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百欧林简报-表界面科学最新文献- KSV NIMA -2020年第2期

artiklar_stende.jpg瑞典百欧林科技有限公司为纳米尺度的表/界面研究提供精确稳定的实验仪器及数据分析系统。借助于我们的仪器,来自全球的科学家在各领域的顶级刊物上发表了数以千计的文章,百欧林为您实时推送科学家们最新发表的科研成果。

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  1. Formation of stable and horse head-like shape platinum nanoparticles at the air/water interface
    Author: Grozev, N., Nedyalkova, M., Tzvetkov, G., Mircheva, K. and Balashev, K.
    Journal: International Society for Optics and Photonics
    DOI: 10.1117/12.2552734
    Abstract: Efficient preparation of dispersions of platinum nanoparticles was achieved by reduction of chloroplatinate ions (PtCl62-) by hexadecylaniline (HDA) as the reaction occurred at the air/water interface where the insoluble monolayer of HDA was spread. The obtaining of the platinum nanoparticles, formed spontaneously at the air–water interface by HDA enables their facile transfer as multilayers onto suitable solid supports by means of the Langmuir-Blodgett technique. Langmuir-Blodgett films were characterized by Atomic force microscopy (AFM) imaging and X-ray photoemission spectroscopy (XPS).
  2. Clinically accurate diagnosis of Alzheimer’s disease via multiplexed sensing of core biomarkers in human plasma
    Authors: Kayoung Kim, Min-Ji Kim, Da Won Kim, Su Yeong Kim, Steve Park and Chan Beum Park
    Journal: Nature Communications
    DOI: 10.1038/s41467-019-13901-z
    Abstract: Alzheimer’s disease (AD) is the most prevalent neurodegenerative disorder, affecting one in ten people aged over 65 years. Despite the severity of the disease, early diagnosis of AD is still challenging due to the low accuracy or high cost of neuropsychological tests and neuroimaging. Here we report clinically accurate and ultrasensitive detection of multiple AD core biomarkers (t-tau, p-tau181, Aβ42, and Aβ40) in human plasma using densely aligned carbon nanotubes (CNTs). The closely packed and unidirectionally aligned CNT sensor array exhibits high precision, sensitivity, and accuracy, evidenced by a low coefficient of variation (<6%), a femtomolar-level limit of detection, and a high degree of recovery (>93.0%). By measuring the levels of t-tau/Aβ42, p-tau181/Aβ42, and Aβ42/Aβ40 in clinical blood samples, the sensor array successfully discriminates the clinically diagnosed AD patients from healthy controls with an average sensitivity of 90.0%, a selectivity of 90.0%, and an average accuracy of 88.6%.
  3. Influence of Semifluorinated Alkane Surface Domains on Phase Behavior and Linear and Nonlinear Viscoelasticity of Phospholipid Monolayers
    Authors: Salomé Mielke, XIANHE LIU, Marie Pierre Krafft and Motomu Tanaka
    Journal: Langmuir
    DOI: 10.1021/acs.langmuir.9b03521
    Abstract: Semifluorinated alkanes self-assemble into 30 – 40 nm-large surface domains (hemimicelles) at the air/water interface. They have been drawing increasing attention to stabilize microbubbles coated with lipids, which are used for enhancing the contrast in sonographic imaging. Although previous studies suggested that semifluorinated alkanes increase the stability of phospholipid membranes, little is known about how semifluorinated alkanes influence phase behaviors and mechanical properties of lipid-coated microbubbles. As a well-defined model of microbubble surfaces, we prepared monolayers consisting of a mixture of phospholipids and semifluorinated alkanes at the air/water interface, and investigated the influence of hemimicelles of semifluorinated alkanes on the phase behavior and interfacial viscoelastic properties of phospholipid monolayers. Hemimicelles are phase-separated from phospholipids and accumulate at the phase boundary, which strongly modulates the correlation between solid phospholipid domains. Intringuingly, we found that the mixed monolayer of semifluorinated alkanes and phospholipids possesses linear and nonlinear viscoelastic properties comparable to those of phospholipid monolayers. Since the mixing of semifluorinated alkanes and phospholipids enables one to overcome the intrinsically low stability of pure semifluorinated alkanes against the change in the surface area of microbubbles through the partial dissolution of gas into the aqueous phase, this is a promising strategy for the stable coating of microbubbles in ultrasound diagnosis.
  4. Synthesis and assembly of zinc oxide microcrystals by a low temperature dissolution–reprecipitation process: Lessons learned about twin formation in heterogeneous reactions
    Authors: Jörg J Schneider, Rudolf C Hoffmann, Maximilian Trapp, Emre Erdem, Markus Kratzer, Christian Teichert and Hans-Joachim Kleebe
    Journal: Chemistry–A European Journal.
    DOI: 10.1002/chem.201904638
    Abstract Cobalt‐doped zinc oxide single crystals with the shape of hexagonal platelets are synthesized by thermohydrolysis of zinc acetate, cobalt acetate and hexamethylenetetramine in mixtures of ethanol and water. The mineralization proceeds by a low temperature dissolution–reprecipitation process from the liquid phase via the formation of basic cobalt zinc salts as intermediates. The crystal shape as well as twin formation of the resulting oxide phase can be influenced by careful choice of solvent mixture and amount of doping. An understanding of the course of the reaction is achieved by comprehensive employment of analytical techniques (SEM, XRD, IR) including an in‐depth HR‐TEM study of precipitates from various reaction stages. In addition, EPR as well as UV/VIS measurements provide information about the insertion of the cobalt dopant into the zincite lattice. The Langmuir‐Blodgett technique is shown to be suitable for depositing coatings of the platelets on glass substrates functionalized with polyelectrolyte multilayers and hence is applied for the formation of monolayers containing domains with ordered tessellation. No major differences are found between deposits on substrates with anionic or cationic surface modification. The adherence to the substrates allows to determine the absolute orientation of the deposited polar single crystals by PFM and KPFM studies.
  5. Characterization of Langmuir-Blodgett Films by Electron Spin Resonance Spectroscopy
    Authors: Hou Nairong
    Journal: University of Waterloo, 2020.
    DOI: hdl.handle.net/10012/15470
    Abstract: Langmuir-Blodgett (LB) films built up with amphiphilic molecules have well-known optical, electrical and magnetic properties. For most applications, it is fundamentally important to understand the structure of the films. Electron spin resonance (ESR) spectroscopy has proven to be a powerful tool for measuring sample structure, yet few studies have been performed on monolayer LB films, primarily due to a lack of sufficient sensitivity. In this work, the fabrication and structural characterization of novel spin-labeled LB films is discussed and demonstrated. Mixed 16-DSA/SA monolayer films containing 10^13 – 10^14 free-radical electron spins were created and characterized for the first-time using continuous wave (CW) ESR spectroscopy and atomic force microscopy (AFM). Through simulation and image analysis, an order parameter was extracted suggesting that the sample assumes a multi-domain liquid crystal structure when deposited on a solid substrate.

    6. Unusual Behavior of Bipolar Molecule, 25–Hydroxycholesterol, at the Air/Water Interface–Langmuir Monolayer Approach Complemented with Theoretical Calculations
    Authors: Wnętrzak, A., Chachaj-Brekiesz, A., Kobierski, J. D., Karwowska, K., Petelska, A. D., and Dynarowicz-Latka, P.
    Journal: The Journal of Physical Chemistry B
    DOI: 10.1021/acs.jpcb.9b10938
    Abstract: In this study, 25–hydroxycholesterol (25–OH), a biamphiphilic compound with a wide range of biological activities, has been investigated at the air/water interface. We were interested in how two hydroxyl groups attached at distal positions of 25–OH molecule (namely at C(3) in the sterane system and at C(25) in the side chain) influence its surface behavior. Apart from traditional Langmuir monolayers, other complementary surface–sensitive techniques, such as electric surface potential measurements, BAM (enabling texture visualization and film thickness measurements) and PM–IRRAS were applied. Experimental data have been interpreted with the aid of theoretical study. Our results show that 25–OH molecules in the monomolecular layer are anchored to the water surface alternatively with C(3) or C(25) hydroxyl group. Theoretical calculations revealed that the populations of these alternative orientations were not equal and molecules anchored with C(3) hydroxyl group were found to be in excess. As a consequence of such an arrangement, surface films of 25–OH are of lower stability as compared to cholesterol (considered as non–oxidized analogue of 25–OH). Moreover, it was found that upon compression, the transition from mono– to bilayer occurred. The molecular mechanism and interactions stabilizing bilayer structure were proposed. The explanation of the observed unusual surface behaviour of 25–OH may contribute to an understanding of differences in biological activity between chain– and ring–oxidized sterols.

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