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Single particle electron microscopy

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https://www.readbyqxmd.com/read/28535412/selective-separation-and-determination-of-glucocorticoids-in-cosmetics-using-dual-template-magnetic-molecularly-imprinted-polymers-and-hplc
#1
Min Liu, Xiaoyan Li, Junjie Li, Zongyuan Wu, Fang Wang, Li Liu, Xuecai Tan, Fuhou Lei
Molecularly imprinting polymers (MIPs) are typically prepared using a single template molecule, which allows selective separation and enrichment of only one target analyte. It is not suitable for determination of complex real samples containing multiple analytes. In order to expand the practical application of imprinted polymers, novel dual-template magnetic molecularly imprinted polymers (MMIPs) were synthesized by surface polymerization using hydrocortisone and dexamethasone as the dual-template molecules in this study...
May 17, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28534300/formulation-and-evaluation-of-naringenin-nanosuspensions-for-bioavailability-enhancement
#2
Sonia Gera, Sreekanth Talluri, Nagarjun Rangaraj, Sunitha Sampathi
The clinical potential of naringenin (NRG) is compromised due to its poor aqueous solubility and low oral bioavailability. The study is aimed at addressing these issues by means of naringenin nanosuspensions (NRG-NS) formulated using polyvinylpyrrolidone (PVP K-90) as stabiliser via antisolvent sonoprecipitation method. Optimisation of sonication time, drug concentration and stabilisers was done based on particle size. Characterisation of pure NRG and NRG-NS was carried out by scanning electron microscopy, differential scanning calorimetry (DSC), x-ray powder diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR)...
May 22, 2017: AAPS PharmSciTech
https://www.readbyqxmd.com/read/28534056/carbon-nanomaterials-enhance-survival-of-agapanthus-praecox-callus-after-cryopreservation-by-vitrification
#3
S M Chen, L Ren, D Zhang, Y F Zhang, X H Shen
BACKGROUND: Adding exogenous compounds is an effective way to improve cell survival after cryopreservation. Carbon nanomaterials (CNMs) are novel exogenous substances with small particle size and good biocompatibility. OBJECTIVE: In this work, four types of CNMs were used for the cryopreservation of Agapanthus praecox callus and their possible effects and mechanism of action were analyzed. MATERIALS AND METHODS: The thermal properties of the vitrification solutions tested were detected by differential scanning calorimetry...
March 2017: Cryo Letters
https://www.readbyqxmd.com/read/28532530/automated-image-acquisition-for-low-dose-stem-at-atomic-resolution
#4
Andreas Mittelberger, Christian Kramberger, Christoph Hofer, Clemens Mangler, Jannik C Meyer
Beam damage is a major limitation in electron microscopy that becomes increasingly severe at higher resolution. One possible route to circumvent radiation damage, which forms the basis for single-particle electron microscopy and related techniques, is to distribute the dose over many identical copies of an object. For the acquisition of low-dose data, ideally no dose should be applied to the region of interest before the acquisition of data. We present an automated approach that can collect large amounts of data efficiently by acquiring images in a user-defined area-of-interest with atomic resolution...
May 23, 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28532144/physically-targeted-intravenous-polyurethane-nanoparticles-for-controlled-release-of-atorvastatin-calcium
#5
Behnaz Sadat Eftekhari, Akbar Karkhaneh, Ali Alizadeh
Background: Intravenous drug delivery is an advantageous choice for rapid administration, immediate drug effect, and avoidance of first-pass metabolism in oral drug delivery. In this study, the synthesis, formulation, and characterization of atorvastatin-loaded polyurethane (PU) nanoparticles were investigated for intravenous route of administration. Methods: First, PU was synthesized and characterized. Second, nanoparticles were prepared in four different ratios of drug to polymer through two different techniques including emulsion-diffusion and single-emulsion...
May 23, 2017: Iranian Biomedical Journal
https://www.readbyqxmd.com/read/28525257/self-etch-adhesive-as-a-carrier-for-acp-nanoprecursors-to-deliver-biomimetic-remineralization
#6
Zhifang Wu, Xiaokan Wang, Zhe Wang, Changyu Shao, Xiaoting Jin, Leiqing Zhang, Haihua Pan, Ruikang Tang, Baiping Fu
Lab biomineralization should be carried out in an actual clinical practice. This study evaluated self-etch adhesive as a carrier for amorphous calcium phosphate (ACP) nanoprecursors to continuously deliver biomimetic remineralization of self-assembly type I collagen and demineralized dentin. Si-containing ACP particles (Si-ACP) stabilized with polyaspartic acid (PAsp) were synthesized and characterized by transmission electron microscopy (TEM), scanning electron microscopy-energy-dispersive X-ray spectroscopy, Fourier transform infrared analysis, X-ray powder diffractometry, and X-ray phototelectron spectroscopy...
May 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28521100/single-step-synthesis-of-small-azide-functionalized-gold-nanoparticles-versatile-water-dispersible-reagents-for-click-chemistry
#7
Edward W Elliott, Aurora L Ginzburg, Zachary C Kennedy, Zhenshuo Feng, James E Hutchison
Nanoparticles possessing functional groups that can be readily conjugated (e.g. through click chemistry) are important precursors for the preparation of customized nanohybrid products. Such nanoparticles, if they are stable against agglomeration, are easily dispersible and have well-defined surface chemistry and size. As click-ready reagents, they can be stored until their time of use and then simply dispersed and reacted with an appropriate substrate. Gold nanoparticles (AuNPs) are excellent candidates for this purpose and some clickable gold nanoparticles have been developed; however, AuNPs for use in aqueous systems are often prepared through difficult multistep processes and/or can be poorly dispersible in water...
May 18, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28516779/synthesis-of-cubic-shaped-pt-particles-with-100-preferential-orientation-by-a-quick-one-step-and-clean-electrochemical-method
#8
Jie Liu, Xiayue Fan, Xiaorui Liu, Zhishuang Song, Yida Deng, Xiaopeng Han, Wenbin Hu, Cheng Zhong
A new approach has been developed for in situ preparing cubic-shaped Pt particles with (100) preferential orientation on the surface of the conductive support by using a quick, one-step and clean electrochemical method with periodic square-wave potential. The whole electrochemical deposition process is very quick (only 6 min is required to produce cubic Pt particles), without the use of particular capping agents. The shape and the surface structure of deposited Pt particles can be controlled by the lower and upper potential limits of the square-wave potential...
May 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28516056/simultaneous-micronization-and-purification-of-bioactive-fraction-by-supercritical-antisolvent-technology
#9
Stevanus Hiendrawan, Bambang Veriansyah, Edward Widjojokusumo, Raymond R Tjandrawinata
Simultaneous micronization and purification of DLBS3233 bioactive fraction, a combination of two Indonesian herbals Lagerstroemia speciosa and Cinnamomum burmannii has been successfully performed via supercritical anti-solvent (SAS) technology. The objective of the present study was to investigate the effectiveness of SAS technology to micronize and reduce coumarin content of DLBS3233. The effects of four SAS process parameters, i.e. pressure, temperature, concentration and solution flow rate on particle formation were investigated...
April 2017: Journal of Advanced Pharmaceutical Technology & Research
https://www.readbyqxmd.com/read/28501440/classification-of-microcrystalline-celluloses-via-structures-of-individual-particles-measured-by-synchrotron-radiation-x-ray-micro-computed-tomography
#10
Longwei Fang, Xianzhen Yin, Li Wu, Yaping He, Yuanzhi He, Wei Qin, Fanyue Meng, Peter York, Xu Xu, Jiwen Zhang
Microcrystalline cellulose (MCC) is one of the most important excipients due to its outstanding binding and tableting properties. Owing to the absence of high resolution characterization techniques at the single particle scale, 3D (three dimension) microstructure of MCC and its effects on formulation performance remain unexamined. The aim of this work was to establish a methodology for single particles of MCC type 102 based on synchrotron radiation X-ray micro computed tomography (SR-μCT), principal component analysis (PCA) and partial least square discriminant analysis (PLSDA)...
May 10, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28490633/single-particle-electron-microscopy-structure-of-udp-glucose-glycoprotein-glucosyltransferase-suggests-a-selectivity-mechanism-for-misfolded-proteins
#11
Daniel Calles-Garcia, Meng Yang, Naoto Soya, Roberto Melero, Marie Ménade, Yukishige Ito, Javier Vargas, Gergely L Lukacs, Justin M Kollman, Guennadi Kozlov, Kalle Gehring
The enzyme UDP-glucose:glycoprotein glucosyltransferase (UGGT) mediates quality control of glycoproteins in the endoplasmic reticulum by attaching glucose to N-linked glycan of misfolded proteins. As a sensor, UGGT ensures that misfolded proteins are recognized by the lectin chaperones and do not leave the secretory pathway. The structure of UGGT and the mechanism of its selectivity for misfolded proteins have been unknown for 25 years. Here, we used negative-stain electron microscopy and small-angle X-ray scattering to determine the structure of UGGT from Drosophila melanogaster at 18 Å resolution...
May 10, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28489347/measurement-of-the-density-of-engineered-silver-nanoparticles-using-centrifugal-fff-tem-and-single-particle-icp-ms
#12
Soheyl Tadjiki, Manuel David Montaño, Shoeleh Assemi, Angela Barber, James Ranville, Ronald Beckett
A methodology has been developed to measure nanoparticle mass and density, by combining centrifugal field-flow fractionation (CeFFF; more commonly called sedimentation FFF or SdFFF) and transmission electron microscopy (TEM). Particle effective mass obtained from CeFFF retention data and particle size obtained from the TEM images were used to calculate the nanoparticle density. The method was initially applied to measure the density of monodispersed polystyrene latex nanoparticles. Measured densities for latex nanoparticles of 160-300 nm in diameter were in the range of 1041-1063 kg m(-3) with standard deviations of 0...
May 17, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28462924/identification-and-characterization-of-a-heterotrimeric-archaeal-dna-polymerase-holoenzyme
#13
Jiangyu Yan, Thomas R Beattie, Adriana L Rojas, Kelly Schermerhorn, Tamzin Gristwood, Jonathan C Trinidad, Sonja V Albers, Pietro Roversi, Andrew F Gardner, Nicola G A Abrescia, Stephen D Bell
Since their initial characterization over 30 years ago, it has been believed that the archaeal B-family DNA polymerases are single-subunit enzymes. This contrasts with the multi-subunit B-family replicative polymerases of eukaryotes. Here we reveal that the highly studied PolB1 from Sulfolobus solfataricus exists as a heterotrimeric complex in cell extracts. Two small subunits, PBP1 and PBP2, associate with distinct surfaces of the larger catalytic subunit and influence the enzymatic properties of the DNA polymerase...
May 2, 2017: Nature Communications
https://www.readbyqxmd.com/read/28448907/characterization-of-typical-metal-particles-during-haze-episodes-in-shanghai-china
#14
Rui Li, Xin Yang, Hongbo Fu, Qingqing Hu, Liwu Zhang, Jianmin Chen
Aerosol particles were collected during three heavy haze episodes at Shanghai in the winter of 2013. Transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy was used to study the morphology and speciation of typical metal particles at a single-particle level. In addition, time-of-flight aerosol mass spectrometry (ATOFMS) was applied to identify the speciation of the Fe-containing particles. TEM analysis indicated that various metal-containing particles were hosted by sulfates, nitrates, and oxides...
April 19, 2017: Chemosphere
https://www.readbyqxmd.com/read/28448005/open-source-single-particle-analysis-for-super-resolution-microscopy-with-virusmapper
#15
Robert D M Gray, Jason Mercer, Ricardo Henriques
Super-resolution fluorescence microscopy is currently revolutionizing cell biology research. Its capacity to break the resolution limit of around 300 nm allows for the routine imaging of nanoscale biological complexes and processes. This increase in resolution also means that methods popular in electron microscopy, such as single-particle analysis, can readily be applied to super-resolution fluorescence microscopy. By combining this analytical approach with super-resolution optical imaging, it becomes possible to take advantage of the molecule-specific labeling capacity of fluorescence microscopy to generate structural maps of molecular elements within a metastable structure...
April 9, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28437792/phase-plate-cryo-em-structure-of-a-class-b-gpcr-g-protein-complex
#16
Yi-Lynn Liang, Maryam Khoshouei, Mazdak Radjainia, Yan Zhang, Alisa Glukhova, Jeffrey Tarrasch, David M Thal, Sebastian G B Furness, George Christopoulos, Thomas Coudrat, Radostin Danev, Wolfgang Baumeister, Laurence J Miller, Arthur Christopoulos, Brian K Kobilka, Denise Wootten, Georgios Skiniotis, Patrick M Sexton
Class B G-protein-coupled receptors are major targets for the treatment of chronic diseases, such as osteoporosis, diabetes and obesity. Here we report the structure of a full-length class B receptor, the calcitonin receptor, in complex with peptide ligand and heterotrimeric Gαsβγ protein determined by Volta phase-plate single-particle cryo-electron microscopy. The peptide agonist engages the receptor by binding to an extended hydrophobic pocket facilitated by the large outward movement of the extracellular ends of transmembrane helices 6 and 7...
April 24, 2017: Nature
https://www.readbyqxmd.com/read/28437606/transfer-study-of-silver-nanoparticles-in-poultry-production
#17
Federica Gallocchio, Giancarlo Biancotto, Veronica Cibin, Carmen Losasso, Simone Belluco, Ruud Peters, Greet van Bemmel, Claudia Cascio, Stefan Weigel, Peter Tromp, Federica Gobbo, Salvatore Catania, Antonia Ricci
Silver nanoparticles (AgNPs) are of interest due to their antimicrobial activity and are seen as potential candidates to replace antibiotics in animal husbandry. A few studies have focused on this new application, but they lack any considerations about residual accumulation of AgNPs in edible animal tissues and animal products. In this research, a 22 day in vivo study was carried out by oral administration of 20 nm spherical PVP coated AgNPs to hens. Six doses of approximately 1 mg kg(-1) of AgNPs-PVP each were administered to animals throughout the experimentation...
April 27, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28432501/high-scale-yield-of-nano-hydroxyapatite-through-combination-of-mechanical-activation-and-chemical-dispersion
#18
Xueling Gao, Chunchu Dai, Weiwei Liu, Yumei Liu, Ru Shen, Xiaotong Zheng, Ke Duan, Jie Weng, Shuxin Qu
The aim of this study is to develop a simple, convenient and effective approach to synthesize nano-sized hydroxyapatite (nano-HA) at high-scale yield. Nano-HA was wet synthesized in the presence or absence of alendronate sodium (ALN), one of bisphosphonates for anti-osteoporotic. Then aged and washed nano-HA precipitate was directly treated by mechanical activation combined with the chemical dispersion of ALN to prevent the agglomeration of nano-HA. ALN acted not only as a chemical dispersant but also as an orthopedic drug...
June 2017: Journal of Materials Science. Materials in Medicine
https://www.readbyqxmd.com/read/28427648/sonochemical-synthesis-characterization-and-effects-of-temperature-power-ultrasound-and-reaction-time-on-the-morphological-properties-of-two-new-nanostructured-mercury-ii-coordination-supramolecule-compounds
#19
Payam Hayati, Ali Reza Rezvani, Ali Morsali, Daniel Ruiz Molina, Samira Geravand, Salvio Suarez-Garcia, Miguel Angel Moreno Villaecija, S García-Granda, Rafael Mendoza-Meroño, Pascal Retailleau
Two new mercury(II) coordination supramolecular compounds (CSCs) (1D and 0D), [Hg(L)(I)2]n (1) and [Hg2(L')2(SCN)2]·2H2O (2) (L=2-amino-4-methylpyridine and L'=2,6-pyridinedicarboxlic acid), have been synthesized under different experimental conditions. Micrometric crystals (bulk) or nano-sized materials have been obtained depending on using the branch tube method or sonochemical irradiation. All materials have been characterized by field emission scanning electron microscope (FESEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and FT-IR spectroscopy...
July 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28424589/the-calcium-channel-c-terminal-and-synaptic-vesicle-tethering-analysis-by-immuno-nanogold-localization
#20
Robert H C Chen, Qi Li, Christine A Snidal, Sabiha R Gardezi, Elise F Stanley
At chemical synapses the incoming action potential triggers the influx of Ca(2+) through voltage-sensitive calcium channels (CaVs, typically CaV2.1 and 2.2) and the ions binds to sensors associated with docked, transmitter filled synaptic vesicles (SVs), triggering their fusion and discharge. The CaVs and docked SVs are located within the active zone (AZ) region of the synapse which faces a corresponding neurotransmitter receptor-rich region on the post-synaptic cell. Evidence that the fusion of a SV can be gated by Ca(2+) influx through a single CaV suggests that the channel and docked vesicle are linked by one or more molecular tethers (Stanley, 1993)...
2017: Frontiers in Cellular Neuroscience
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