共查询到20条相似文献，搜索用时 15 毫秒
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Ece N. Aybeke Gaël Belliot Stéphanie Lemaire‐Ewing Marie Estienney Yvon Lacroute Pierre Pothier Eric Bourillot Eric Lesniewska 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(1)
Studies on human norovirus are severely hampered by the absence of a cell culture system until the discovery of murine norovirus (MNV). The cell membrane domains called lipid rafts have been defined as a port of entry for viruses. This study is conducted to investigate murine norovirus binding on the mouse leukemic monocyte macrophage cell line. Lipid raft related structures are extracted from cells by detergent treatment resulting detergent‐resistant membrane (DRMs) domains. The real‐time polymerase chain reaction technique is performed to detect the viral genome, thereby the MNV binding on the DRMs. The interactions between MNV and DRMs are investigated by high‐speed atomic force microscopy (HS‐AFM) combined with surface‐enhanced Raman spectroscopy (SERS). The inoculation of the virus onto cells results in the aggregations of detergent‐resistant membrane domains significantly. The characteristic Raman band of MNV is found in inoculated samples. To be sure that these results are originated from specific interactions between DRM and MNV, methyl‐β‐cyclo‐dextrin (MβCD) is applied to disrupt lipid rafts. The MNV binding on DRMs is precluded by the MβCD treatment. The cholesterols chains are defined as a key factor in the interactions between norovirus and DRMs. The authors conclude that the MNV binding involves the presence of DRMs and cholesterol dependent. 相似文献
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Adrian P. Nievergelt Christoph Kammer Charlne Brillard Eva Kurisinkal Maartje M. C. Bastings Alireza Karimi Georg E. Fantner 《Small Methods》2019,3(7)
Understanding hierarchical self‐assembly of biological structures requires real‐time measurement of the self‐assembly process over a broad range of length‐ and timescales. The success of high‐speed atomic force microscopy (HS‐AFM) in imaging small‐scale molecular interactions has fueled attempts to introduce this method as a routine technique for studying biological and artificial self‐assembly processes. Current state‐of‐the‐art HS‐AFM scanners achieve their high imaging speed by trading achievable field of view for bandwidth. This limits their suitability when studying larger biological structures. In ambient conditions, large‐range scanners with lower resonance frequencies offer a solution when combined with first principle model–based schemes. For imaging molecular self‐assembly processes in fluid, however, such traditional control techniques are less suited. In liquid, the time‐varying changes in the behavior of the complex system necessitate frequent update of the compensating controller. Recent developments in data‐driven control theory offer a model‐free, automatable approach to compensate the complex system behavior and its changes. Here, a data‐driven control design method is presented to extend the imaging speed of a conventional AFM tube scanner by one order of magnitude. This enables the recording of the self‐assembly process of DNA tripods into a hexagonal lattice at multiple length scales. 相似文献
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Benjamin P. Brown Loren Picco Mervyn J. Miles Charl F. J. Faul 《Small (Weinheim an der Bergstrasse, Germany)》2013,9(19):3201-3211
The atomic force microscope (AFM) has become integrated into standard characterisation procedures in many different areas of research. Nonetheless, typical imaging rates of commercial microscopes are still very slow, much to the frustration of the user. Developments in instrumentation for “high‐speed AFM” (HSAFM) have been ongoing since the 1990s, and now nanometer resolution imaging at video rate is readily achievable. Despite thorough investigation of samples of a biological nature, use of HSAFM instruments to image samples of interest to materials scientists, or to carry out AFM lithography, has been minimal. This review gives a summary of different approaches to and advances in the development of high‐speed AFMs, highlights important discoveries made with new instruments, and briefly discusses new possibilities for HSAFM in materials science. 相似文献
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Matthias Schürmann Natalie Frese Andr Beyer Peter Heimann Darius Widera Viola Mnkemller Thomas Huser Barbara Kaltschmidt Christian Kaltschmidt Armin Glzhuser 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(43):5781-5789
Cell membranes are composed of 2D bilayers of amphipathic lipids, which allow a lateral movement of the respective membrane components. These components are arranged in an inhomogeneous manner as transient micro‐ and nanodomains, which are believed to be crucially involved in the regulation of signal transduction pathways in mammalian cells. Because of their small size (diameter 10–200 nm), membrane nanodomains cannot be directly imaged using conventional light microscopy. Here, direct visualization of cell membrane nanodomains by helium ion microscopy (HIM) is presented. It is shown that HIM is capable to image biological specimens without any conductive coating and that HIM images clearly allow the identification of nanodomains in the ultrastructure of membranes with 1.5 nm resolution. The shape of these nanodomains is preserved by fixation of the surrounding unsaturated fatty acids while saturated fatty acids inside the nanodomains are selectively removed. Atomic force microscopy, fluorescence microscopy, 3D structured illumination microscopy, and direct stochastic optical reconstruction microscopy provide additional evidence that the structures in the HIM images of cell membranes originate from membrane nanodomains. The nanodomains observed by HIM have an average diameter of 20 nm and are densely arranged with a minimal nearest neighbor distance of ≈15 nm. 相似文献
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Interfacial phenomena at solid/water interfaces play an important role in a wide range of industrial technologies and biological processes. However, it has been a great challenge to directly probe the molecular-scale behavior of water at solid/water interfaces. Recently, there have been tremendous advancements in frequency modulation atomic force microscopy (FM-AFM), enabling its operation in liquids with atomic resolution. The high spatial and force resolutions of FM-AFM have enabled the visualization of one-dimensional (1D) profiles of the hydration force, two-dimensional (2D) images of hydration layers and three-dimensional (3D) images of the water distribution at solid/water interfaces. Here I present an overview of the recent advances in FM-AFM instrumentation and its applications to the study of solid/water interfaces. 相似文献
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AbstractInterfacial phenomena at solid/water interfaces play an important role in a wide range of industrial technologies and biological processes. However, it has been a great challenge to directly probe the molecular-scale behavior of water at solid/water interfaces. Recently, there have been tremendous advancements in frequency modulation atomic force microscopy (FM-AFM), enabling its operation in liquids with atomic resolution. The high spatial and force resolutions of FM-AFM have enabled the visualization of one-dimensional (1D) profiles of the hydration force, two-dimensional (2D) images of hydration layers and three-dimensional (3D) images of the water distribution at solid/water interfaces. Here I present an overview of the recent advances in FM-AFM instrumentation and its applications to the study of solid/water interfaces. 相似文献
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Cai M Zhao W Shang X Jiang J Ji H Tang Z Wang H 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(8):1243-1250
Lipid rafts are membrane microdomains enriched with cholesterol, glycosphingolipids, and proteins. Although they are broadly presumed to play a pivotal role in various cellular functions, there are still fierce debates about the composition, functions, and even existence of lipid rafts. Here high-resolution and time-lapse in situ atomic force microscopy is used to directly confirm the existence of lipid rafts in native erythrocyte membranes. The results indicate some important aspects of lipid rafts: most of the lipid rafts are in the size range of 100-300 nm and have irregular shape; the detergent-resistant membranes consist of cholesterol microdomains and are not likely the same as the lipid rafts; cholesterol contributes significantly to the formation and stability of the protein domains; and Band III is an important protein of lipid rafts in the inner leaflet of erythrocyte membranes, indicating that lipid rafts are exactly the functional domains in plasma membrane. This work provides direct evidence of the presence, size, and main constitutive protein of lipid rafts at a resolution of a few nanometers, which will pave the way for studying their structure and functions in detail. 相似文献
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Eric L. Kendall Chenren Shao Don L. DeVoe 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(23):3613-3619
A microfluidic platform enabling optical monitoring of bilayer lipid membrane formation by a new monolayer folding process is described. The thermoplastic chips integrate dried lipid films that are rehydrated by microfluidic perfusion, which enables delivery of lipid‐laden air bubbles across a membrane‐supporting aperture. As in traditional Montal–Mueller bilayer formation, lipid monolayers are delivered independently to each side of the aperture, thereby allowing asymmetric lipid composition in the resulting bilayer to be achieved. Confocal microscopy is used to image the monolayer folding process, and reveals the growth and dynamics of asymmetric liquid‐ordered domains during bilayer stabilization. 相似文献
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Guo S Solares SD Mochalin V Neitzel I Gogotsi Y Kalinin SV Jesse S 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(8):1264-1269
The cantilever dynamics in single-frequency scanning probe microscopy (SPM) are undefined due to having only two output variables, which leads to poorly understood image contrast. To address this shortcoming, generalized phase imaging scanning probe microscopy (GP-SPM), based on broad band detection and multi-eigenmode operation, is developed and demonstrated on diamond nanoparticles with different functionalization layers. It is shown that rich information on tip-surface interactions can be acquired by separating the response amplitude, instant resonance frequency, and quality factor. The obtained data allow high-resolution imaging even in the ambient environment. By tuning the strength of tip-surface interaction, different surface functionalizations can be discerned. 相似文献
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Prashant Kumar M. Ghanashyam Krishna A. K. Bhattacharya 《Bulletin of Materials Science》2009,32(3):263-270
The magnetic properties of Ni thin films, in the range 20–500 nm, at the crystalline-nanocrystalline interface are reported.
The effect of thickness, substrate and substrate temperature has been studied. For the films deposited at ambient temperatures
on borosilicate glass substrates, the crystallite size, coercive field and magnetization energy density first increase and
achieve a maximum at a critical value of thickness and decrease thereafter. At a thickness of 50 nm, the films deposited at
ambient temperature onto borosilicate glass, MgO and silicon do not exhibit long-range order but are magnetic as is evident
from the non-zero coercive field and magnetization energy. Phase contrast microscopy revealed that the grain sizes increase
from a value of 30–50 nm at ambient temperature to 120–150 nm at 503 K and remain approximately constant in this range up
to 593 K. The existence of grain boundary walls of width 30–50 nm is demonstrated using phase contrast images. The grain boundary
area also stagnates at higher substrate temperature. There is pronounced shape anisotropy as evidenced by the increased aspect
ratio of the grains as a function of substrate temperature. Nickel thin films of 50 nm show the absence of long-range crystalline
order at ambient temperature growth conditions and a preferred [111] orientation at higher substrate temperatures. Thin films
are found to be thermally relaxed at elevated deposition temperature and having large compressive strain at ambient temperature.
This transition from nanocrystalline to crystalline order causes a peak in the coercive field in the region of transition
as a function of thickness and substrate temperature. The saturation magnetization on the other hand increases with increase
in substrate temperature. 相似文献
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Owoong Kwon Daehee Seol Dongkyu Lee Hee Han Ionela Lindfors‐Vrejoiu Woo Lee Stephen Jesse Ho Nyung Lee Sergei V. Kalinin Marin Alexe Yunseok Kim 《Advanced materials (Deerfield Beach, Fla.)》2018,30(1)
Ferroelectric materials possess spontaneous polarization that can be used for multiple applications. Owing to a long‐term development of reducing the sizes of devices, the preparation of ferroelectric materials and devices is entering the nanometer‐scale regime. Accordingly, to evaluate the ferroelectricity, there is a need to investigate the polarization charge at the nanoscale. Nonetheless, it is generally accepted that the detection of polarization charges using a conventional conductive atomic force microscopy (CAFM) without a top electrode is not feasible because the nanometer‐scale radius of an atomic force microscopy (AFM) tip yields a very low signal‐to‐noise ratio. However, the detection is unrelated to the radius of an AFM tip and, in fact, a matter of the switched area. In this work, the direct probing of the polarization charge at the nanoscale is demonstrated using the positive‐up‐negative‐down method based on the conventional CAFM approach without additional corrections or circuits to reduce the parasitic capacitance. The polarization charge densities of 73.7 and 119.0 µC cm?2 are successfully probed in ferroelectric nanocapacitors and thin films, respectively. The obtained results show the feasibility of the evaluation of polarization charge at the nanoscale and provide a new guideline for evaluating the ferroelectricity at the nanoscale. 相似文献
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Chia‐Wei Lee Ya‐Ling Chiang Ji‐Ting Liu Yi‐Xian Chen Chau‐Hwang Lee Yeng‐Long Chen Ing‐Shouh Hwang 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(40)
Recent studies indicate that changing the physical properties of lipid bilayers may profoundly change the function of membrane proteins. Here, the effects of dissolved nitrogen and oxygen molecules on the mechanical properties and stability of lipid bilayers are investigated using differential confocal microscopy, atomic force microscopy, and molecular dynamics simulations. All experiments evidence the presence of dissolved air gas in lipid bilayers prepared without gas control. The lipid bilayers in degassed solutions are softer and less stable than those in ambient solutions. High concentrations of nitrogen increase the bending moduli and stability of the lipid bilayers and impede phase separation in ternary lipid bilayers. The effect of oxygen is less prominent. Molecular dynamics simulations indicate that higher nitrogen affinity accounts for increased rigidity. These findings have fundamental and wide implications for phenomena related to lipid bilayers and cell membranes, including the origin of life. 相似文献
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Ji Xu Thomas P. Russell Antonio Checco 《Small (Weinheim an der Bergstrasse, Germany)》2013,9(5):779-784
The self‐assembly of cylinder‐forming block copolymer (BCP) microdomains confined within chemical stripe patterns of widths incommensurate with the natural period of the copolymers, L0, is studied. It is shown that this incommensurability causes changes in both the shapes of the microdomains and their spatial period. Specifically, a transition from n to n + 1 rows of microdomains is observed when the stripe width is about n ± 1/2 L0. When the stripe's width is comparable to L0, ellipticity of microdomains can be induced with an aspect ratio up to 2.2. Free energy models are applied to describe the energetic origin of such behavior. Although our observations qualitatively resemble results in sphere‐forming BCPs confined in topographical trenches, the quantitative difference is noteworthy and technologically important for the design of nanostructures with programmable shapes. 相似文献