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single particle tracking

Matthew D Wehrman, Melissa J Milstrey, Seth Lindberg, Kelly M Schultz
A microfluidic device is designed to measure repeated phase transitions, gelation and degradation, on a single sample by exchanging the surrounding fluid while minimizing shear stress. This device enables quantitative microrheological characterization of material properties over multiple phase transitions, determining whether the material returns to the same equilibrium state. Fluid exchange is accomplished by using a two layer design, the sample is trapped in the first layer and the second layer is a well for the exchanging fluid...
May 26, 2017: Lab on a Chip
Qingfei Bian, Jin Wang, Yi-Tung Chen, Qiuwang Wang, Min Zeng
The working gas turbine blades are exposed to the environment of high temperature, especially in the leading-edge region. The mist/air two-phase impingement cooling has been adopted to enhance the heat transfer on blade surfaces and investigate the leading-edge cooling effectiveness. An Euler-Lagrange particle tracking method is used to simulate the two-phase impingement cooling on the blade leading-edge. The mesh dependency test has been carried out and the numerical method is validated based on the available experimental data of mist/air cooling with jet impingement on a concave surface...
May 23, 2017: Journal of Environmental Management
Shareef Akbari, Rima Abou-Arkoub, Suzy Sun, Swapnil Hiremath, Arkadiy Reunov, Brendan B McCormick, Marcel Ruzicka, Dylan Burger
BACKGROUND: Injury to the mesothelial layer of the peritoneal membrane during peritoneal dialysis (PD) is implicated in loss of ultrafiltration capacity, but there are no validated biomarkers for mesothelial cell injury. Microparticles (MPs) are 0.1 to 1.0 µm membrane vesicles shed from the cell surface following injury and are sensitive markers of tissue damage. Formation of MPs in the peritoneal cavity during PD has not been reported to date. METHODS: We designed a single-center, proof of concept study to assess whether peritoneal solution exposure induces formation of mesothelial MPs suggestive of PD membrane injury...
2017: Canadian Journal of Kidney Health and Disease
Hongqiang Ma, Jianquan Xu, Jingyi Jin, Yi Huang, Yang Liu
High-precision fluorescence microscopy such as superresolution imaging or single-particle tracking often requires an online drift correction method to maintain the stability of the three-dimensional (3D) position of the sample at a nanometer precision throughout the entire data acquisition process. Current online drift correction methods require modification of the existing two-dimensional (2D) fluorescence microscope with additional optics and detectors, which can be cumbersome and limit its use in many biological laboratories...
May 23, 2017: Biophysical Journal
Hao Shen, Lawrence J Tauzin, Rashad Baiyasi, Wenxiao Wang, Nicholas Moringo, Bo Shuang, Christy F Landes
After three decades of developments, single particle tracking (SPT) has become a powerful tool to interrogate dynamics in a range of materials including live cells and novel catalytic supports because of its ability to reveal dynamics in the structure-function relationships underlying the heterogeneous nature of such systems. In this review, we summarize the algorithms behind, and practical applications of, SPT. We first cover the theoretical background including particle identification, localization, and trajectory reconstruction...
May 18, 2017: Chemical Reviews
I-Hsuan Wang, Christoph J Burckhardt, Artur Yakimovich, Matthias K Morf, Urs F Greber
Transport of large cargo through the cytoplasm requires motor proteins and polarized filaments. Viruses that replicate in the nucleus of post-mitotic cells use microtubules and the dynein/dynactin motor to traffic to the nuclear membrane, and deliver their genome through nuclear pore complexes (NPCs) into the nucleus. How virus particles (virions) or cellular cargo are transferred from microtubules to the NPC is unknown. Here, we analyzed trafficking of incoming cytoplasmic adenoviruses by single particle tracking and super-resolution microscopy...
May 17, 2017: Journal of Cell Science
Xiaohui Liu, Ting Ouyang, Hongsheng Ouyang, Linzhu Ren
Real-time and visual tracking of viral infection is crucial for elucidating the infectious and pathogenesis mechanisms. To track the virus successfully, an efficient labeling method is necessary. In this review, we first discuss the practical labeling techniques for virus tracking in live cells. We then describe the current knowledge of interactions between RNA viruses (especially influenza viruses, immunodeficiency viruses, and Flaviviruses) and host cellular structures, obtained using single particle labeling techniques combined with real-time fluorescence microscopy...
May 12, 2017: Virus Research
Nerea Epelde-Elezcano, Ruth Prieto-Montero, Virginia Martínez-Martínez, María J Ortiz, Alejandro Prieto-Castañeda, Eduardo Peña-Cabrera, José L Belmonte-Vázquez, Iñigo López-Arbeloa, Ross Brown, Sylvie Lacombe
A modified Stöber method is used to synthesize spherical core-shell silica nanoparticles (NPs) with an external surface functionalized by amino groups and with an average size around 50 nm. Fluorescent dyes and photosensitizers of singlet oxygen were fixed, either separately or conjointly, respectively in the core or in the shell. Rhodamines were encapsulated in the core with relatively high fluorescence quantum yields (Φfl ≥ 0.3), allowing fluorescence tracking of the particles. Various photosensitizers of singlet oxygen (PS) were covalenty coupled to the shell, allowing singlet oxygen production...
May 15, 2017: Physical Chemistry Chemical Physics: PCCP
Chun-Ting Kuo, Hong-Shang Peng, Yu Rong, Jiangbo Yu, Wei Sun, Bryant S Fujimoto, Daniel T Chiu
Multiplexed optical encoding is emerging as a powerful technique for high-throughput cellular analysis and molecular assays. Most of the developed optical barcodes, however, either suffer from large particle size or are incompatible with most commercial optical instruments. Here, a new type of nanoscale fluorescent barcodes (Pdot barcodes) was prepared from semiconducting polymers. The Pdot barcodes possess the merits of small size (~20 nm in diameter), narrow emission bands (FWHM of 30-40 nm), three-color emissions (blue, green, and red) under single-wavelength excitation, a high brightness, good pH and thermal stability, and efficient cellular uptake...
May 12, 2017: Analytical Chemistry
Ting Wang, Lu Wang, Xiaoming Li, Xingjie Hu, Yuping Han, Yao Luo, Zejun Wang, Qian Li, Ali Aldalbahi, Lihua Wang, Shiping Song, Chunhai Fan, Yun Zhao, Maolin Wang, Nan Chen
Nanoparticles (NPs) have shown great promise as intracellular imaging probes or nanocarriers and are increasingly being used in biomedical applications. A detailed understanding of how NPs get "in and out" of cells is important for developing new nanomaterials with improved selectivity and less cytotoxicity. Both physical and chemical characteristics have been proven to regulate the cellular uptake of NPs. However, the exocytosis process and its regulation are less explored. Herein, we investigated the size-regulated endocytosis and exocytosis of carboxylated polystyrene (PS) NPs...
May 24, 2017: ACS Applied Materials & Interfaces
N G Martin Palmqvist, Jean-Marie Nedelec, Gulaim A Seisenbaeva, Vadim G Kessler
Calcium carbonate is an extremely attractive material in a plethora of biomedical applications. Intensive efforts have recently been made to achieve the control over its nucleation and subsequent aggregation, growth and crystallization; focusing on bringing insight into the role of precursors, solvents and templates. Having analyzed the recently acquired knowledge, we addressed this challenge using CO2 sequestration synthesis, using an unusual reactant, a solution of calcium ethoxide, Ca(OC2H5)2, as precursor...
May 5, 2017: Acta Biomaterialia
Li Zhong, Yang Liu, Wei-Qiang Han, Jian Yu Huang, Scott X Mao
Many lithium-storage materials operate via first-order phase transformations with slow kinetics largely restricted by the nucleation and growth of a new phase. Due to the energy penalties associated with interfaces between coexisting phases, the tendency for a single-phase solid-solution pathway with exceptional reaction kinetics has been predicted to increase with decreasing particle size. Unfortunately, phase evolutions inside such small particles (tens of nanometers) are often shrouded by electrode-scale inhomogeneous reactions containing millions of particles, leading to intensive debate over the size-dependent microscopic reaction mechanisms...
May 5, 2017: Advanced Materials
M Marchetti, A Malinowska, I Heller, Gijs J L Wuite
RNA polymerase (RNAP) is the central motor of gene expression since it governs the process of transcription. In prokaryotes, this holoenzyme is formed by the RNAP core and a sigma factor. After approaching and binding the specific promoter site on the DNA, the holoenzyme-promoter complex undergoes several conformational transitions that allow unwinding and opening of the DNA duplex. Once the first DNA basepairs (∼10bp) are transcribed in an initial transcription process, the enzyme unbinds from the promoter and proceeds downstream along the DNA while continuously opening the helix and polymerizing the ribonucleotides in correspondence with the template DNA sequence...
May 3, 2017: Protein Science: a Publication of the Protein Society
Fei Zhao, Kuangcai Chen, Bin Dong, Kai Yang, Yan Gu, Ning Fang
The Single Particle Orientation and Rotational Tracking (SPORT) technique, which utilizes anisotropic plasmonic gold nanorods and differential interference contrast (DIC) microscopy, has shown potential as an effective alternative to fluorescence-based techniques to decipher rotational motions on the cellular and molecular levels. However, localizing gold nanorods from their DIC images with high accuracy and precision is more challenging than the procedures applied in fluorescence or scattering microscopy techniques due to the asymmetric DIC point spread function with bright and dark parts superimposed over a grey background...
May 1, 2017: Optics Express
Martin Lindén, Vladimir Ćurić, Elias Amselem, Johan Elf
Pointwise localization of individual fluorophores is a critical step in super-resolution localization microscopy and single particle tracking. Although the methods are limited by the localization errors of individual fluorophores, the pointwise localization precision has so far been estimated using theoretical best case approximations that disregard, for example, motion blur, defocus effects and variations in fluorescence intensity. Here, we show that pointwise localization precision can be accurately estimated directly from imaging data using the Bayesian posterior density constrained by simple microscope properties...
May 3, 2017: Nature Communications
B Christoffer Lagerholm, Débora M Andrade, Mathias P Clausen, Christian Eggeling
Fluorescence correlation spectroscopy (FCS) in combination with the super-resolution imaging method STED (STED-FCS), and single-particle tracking (SPT) are able to directly probe the lateral dynamics of lipids and proteins in the plasma membrane of live cells at spatial scales much below the diffraction limit of conventional microscopy. However, a major disparity in interpretation of data from SPT and STED-FCS remains, namely the proposed existence of a very fast (unhindered) lateral diffusion coefficient, ⩾5 µm(2) s(-1), in the plasma membrane of live cells at very short length scales, ≈⩽ 100 nm, and time scales, ≈1-10 ms...
February 15, 2017: Journal of Physics D: Applied Physics
Yuanqing Ma, Elvis Pandzic, Philip R Nicovich, Yui Yamamoto, Joanna Kwiatek, Sophie V Pageon, Aleš Benda, Jérémie Rossy, Katharina Gaus
Clustering of the T-cell receptor (TCR) is thought to initiate downstream signalling. However, the detection of protein clustering with high spatial and temporal resolution remains challenging. Here we establish a Förster resonance energy transfer (FRET) sensor, named CliF, which reports intermolecular associations of neighbouring proteins in live cells. A key advantage of the single-chain FRET sensor is that it can be combined with image correlation spectroscopy (ICS), single-particle tracking (SPT) and fluorescence lifetime imaging microscopy (FLIM)...
April 28, 2017: Nature Communications
Josh Lawrimore, Timothy M Barry, Raymond M Barry, Alyssa C York, Diana M Cook, Kristen Akialis, Jolien Tyler, Paula Vasquez, Elaine Yeh, Kerry Bloom
Chromatin exhibits increased mobility upon DNA damage, but the biophysical basis for this behavior remains unknown. To explore the mechanisms that drive DNA damage-induced chromosome mobility, we employ single-particle tracking of tagged chromosomal loci during interphase in live yeast cells together with polymer models of chromatin chains. Telomeres become mobilized from sites on the nuclear envelope and the pericentromere expands following exposure to DNA damaging agents. The magnitude of chromatin mobility induced by a single double strand break requires active microtubule function...
April 27, 2017: Molecular Biology of the Cell
John Hartman, Brian Kirby
Nanoparticle tracking analysis, a multiprobe single particle tracking technique, is a widely used method to quickly determine the concentration and size distribution of colloidal particle suspensions. Many popular tools remove non-Brownian components of particle motion by subtracting the ensemble-average displacement at each time step, which is termed dedrifting. Though critical for accurate size measurements, dedrifting is shown here to introduce significant biasing error and can fundamentally limit the dynamic range of particle size that can be measured for dilute heterogeneous suspensions such as biological extracellular vesicles...
March 2017: Physical Review. E
Grzegorz Sikora, Krzysztof Burnecki, Agnieszka Wyłomańska
Anomalous diffusion in crowded fluids, e.g., in cytoplasm of living cells, is a frequent phenomenon. A common tool by which the anomalous diffusion of a single particle can be classified is the time-averaged mean square displacement (TAMSD). A classical mechanism leading to the anomalous diffusion is the fractional Brownian motion (FBM). A validation of such process for single-particle tracking data is of great interest for experimentalists. In this paper we propose a rigorous statistical test for FBM based on TAMSD...
March 2017: Physical Review. E
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