Gunnarsson A.,Chalmers University of Technology |
Gunnarsson A.,SP Technical Research Institute of Sweden |
Bally M.,Chalmers University of Technology |
Jonsson P.,University of Cambridge |
And 2 more authors.
Analytical Chemistry | Year: 2012
We have applied surface-enhanced ellipsometry contrast (SEEC) imaging for time-resolved label-free visualization of biomolecular recognition events on spatially heterogeneous supported lipid bilayers (SLB). Using a conventional inverted microscope equipped with total internal reflection (TIR) illumination, biomolecular binding events were monitored with a lateral resolution near the optical diffraction limit at an acquisition rate of ∼1 Hz with a sensitivity in terms of surface coverage of ∼1 ng/cm2. Despite the significant improvement in spatial resolution compared to alternative label-free surface-based imaging technologies, the sensitivity remains competitive with surface plasmon resonance (SPR) imaging and imaging ellipsometry. The potential of the technique to discriminate local differences in protein binding kinetics was demonstrated by time-resolved imaging of anti-GalCer antibodies binding to phase-separated lipid bilayers consisting of phosphatidylcholine (POPC) and galactosylceramide (GalCer). A higher antibody binding capacity was observed on the GalCer-diluted fluid region in comparison to the GalCer-rich gel phase domains. This observation is tentatively attributed to differences in the presentation of the GalCer epitope in the two phases, resulting in differences in availability of the ligand for antibody binding. The complementary information obtained by swiftly switching between SEEC and fluorescence (including TIR fluorescence) imaging modes was used to support the data interpretation. The simplicity and generic applicability of the concept is discussed in terms of microfluidic applications. © 2012 American Chemical Society.
Kudaibergenov S.E.,Kazakh National Technical University |
Kudaibergenov S.E.,Institute of Polymer Materials and Technology |
Sadakbayeva Z.K.,Kazakh National Technical University |
Sadakbayeva Z.K.,Institute of Polymer Materials and Technology |
And 5 more authors.
Macromolecular Symposia | Year: 2012
Organosoluble polyelectrolyte-surfactant complexes (PSCs) based on cationic polymer - JR-400 and anionic surfactant - sodium salt of dodecylbenzenesulfonate (SDDBS) were isolated as a precipitate from polyelectrolyte/surfactant aqueous mixture. The reduced viscosity of JR-400/SDDBS in ethanol showed polyelectrolyte anomaly that was suppressed upon addition of 0.05N and 0.1N KBr. Light scattering measurements of JR-400/SDDBS in ethanol showed 4 peaks belonging to non-aggregated and aggregated polycomplex particles. The elemental composition and morphology of thin layers of polyelectrolyte-surfactant complexes deposited on SiO 2 surface were evaluated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The height of PSC aggregates evaluated using AFM and Surface Enhanced Ellipsometry Contrast (SEEC) microscopy data is in good agreement and range within 10-50 nm. The XRD analysis revealed that PSCs have amorphous structure with a broad halo near 20 °. The contact angle measurements were used to demonstrate the hydrophobization of glass surface after the deposition of PSCs. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Dochter A.,CNRS Institute of Genetics and of Molecular and Cellular Biology |
Pichon B.P.,CNRS Institute of Genetics and of Molecular and Cellular Biology |
Fleutot S.,CNRS Institute of Genetics and of Molecular and Cellular Biology |
Medard N.,Nanolane |
Begin-Colin S.,CNRS Institute of Genetics and of Molecular and Cellular Biology
Solid State Sciences | Year: 2013
Arrays of magnetic nanoparticles (NPs) represent a very interesting challenge toward the development of new devices for magnetic applications such as data storage and spintronic. The final properties of such assemblies depending essentially on the spatial arrangement of NPs, it is of first importance to investigate precisely their structure. Here, the structure of monolayer and multilayer films of magnetic iron oxide NPs assembled by the Langmuir-Blodgett (LB) technique has been studied by usual techniques such as SEM, AFM and ellipsometry and by a new and an easy to process enhanced optical technique: the Surface Enhancement Ellipsometry Contrast (SEEC) microscopy. This technique is based on the use of a new generation of microscope slides used as substrates which allow the strong enhancement of the sample contrast to a point where it becomes possible to visualize the structure of monolayer and multilayer films at the nanoscale with a conventional optical microscope. The SEEC microscopy is demonstrated to be complementary to usual characterization techniques to study the structure of NPs films, especially for films containing very small nanosized NPs which are more difficult to analyze by usual techniques. While the film structure is investigated with lateral resolution of microns, the layer thickness is analyzed at the nanoscale (with a precision of 0.3 nm) with a close fit to the experimental measurements on local (AFM) and on larger (ellipsometry) areas. This technique presents the advantage to visualize directly the topography of NPs assemblies on very large areas by extracting information such as the height profile, the film roughness and generating 3D images.© 2012 Elsevier Masson SAS. All rights reserved.
Hirtz M.,Karlsruhe Institute of Technology |
Corso R.,Nanolane |
Sekula-Neuner S.,Karlsruhe Institute of Technology |
Fuchs H.,Karlsruhe Institute of Technology |
Fuchs H.,University of Munster
Langmuir | Year: 2011
Dip-pen nanolithography (DPN) with phospholipids has been shown to be a powerful tool for the generation of biologically active surface patterns, but screening of the obtained lithographic structures is still a bottleneck in the quality control of the prepared samples. Here we performed a comparative study with atomic force microscopy (AFM), fluorescence microscopy (FM), and surface-enhanced ellipsometric contrast (SEEC) microscopy of phospholipid membrane stacks consisting of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) with high admixing of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[6-[(2, 4-dinitrophenyl)amino]hexanoyl] (DNP Cap PE) produced by DPN. We present a structural model of membrane stacking based on the combined information gained from the three microscopic techniques. Domains of phase-separated DNP Cap PE can be detected at high DNP Cap PE admixing that are not present at medium or low admixings. While the optical methods allow for a high-throughput screening of lithographic structures (compared to AFM), it was found that, when relying on FM alone, artifacts due to phase-separation phenomena can be introduced in the case of thin membrane stacks. © 2011 American Chemical Society.
Evangelopoulos A.E.A.S.,University of Edinburgh |
Glynos E.,University of Michigan |
Madani-Grasset F.,Nanolane |
Koutsos V.,University of Edinburgh
Langmuir | Year: 2012
We redevelop a theoretical model that, in conjunction with atomic force microscopy (AFM), can be used as a noninvasive method for determination of the elastic modulus of a polymer nanodroplet residing on a flat, rigid substrate. The model is a continuum theory that combines surface and elasticity theories for prediction of the droplet's elastic modulus, given experimental measurement of its adsorbed height. Utilization of AFM-measured heights for relevant droplets reported in the literature and from our own experiments illustrated the following: the significance of both surface and elasticity effects in determining a polymer droplet's spreading behavior; the extent of a continuum theory's validity as one approaches the nanoscale; and a droplet size effect on the elastic modulus. © 2012 American Chemical Society.