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Dark field microscopy

Ángel Serrano-Aroca, Sanjukta Deb
Micrometer length tubes of graphene oxide (GO) with irregular form were synthesised following facile and green metal complexation reactions. These materials were obtained by crosslinking of GO with calcium, zinc or strontium chlorides at three different temperatures (24, 34 and 55°C) using distilled water as solvent for the compounds and following a remarkably simple and low-cost synthetic method, which employs no hazardous substances and is conducted without consumption of thermal or sonic energy. These irregular continuous GO networks showed a very particular interconnected structure by Field Emission Scanning Electron Microscopy with Energy-Disperse X-Ray Spectroscopy for elemental analysis and High-resolution Transmission Electron Microscopy with Scanning Transmission Electron Microscope Dark Field Imaging, and were analysed by Raman Spectroscopy...
2017: PloS One
Luying Li, Fan Jiang, Fanfan Tu, Shuangfeng Jia, Yihua Gao, Jianbo Wang
It has long been accepted that the formation of superlattices in hexagonal-based potassium tungsten bronzes is attributed to K vacancies only, together with small displacements of W cations. Here, the superlattices within potassium tungsten bronze nanosheets both structurally and spectroscopically at atomic resolution using comprehensive transmission electron microscopy techniques are studied. The multidimensional chemical analyses are realized by energy-dispersive X-ray spectroscopy, electron energy-loss spectroscopy, and X-ray photoelectron spectroscopy, the atomic-scale structures are characterized using aberration-corrected scanning transmission electron microscopy with high-angle annular-dark-field detector...
September 2017: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Robert R Mercer, James F Scabilloni, Liying Wang, Lori A Battelli, James M Antonini, Jenny R Roberts, Yong Qian, Jennifer D Sisler, Vincent Castranova, Dale W Porter, Ann F Hubbs
Assessing the potential health risks for newly developed nanoparticles poses a significant challenge. Nanometer-sized particles are not generally detectable with the light microscope. Electron microscopy typically requires high-level doses, above the physiologic range, for particle examination in tissues. Enhanced dark-field microscopy (EDM) is an adaption of the light microscope that images scattered light. Nanoparticles scatter light with high efficiency while normal tissues do not. EDM has the potential to identify the critical target sites for nanoparticle deposition and injury in the lungs and other organs...
January 1, 2017: Toxicologic Pathology
Yutsung Tsai, Zhaodong Chu, Yimo Han, Chih-Piao Chuu, Di Wu, Alex Johnson, Fei Cheng, Mei-Yin Chou, David A Muller, Xiaoqin Li, Keji Lai, Chih-Kang Shih
Semiconductor heterostructures have played a critical role as the enabler for new science and technology. The emergence of transition-metal dichalcogenides (TMDs) as atomically thin semiconductors has opened new frontiers in semiconductor heterostructures either by stacking different TMDs to form vertical heterojunctions or by stitching them laterally to form lateral heterojunctions via direct growth. In conventional semiconductor heterostructures, the design of multijunctions is critical to achieve carrier confinement...
September 11, 2017: Advanced Materials
Geun Wan Kim, Ji Won Ha
We characterized the optical properties of single platinum-coated core-shell gold nanorods (Pt-AuNRs) under dark-field (DF) and differential interference contrast (DIC) microscopy. Furthermore, we examined their potential use as multifunctional orientation probes. Longitudinal surface plasmon resonance damping was observed for single Pt-AuNRs due to Pt metals coated on the AuNR surface under single-particle scattering spectroscopy. Despite the strong plasmon damping with a much-decreased scattering intensity, DIC microscopy allowed us to detect single Pt-AuNRs with much higher sensitivity...
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Shuping Li, Ying Du, Ting He, Yangbin Shen, Chuang Bai, Fandi Ning, Xin Hu, Wenhui Wang, Shaobo Xi, Xiaochun Zhou
Gas-generating catalysis is important to many energy-related research fields, such as photocatalytic water splitting, water electrolysis, etc. The technique of single-nanoparticle catalysis is an effective way to search for highly active nanocatalysts and elucidate the reaction mechanism. However, gas-generating catalysis remains difficult to investigate at the single-nanoparticle level because product gases, such as H2 and O2, are difficult to detect on an individual nanoparticle. Here, we successfully find that nanobubbles can be used to study the gas-generating catalysis, i...
September 8, 2017: Journal of the American Chemical Society
David N Naumann, Jon Hazeldine, Mark J Midwinter, Sam D Hutchings, Paul Harrison
BACKGROUND: Endothelial cell damage and glycocalyx shedding following trauma can increase the risk of inflammation, coagulopathy, vascular permeability and death. Bedside sublingual video-microscopy may detect worse flow and perfusion associated with this endotheliopathy. We compared markers of endotheliopathy with physical flow dynamics following traumatic hemorrhagic shock (THS). METHODS: Sublingual incident dark field video-microscopy was performed at three time-points following injury (<10h; 10-30h; and 30-50h)...
September 5, 2017: Journal of Trauma and Acute Care Surgery
Jan Martel, Cheng-Yeu Wu, Pei-Rong Huang, Wei-Yun Cheng, John D Young
Although human blood is believed to be a sterile environment, recent studies suggest that pleomorphic bacteria exist in the blood of healthy humans. These studies have led to the development of "live-blood analysis," a technique used by alternative medicine practitioners to diagnose various human conditions, including allergies, cancer, cardiovascular disease and septicemia. We show here that bacteria-like vesicles and refringent particles form in healthy human blood observed under dark-field microscopy. These structures gradually increase in number during incubation and show morphologies reminiscent of cells undergoing division...
September 6, 2017: Scientific Reports
Monica Potara, Timea Nagy-Simon, Ana Maria Craciun, Sorina Suarasan, Emilia Licarete, Florica Imre-Lucaci, Simion Astilean
Ovarian cancer is a common cause of cancer death in women and is associated with the highest mortality rates of all gynecological malignancies. Carboplatin (CBP) is the most used cytotoxic agent in the treatment of ovarian cancer. Herein, we design and assess a CBP nanotherapeutic delivery system which allows combinatorial functionalities of chemotherapy, pH sensing, and multimodal traceable properties inside live NIH:OVCAR-3 ovarian cancer cells. In our design, a pH-sensitive Raman reporter, 4-mercaptobenzoic acid (4MBA) is anchored onto the surface of chitosan-coated silver nanotriangles (chit-AgNTs) to generate a robust surface-enhanced Raman scattering (SERS) traceable system...
September 13, 2017: ACS Applied Materials & Interfaces
Yu Gu, Juan Song, Mei-Xing Li, Tingting Zhang, Wei Zhao, Jing-Juan Xu, Maili Liu, Hong-Yuan Chen
Quantification of trace serum circulate microRNAs is extremely important in clinical diagnosis but remains a great challenge. Herein we developed an ultra-sensitive platform for microRNA 141 (miR-141) detection based on a silver coated gold nanorods (Au@Ag NRs) etching process accompanied by surface plasmon resonance (SPR) shift. Both SPR absorption and scattering responses were monitored. Combined amplification cascades of catalyzed hairpin assembly (CHA) and hybridization chain reaction (HCR) with the sensitive SPR responses of plasmonic Au@Ag NRs, the proposed bioassay exhibited ultra-high sensitivity toward miRNA-141 with dynamic range from 5...
September 5, 2017: Analytical Chemistry
Meng-Ting Liu, Li-Xian Chen, Dong-Ning Li, Ai-Jun Wang, Qian-Li Zhang, Jiu-Ju Feng
In this work, AuPd@Pd core-shell nanocrystals (AuPd@Pd NCs) were fabricated by a one-pot co-reduction approach, where theophylline-7-acetic acid (TAA) acted asa new structure-directing agent. The crystal structure and composition were mainly characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray diffraction (XRD), together with X-ray photoelectron spectroscopy (XPS). The growth mechanism of AuPd@Pd NCs was investigated in detail...
August 16, 2017: Journal of Colloid and Interface Science
Andreas Beyer, Lennart Duschek, Jürgen Belz, Jan Oliver Oelerich, Kakhaber Jandieri, Kerstin Volz
The surfaces of thin transmission electron microscopy (TEM) specimens of strained heterostructures can relax. The resulting bending of the lattice planes significantly influences high-angle annular dark field (HAADF) measurements. We investigate the impact by evaluating the intensities measured at the atomic columns as well as their positions in high-resolution HAADF images. In addition, the consequences in the diffraction plane will be addressed by simulated position averaged convergent beam electron diffraction (PACBED) patterns...
September 1, 2017: Journal of Microscopy
Giorgia Giacometti, Carla Ferreri, Anna Sansone, Chryssostomos Chatgilialoglu, Carla Marzetti, Ellas Spyratou, Alexandros G Georgakilas, Marina Marini, Provvidenza M Abruzzo, Alessandra Bolotta, Alessandro Ghezzo, Renato Minguzzi, Annio Posar, Paola Visconti
Membranes attract attention in medicine, concerning lipidome composition and fatty acid correlation with neurological diseases. Hyperspectral dark field microscopy (HDFM), a biophotonic imaging using reflectance spectra, provides accurate characterization of healthy adult RBC identifying a library of 8 spectral end-members. Here we report hyperspectral RBC imaging in children affected by Autism Spectrum Disorder (ASD) (n = 21) compared to healthy age-matched subjects (n = 20), investigating if statistically significant differences in their HDFM spectra exist, that can comprehensively map a membrane impairment involved in disease...
August 29, 2017: Scientific Reports
Shanshan Wang, Hidetaka Sawada, Christopher S Allen, Angus I Kirkland, Jamie H Warner
We have studied the atomic structure of small secondary domains that nucleate on monolayer MoS2 grown by chemical vapour deposition (CVD), which form the basis of bilayer MoS2. The small secondary bilayer domains have a faceted geometry with three-fold symmetry and adopt two distinct orientations with 60° rotation relative to an underlying monolayer MoS2 single crystal sheet. The two distinct orientations are associated with the 2H and 3R stacking configuration for bilayer MoS2. Atomic resolution images have been recorded using annular dark field scanning transmission electron microscopy (ADF-STEM) that show the edge termination, lattice orientation and stacking sequence of the bilayer domains relative to the underlying monolayer MoS2...
September 14, 2017: Nanoscale
Hao Tan, Wei Hu, Chao Wang, Chao Ma, Hengli Duan, Wensheng Yan, Liang Cai, Peng Guo, Zhihu Sun, Qinghua Liu, Xusheng Zheng, Fengchun Hu, Shiqiang Wei
Doping atomically thick nanosheets is a great challenge due to the self-purification effect that drives the precipitation of dopants. Here, a breakthrough is made to dope Mn atoms substitutionally into MoS2 nanosheets in a sulfur-rich supercritical hydrothermal reaction environment, where the formation energy of Mn substituting for Mo sites in MoS2 is significantly reduced to overcome the self-purification effect. The substitutional Mn doping is convincingly evidenced by high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine spectroscopy characterizations...
August 21, 2017: Small
Sanne M Jansen, Daniel M de Bruin, Dirk J Faber, Iwan J G G Dobbe, Erik Heeg, Dan M J Milstein, Simon D Strackee, Ton G van Leeuwen
Patient morbidity and mortality due to hemodynamic complications are a major problem in surgery. Optical techniques can image blood flow in real-time and high-resolution, thereby enabling perfusion monitoring intraoperatively. We tested the feasibility and validity of laser speckle contrast imaging (LSCI), optical coherence tomography (OCT), and sidestream dark-field microscopy (SDF) for perfusion diagnostics in a phantom model using whole blood. Microvessels with diameters of 50, 100, and 400  μm were constructed in a scattering phantom...
August 2017: Journal of Biomedical Optics
Eduardo Ortega, Jesús Cantu-Valle, Germán Plascencia-Villa, Sandra Vergara, Fernando Mendoza-Santoyo, Alejandra Londono-Calderon, Ulises Santiago, Arturo Ponce
In the current work, irregular morphology of Staphylococcus aureus bacteria has been visualized by phase retrieval employing off-axis electron holography (EH) and 3D reconstruction electron tomography using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). Bacteria interacting with gold nanoparticles (AuNP) acquired a shrunken or irregular shape due to air dehydration processing. STEM imaging shows the attachment of AuNP on the surface of cells and suggests an irregular 3D morphology of the specimen...
August 11, 2017: Microscopy Research and Technique
Nader Elmelegy, Dalia Mohamed Mofreh El Sakka
BACKGROUND: Hypopigmentation is a troublesome often-permanent sequelae after burn injury, particularly in dark races. A number of methods have been described to treat this phenomenon. In this work, we are going to study the effect of E light (intensive pulsed light+radiofrequency+cooling) in repigmentation of partial thickness and full thickness burn wounds in adult patients and light microscopic changes of biopsy material at various stages of repigmentation. PATIENTS AND METHODS: In this study, 24 patients with postburn hypopigmentation were selected and E light was used, using different filters, according to the skin color...
September 2017: Annals of Plastic Surgery
So Young Lee, Yeji Han, Jong Wook Hong, Ji Won Ha
Plasmonic gold bipyramids (AuBPs) with sharp tips are promising orientation probes in biological studies because of their anisotropic shape, strong electric field enhancement at the tips, and convenient manipulation into other shapes. Herein, we elucidate the optical properties of single AuBPs at their localized surface plasmon resonance (LSPR) wavelengths using dark-field (DF) microscopy and differential interference contrast (DIC) microscopy and test their use as orientation probes in a dynamic biological environment...
August 24, 2017: Nanoscale
Daeseong Jung, Jun-Ho Choi, Soocheol Kim, Suho Ryu, Wonchan Lee, Jong-Seok Lee, Chulmin Joo
We present a portable multi-contrast microscope capable of producing bright-field, dark-field, and differential phase contrast images of thin biological specimens on a smartphone platform. The microscopy method is based on an imaging scheme termed "color-coded light-emitting-diode (LED) microscopy (cLEDscope)," in which a specimen is illuminated with a color-coded LED array and light transmitted through the specimen is recorded by a color image sensor. Decomposition of the image into red, green, and blue colors and subsequent computation enable multi-contrast imaging in a single shot...
August 8, 2017: Scientific Reports
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