76
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Cui Q, Xia B, Mitzscherling S, Masic A, Li L, Bargheer M, Möhwald H. Preparation of gold nanostars and their study in selective catalytic reactions. Colloids Surf A Physicochem Eng Asp 2015. [DOI: 10.1016/j.colsurfa.2014.10.028] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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77
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Baidukova O, Möhwald H, Mazheika AS, Sviridov DV, Palamarciuc T, Weber B, Cherepanov PV, Andreeva DV, Skorb EV. Sonogenerated metal-hydrogen sponges for reactive hard templating. Chem Commun (Camb) 2015; 51:7606-9. [DOI: 10.1039/c4cc10026c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Sonogenerated magnesium-hydrogen sponges with low dehydrogenation energy are used as prospective reactive hard templates for the synthesis of organized nanostructures.
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78
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Chan WCW, Gogotsi Y, Hafner JH, Hammond PT, Hersam MC, Javey A, Kagan CR, Khademhosseini A, Kotov NA, Lee ST, Möhwald H, Mulvaney PA, Nel AE, Nordlander PJ, Parak WJ, Penner RM, Rogach AL, Schaak RE, Stevens MM, Wee ATS, Willson CG, Weiss PS. A year for nanoscience. ACS NANO 2014; 8:11901-11903. [PMID: 25533169 DOI: 10.1021/nn5070716] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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79
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Dannehl C, Brezesinski G, Möhwald H. Interactions of Two Fragments of the Human Antimicrobial Peptide LL-37 with Zwitterionic and Anionic Lipid Monolayers. ACTA ACUST UNITED AC 2014. [DOI: 10.1515/zpch-2014-0565] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The interactions of two fragments of the human antimicrobial LL-37
(LL-32 and LL-20) with lipid monolayers at the soft liquid/air
interface have been characterized. To model the interaction with
mammalian cell membranes, lipid monolayers composed of the
zwitterionic DPPC and DOPC were used. To investigate the interaction
with bacterial cell membranes, lipid monolayers of anionic DPPG and
POPG were used. DPPC and DPPG exhibit a first-order phase transition
from the disordered liquid to the ordered condensed state, whereas
POPG and DOPC monolayers are in the fluid disordered state at all
surface pressures studied. Therefore, the influence of the monolayer
phase state on peptide-lipid interactions can be studied. To obtain
insight into the peptide structure and their influence on phospholipid
membranes, film balance measurements were coupled with surface
sensitive Infrared Reflection-Absorption Spectroscopy (IRRAS). The
results were compared to CD measurements in bulk.
LL-32 is more surface active and can better intercalate into lipid
monolayers than LL-20. Even though LL-32 has no cell-selectivity, our
results show how the peptide interacts differently with zwitterionic
compared to anionic membrane models. The interaction with DPPC
monolayers is based on simple intercalation of the peptides between
the lipid molecules. However, the peptides bind in a two-step process
to DPPG monolayers, which results in a fluidization of the lipid
film. This can be related to a membrane thinning.
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80
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Wettstein C, Kyne C, Doolan AM, Möhwald H, Crowley PB, Lisdat F. Study of cytochrome c-DNA interaction--evaluation of binding sites on the redox protein. NANOSCALE 2014; 6:13779-13786. [PMID: 25286363 DOI: 10.1039/c4nr05301j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Artificial assemblies consisting of the cationic cytochrome c (cyt c) and double-stranded DNA are interesting for the field of biohybrid systems because of the high electro-activity of the incorporated redox protein. However, little is known about the interactions between these two biomolecules. Here, the complex of reduced cyt c and a 41 base pair oligonucleotide was characterized in solution as a function of pH and ionic strength. Persistent cyt c-DNA agglomerates were observed by UV-vis and DLS (dynamic light scattering) at pH 5.0 and low ionic strength. The strength of the interaction was attenuated by raising the pH or the ionic strength. At pH 7.0 agglomerates were not formed, allowing interaction analysis by NMR spectroscopy. Using TROSY (transverse relaxation-optimized spectroscopy)-HSQC (heteronuclear single quantum coherence) experiments it was possible to identify the DNA binding site on the cyt c surface. Numerous residues surrounding the exposed heme edge of cyt c were involved in transient binding to DNA under these conditions. This result was supported by SEC (size exclusion chromatography) experiments at pH 7.0 showing that the interaction is sufficient for co-elution of cyt c and DNA.
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81
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Liu K, Xing R, Chen C, Shen G, Yan L, Zou Q, Ma G, Möhwald H, Yan X. Peptide-induced hierarchical long-range order and photocatalytic activity of porphyrin assemblies. Angew Chem Int Ed Engl 2014; 54:500-5. [PMID: 25377526 DOI: 10.1002/anie.201409149] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 10/07/2014] [Indexed: 11/06/2022]
Abstract
Long-range structural order and alignment over different scales are of key importance for the regulation of structure and functionality in biology. However, it remains a great challenge to engineer and assemble such complex functional synthetic systems with order over different length scales from simple biologically relevant molecules, such as peptides and porphyrins. Herein we describe the successful introduction of hierarchical long-range order in dipeptide-adjusted porphyrin self-assembly by a thermodynamically driven self-orienting assembly pathway associated with multiple weak interactions. The long-range order and alignment of fiber bundles induced new properties, including anisotropic birefringence, a large Stokes shift, amplified chirality, and excellent photostability as well as sustainable photocatalytic activity. We also demonstrate that the aligned fiber bundles are able to induce the epitaxially oriented growth of Pt nanowires in a photocatalytic reaction.
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82
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Liu K, Xing R, Chen C, Shen G, Yan L, Zou Q, Ma G, Möhwald H, Yan X. Peptide-Induced Hierarchical Long-Range Order and Photocatalytic Activity of Porphyrin Assemblies. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201409149] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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83
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Ai B, Wang L, Möhwald H, Yu Y, Zhao Z, Zhou Z, Zhang G, Lin Q. Real-time control of uni-directional liquid spreading on a half-cone nanoshell array. Sci Rep 2014; 4:6751. [PMID: 25341416 PMCID: PMC4208037 DOI: 10.1038/srep06751] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 10/03/2014] [Indexed: 11/08/2022] Open
Abstract
Half-cone nanoshell arrays, fabricated by a simple and efficient colloidal lithography method, enable uni-directional liquid spreading on their hydrophilic asymmetric nanostructured surface. The preferred direction of the liquid flow is reversed when the surface is made hydrophobic. Accordingly, poly(N-isopropyl-acrylamide) is polymerized onto the surface for in-site controlling the transition of liquid spreading direction via its temperature dependent hydrophobicity. Furthermore, we also explain theoretically, that the spreading direction on hexagonal nanocone arrays is independent of the lattice orientation and only depends on the slanting direction. The insights gained from this work offer new opportunities for smart microfluidics, water harvesting and making use of other wetting conditions on demand.
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84
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Korte M, Akari S, Kühn H, Baghdadli N, Möhwald H, Luengo GS. Distribution and localization of hydrophobic and ionic chemical groups at the surface of bleached human hair fibers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:12124-12129. [PMID: 25203784 DOI: 10.1021/la500461y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A chemical mapping with high lateral resolution using an atomic force microscope in the pulsed force mode with chemically modified tips, introduced as "dynamic chemical force microscopy" (dCFM), was carried out to investigate the chemical properties of the cuticle of human hair and its changes following an oxidative treatment. Chemically modified atomic force microscopy (AFM) tips, CH3- and NH2-terminated, were applied to achieve a defined chemical contrast (hydrophobic and ionic) in aqueous medium. A comparative Fourier transform infrared spectroscopy-attenuated total reflection identified the dominant chemical groups of the surface vicinity of the hair fiber resulting from the bleaching process. The combined experimental results lead to the conclusion that the hydrophobic top layer is partially removed after bleaching, resulting mostly in hydrophilic SO3(-) end groups at the top of the surface of the hair, with a mean surface density "δ(mean)" of negatively charged groups of approximately 2.2 molecules/nm(2), corresponding to ∼600 μg/m(2) cysteic acid. This indicates that thioester bonds are disrupted and fatty acids are removed as a result of cysteine oxidation. At the molecular level, our results indicate a clustered "self-assembled monolayer" alignment of cysteic acid with a crystal-like structuring, reminiscent of the "fluid mosaic model of cell membranes", with a surface energy of approximately 0.04 N/m. Despite previous extensive works of AFM on human hair, this is, to our knowledge, the first time that the hydrophobic and ionic sites at the top surface of hair have been imaged at the nanoscale with dCFM.
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85
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Cui Q, Shen G, Yan X, Li L, Möhwald H, Bargheer M. Fabrication of Au@Pt multibranched nanoparticles and their application to in situ SERS monitoring. ACS APPLIED MATERIALS & INTERFACES 2014; 6:17075-17081. [PMID: 25215532 DOI: 10.1021/am504709a] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Here, we present an Au@Pt core-shell multibranched nanoparticle as a new substrate capable of in situ surface-enhanced Raman scattering (SERS), thereby enabling monitoring of the catalytic reaction on the active surface. By careful control of the amount of Pt deposited bimetallic Au@Pt, nanoparticles with moderate performance both for SERS and catalytic activity were obtained. The Pt-catalyzed reduction of 4-nitrothiophenol by borohydride was chosen as the model reaction. The intermediate during the reaction was captured and clearly identified via SERS spectroscopy. We established in situ SERS spectroscopy as a promising and powerful technique to investigate in situ reactions taking place in heterogeneous catalysis.
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86
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Hollamby MJ, Karny M, Bomans PHH, Sommerdijk NAJM, Saeki A, Seki S, Minamikawa H, Grillo I, Pauw BR, Brown P, Eastoe J, Möhwald H, Nakanishi T. Erratum: Corrigendum: Directed assembly of optoelectronically active alkyl–π-conjugated molecules by adding n-alkanes or π-conjugated species. Nat Chem 2014. [DOI: 10.1038/nchem.2069] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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87
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Palankar R, Pinchasik BE, Khlebtsov BN, Kolesnikova TA, Möhwald H, Winterhalter M, Skirtach AG. Nanoplasmonically-induced defects in lipid membrane monitored by ion current: transient nanopores versus membrane rupture. NANO LETTERS 2014; 14:4273-4279. [PMID: 24961609 DOI: 10.1021/nl500907k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We have developed a nanoplasmonic-based approach to induce nanometer-sized local defects in the phospholipid membranes. Here, gold nanorods and nanoparticles having plasmon resonances in the near-infrared (NIR) spectral range are used as optical absorption centers in the lipid membrane. Defects optically induced by NIR-laser irradiation of gold nanoparticles are continuously monitored by high-precision ion conductance measurement. Localized laser-mediated heating of nanorods and nanoparticle aggregates cause either (a) transient nanopores in lipid membranes or (b) irreversible rupture of the membrane. To monitor transient opening and closing, an electrophysiological setup is assembled wherein a giant liposome is spread over a micrometer hole in a glass slide forming a single bilayer of high Ohmic resistance (so-called gigaseal), while laser light is coupled in and focused on the membrane. The energy associated with the localized heating is discussed and compared with typical elastic parameters in the lipid membranes. The method presented here provides a novel methodology for better understanding of transport across artificial or natural biological membranes.
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88
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Ai B, Wang L, Möhwald H, Yu Y, Zhang G. Asymmetric half-cone/nanohole array films with structural and directional reshaping of extraordinary optical transmission. NANOSCALE 2014; 6:8997-9005. [PMID: 24969165 DOI: 10.1039/c4nr01385a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Structured films with periodic arrays of nanoholes covered by half-cone shells are fabricated via a simple and efficient colloidal lithography method. The designed films show strong polarization dependence in optical transmission. By decreasing the height of half-cone shells the peak shifts and this shift varies strongly for different orthogonal polarizations. Furthermore, the three-dimensional (3D) asymmetric arrays exhibit a pronounced increase in the transmission intensity by changing the direction of the incident light from the half-cone shell (shelter) side to the empty side. Special surface plasmon resonances excited by the unique 3D asymmetric structure are responsible for these novel properties, and the experimental results are in good agreement with numerical simulations. The nanostructured films in this work will be useful for metallic nanophotonic elements in many applications, including surface plasmon enhanced optical sensing and ultrafast optical switching, as well as versatile substrates for surface enhanced Raman spectroscopy, anisotropic wettability and other potential uses.
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89
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Parakhonskiy BV, Yashchenok AM, Donatan S, Volodkin DV, Tessarolo F, Antolini R, Möhwald H, Skirtach AG. Macromolecule loading into spherical, elliptical, star-like and cubic calcium carbonate carriers. Chemphyschem 2014; 15:2817-22. [PMID: 25044943 DOI: 10.1002/cphc.201402136] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 05/08/2014] [Indexed: 11/11/2022]
Abstract
We fabricated calcium carbonate particles with spherical, elliptical, star-like and cubical morphologies by varying relative salt concentrations and adding ethylene glycol as a solvent to slow down the rate of particle formation. The loading capacity of particles of different isotropic (spherical and cubical) and anisotropic (elliptical and star-like) geometries is investigated, and the surface area of such carriers is analysed. Potential applications of such drug delivery carriers are highlighted.
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90
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Wu Y, Lin X, Wu Z, Möhwald H, He Q. Self-propelled polymer multilayer Janus capsules for effective drug delivery and light-triggered release. ACS APPLIED MATERIALS & INTERFACES 2014; 6:10476-81. [PMID: 24909305 DOI: 10.1021/am502458h] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We present herein a novel hybrid, polymer-based motor that was fabricated by the template-assisted polyelectrolyte layer-by-layer (LbL) deposition of a thin gold layer on one side, followed by chemical immobilization of a catalytic enzyme. Such Janus capsule motors can self-propel at 0.1% peroxide fuel concentration at physiological temperature and have a higher speed as compared to Pt-based synthetic motors. They were exploited for encapsulation of the chemotherapeutic anticancer drug, doxorubicin, for navigation to target a cell layer by an external magnetic field, and for triggered drug release activated by NIR light. This work provides high potential in the development of multifunctional polymer-based engines for biomedical applications such as targeted drug delivery.
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91
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Pinchasik BE, Möhwald H, Skirtach AG. Mimicking bubble use in nature: propulsion of Janus particles due to hydrophobic-hydrophilic interactions. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:2670-7. [PMID: 24664591 DOI: 10.1002/smll.201303571] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 01/14/2014] [Indexed: 05/25/2023]
Abstract
Bubbles are widely used by animals in nature in order to fulfill important functions. They are used by animals in order to walk underwater or to stabilize themselves at the water/air interface. The main aim of this work is to imitate such phenomena, which is the essence of biomimetics. Here, bubbles are used to propel and to control the location of Janus particles in an aqueous medium. The synthesis of Janus SiO2-Ag and polystyrene-Ag (PS-Ag) particles through embedment in Parafilm is presented. The Janus particles, partially covered with catalytically active Ag nanoparticles, are redispersed in water and placed on a glass substrate. The active Ag sites are used for the splitting of H2O2 into water and oxygen. As a result, an oxygen bubble is formed on one side of the particle and promotes its propulsion. Once formed, the bubble-particle complex is stable and therefore, can be manipulated by tuning hydrophilic-hydrophobic interactions with the surface. In this way a transition between two- and three- dimensional motion is possible by changing the hydrophobicity of the substrate. Similar principles are used in nature.
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92
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Hollamby MJ, Karny M, Bomans PHH, Sommerdjik NAJM, Saeki A, Seki S, Minamikawa H, Grillo I, Pauw BR, Brown P, Eastoe J, Möhwald H, Nakanishi T. Directed assembly of optoelectronically active alkyl–π-conjugated molecules by adding n-alkanes or π-conjugated species. Nat Chem 2014; 6:690-6. [DOI: 10.1038/nchem.1977] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 05/15/2014] [Indexed: 12/23/2022]
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93
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Abstract
Mixed monolayers containing chlorophyll a and dim yristoyllecithin (DML) have been investigated by simultaneous thermodynamic, fluorescence and absorption spectroscopic measurements. It has been shown that the solubility limit of chlorophyll a in the fluid, as well as in the solid lipid matrix, is above 20 mol%. This contrasts to previous findings for pheophytin a containing monolayers and indicates the existance of an interaction between the phospholipid head group and the central Mg atom.
A fluorescence decrease on solidifying the monolayer was observed and it is suggested that it is due to an enhanced self quenching as a consequence of the reorientation of the porphyrin rings, accompanying the phase transition
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94
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Möhwald H, Sackmann E. Mobile and Trapped Triplet States in Single Crystals of Charge Transfer Complexes. ACTA ACUST UNITED AC 2014. [DOI: 10.1515/zna-1974-0817] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Homogeneously doped crystals of charge transfer (CT-) complexes were grown by incorporating aromatic guest donors in host CT-crystals. The host crystals contained 1,2.4,5-tetracyanobenzene (TCNB) as acceptor and deuterated aromatic electron donors. By using such doped crystals CT complexes in a well defined configuration may be studied. The triplet states of the guest complexes were used as ESR spectroscopic probes in order to determine the molecular arrangement in the host lattice. The zero-field-splitting (ZFS) parameters, D and E, of the triplet energy traps were determined and the degree of electron derealization in the triplet state was calculated from these values. In some cases a very strong guest host interaction (multicomplex formation) was established. A method for the determination of CT-triplet energies is described (accuracy 200 cm-1) . The phosphorescence spectrum of the anthracene-TCNB complex was obtained from the delayed emission spectra of different anthracene doped CT-crystals. The vibronic structure is identical to that of anthracene, while the O-O-band of the complex is blue shifted by 600 cm-1.
It is shown that the undoped anthracene-TCNB crystal exhibits P-type delayed fluorescence and that the triplet exciton diffusion in this crystal is nearly temperature independent. In the undoped biphenyl-TCNB crystal E-type delayed fluorescence originating from the thermal depopulation of the mobile triplet excitons is established. The remarkable differences of the two types of triplet excitons are interpreted in terms of the different polarity in the triplet states of the two CT-crystals.
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95
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Besenhard J., Fritz HP, Möhwald H, Nicki JJ. Elektrochemische Intercalation und elektrische Leitfähigkeit von Graphitfasern / Electrochemical Intercalation and Electrical Conductivity of Graphite Fibers. ACTA ACUST UNITED AC 2014. [DOI: 10.1515/znb-1978-0710] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Lamellar compounds of graphite fibers have been prepared by electrochemical intercalation. The dependence of the electrical resistance on the intercalate concentration was determined by a quasi simultaneous method. A factor 30 decrease of the relative fiber resistance was obtained with fluorosulfuric acid.
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96
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Giner-Casares JJ, Brezesinski G, Möhwald H. Langmuir monolayers as unique physical models. Curr Opin Colloid Interface Sci 2014. [DOI: 10.1016/j.cocis.2013.07.006] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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97
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Stefaniu C, Brezesinski G, Möhwald H. Langmuir monolayers as models to study processes at membrane surfaces. Adv Colloid Interface Sci 2014; 208:197-213. [PMID: 24612663 DOI: 10.1016/j.cis.2014.02.013] [Citation(s) in RCA: 161] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 02/13/2014] [Accepted: 02/14/2014] [Indexed: 12/12/2022]
Abstract
The use of new sophisticated and highly surface sensitive techniques as synchrotron based X-ray scattering techniques and in-house infrared reflection absorption spectroscopy (IRRAS) has revolutionized the monolayer research. Not only the determination of monolayer structures but also interactions between amphiphilic monolayers at the soft air/liquid interface and molecules dissolved in the subphase are important for many areas in material and life sciences. Monolayers are convenient quasi-two-dimensional model systems. This review focuses on interactions between amphiphilic molecules in binary and ternary mixtures as well as on interfacial interactions with interesting biomolecules dissolved in the subphase. The phase state of monolayers can be easily triggered at constant temperature by increasing the packing density of the lipids by compression. Simultaneously the monolayer structure changes are followed in situ by grazing incidence X-ray diffraction or IRRAS. The interactions can be indirectly determined by the observed structure changes. Additionally, the yield of enzymatic reaction can be quantitatively determined, secondary structures of peptides and proteins can be measured and compared with those observed in bulk. In this way, the influence of a confinement on the structural properties of biomolecules can be determined. The adsorption of DNA can be quantified as well as the competing adsorption of ions at charged interfaces. The influence of modified nanoparticles on model membranes can be clearly determined. In this review, the relevance and utility of Langmuir monolayers as suitable models to study physical and chemical interactions at membrane surfaces are clearly demonstrated.
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98
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Wang H, Yan X, Li GL, Pilz-Allen C, Möhwald H, Shchukin D. Sono-assembly of highly biocompatible polysaccharide capsules for hydrophobic drug delivery. Adv Healthc Mater 2014; 3:825-31. [PMID: 24323846 DOI: 10.1002/adhm.201300596] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 11/18/2013] [Indexed: 01/24/2023]
Abstract
Cells like sugar. General synthesis and potential of intracellular hydrophobic drug delivery of single-component polysaccharide capsules are pursued. The capsules can be generally assembled through hydrogen bonding networks but show striking shell robustness. The evidenced cell internalization, stimuli-responsiveness to local pH changes and high biocompatibilities of the capsules specifically favor their potential intracellular drug delivery.
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99
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Cui Q, He F, Li L, Möhwald H. Controllable metal-enhanced fluorescence in organized films and colloidal system. Adv Colloid Interface Sci 2014; 207:164-77. [PMID: 24182686 DOI: 10.1016/j.cis.2013.10.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Revised: 10/10/2013] [Accepted: 10/10/2013] [Indexed: 12/28/2022]
Abstract
In recent years, considerable efforts have been devoted to better understand the unique emission properties of fluorophores enhanced by the localized surface plasmon resonance of metal nanoparticles (NPs), due to the widespread applications of fluorescence techniques. It is demonstrated by experiment and theoretical calculation that the enhancement efficiency strongly depends on the morphology of the metal NPs, the spectral overlap between metal and fluorophores, the separation distance between them, and other factors. Among these aspects to be considered are suitable spacer material and assembling methods to control the spatial arrangement of plasmonic NPs and fluorophore with proper optical properties and interactions. In this contribution, we provide a brief overview on recent progress of metal-enhanced fluorescence in organized films and colloidal systems.
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100
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Liu B, Möhwald H, Wang D. Synthesis of Janus particles via kinetic control of phase separation in emulsion droplets. Chem Commun (Camb) 2014; 49:9746-8. [PMID: 24030455 DOI: 10.1039/c3cc45813j] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A reaction-induced phase separation strategy in emulsion droplets has been developed to fabricate non-spherical Janus particles. The final morphology of the resulting Janus particles is controlled by a reaction sequence. These Janus particles are amphiphilic and show regio-selective adsorption orientation at oil/water interfaces.
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