Wolfgang Eck

Publications of Wolfgang Eck

• Anti-CD4-targeted gold nanoparticles induce specific contrast enhancement of peripheral lymph nodes in X-ray computed tomography of live mice.

  Authors: Wolfgang Eck, Anthony I Nicholson, Hanswalter Zentgraf, Wolfhard Semmler, Sönke Bartling

  Nano letters. 05/2010; 10(7):2318-22.

  Antibody-conjugated gold nanoparticles have been applied as a biologically targeted contrast agent in live mice for one of the most widely used medical imaging methods, X-ray computed tomography.Antibody-conjugated gold nanoparticles have been applied as a biologically targeted contrast agent in live mice for one of the most widely used medical imaging methods, X-ray computed tomography. Such nanoprobes directed toward the CD4 receptor lead to distinctly enhanced X-ray contrast of peripheral lymph nodes. This study demonstrates the general feasibility of biologically specific X-ray imaging in living animals and discusses basic requirements for the use of nanoparticles as a targeted X-ray contrast agent.

• PEGylated gold nanoparticles conjugated to monoclonal F19 antibodies as targeted labeling agents for human pancreatic carcinoma tissue.

  Authors: Wolfgang Eck, Gary Craig, Aruna Sigdel, Gerd Ritter, Lloyd J Old, Laura Tang, Murray F Brennan, Peter J Allen, Michael D Mason

  ACS nano. 12/2008; 2(11):2263-72.

  In this study, we describe optical detection of antibody-conjugated nanoparticles bound to surgically resected human pancreatic cancer tissue. Gold nanoparticles stabilized by heterobifunctionalIn this study, we describe optical detection of antibody-conjugated nanoparticles bound to surgically resected human pancreatic cancer tissue. Gold nanoparticles stabilized by heterobifunctional polyethylene glycol (PEG) were prepared using approximately 15 nm spherical gold cores and covalently coupled to F19 monoclonal antibodies. The heterobifunctional PEG ligands contain a dithiol group for stable anchoring onto the gold surface and a terminal carboxy group for coupling of antibodies to the outside of the PEG shell. The nanoparticle-antibody bioconjugates form highly stable dispersions and exhibit long-term resistance to agglomeration. This has been demonstrated by dynamic light scattering, size exclusion chromatography, and transmission electron microscopy. The nanoparticle bioconjugates were used to label tumor stroma in approximately 5 mum thick sections of resected human pancreatic adenocarcinoma. After rinsing away nonbound nanoparticles and fixation, the tissue samples were imaged by darkfield microscopy near the nanoparticle resonance scattering maximum (approximately 560 nm). The images display pronounced tissue features and suggest that this novel labeling method could provide for facile identification of cancer tissue. Tumor samples treated with gold nanoparticles conjugated to nonspecific control antibodies and noncancerous pancreatic tissue treated with mAb-F19-conjugated gold nanoparticles both exhibited correctly negative results and showed no tissue staining.

• Novel carbon nanosheets as support for ultrahigh-resolution structural analysis of nanoparticles.

  Authors: Christoph T Nottbohm, Andre Beyer, Alla S Sologubenko, Inga Ennen, Andreas Hütten, Harald Rösner, Wolfgang Eck, Joachim Mayer, Armin Gölzhäuser

  Ultramicroscopy. 04/2008;

  The resolution in transmission electron microscopy (TEM) has reached values as low as 0.08nm. However, these values are not accessible for very small objects in the size range of a few nanometers orThe resolution in transmission electron microscopy (TEM) has reached values as low as 0.08nm. However, these values are not accessible for very small objects in the size range of a few nanometers or lower, as they have to be placed on some support, which contributes to the overall electron-scattering signal, thereby blurring the contrast. Here, we report on the use of nanosheets made from cross-linked aromatic self-assembled monolayers as TEM sample supports. When transferred onto a copper grid, a single 1.6-nm-thick nanosheet can cover the grid and is free standing within the micron-sized openings. Despite its thinness, the sheet is stable under the impact of the electron beam. Micrographs taken from nanoclusters onto these nanosheets show highly increased contrast in comparison to the images taken from amorphous carbon supports. In scanning transmission electron microscopy with nanosheet support, a size analysis of sub-nanometer Au clusters was performed and single Au atoms were resolved.

• Protein deformation of lipid hybrid bilayer membranes studied by sum frequency generation vibrational spectroscopy.

  Authors: Andrew W Doyle, Joerg Fick, Michael Himmelhaus, Wolfgang Eck, Irene Graziani, Igor Prudovsky, Michael Grunze, Thomas Maciag, David J Neivandt

  Langmuir : the ACS journal of surfaces and colloids. 11/2004; 20(21):8961-5.

  Structural deformations of lipid hybrid bilayer membranes induced by signal peptideless (SPL) proteins have been studied for the first time using the inherently surface specific nonlinear opticalStructural deformations of lipid hybrid bilayer membranes induced by signal peptideless (SPL) proteins have been studied for the first time using the inherently surface specific nonlinear optical technique of sum frequency generation vibrational spectroscopy. Specifically, deformations of 1,2-distearoylphosphatidylglycerol(DSPG) membranes induced by interaction with FGF-1, a SPL protein which is released asa function of cellular stress through a nonclassical pathway, have been investigated. FGF-1 was found to induce lipid alkyl chain deformations in previously highly ordered DSPG membranes at the extremely low concentration of 1 nM at 60 degrees C. The deformation process was shown to exhibit a degree of reversibility upon removal of the protein by rinsing with buffer solution.

• Activation of integrin function by nanopatterned adhesive interfaces.

  Authors: Marco Arnold, Elisabetta Ada Cavalcanti-Adam, Roman Glass, Jacques Blümmel, Wolfgang Eck, Martin Kantlehner, Horst Kessler, Joachim P Spatz

  Chemphyschem : a European journal of chemical physics and physical chemistry. 03/2004; 5(3):383-8.

  To study the function behind the molecular arrangement of single integrins in cell adhesion, we designed a hexagonally close-packed rigid template of cell-adhesive gold nanodots coated with cyclicTo study the function behind the molecular arrangement of single integrins in cell adhesion, we designed a hexagonally close-packed rigid template of cell-adhesive gold nanodots coated with cyclic RGDfK peptide by using block-copolymer micelle nanolithography. The diameter of the adhesive dots is < 8 nm, which allows the binding of one integrin per dot. These dots are positioned with high precision at 28, 58, 73, and 85 nm spacing at interfaces. A separation of > or = 73 nm between the adhesive dots results in limited cell attachment and spreading, and dramatically reduces the formation of focal adhesion and actin stress fibers. We attribute these cellular responses to restricted integrin clustering rather than insufficient number of ligand molecules in the cell-matrix interface since "micro-nanopatterned" substrates consisting of alternating fields with dense and no nanodots do support cell adhesion. We propose that the range between 58-73 nm is a universal length scale for integrin clustering and activation, since these properties are shared by a variety of cultured cells.

• Factors that determine the protein resistance of oligoether self-assembled monolayers --internal hydrophilicity, terminal hydrophilicity, and lateral packing density.

  Authors: Sascha Herrwerth, Wolfgang Eck, Sven Reinhardt, Michael Grunze

  Journal of the American Chemical Society. 09/2003; 125(31):9359-66.

  Protein resistance of oligoether self-assembled monolayers (SAMs) on gold and silver surfaces has been investigated systematically to elucidate structural factors that determine whether a SAM will beProtein resistance of oligoether self-assembled monolayers (SAMs) on gold and silver surfaces has been investigated systematically to elucidate structural factors that determine whether a SAM will be able to resist protein adsorption. Oligo(ethylene glycol) (OEG)-, oligo(propylene glycol)-, and oligo(trimethylene glycol)-terminated alkanethiols with different chain lengths and alkyl termination were synthesized as monolayer constituents. The packing density and chemical composition of the SAMs were examined by XPS spectroscopy; the terminal hydrophilicity was characterized by contact angle measurements. IRRAS spectroscopy gave information about the chain conformation of specific monolayers; the amount of adsorbed protein as compared to alkanethiol monolayers was determined by ellipsometry. We found several factors that in combination or by themselves suppress the protein resistance of oligoether monolayers. Monolayers with a hydrophobic interior, such as those containing oligo(propylene glycol), show no protein resistance. The lateral compression of oligo(ethylene glycol) monolayers on silver generates more highly ordered monolayers and may cause decreased protein resistance, but does not necessarily lead to an all-trans chain conformation of the OEG moieties. Water contact angles higher than 70 degrees on gold or 65 degrees on silver reduce full protein resistance. We conclude that both internal and terminal hydrophilicity favor the protein resistance of an oligoether monolayer. It is suggested that the penetration of water molecules in the interior of the SAM is a necessary prerequisite for protein resistance. We discuss and summarize the various factors which are critical for the functionality of "inert" organic films.

• Surface-initiated polymerization on self-assembled monolayers: amplification of patterns on the micrometer and nanometer scale.

  Authors: Ursula Schmelmer, Rainer Jordan, Wolfgang Geyer, Wolfgang Eck, Armin Gölzhäuser, Michael Grunze, Abraham Ulman

  Angewandte Chemie (International ed. in English). 03/2003; 42(5):559-63.

• Nanoscale patterning of self-assembled monolayers by e-beam lithography

  Authors: Thomas Weimann, Wolfgang Geyer, Peter Hinze, Volker Stadler, Wolfgang Eck, Armin Gölzhäuser

  Microelectronic Engineering.

  The resolution of e-beam lithography in standard resists is limited by the size of the molecules in the resist. High resolution e-beam resists therefore should not only show a specific sensitivity toThe resolution of e-beam lithography in standard resists is limited by the size of the molecules in the resist. High resolution e-beam resists therefore should not only show a specific sensitivity to electrons but also be thin and composed of small subunits. Self-assembled monolayers (SAMs) fulfil these criteria because they are homogeneous, highly ordered films of amphiphilic molecules with a typical thickness of 1–2 nm and an intermolecular spacing of 1–0.5 nm. We demonstrate that gold nanostructures can be fabricated using aliphatic and aromatic thiol self-assembled monolayers as positive and negative electron beam resists.