共查询到20条相似文献,搜索用时 15 毫秒
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Liangliang Liang Wei Yan Xian Qin Xiao Peng Han Feng Yu Wang Ziyu Zhu Lingmei Liu Yu Han Qinghua Xu Junle Qu Xiaogang Liu 《Angewandte Chemie (International ed. in English)》2020,59(2):746-751
Stimulated emission depletion (STED) microscopy enables ultrastructural imaging of biological samples with high spatiotemporal resolution. STED nanoprobes based on fluorescent organosilica nanohybrids featuring sub‐2 nm size and near‐unity quantum yield are presented. The spin–orbit coupling (SOC) of heavy‐atom‐rich organic fluorophores is mitigated through a silane‐molecule‐mediated condensation/dehalogenation process, resulting in bright fluorescent organosilica nanohybrids with multiple emitters in one hybrid nanodot. When harnessed as STED nanoprobes, these fluorescent nanohybrids show intense photoluminescence, high biocompatibility, and long‐term photostability. Taking advantage of the low‐power excitation (0.5 μW), prolonged singlet‐state lifetime, and negligible depletion‐induced re‐excitation, these STED nanohybrids present high depletion efficiency (>96 %), extremely low saturation intensity (0.54 mW, ca. 0.188 MW cm?2), and ultra‐high lateral resolution (ca. λem/28). 相似文献
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Soohyun Jang Mingi Kim Sang‐Hee Shim 《Angewandte Chemie (International ed. in English)》2020,59(29):11758-11762
In DNA points accumulation in nanoscale topography (DNA‐PAINT), capable of single‐molecule localization microscopy with sub‐10‐nm resolution, the high background stemming from the unbound fluorescent probes in solution limits the imaging speed and throughput. Herein, we reductively cage the fluorescent DNA probes conjugated with a cyanine dye to hydrocyanine, acting as a photoactivatable dark state. The additional dark state from caging lowered the fluorescent background while enabling optically selective activation by total internal reflection (TIR) illumination at 405 nm. These benefits from “reductive caging” helped to increase the localization density or the imaging speed while preserving the image quality. With the aid of high‐density analysis, we could further increase the imaging speed of conventional DNA‐PAINT by two orders of magnitude, making DNA‐PAINT capable of high‐throughput super‐resolution imaging. 相似文献
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Direct Observation of the Distribution of Gelatin in Calcium Carbonate Crystals by Super‐Resolution Fluorescence Microscopy 下载免费PDF全文
Meifang Fu Dr. Anhe Wang Dr. Xiaoming Zhang Prof. Dr. Luru Dai Prof. Dr. Junbai Li 《Angewandte Chemie (International ed. in English)》2016,55(3):908-911
Biological organic–inorganic hybrid materials often achieve excellent properties and provide inspiration for the design of advanced materials. The organic phase plays a key role in determining the properties of biogenic materials, and the spatial arrangement of organic and inorganic phases provides direct evidence for interaction between the two phases. Super‐resolution fluorescence microscopy was used to visualize the gelatin distribution in two different crystalline polymorphs of calcium carbonate (vaterite and calcite) and to investigate the process by which gelatin is excluded from the crystals. The results demonstrated that gelatin is distributed through vaterite microspheres in the form of nanoparticles, whereas it tends to accumulate on the edges of the calcite rhombohedra. 相似文献
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Synthesis of a Far‐Red Photoactivatable Silicon‐Containing Rhodamine for Super‐Resolution Microscopy 下载免费PDF全文
Jonathan B. Grimm Dr. Teresa Klein Dr. Benjamin G. Kopek Dr. Gleb Shtengel Dr. Harald F. Hess Prof. Dr. Markus Sauer Dr. Luke D. Lavis 《Angewandte Chemie (International ed. in English)》2016,55(5):1723-1727
The rhodamine system is a flexible framework for building small‐molecule fluorescent probes. Changing N‐substitution patterns and replacing the xanthene oxygen with a dimethylsilicon moiety can shift the absorption and fluorescence emission maxima of rhodamine dyes to longer wavelengths. Acylation of the rhodamine nitrogen atoms forces the molecule to adopt a nonfluorescent lactone form, providing a convenient method to make fluorogenic compounds. Herein, we take advantage of all of these structural manipulations and describe a novel photoactivatable fluorophore based on a Si‐containing analogue of Q‐rhodamine. This probe is the first example of a “caged” Si‐rhodamine, exhibits higher photon counts compared to established localization microscopy dyes, and is sufficiently red‐shifted to allow multicolor imaging. The dye is a useful label for super‐resolution imaging and constitutes a new scaffold for far‐red fluorogenic molecules. 相似文献
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We assess the elastic properties of PS‐b‐PAA vesicle membranes under different pH values by AFM force measurements. We find that based on the shell deformation theory, the values of the estimated apparent Young's modulus of the vesicle membranes decrease as the pH of the solution increases. The onset of the decrease of E coincides with the surface pKa determined from ζ‐potential measurements. This decrease of E at higher pH is attributed to electrostatic repulsion between the deprotonated PAA chains resulting in the thinning of the vesicle membrane.
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Inside Back Cover: Synthesis of a Far‐Red Photoactivatable Silicon‐Containing Rhodamine for Super‐Resolution Microscopy (Angew. Chem. Int. Ed. 5/2016) 下载免费PDF全文
Jonathan B. Grimm Dr. Teresa Klein Dr. Benjamin G. Kopek Dr. Gleb Shtengel Dr. Harald F. Hess Prof. Dr. Markus Sauer Dr. Luke D. Lavis 《Angewandte Chemie (International ed. in English)》2016,55(5):1925-1925
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In Situ Visualization of Block Copolymer Self‐Assembly in Organic Media by Super‐Resolution Fluorescence Microscopy 下载免费PDF全文
Charlotte E. Boott John R. Finnegan Dr. Erin M. Leitao Dr. Stephen E. D. Webb Prof. Clemens F. Kaminski Prof. Ian Manners 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(51):18539-18542
Analytical methods that enable visualization of nanomaterials derived from solution self‐assembly processes in organic solvents are highly desirable. Herein, we demonstrate the use of stimulated emission depletion microscopy (STED) and single molecule localization microscopy (SMLM) to map living crystallization‐driven block copolymer (BCP) self‐assembly in organic media at the sub‐diffraction scale. Four different dyes were successfully used for single‐colour super‐resolution imaging of the BCP nanostructures allowing micelle length distributions to be determined in situ. Dual‐colour SMLM imaging was used to measure and compare the rate of addition of red fluorescent BCP to the termini of green fluorescent seed micelles to generate block comicelles. Although well‐established for aqueous systems, the results highlight the potential of super‐resolution microscopy techniques for the interrogation of self‐assembly processes in organic media. 相似文献
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Dr. Pablo Cubillas Prof. Michael W. Anderson Dr. Martin P. Attfield 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(48):15406-15415
Crystal growth of the metal–organic framework MOF‐5 was studied by atomic force microscopy (AFM) for the first time. Growth under low supersaturation conditions was found to occur by a two‐dimensional or spiral crystal growth mechanism. Observation of developing nuclei during the former reveals growth occurs through a process of nucleation and spreading of metastable and stable sub‐layers revealing that MOFs may be considered as dense phase structures in terms of crystal growth, even though they contain sub‐layers consisting of ordered framework and disordered non‐framework components. These results also support the notion this may be a general mechanism of surface crystal growth at low supersaturation applicable to crystalline nanoporous materials. The crystal growth mechanism at the atomistic level was also seen to vary as a function of the growth solution Zn/H2bdc ratio producing square terraces with steps parallel to the <100> direction or rhombus‐shaped terraces with steps parallel to the <110> direction when the Zn/H2bdc ratio was >1 or about 1, respectively. The change in relative growth rates can be explained in terms of changes in the solution species concentrations and their influence on growth at different terrace growth sites. These results were successfully applied to the growth of as‐synthesized cube‐shaped crystals to increase expression of the {111} faces and to grow octahedral crystals of suitable quality to image using AFM. This modulator‐free route to control the crystal morphology of MOF‐5 crystals should be applicable to a wide variety of MOFs to achieve the desired morphological control for performance enhancement in applications. 相似文献
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Dr. Pablo Cubillas Prof. Michael W. Anderson Dr. Martin P. Attfield 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(25):8236-8243
A new zeolitic–imidazolate framework (ZIF), [Zn(imidazolate)2?x(benzimidazolate)x], that has the zeolite A (LTA) framework topology and contains relatively inexpensive organic linkers has been revealed using in situ atomic force microscopy. The new material was grown on the structure‐directing surface of [Zn(imidazolate)1.5(5‐chlorobenzimidazolate)0.5] (ZIF‐76) crystals, a metal–organic framework (MOF) that also possesses the LTA framework topology. The crystal growth processes for both [Zn(imidazolate)2?x(benzimidazolate)x] and ZIF‐76 were observed using in situ atomic force microscopy; it is the first time the growth process of a nanoporous material with the complex zeolite A (LTA) framework topology has been monitored temporally at the nanoscale. The results reveal the crystal growth mechanisms and possible surface terminations on the {100} and {111} facets of the materials under low supersaturation conditions. Surface growth of these structurally complex materials was found to proceed through both “birth‐and‐spread” and spiral crystal‐growth mechanisms, with the former occurring through the nucleation and spreading of metastable and stable sub‐layers reliant on the presence of non‐framework species to bridge the framework during formation. These results support the notion that the latter process may be a general mechanism of surface crystal growth applicable to numerous crystalline nanoporous materials of differing complexity and demonstrate that the methodology of seeded crystal growth can be used to discover previously unobtainable ZIFs and MOFs with desirable framework compositions. 相似文献
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Dr. Hans Wienk Uschi Siebler Dr. Monika Burg‐Roderfeld Dr. Thomas Eckert Bianca Kulik Dr. Rainer Wechselberger Judith Sewing Prof. Dr. Jürgen Steinmeyer Dr. Steffen Oesser Prof. Dr. Rolf Boelens Prof. Dr. Hans‐Christian Siebert 《Chemphyschem》2012,13(13):3117-3125
Heterogeneous mixtures of collagen fragments can be used as nutrition supplement or as key ingredients for ointments with therapeutic relevance in wound healing. Some mixtures of collagen fragments are referred to as collagen hydrolysates owing to the production process with hydrolytic enzymes. Since the precise composition of collagen hydrolysates is generally unknown, it is of interest to analyze samples containing various collagen fragments with appropriate biophysical methods. Any product optimization without a profound knowledge concerning the size and the molecular weight distribution of its components is nearly impossible. It turned out that a combination of AFM methods with NMR techniques is exceptionally suited to examine the size range and the aggregation behavior of the collagen fragments in the hydrolysates of fish, jellyfish, chicken, porcine and bovine collagen. Supported by molecular modeling calculations, the AFM and NMR experiments provide a detailed knowledge about the composition of collagen hydrolysates and collagen ointments. Furthermore, the data allow a correlation between the size of the fragments and their potential bioactivity. 相似文献
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Functional Dynamics of Deuterated β2‐Adrenergic Receptor in Lipid Bilayers Revealed by NMR Spectroscopy 下载免费PDF全文
Dr. Yutaka Kofuku Dr. Takumi Ueda Junya Okude Yutaro Shiraishi Keita Kondo Takuya Mizumura Shiho Suzuki Prof. Dr. Ichio Shimada 《Angewandte Chemie (International ed. in English)》2014,53(49):13376-13379
G‐protein‐coupled receptors (GPCRs) exist in conformational equilibrium between active and inactive states, and the former population determines the efficacy of signaling. However, the conformational equilibrium of GPCRs in lipid bilayers is unknown owing to the low sensitivities of their NMR signals. To increase the signal intensities, a deuteration method was developed for GPCRs expressed in an insect cell/baculovirus expression system. The NMR sensitivities of the methionine methyl resonances from the β2‐adrenergic receptor (β2AR) in lipid bilayers of reconstituted high‐density lipoprotein (rHDL) increased by approximately 5‐fold upon deuteration. NMR analyses revealed that the exchange rates for the conformational equilibrium of β2AR in rHDLs were remarkably different from those measured in detergents. The timescales of GPCR signaling, calculated from the exchange rates, are faster than those of receptor tyrosine kinases and thus enable rapid neurotransmission and sensory perception. 相似文献
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Albert K. Engstfeld Stephan Beckord Christoph D. Lorenz Prof. Dr. R. Jürgen Behm 《Chemphyschem》2012,13(14):3313-3319
We report on results of a detailed scanning tunnelling microscopy study on the formation, size and size distribution, and internal structure of small bimetallic PtRu clusters on a graphene monolayer film supported on a Ru(0001) substrate. These clusters, with sizes around ~15 (Ru) or ~40 (Pt) atoms per cluster at the lowest coverage, are interesting model systems for the catalytic behaviour of small metal PtRu particles, for example for application in electrocatalytic oxidation reactions. The clusters were generated by sequential deposition of the two metals at room temperature. The data reveal a distinct influence of the deposition sequence on the cluster formation process, with Ru pre‐deposition followed by Pt deposition leading to predominantly bimetallic clusters, possibly with a core–shell‐type structure, while the reverse sequence results in co‐existent mono‐ and bimetallic clusters, where the latter are likely to intermix at the interface. The observations are related to the nucleation process of the respective metals on the templated surface, and the 2D growth behaviour of the two metals. 相似文献
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Summary: We investigate the influence of the polydispersity of colloidal particles and polymer, respectively, on the form factor and depletion interaction by using the laser distribution for parallel plates immersed in a solution of nonadsorbing polymers. For colloidal particles, we show that the measurement of scattering intensity of a polymer‐colloid mixture can be described qualitatively in terms of the parameters K and M of the laser distribution. The form factor of the monodisperse system varies considerably, but generally stays close to the average value that corresponds to the form factor of polydisperse system. By using the laser distribution in the chain length of polymers, we present the complex polymer segment density of polymer chain between particles with the product‐function approximation comprehensively and accurately. In particular, we find that for small values of parameter M, the change of values of parameter K has no effect on depletion interaction.
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Analysis of Interactions between the Epidermal Growth Factor Receptor and Soluble Ligands on the Basis of Single‐Molecule Diffusivity in the Membrane of Living Cells 下载免费PDF全文
Soyeon Park Jungeun Noh Yonghoon Kwon Dayea Kim Dr. Nam Woong Song Prof. Jong‐Bong Lee Prof. Pann‐Ghill Suh Prof. Nam Ki Lee Prof. Sung Ho Ryu 《Angewandte Chemie (International ed. in English)》2015,54(24):7028-7032
We present a single‐molecule diffusional‐mobility‐shift assay (smDIMSA) for analyzing the interactions between membrane and water‐soluble proteins in the crowded membrane of living cells. We found that ligand–receptor interactions decreased the diffusional mobility of ErbB receptors and β‐adrenergic receptors, as determined by single‐particle tracking with super‐resolution microscopy. The shift in diffusional mobility was sensitive to the size of the water‐soluble binders that ranged from a few tens of kilodaltons to several hundred kilodaltons. This technique was used to quantitatively analyze the dissociation constant and the cooperativity of antibody interactions with the epidermal growth factor receptor and its mutants. smDIMSA enables the quantitative investigation of previously undetected ligand–receptor interactions in the intact membrane of living cells on the basis of the diffusivity of single‐molecule membrane proteins without ligand labeling. 相似文献