibacterial activity of the synthesized structures was investigated against E. coli and St. aureus. The toxic effect of these nanostructures against themore » Neuro-2a neuroblastoma cell line was investigated. AlOOH/Cu nanostructures are shown to inhibit cell proliferation. The AlOOH/Cu nanostructures are good candidates for medical applications.« less

A simple backscattering microscope for fast tracking of biological molecules

PubMed Central

Sowa, Yoshiyuki; Steel, Bradley C.; Berry, Richard M.

2010-01-01

Recent developments in techniques for observing single molecules under light microscopes have helped reveal the mechanisms by which molecular machines work. A wide range of markers can be used to detect molecules, from single fluorophores to micron sized markers, depending on the research interest. Here, we present a new and simple objective-type backscattering microscope to track gold nanoparticles with nanometer and microsecond resolution. The total noise of our system in a 55 kHz bandwidth is ∼0.6 nm per axis, sufficient to measure molecular movement. We found our backscattering microscopy to be useful not only for in vitro but also for in vivo experiments because of lower background scattering from cells than in conventional dark-field microscopy. We demonstrate the application of this technique to measuring the motion of a biological rotary molecular motor, the bacterial flagellar motor, in live Escherichia coli cells. PMID:21133475

Characterization of semiconductor materials using synchrotron radiation-based near-field infrared microscopy and nano-FTIR spectroscopy.

PubMed

Hermann, Peter; Hoehl, Arne; Ulrich, Georg; Fleischmann, Claudia; Hermelink, Antje; Kästner, Bernd; Patoka, Piotr; Hornemann, Andrea; Beckhoff, Burkhard; Rühl, Eckart; Ulm, Gerhard

2014-07-28

We describe the application of scattering-type near-field optical microscopy to characterize various semiconducting materials using the electron storage ring Metrology Light Source (MLS) as a broadband synchrotron radiation source. For verifying high-resolution imaging and nano-FTIR spectroscopy we performed scans across nanoscale Si-based surface structures. The obtained results demonstrate that a spatial resolution below 40 nm can be achieved, despite the use of a radiation source with an extremely broad emission spectrum. This approach allows not only for the collection of optical information but also enables the acquisition of near-field spectral data in the mid-infrared range. The high sensitivity for spectroscopic material discrimination using synchrotron radiation is presented by recording near-field spectra from thin films composed of different materials used in semiconductor technology, such as SiO2, SiC, SixNy, and TiO2.

Self-Assembly of a Tripodal Triszwitterion Forms a pH-Switchable Hydrogel that Can Reversibly Encapsulate Hydrophobic Guests in Water.

PubMed

Jana, Poulami; Schmuck, Carsten

2017-01-05

The development of supramolecular smart materials, which exhibit physicochemical structural changes in response to external stimuli is of current interest for various applications. Herein, we have developed the novel tripodal triszwitterion 1, derived from a C 3 -symmetric benzene-1,3,5-tricarboxamide (BTA) core, which forms a thermo-reversible and pH-switchable transparent hydrogel through intermolecular self-complementary zwitterionic interactions at a neutral pH value. The hierarchical supramolecular self-aggregation was fully analyzed by microscopy (AFM, field emission scanning electron microscopy (FESEM)), viscosity, dynamic light scattering (DLS), and rheology studies. Moreover, compound 1 enables to encapsulate hydrophobic guests, such as the dye Nile red in aqueous medium at pH 6, which makes it an interesting candidate for drug delivery and controlled release. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of Norbornene Derived Helical Copolymer by Simple Molecular Marriage Approach to Produce Smart Nanocarrier

NASA Astrophysics Data System (ADS)

Mane, Shivshankar R.; Sathyan, Ashlin; Shunmugam, Raja

2017-03-01

A novel library of norbornene derived helical copolymer has been synthesized through the coupling of two homopolymers via Molecular Marriage Approach. The helicity is governed by the non-covalent interactions like hydrogen bonding, π-π stacking and the influence of hydrophobic and hydrophilic motifs. The detailed characterization of the copolymer (Copoly 1) has been provided and the super structures are confirmed through dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The observed size of the aggregates was about 200 nm. The density functional theory (DFT) is favorably supported for the formation of proposed structure of Copoly 1. Circular dichroism (CD) measurement has confirmed the one handed helical structure of the copolymer. Reservoir capability of this pH responsive polymer (Copoly 1) to encapsulate anti-cancer drug doxorubicin (DOX) warrants its potential applications in the field of bio-medical sciences.

Effect of silver thickness on structural, optical and morphological properties of nanocrystalline Ag/NiO thin films

NASA Astrophysics Data System (ADS)

Jalili, S.; Hajakbari, F.; Hojabri, A.

2018-03-01

Silver (Ag) nanolayers were deposited on nickel oxide (NiO) thin films by DC magnetron sputtering. The thickness of Ag layers was in range of 20-80 nm by variation of deposition time between 10 and 40 s. X-ray diffraction results showed that the crystalline properties of the Ag/NiO films improved by increasing the Ag film thickness. Also, atomic force microscopy and field emission scanning electron microscopy images demonstrated that the surface morphology of the films was highly affected by film thickness. The film thickness and the size of particles change by elevating the Ag deposition times. The composition of films was determined by Rutherford back scattering spectroscopy. The transmission of light was gradually reduced by augmentation of Ag films thickness. Furthermore; the optical band gap of the films was also calculated from the transmittance spectra.

Ultrasensitive ROS-Responsive Coassemblies of Tellurium-Containing Molecules and Phospholipids.

PubMed

Wang, Lu; Fan, Fuqiang; Cao, Wei; Xu, Huaping

2015-07-29

Reactive oxygen species (ROS) play crucial roles in cell signaling and redox homeostasis and are strongly related to metabolic activities. The increase of the ROS concentration in organisms can result in several diseases, such as cardiovascular diseases and cancer. The concentration of ROS in biologically relevant conditions is typically as low as around tens of micromolars to 100 μM H2O2, which makes it necessary to develop ultrasensitive ROS-responsive systems. A general approach is reported here to fabricate an ultrasensitive ROS-responsive system via coassembly between tellurium-containing molecules and phospholipids, combining the ROS-responsiveness of tellurium and the biocompatibility of phospholipids. By using dynamic light scattering, transmission electron microscopy, scanning electron microscopy, and NMR spectra, coassembly behaviors and the responsiveness of the coassemblies have been investigated. These coassemblies can respond to 100 μM H2O2, which is a biologically relevant ROS concentration, and demonstrate reversible redox properties.

Vapor-condensation-assisted optical microscopy for ultralong carbon nanotubes and other nanostructures.

PubMed

Wang, Jiangtao; Li, Tianyi; Xia, Bingyu; Jin, Xiang; Wei, Haoming; Wu, Wenyun; Wei, Yang; Wang, Jiaping; Liu, Peng; Zhang, Lina; Li, Qunqing; Fan, Shoushan; Jiang, Kaili

2014-06-11

Here we present a simple yet powerful approach for the imaging of nanostructures under an optical microscope with the help of vapor condensation on their surfaces. Supersaturated water vapor will first form a nanometer-sized water droplet on the condensation nuclei on the surface of nanostructures, and then the water droplet will grow bigger and scatter more light to make the outline of the nanostructure be visible under dark-field optical microscope. This vapor-condensation-assisted (VCA) optical microscopy is applicable to a variety of nanostructures from ultralong carbon nanotubes to functional groups, generating images with contrast coming from the difference in density of the condensation sites, and does not induce any impurities to the specimens. Moreover, this low-cost and efficient technique can be conveniently integrated with other facilities, such as Raman spectroscope and so forth, which will pave the way for widespread applications.

Sonoelectrochemical one-pot synthesis of Pt - Carbon black nanocomposite PEMFC electrocatalyst.

PubMed

Karousos, Dionysios S; Desdenakis, Kostantinos I; Sakkas, Petros M; Sourkouni, Georgia; Pollet, Bruno G; Argirusis, Christos

2017-03-01

Simultaneous electrocatalytic Pt-nanoparticle synthesis and decoration of Vulcan XC-72 carbon black substrate was achieved in a novel one-step-process, combining galvanostatic pulsed electrodeposition and pulsed ultrasonication with high power, low-frequency (20kHz) ultrasound. Aqueous chloroplatinic acid precursor baths, as well as carbon black suspensions in the former, were examined and decoration was proven by a combination of characterization methods, namely: dynamic light scattering, transmission electron microscopy, scanning electron microscopy with EDX-analysis and cyclic voltammetry. In particular, PVP was shown to have a beneficial stabilizing effect against free nanoparticle aggregation, ensuring narrow size distributions of the nanoparticles synthesized, but is also postulated to prevent the establishment of a strong metal-substrate interaction. Current pulse amplitude was identified as the most critical nanoparticle size-determining parameters, while only small size particles, under 10nm, appeared to be attached to carbon black. Copyright © 2016 Elsevier B.V. All rights reserved.

Nanostructured zirconium phosphate as ion exchanger: Synthesis, size dependent property and analytical application in radiochemical separation.

PubMed

Chakraborty, Rajesh; Bhattacharaya, Koustava; Chattopadhyay, Pabitra

2014-02-01

Nanostructured zirconium phosphates (ZPs) of different sizes were synthesized using Tritron X-100 (polyethylene glycol-p-isooctylphenyl ether) surfactant. The materials were characterized by FTIR and powdered X-ray diffraction (XRD). The structural and morphological details of the material were established by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM study was followed by energy dispersive spectroscopic analysis (EDS) for elemental analysis of the sample. The particle sizes were determined by dynamic light scattering (DLS) method. Ion exchange capacity of these nanomaterials towards different metal ions was measured and size-dependent ion exchange property of the materials was investigated thoroughly. The nanomaterial of the smallest size (ca. 21.04nm) was employed to separate carrier-free (137m)Ba from (137)Cs in column chromatographic technique using 1.0M HNO3 as eluting agent at pH=5. © 2013 Elsevier Ltd. All rights reserved.

Physicochemical properties of micelles of poly(styrene-b-[3-(methacryloylamino)propyl]trimethylammonium chloride-b-ethylene oxide) in aqueous solutions.

PubMed

Liu, Jingjing; Liu, Dian; Yokoyama, Yuuichi; Yusa, Shin-Ichi; Nakashima, Kenichi

2009-01-20

Polymeric micelles from a new triblock copolymer, polystyrene-block-poly[(3-(methacryloylamino)propyl)trimethylammonium chloride]-block-poly(ethylene oxide) (PS-b-PMAPTAC-b-PEO), were prepared in aqueous solutions and characterized by various techniques including dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and fluorescence spectroscopy. The micelle consists of a PS core, PMAPTAC shell, and PEO corona. It was revealed by SEM and DLS measurements that the micelles have a spherical structure with a hydrodynamic diameter about 75 nm. The addition of tungstate to the micellar solution caused a morphological change in the micelles from extended to shrunken spheres, which can be attributed to the fact that electrostatic repulsion among the cationic PMAPTAC blocks is canceled by the negative charge of the bound tungstate ions. Effective incorporation of tungstate ions into the micelles were confirmed by TEM and zeta-potential measurements.

Total Internal Reflection Microscopy (TIRM) as a nondestructive surface damage assessment tool

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liao, Z.M.; Cohen, S.J.; Taylor, J.R.

1994-10-01

An easy to use, nondestructive, method for evaluating subsurface damage in polished substrates has been established at LLNL. Subsurface damage has been related to laser damage in coated optical components used in high power, high repetition rate laser systems. Total Internal Reflection Microscopy (TIRM) has been shown to be a viable nondestructive technique in analyzing subsurface damage in optical components. A successful TIRM system has been established for evaluating subsurface damage on fused silica components. Laser light scattering from subsurface damage sites is collected through a Nomarski microscope. These images are then captured by a CCD camera for analysis onmore » a computer. A variety of optics, including components with intentional subsurface damage due to grinding and polishing, have been analyzed and their TIRM images compared to an existing destructive etching method. Methods for quantitative measurement of subsurface damage are also discussed.« less

Ultra-small and anionic starch nanospheres: formation and vitro thrombolytic behavior study.

PubMed

Huang, Yinjuan; Ding, Shenglong; Liu, Mingzhu; Gao, Chunmei; Yang, Jinlong; Zhang, Xinjie; Ding, Bin

2013-07-25

This paper is considered as the first report on the investigation of nattokinase (NK) release from anionic starch nanospheres. The ultra-small and anionic starch nanospheres were prepared by the method of reverse micro-emulsion crosslinking in this work. Starch nanospheres were characterized through Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS). Effects of preparation conditions on particle size were studied. The cytotoxicity, biodegradable and vitro thrombolytic behaviors of nattokinase (NK) loaded anionic starch nanospheres were also studied. The results showed that the anionic starch nanospheres are non-toxic, biocompatible and biodegradable. Moreover, the anionic starch nanospheres can protect NK from fast biodegradation hence prolongs the circulation in vivo and can reduce the risk of acute hemorrhage complication by decreasing the thrombolysis rate. Copyright © 2013 Elsevier Ltd. All rights reserved.

Determination of the size, concentration, and refractive index of silica nanoparticles from turbidity spectra.

PubMed

Khlebtsov, Boris N; Khanadeev, Vitaly A; Khlebtsov, Nikolai G

2008-08-19

The size and concentration of silica cores determine the size and concentration of silica/gold nanoshells in final preparations. Until now, the concentration of silica/gold nanoshells with Stober's silica core has been evaluated through the material balance assumption. Here, we describe a method for simultaneous determination of the average size and concentration of silica nanospheres from turbidity spectra measured within the 400-600 nm spectral band. As the refractive index of silica nanoparticles is the key input parameter for optical determination of their concentration, we propose an optical method and provide experimental data on a direct determination of the refractive index of silica particles n = 1.475 +/- 0.005. Finally, we exemplify our method by determining the particle size and concentration for 10 samples and compare the results with transmission electron microscopy (TEM), atomic force microscopy (AFM), and dynamic light scattering data.

Solution and electron microscopy characterization of lactococcal phage baseplates expressed in Escherichia coli.

PubMed

Campanacci, Valérie; Veesler, David; Lichière, Julie; Blangy, Stéphanie; Sciara, Giuliano; Moineau, Sylvain; van Sinderen, Douwe; Bron, Patrick; Cambillau, Christian

2010-10-01

We report here the characterization of several large structural protein complexes forming the baseplates (or part of them) of Siphoviridae phages infecting Lactococcus lactis: TP901-1, Tuc2009 and p2. We revisited a "block cloning" expression strategy and extended this approach to genomic fragments encoding proteins whose interacting partners have not yet been clearly identified. Biophysical characterization of some of these complexes using circular dichroism and size exclusion chromatography, coupled with on-line light scattering and refractometry, demonstrated that the over-produced recombinant proteins interact with each other to form large (up to 1.9MDa) and stable baseplate assemblies. Some of these complexes were characterized by electron microscopy confirming their structural homogeneity as well as providing a picture of their overall molecular shapes and symmetry. Finally, using these results, we were able to highlight similarities and differences with the well characterized much larger baseplate of the myophage T4.

Preparation and characterization of novel carbon dioxide adsorbents based on polyethylenimine-modified Halloysite nanotubes.

PubMed

Cai, Haohao; Bao, Feng; Gao, Jie; Chen, Tao; Wang, Si; Ma, Rui

2015-01-01

New nano-sized carbon dioxide (CO2) adsorbents based on Halloysite nanotubes impregnated with polyethylenimine (PEI) were designed and synthesized, which were excellent adsorbents for the capture of CO2 at room temperature and had relatively high CO2 adsorption capacity. The prepared adsorbents were characterized by various techniques such as Fourier transform infrared spectrometry, gel permeation chromatography, dynamic light scattering, thermogravimetry, thermogravimetry-Fourier transform-infrared spectrometry, scanning electron microscopy and transmission electron microscopy. The adsorption characteristics and capacity were studied at room temperature, the highest CO2 adsorption capacity of 156.6 mg/g-PEI was obtained and the optimal adsorption capacity can reach a maximum value of 54.8 mg/g-adsorbent. The experiment indicated that this kind of adsorbent has a high stability at 80°C and PEI-impregnated adsorbents showed good reversibility and stability during cyclic adsorption-regeneration tests.

Comparative analysis of the effect of low-dimensional alumina structures on cell lines L929 and Neuro-2a

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fomenko, A. N., E-mail: alserova@ispms.tsc.ru; Korovin, M. S., E-mail: msk@ispms.tsc.ru

The paper presents the toxicity evaluation of nanostructures on the basis of alumina of different shape (nanofibers, nanoplates, nanosheets, nanosheet agglomerates) and with similar physical and chemical properties (particle size, specific surface area, phase composition, and zeta potential). The nanostructures were examined by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), low-temperature nitrogen adsorption, and dynamic light scattering (DLS). The cytotoxicity of nanostructures was estimated using L929 fibroblast cells and Neuro-2a tumor cells. It has been found that the L929 cells are less subject to the influence of alumina nanoparticles than the Neuro-2a tumor cells. Probably, themore » differences in the proliferation activity of normal and tumor cells in contact with the synthesized nanostructures are due to a change in the pH of the cell microenvironment.« less

Novel of core-shell AlOOH/Cu nanostructures: Synthesis, characterization, antimicrobial activity and in vitro toxicity in Neuro-2a cells

NASA Astrophysics Data System (ADS)

Bakina, O. V.; Fomenko, A. N.; Korovin, M. S.; Glazkova, E. A.; Svarovskaya, N. V.

2016-08-01

Core-shell micro/nanostructures were fabricated by the reaction of Al/Cu bimetallic nanoparticles with water. Al/Cu nanoparticles have been obtained using the method of simultaneous electrical explosion of a pair of the corresponding metal wires in an argon atmosphere. The nanoparticles are chemically active and interact with water at 60°C to form core-shell micro/nanostructures. The obtained products were characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy and dynamic light scattering and the nitrogen adsorption method. The antibacterial activity of the synthesized structures was investigated against E. coli and St. aureus. The toxic effect of these nanostructures against the Neuro-2a neuroblastoma cell line was investigated. AlOOH/Cu nanostructures are shown to inhibit cell proliferation. The AlOOH/Cu nanostructures are good candidates for medical applications.

Comparative analysis of the effect of low-dimensional alumina structures on cell lines L929 and Neuro-2a

NASA Astrophysics Data System (ADS)

Fomenko, A. N.; Korovin, M. S.

2016-08-01

The paper presents the toxicity evaluation of nanostructures on the basis of alumina of different shape (nanofibers, nanoplates, nanosheets, nanosheet agglomerates) and with similar physical and chemical properties (particle size, specific surface area, phase composition, and zeta potential). The nanostructures were examined by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), low-temperature nitrogen adsorption, and dynamic light scattering (DLS). The cytotoxicity of nanostructures was estimated using L929 fibroblast cells and Neuro-2a tumor cells. It has been found that the L929 cells are less subject to the influence of alumina nanoparticles than the Neuro-2a tumor cells. Probably, the differences in the proliferation activity of normal and tumor cells in contact with the synthesized nanostructures are due to a change in the pH of the cell microenvironment.

Synthesis of Norbornene Derived Helical Copolymer by Simple Molecular Marriage Approach to Produce Smart Nanocarrier.

PubMed

Mane, Shivshankar R; Sathyan, Ashlin; Shunmugam, Raja

2017-03-22

A novel library of norbornene derived helical copolymer has been synthesized through the coupling of two homopolymers via Molecular Marriage Approach. The helicity is governed by the non-covalent interactions like hydrogen bonding, π-π stacking and the influence of hydrophobic and hydrophilic motifs. The detailed characterization of the copolymer (Copoly 1) has been provided and the super structures are confirmed through dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The observed size of the aggregates was about 200 nm. The density functional theory (DFT) is favorably supported for the formation of proposed structure of Copoly 1. Circular dichroism (CD) measurement has confirmed the one handed helical structure of the copolymer. Reservoir capability of this pH responsive polymer (Copoly 1) to encapsulate anti-cancer drug doxorubicin (DOX) warrants its potential applications in the field of bio-medical sciences.

Statistical-thermodynamic model for light scattering from eye lens protein mixtures

NASA Astrophysics Data System (ADS)

Bell, Michael M.; Ross, David S.; Bautista, Maurino P.; Shahmohamad, Hossein; Langner, Andreas; Hamilton, John F.; Lahnovych, Carrie N.; Thurston, George M.

2017-02-01

We model light-scattering cross sections of concentrated aqueous mixtures of the bovine eye lens proteins γB- and α-crystallin by adapting a statistical-thermodynamic model of mixtures of spheres with short-range attractions. The model reproduces measured static light scattering cross sections, or Rayleigh ratios, of γB-α mixtures from dilute concentrations where light scattering intensity depends on molecular weights and virial coefficients, to realistically high concentration protein mixtures like those of the lens. The model relates γB-γB and γB-α attraction strengths and the γB-α size ratio to the free energy curvatures that set light scattering efficiency in tandem with protein refractive index increments. The model includes (i) hard-sphere α-α interactions, which create short-range order and transparency at high protein concentrations, (ii) short-range attractive plus hard-core γ-γ interactions, which produce intense light scattering and liquid-liquid phase separation in aqueous γ-crystallin solutions, and (iii) short-range attractive plus hard-core γ-α interactions, which strongly influence highly non-additive light scattering and phase separation in concentrated γ-α mixtures. The model reveals a new lens transparency mechanism, that prominent equilibrium composition fluctuations can be perpendicular to the refractive index gradient. The model reproduces the concave-up dependence of the Rayleigh ratio on α/γ composition at high concentrations, its concave-down nature at intermediate concentrations, non-monotonic dependence of light scattering on γ-α attraction strength, and more intricate, temperature-dependent features. We analytically compute the mixed virial series for light scattering efficiency through third order for the sticky-sphere mixture, and find that the full model represents the available light scattering data at concentrations several times those where the second and third mixed virial contributions fail. The model indicates that increased γ-γ attraction can raise γ-α mixture light scattering far more than it does for solutions of γ-crystallin alone, and can produce marked turbidity tens of degrees celsius above liquid-liquid separation.

Light scattering from an atomic gas under conditions of quantum degeneracy

NASA Astrophysics Data System (ADS)

Porozova, V. M.; Gerasimov, L. V.; Havey, M. D.; Kupriyanov, D. V.

2018-05-01

Elastic light scattering from a macroscopic atomic sample existing in the Bose-Einstein condensate phase reveals a unique physical configuration of interacting light and matter waves. However, the joint coherent dynamics of the optical excitation induced by an incident photon is influenced by the presence of incoherent scattering channels. For a sample of sufficient length the excitation transports as a polariton wave and the propagation Green's function obeys the scattering equation which we derive. The polariton dynamics could be tracked in the outgoing channel of the scattered photon as we show via numerical solution of the scattering equation for one-dimensional geometry. The results are analyzed and compared with predictions of the conventional macroscopic Maxwell theory for light scattering from a nondegenerate atomic sample of the same density and size.

An analysis of scattered light in low dispersion IUE spectra

NASA Technical Reports Server (NTRS)

Basri, G.; Clarke, J. T.; Haisch, B. M.

1985-01-01

A detailed numerical simulation of light scattering from the low-resolution grating in the short wavelength spectrograph of the IUE Observatory was developed, in order to quantitatively analyze the effects of scattering on both continuum and line emission spectra. It is found that: (1) the redistribution of light by grating scattering did not appreciably alter either the shape or the absolute flux level of continuum spectra for A-F stars; (2) late-type stellar continua showed a tendency to flatten when observed in scattered light toward the shorter wavelengths; and (3) the effect of grating scattering on emission lines is to decrease measured line intensities by an increasing percentage toward the shorter wavelengths. The spectra obtained from scattering experiments for solar-type and late type stars are reproduced in graphic form.

Optimizing Nanoscale Quantitative Optical Imaging of Subfield Scattering Targets

PubMed Central

Henn, Mark-Alexander; Barnes, Bryan M.; Zhou, Hui; Sohn, Martin; Silver, Richard M.

2016-01-01

The full 3-D scattered field above finite sets of features has been shown to contain a continuum of spatial frequency information, and with novel optical microscopy techniques and electromagnetic modeling, deep-subwavelength geometrical parameters can be determined. Similarly, by using simulations, scattering geometries and experimental conditions can be established to tailor scattered fields that yield lower parametric uncertainties while decreasing the number of measurements and the area of such finite sets of features. Such optimized conditions are reported through quantitative optical imaging in 193 nm scatterfield microscopy using feature sets up to four times smaller in area than state-of-the-art critical dimension targets. PMID:27805660

Characteristics of large particles and their effects on the submarine light field

NASA Astrophysics Data System (ADS)

Hou, Weilin

Large particles play important roles in the ocean by modifying the underwater light field and effecting material transfer. The particle size distribution of large particles has been measured in-situ with multiple- camera video microscopy and the automated particle sizing and recognition software developed. Results show that there are more large particles in coastal waters than previously thaught, based upon by a hyperbolic size- distribution curve with a (log-log) slope parameter of close to 3 instead of 4 for the particles larger than 100μm diameter. Larger slopes are more typical for particles in the open ocean. This slope permits estimation of the distribution into the small-particle size range for use in correcting the beam-attenuation measurements for near-forward scattering. The large- particle slope and c-meter were used to estimate the small-particle size distributions which nearly matched those measured with a Coulter Counteroler (3.05%). There is also a fair correlation (r2=0.729) between the slope of the distribution and its concentration parameters. Scattering by large particles is influenced by not only the concentrations of these particles, but also the scattering phase functions. This first in-situ measurement of large-particle scattering with multiple angles reveals that they scatter more in the backward direction than was previously believed, and the enhanced backscattering can be explained in part by multiple scattering of aggregated particles. Proper identification of these large particles can be of great help in understanding the status of the ecosystem. By extracting particle features using high-resolution video images via moment-invariant functions and applying this information to lower-resolution images, we increase the effective sample volume without severely degrading classification efficiency. Traditional pattern recognition algorithms of images classified zooplankton with results within 24% of zooplankton collected using bottle samples. A faster particle recognition scheme using optical scattering is introduced and test results are satisfactory with an average error of 32%. This method promises given that the signal-to-noise ratio of the observations can be improved.

Unified Mie and fractal scattering by cells and experimental study on application in optical characterization of cellular and subcellular structures.

PubMed

Xu, Min; Wu, Tao T; Qu, Jianan Y

2008-01-01

A unified Mie and fractal model for light scattering by biological cells is presented. This model is shown to provide an excellent global agreement with the angular dependent elastic light scattering spectroscopy of cells over the whole visible range (400 to 700 nm) and at all scattering angles (1.1 to 165 deg) investigated. Mie scattering from the bare cell and the nucleus is found to dominate light scattering in the forward directions, whereas the random fluctuation of the background refractive index within the cell, behaving as a fractal random continuous medium, is found to dominate light scattering at other angles. Angularly dependent elastic light scattering spectroscopy aided by the unified Mie and fractal model is demonstrated to be an effective noninvasive approach to characterize biological cells and their internal structures. The acetowhitening effect induced by applying acetic acid on epithelial cells is investigated as an example. The changes in morphology and refractive index of epithelial cells, nuclei, and subcellular structures after the application of acetic acid are successfully probed and quantified using the proposed approach. The unified Mie and fractal model may serve as the foundation for optical detection of precancerous and cancerous changes in biological cells and tissues based on light scattering techniques.

Characterization of single particle aerosols by elastic light scattering at multiple wavelengths

NASA Astrophysics Data System (ADS)

Lane, P. A.; Hart, M. B.; Jain, V.; Tucker, J. E.; Eversole, J. D.

2018-03-01

We describe a system to characterize individual aerosol particles using stable and repeatable measurement of elastic light scattering. The method employs a linear electrodynamic quadrupole (LEQ) particle trap. Charged particles, continuously injected by electrospray into this system, are confined to move vertically along the stability line in the center of the LEQ past a point where they are optically interrogated. Light scattered in the near forward direction was measured at three different wavelengths using time-division multiplexed collinear laser beams. We validated our method by comparing measured silica microsphere data for four selected diameters (0.7, 1.0, 1.5 and 2.0 μm) to a model of collected scattered light intensities based upon Lorenz-Mie scattering theory. Scattered light measurements at the different wavelengths are correlated, allowing us to distinguish and classify inhomogeneous particles.

Dynamic Light Scattering of Diabetic Vitreopathy

NASA Technical Reports Server (NTRS)

Sebag, J.; Ansari, Rafat R.; Dunker, Stephan; Suh, Kwang I.

1999-01-01

Diabetes induces pathology throughout the body via nonenzymatic glycation of proteins. Vitreous, which is replete with type 11 collagen, undergoes significant changes in diabetes. The resultant diabetic vitreopathy plays an important role in diabetic retinopathy. Detecting these molecular changes could provide insight into diabetic eye disease as well as molecular effects elsewhere in the body. Human eyes were obtained at autopsy and studied in the fresh, unfixed state. Sclera, choroid, and retina were dissected off the vitreous for dark-field slit microscopy and dynamic light scattering (DLS). For the former, the entire vitreous was exposed. For the latter, only a window at the equator was dissected in some specimens, and the anterior segment was removed leaving the posterior lens capsule intact in others. DLS was performed to determine particle sizes at multiple sites 0.5 mm apart, spanning the globe at the equator (window dissections) and along the antero-posterior axis. Dark-field slit microscopy in diabetic subjects detected findings typical of age-related vitreous degeneration, but at much younger ages than nondiabetic controls. Noninvasive DLS measurements found a greater heterogeneity and larger particle sizes in vitreous of subjects with diabetes as compared to age-matched controls. DLS can detect and quantify the early molecular effects that cause vitreous collagen fibrils to cross-link and aggregate. This could provide valuable insight into ocular and systemic effects of hyperglycemia, because the molecular changes in diabetic vitreopathy could serve as an index of such effects throughout the body. In addition to the diagnostic implications, this methodology could provide a rapid, reproducible way to monitor the response to therapy with novel agents intended to prevent the complications of diabetes on a molecular level.

Size-segregated urban aerosol characterization by electron microscopy and dynamic light scattering and influence of sample preparation

NASA Astrophysics Data System (ADS)

Marvanová, Soňa; Kulich, Pavel; Skoupý, Radim; Hubatka, František; Ciganek, Miroslav; Bendl, Jan; Hovorka, Jan; Machala, Miroslav

2018-04-01

Size-segregated particulate matter (PM) is frequently used in chemical and toxicological studies. Nevertheless, toxicological in vitro studies working with the whole particles often lack a proper evaluation of PM real size distribution and characterization of agglomeration under the experimental conditions. In this study, changes in particle size distributions during the PM sample manipulation and also semiquantitative elemental composition of single particles were evaluated. Coarse (1-10 μm), upper accumulation (0.5-1 μm), lower accumulation (0.17-0.5 μm), and ultrafine (<0.17 μm) PM fractions were collected by high volume cascade impactor in Prague city center. Particles were examined using electron microscopy and their elemental composition was determined by energy dispersive X-ray spectroscopy. Larger or smaller particles, not corresponding to the impaction cut points, were found in all fractions, as they occur in agglomerates and are impacted according to their aerodynamic diameter. Elemental composition of particles in size-segregated fractions varied significantly. Ns-soot occurred in all size fractions. Metallic nanospheres were found in accumulation fractions, but not in ultrafine fraction where ns-soot, carbonaceous particles, and inorganic salts were identified. Dynamic light scattering was used to measure particle size distribution in water and in cell culture media. PM suspension of lower accumulation fraction in water agglomerated after freezing/thawing the sample, and the agglomerates were disrupted by subsequent sonication. Ultrafine fraction did not agglomerate after freezing/thawing the sample. Both lower accumulation and ultrafine fractions were stable in cell culture media with fetal bovine serum, while high agglomeration occurred in media without fetal bovine serum as measured during 24 h.

Physical characterization of plakophilin 1 reconstituted with and without zinc.

PubMed

Hofmann, I; Mücke, N; Reed, J; Herrmann, H; Langowski, J

2000-07-01

Plakophilin 1 (PKP1) belongs to the arm-repeat protein family which is characterized by the presence of a conserved 42-amino-acid motif. Despite individual members of the family containing a similar type of structural domain, they exhibit diverse cellular functions. PKP1 is ubiquitously expressed in human tissues and, depending on the type of cell, found prominently in the karyoplasm and/or in desmosomes. In surface plasmon resonance detection experiments, we noticed that PKP1 specifically bound zinc but not calcium or magnesium. Therefore we have used circular dichroism spectroscopy, limited proteolysis, analytical ultracentrifugation, electron microscopy and dynamic light scattering to establish the physical properties of recombinant PKP1 depending on the presence or absence of zinc. The alpha helix content of PKP1 was considerably higher when reconstituted with zinc than without. By atomic absorption spectroscopy 7.3 atoms zinc were shown to be tightly associated with one molecule of wild-type PKP1. The zinc-reconstituted protein formed globular particles of 21.9 +/- 8.4 nm diameter, as measured by electron microscopy after glycerol spraying/rotary metal shadowing. In parallel, the average sedimentation coefficient (s20, w) for zinc-containing PKP1 was 41S and its diffusion coefficient, as obtained by dynamic light scattering, 1.48 x 10-7 cm2.s-1. The molecular mass of 2.44 x 106 obtained from s and D yields an average stoichiometry of 30 for the PKP1 oligomer. In contrast, PKP1, reconstituted without zinc, contained no significant amount of zinc, sedimented with 4.6S, and was present in monomeric form as determined by sedimentation equilibrium centrifugation.

Nanobarcoding: detecting nanoparticles in biological samples using in situ polymerase chain reaction

PubMed Central

Eustaquio, Trisha; Leary, James F

2012-01-01

Background Determination of the fate of nanoparticles (NPs) in a biological system, or NP biodistribution, is critical in evaluating an NP formulation for nanomedicine. Current methods to determine NP biodistribution are greatly inadequate, due to their limited detection thresholds. Herein, proof of concept of a novel method for improved NP detection based on in situ polymerase chain reaction (ISPCR), coined “nanobarcoding,” is demonstrated. Methods Nanobarcoded superparamagnetic iron oxide nanoparticles (NB-SPIONs) were characterized by dynamic light scattering, zeta potential, and hyperspectral imaging measurements. Cellular uptake of Cy5-labeled NB-SPIONs (Cy5-NB-SPIONs) was imaged by confocal microscopy. The feasibility of the nanobarcoding method was first validated by solution-phase PCR and “pseudo”-ISPCR before implementation in the model in vitro system of HeLa human cervical adenocarcinoma cells, a cell line commonly used for ISPCR-mediated detection of human papilloma virus (HPV). Results Dynamic light-scattering measurements showed that NB conjugation stabilized SPION size in different dispersion media compared to that of its precursor, carboxylated SPIONs (COOH-SPIONs), while the zeta potential became more positive after NB conjugation. Hyperspectral imaging confirmed NB conjugation and showed that the NB completely covered the SPION surface. Solution-phase PCR and pseudo-ISPCR showed that the expected amplicons were exclusively generated from the NB-SPIONs in a dose-dependent manner. Although confocal microscopy revealed minimal cellular uptake of Cy5-NB-SPIONs at 50 nM over 24 hours in individual cells, ISPCR detected definitive NB-SPION signals inside HeLa cells over large sample areas. Conclusion Proof of concept of the nanobarcoding method has been demonstrated in in vitro systems, but the technique needs further development before its widespread use as a standardized assay. PMID:23144562

Two-Photon Fluorescence Microscopy Developed for Microgravity Fluid Physics

NASA Technical Reports Server (NTRS)

Fischer, David G.; Zimmerli, Gregory A.; Asipauskas, Marius

2004-01-01

Recent research efforts within the Microgravity Fluid Physics Branch of the NASA Glenn Research Center have necessitated the development of a microscope capable of high-resolution, three-dimensional imaging of intracellular structure and tissue morphology. Standard optical microscopy works well for thin samples, but it does not allow the imaging of thick samples because of severe degradation caused by out-of-focus object structure. Confocal microscopy, which is a laser-based scanning microscopy, provides improved three-dimensional imaging and true optical sectioning by excluding the out-of-focus light. However, in confocal microscopy, out-of-focus object structure is still illuminated by the incoming beam, which can lead to substantial photo-bleaching. In addition, confocal microscopy is plagued by limited penetration depth, signal loss due to the presence of a confocal pinhole, and the possibility of live-cell damage. Two-photon microscopy is a novel form of laser-based scanning microscopy that allows three-dimensional imaging without many of the problems inherent in confocal microscopy. Unlike one-photon microscopy, it utilizes the nonlinear absorption of two near-infrared photons. However, the efficiency of two-photon absorption is much lower than that of one-photon absorption because of the nonlinear (i.e., quadratic) electric field dependence, so an ultrafast pulsed laser source must typically be employed. On the other hand, this stringent energy density requirement effectively localizes fluorophore excitation to the focal volume. Consequently, two-photon microscopy provides optical sectioning and confocal performance without the need for a signal-limiting pinhole. In addition, there is a reduction in photo-damage because of the longer excitation wavelength, a reduction in background fluorescence, and a 4 increase in penetration depth over confocal methods because of the reduction in Rayleigh scattering.

Scattering of Light by Colloidal Aluminosilicate Particles Produces the Unusual Sky-Blue Color of Río Celeste (Tenorio Volcano Complex, Costa Rica)

PubMed Central

Castellón, Erick; Martínez, María; Madrigal-Carballo, Sergio; Arias, María Laura; Vargas, William E.; Chavarría, Max

2013-01-01

Río Celeste (Sky-Blue River) in Tenorio National Park (Costa Rica), a river that derives from the confluence and mixing of two colorless streams—Río Buenavista (Buenavista River) and Quebrada Agria (Sour Creek)—is renowned in Costa Rica because it presents an atypical intense sky-blue color. Although various explanations have been proposed for this unusual hue of Río Celeste, no exhaustive tests have been undertaken; the reasons hence remain unclear. To understand this color phenomenon, we examined the physico-chemical properties of Río Celeste and of the two streams from which it is derived. Chemical analysis of those streams with ion-exchange chromatography (IC) and inductively coupled plasma atomic emission spectroscopy (ICP-OES) made us discard the hypothesis that the origin of the hue is due to colored chemical species. Our tests revealed that the origin of this coloration phenomenon is physical, due to suspended aluminosilicate particles (with diameters distributed around 566 nm according to a lognormal distribution) that produce Mie scattering. The color originates after mixing of two colorless streams because of the enlargement (by aggregation) of suspended aluminosilicate particles in the Río Buenavista stream due to a decrease of pH on mixing with the acidic Quebrada Agria. We postulate a chemical mechanism for this process, supported by experimental evidence of dynamic light scattering (DLS), zeta potential measurements, X-ray diffraction and scanning electron microscopy (SEM) with energy-dispersive spectra (EDS). Theoretical modeling of the Mie scattering yielded a strong coincidence between the observed color and the simulated one. PMID:24058661

In vivo diagnosis of skin cancer using polarized and multiple scattered light spectroscopy

NASA Astrophysics Data System (ADS)

Bartlett, Matthew Allen

This thesis research presents the development of a non-invasive diagnostic technique for distinguishing between skin cancer, moles, and normal skin using polarized and multiple scattered light spectroscopy. Polarized light incident on the skin is single scattered by the epidermal layer and multiple scattered by the dermal layer. The epidermal light maintains its initial polarization while the light from the dermal layer becomes randomized and multiple scattered. Mie theory was used to model the epidermal light as the scattering from the intercellular organelles. The dermal signal was modeled as the diffusion of light through a localized semi-homogeneous volume. These models were confirmed using skin phantom experiments, studied with in vitro cell cultures, and applied to human skin for in vivo testing. A CCD-based spectroscopy system was developed to perform all these experiments. The probe and the theory were tested on skin phantoms of latex spheres on top of a solid phantom. We next extended our phantom study to include in vitro cells on top of the solid phantom. Optical fluorescent microscope images revealed at least four distinct scatterers including mitochondria, nucleoli, nuclei, and cell membranes. Single scattering measurements on the mammalian cells consistently produced PSD's in the size range of the mitochondria. The clinical portion of the study consisted of in vivo measurements on cancer, mole, and normal skin spots. The clinical study combined the single scattering model from the phantom and in vitro cell studies with the diffusion model for multiple scattered light. When parameters from both layers were combined, we found that a sensitivity of 100% and 77% can be obtained for detecting cancers and moles, respectively, given the number of lesions examined.

Preparation of N-doped ZnO-loaded halloysite nanotubes catalysts with high solar-light photocatalytic activity.

PubMed

Cheng, Zhi-Lin; Sun, Wei

2015-01-01

N-doped ZnO nanoparticles were successfully assembled into hollow halloysite nanotubes (HNTs) by using the impregnation method. The catalysts based on N-doped ZnO-loaded HNTs nanocomposites (N-doped ZnO/HNTs) were characterized by X-ray diffraction (XRD), transmission electron microscopy-energy dispersive X-ray (TEM-EDX), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), UV-vis and Fourier transform infrared spectroscopy (FT-IR) techniques. The XRD pattern showed ZnO nanoparticles with hexagonal structure loaded on HNTs. The TEM-EDX analysis indicated ZnO particles with the crystal size of ca.10 nm scattered in hollow structure of HNTs, and furthermore the concentration of N atom in nanocomposites was up to 2.31%. The SEM-EDX verified most of N-ZnO nanoparticles existing in hollow nanotubes of HNTs. Besides containing an obvious ultraviolet absorbance band, the UV-vis spectra of the N-doped ZnO/HNTs catalysts showed an available visible absorbance band by comparing to HNTs and non-doped ZnO/HNTs. The photocatalytic activity of the N-doped ZnO/HNTs catalysts was evaluated by the degradation of methyl orange (MO) solution with the concentration of 20 mg/L under the simulated solar-light irradiation. The result showed that the N-doped ZnO/HNTs catalyst exhibited a desirable solar-light photocatalytic activity.