Alexander M Bittner

We prepared a small library of short peptidomimetics based on 3-pyrrolo-pyrazole carboxylate, a non-coded γ-amino acid, and glycine or alanine. The robust and eco-friendly synthetic approach adopted allows to obtain the dipeptides in two steps from commercial starting materials. This gives the possibility to shape these materials by electrospinning...

Incorporating biomolecules as integral parts of computational systems represents a frontier challenge in bio- and nanotechnology. Using DNA to store digital data is an attractive alternative to conventional information technologies due to its high information density and long lifetime. However, developing an adequate DNA storage medium remains a si...

Columnar mesoporous silicon (PSi) with hydrophobic vs. hydrophilic chemistries was chosen as a model for the local (pore-by-pore) study of water-pore interactions. Tomographic reconstructions provided a 3D view of the ramified pore structure. An in situ study of PSi wetting was conducted for categorized pore diameters by environmental scanning TEM....

We report the development and characterization of a detection technique for scattering-type scanning near-field optical microscopy (s-SNOM) that enables near-field amplitude and phase imaging at two or more wavelengths simultaneously. To this end, we introduce multispectral pseudoheterodyne (PSH) interferometry, where infrared lasers are combined t...

When doped into a certain range of charge carrier concentrations, MoS2 departs from its pristine semiconducting character to become a strongly correlated material characterized by exotic phenomena such as charge density waves or superconductivity. However, the required doping levels are typically achieved using ionic‐liquid gating or air‐sensitive...

Some of the best nucleating agents in nature are ice-nucleating proteins, which boost ice growth better than any other material. They can induce immersion freezing of supercooled water only a few degrees below 0 °C. An open question is whether this ability also extends to the deposition mode, i.e., to water vapor. In this work, we used three protei...

While the molecular mechanisms of virus infectivity are rather well known, the detailed consequences of environmental factors on virus biophysical properties are poorly understood. Seasonal influenza outbreaks are usually connected to the low winter temperature, but also to the low relative air humidity. Indeed, transmission rates increase in cold...

Atomically thin van der Waals magnetic crystals are characterized by tunable magnetic properties related to their low dimensionality. While electrostatic gating has been used to tailor their magnetic response, chemical approaches like intercalation remain largely unexplored. Here, we demonstrate the manipulation of the magnetism in the van der Waal...

We employed environmental scanning electron microscopy (ESEM) in low-humidity atmosphere to study the ice growth, coalescence of crystallites, polycrystalline film morphology, and sublimation, in the temperature range of -10 to -20 ∘C. First, individual ice crystals grow in the shape of micron-sized hexagonal columns with stable basal faces. Their...

Atomically thin van der Waals magnetic crystals are characterized by tunable magnetic properties related to their low dimensionality. While electrostatic gating has been used to tailor their magnetic response, chemical approaches like intercalation remain largely unexplored. Here, we demonstrate the manipulation of the magnetism in the van der Waal...

While the molecular mechanisms of virus infectivity are rather well known, the detailed consequences of environmental factors on virus biophysical properties are poorly understood. 20 Seasonal influenza outbreaks are usually connected to the low winter temperature, but also to the low relative air humidity. Indeed, transmission rates increase in co...

The epidemic spread of many viral infections is mediated by the environmental conditions and influenced by the ambient humidity. Single virus particles have been mainly visualized by atomic force microscopy (AFM) in liquid conditions, where the effect of the relative humidity on virus topography and surface cannot be systematically assessed. In thi...

Electrospinning is a well-known, straightforward, and versatile technique, widely used for the preparation of fibers by electrifying a polymer solution. However, a high molecular weight is not essential for obtaining uniform electrospun fibers; in fact, the primary criterion to succeed is the presence of sufficient intermolecular interactions, whic...

We employed Environmental Scanning Electron Microscopy (ESEM) in low humidity atmosphere to study the complete scenario of ice growth, coalescence of crystallites, polycrystalline film morphology and sublimation, in the temperature range of −10 ºC to −20 ºC. First, individual ice crystals grow in the shape of micron-sized hexagonal columns with sta...

Biological material has gained increasing attention recently as a source of ice-nucleating particles that may account for cloud glaciation at moderate supercooling. While the ice-nucleation (IN) ability of some bacteria can be related to membrane-bound proteins with epitaxial fit to ice, little is known about the IN-active entities present in biolo...

Ikerbasque Research Professor y jefe del grupo "Self-Assembly" a CIC nanoGUNE Electrospinning es una técnica que se basa en generar fibras a partir de un líquido, una disolución viscosa o de un polímero fundido mediante la aplicación de un campo eléctrico. Las fibras se pueden recolectar en un colector a modo de fibras textiles (denominado "spinnin...

Ikerbasque Research Professor and head of the "Self-Assembly" group at CIC nanoGUNE Electrospinning is a technique that is based on generating fibers from a liquid, a viscous solution or a molten polymer by means of application of an electric field. The fibers can be collected as a textile fiber (called "spinning"), a process that was patented 90 y...

Biological material has gained increasing attention recently as a source of ice-nucleating particles that may account for cloud glaciation at moderate supercooling. While the ice-nucleation (IN) ability of some bacteria can be related to membrane-bound proteins with epitaxial fit to ice, little is known about the IN active entities present in biolo...

We investigate the electrospinning of small molecules, specifically designed peptide derivatives of the pyrazole-isothiazole scaffold. Such non-natural peptides enhance the spectrum of fundamental materials used for electrospinning. Unlike standard electrospun materials, our peptides are not polymeric, but able to aggregate in solution and especial...

In this Communication, our recent results on biomolecules with Huisgenase activity will be presented. The reaction tested consists of a formal (3+2) cycloaddition between in situ formed azomethine ylides and p-deficient alkenes to yield unnatural proline ester derivatives (Figure 1). The behavior of both Nmetallated and NH-azomethine ylides has bee...

One of the most important effects of water on earth is that surfaces in air adsorb small amounts of water, usually in the form of a thin film. Real surfaces, especially the rather soft biomolecular surfaces, are covered by highly curved micro- and nanostructures, which induce more complex wetting geometries, such as films, droplets, and filaments....

Metals and polymers are probably the most important construction materials, but also have many more functions, e.g., for electronics. The interaction of metal ions with tobacco mosaic virus (TMV) was originally used for the preparation of heavy metal isomorphic replacement for structural analysis. Metal ions can also be the precursors for metal clu...

The electroless (chemical) deposition of cobalt on palladium-sensitized oxidized silicon wafers produces nanowires and chains made up by nanoparticles. We demonstrate that the application of moderate magnetic fields, provided by permanent magnets, during the growth produces highly oriented cobalt nanowires and nanoparticle chains. By adjusting the...

A novel catalytic system based on covalently modified DNA is described. This catalyst promotes 1,3-dipolar reactions between azomethine ylides and maleimides. The catalytic system is based on the distortion of the double helix of DNA by means of the formation of Pt(II) adducts with guanine units. This distortion, similar to that generated in the in...

The characterization of energy storage applications usually asks for standard macroscale techniques. Nanoscale methods, as introduced here, can provide more information, which are useful for porous materials, for nanoscale crystallites or surface patterns, and for the case of chemical inhomogeneities, as in material blends. The techniques can be cl...

We present a simple synthesis of iron oxide nanotubes, grown under very mild conditions from a solution containing Fe(II) and Fe(III), on rod-shaped tobacco mosaic virus templates. Their well-defined shape and surface chemistry suggest these robust bionanoparticles as a versatile platform for synthesis of small, thin mineral tubes, which was achiev...

The rod-shaped nanoparticles of the widespread plant pathogen tobacco mosaic virus (TMV) have been a matter of intense debates and cutting-edge research for more than a hundred years. During the late 19th century, their behavior in filtration tests applied to the agent causing the 'plant mosaic disease' eventually led to the discrimination of virus...

High-resolution microscopy techniques have been extensively used to investigate the structure of soft, biological matter at the nanoscale, from very thin membranes to small objects, like viruses. Electron microscopy techniques allow for obtaining extraordinary resolution by averaging signals from multiple identical structures. In contrast, atomic f...

Virus particles and proteins are excellent examples of naturally occurring structures with well-defined nanoscale architectures, for example, cages and tubes. These structures can be employed in a bottom-up assembly strategy to fabricate repetitive patterns of hybrid organic–inorganic materials. In this paper, we review methods of assembly that mak...

Magnetic nanobeads are synthesized by co-precipitation of hollow iron oxide nanoparticles and an amphiphilic polymer. The resulting nanobeads can be tuned in diameter and nanoparticle content. X-ray Absorption Near-Edge Structure (XANES) spectroscopy and superconducting quantum interferometer device (SQUID) characterization of the nanobeads reveal...

Ultrathin hybrid gate dielectrics based on aluminum oxide (AlOx) and a mixed-type phosphonic-acid self-assembled monolayers (PA-SAM) are studied with a high performance liquid-crystalline semiconducting polymer, viz. poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene (pBTTT). We present a simple assembly procedure to obtain mixed-type PA-SAMs...

Electrospinning is known mainly for polymers. We show that this simple technique allows to shape molecules that are useful for organic photovoltaic cells into wires, a morphology that is otherwise not generally obtained. A special advantage of our method is the simple mixing approach that allows to test blends of promising compounds, without the ne...

Mid-infrared spectroscopy offers important chemical and structural information about biological samples but diffraction prevents nanoscale studies. Amenabar et al. demonstrate Fourier transform infrared nanospectroscopy for analysing the secondary structure of protein complexes with 30 nm spatial resolution.

Mid-infrared spectroscopy is a widely used tool for material identification and secondary structure analysis in chemistry, biology and biochemistry. However, the diffraction limit prevents nanoscale protein studies. Here we introduce mapping of protein structure with 30 nm lateral resolution and sensitivity to individual protein complexes by Fourie...

For the example of peptides and proteins, we contrast "natural" self-assembly, i.e. aggregation in solutions, with "forced" assembly by electrospinning, i.e. by application of strong electrical fields to concentrated solutions. We were able to spin fibres that contain short stretches of diameters down to 5 nm; the ultimate aim is a fibre of the siz...

The electrical transport of the highly conductive poly-(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) is investigated with Ohmic and spin-polarized tunnel contacts at nanoscale lateral dimensions. Temperature-dependent charge transport measurements reveal that electrical conductivity scales non-linearly as a function of electro...

The wetting and dewetting behavior of biological nanostructures and to a greater degree single molecules, is not well known, even though their contact with water is the basis for all biology. Here we show that environmental electron microscopy (EM) can be applied as a means of imaging the condensation of water onto viruses. We captured the formatio...

Tobacco mosaic virus (TMV) is the best-characterized virus. Compared to most other viruses, its structure and physical and chemical properties are well known. TMV exclusively infects plants and is completely harmless for mammals. This virus is resilient against environmental changes, and it can easily be modified with functional materials. Our revi...

Nanoscale science refers to the study and manipulation of matter at the atomic and molecular scales, including nanometer-sized single objects, while nanotechnology is used for the synthesis, characterization, and for technical applications of structures up to 100 nm size (and more). The broad nature of the fields encompasses disciplines such as sol...

Tobacco mosaic virus (TMV) is the textbook example of a virus, and also of a self-assembling nanoscale structure. This tubular RNA/protein architecture has also found applications as biotemplate for the synthesis of nanomaterials such as wires, as tubes, or as nanoparticle assemblies. Although TMV is, being a biological structure, quite resilient t...

We present the synthesis of polymer embedded colloidal ordered assemblies, built from highly ordered superparamagnetic manganese iron oxide nanocrystals. Each assembly is wrapped into a thin polymer shell. In-depth characterization of the nanoparticles by TEM, SAXS, SQUID, and magnetophoresis indicates that these colloidal hybrids exhibit high mobi...

We report the binding of nanoparticles (NPs) to wild type (unmodified) Tobacco mosaic virus (TMV). The viruses are simply mixed with citrate-coated, negatively charged gold and iron oxide nanoparticles (IONPs) in acidic solution. This results in TMV decorated along its whole length by the respective particles. Such a decoration usually requires che...

Targeted drug delivery presents one of the most promising applications of nanotechnology in medicine. In the following we report on the decoration of Tobacco mosaic virus with magnetic nanoparticles by a combination of genetic modification, chemical coupling and biochemical interactions. Furthermore first experiments were performed to describe the...

Peptides can assemble to supramolecular structures, of which fibers are of special biochemical and medical relevance. We employed Raman and infrared spectroscopy to elucidate the chemical integrity of fibers built from peptides and peptide derivates that contain the aromatic side groups fluorenyl and phenyl. Because the observed spectra compare ver...

Peptides can assemble to supramolecular structures, of which fibers are of special biochemical and medical relevance. We employed Raman and infrared spectroscopy to elucidate the chemical integrity of fibers built from peptides and peptide derivates that contain the aromatic side groups fluorenyl and phenyl. Because the observed spectra compare ver...

The activated carbon in electrochemical double layer electrodes undergoes slow ageing. The effect becomes only apparent when capacitors are polarized to voltages at or above specified limits, or at high temperatures, for at least several months. A combination of "post mortem" analysis methods shows that the pores in the carbon are modified structur...

We show that 3 nm wide cobalt-iron alloy nanowires can be synthesized by simple wet chemical electroless deposition inside tubular Tobacco mosaic virus particles. The method is based on adsorption of Pd(II) ions, formation of a Pd catalyst, and autocatalytic deposition of the alloy from dissolved metal salts, reduced by a borane compound. Extensive...

Tobacco mosaic virus (TMV) is a tube-shaped, exceptionally stable plant virus, which is among the biomolecule complexes offering most promising perspectives for nanotechnology applications. Every viral nanotube self-assembles from a single RNA strand and numerous identical coat protein (CP) subunits. Here we demonstrate that biotechnologically engi...

Tobacco mosaic virus mutants were engineered to alter either the stability or surface chemistry of the virion: within the coat protein, glutamic acid was exchanged for glutamine in a buried portion to enhance the inter-subunit binding stability (E50Q), or a hexahistidine tract was fused to the surface-exposed carboxy terminus of the coat protein (6...

Current models for magnetoviscosity suggest that replacing the spherical nanoparticles of a conventional ferrofluid with magnetic nanotubes would lead to a stronger field-induced viscosity enhancement and a much-improved stability against shear thinning – two important parameters for technological exploitation of the magnetoviscous effect. We repor...

Applying a magnetic field to many ferrofluids leads to a significant increase in viscosity, but the phenomenon has yet to find technological exploitation because of the thinning caused by even weak shear flows. We have discovered that the addition of plant-virus-derived nanotubes to a commercial ferrofluid can give rise to a dramatic enhancement in...

We show that the rod-shaped Tobacco mosaic virus (TMV) can be coated with the wide band gap semiconductor zinc oxide by electroless deposition under mild reaction conditions. The process involves pretreatment with aqueous Pd(II), followed by nucleation of ZnO, directed to palladium centers formed on the surface of TMV. The mechanism is based on the...

We show that the rod-shaped Tobacco mosaic virus (TMV) can be coated with the wide band gap semiconductor zinc oxide by electroless deposition under mild reaction conditions. The process involves pretreatment with aqueous Pd(II), followed by nucleation of ZnO, directed to palladium centers formed on the surface of TMV. The mechanism is based on the...

Electroless deposition (ELD) encompasses quite a range of chemical deposition processes at the solid/liquid interface. Here I focus exclusively on autocatalytic ELD of metals, i.e., the plated metal catalyzes its own deposition, and hence the process is continuous as long as sufficient amounts of reactants are provided [1–5]. Such a reaction requir...

Soft matter surfaces, such as organic layers or polymer surfaces, are dynamical and inhomogeneous (only in special cases crystalline). In contact with solutions, the situation becomes more complex, but still addressable with Surface Science methods. In single molecules and supramolecular assemblies, a large fraction of the molecule forms the surfac...

Electrochemical double layer capacitors–supercapacitors–are usually based on highly porous activated carbon electrodes. The chemical and electrochemical inertness of carbon assures a very long lifetime. However, on the timescale of months the capacitors slowly lose some capacitance, and the equivalent series resistance rises. This “ageing” is faste...

A study was conducted to present electrospinning from concentrated diphenylalanine solutions in a low-boiling-point solvent,resulting in tubes that are chemically identical to self-assembled tubes. The study focused on electrospinning of tubes,as it offers more possibilities for manipulation. It was also demonstrated that electrospinning requires a...

A study was conducted to demonstrate the use of Tobacco mosaic virus (TMV), as molecular building block for mesoscale chemical structuring of surfaces. TMV nanoarrays at the single-particle level were fabricated,by initially generating chemical templates of 16-thiohexadecanoic acid on a gold thin fim with dip-pen nanolithography (DPN), followed by...

We studied four trialkoxysilane thin films, fabricated via self-assembly by casting neat silane reagents onto hydrophilic SiOx/Si substrates in the ambient. This drop-casting method is simple, yet rarely studied for the production of silane self-assembled monolayers (SAMs). Various ex-situ techniques were utilized to systematically characterize the...

The tobacco mosaic virus (TMV) is a protein-RNA tube that can either be propagated in plants or assembled from coat proteins and RNA strands. While TMV is the standard example for natural self-assembly (of proteins), and its biology and biochemistry are very well known, the concept of using TMV as scaffold for inorganic structures is relatively new...

Individual graphene oxide sheets subjected to chemical reduction were electrically characterized as a function of temperature and external electric fields. The fully reduced monolayers exhibited conductivities ranging between 0.05 and 2 S/cm and field effect mobilities of 2-200 cm2/Vs at room temperature. Temperature-dependent electrical measuremen...

We report surface-enhanced Raman scattering (SERS) from a “sandwich” structure of two silver layers, in which a thin film of activated carbon is embedded. The first silver layer is prepared by electroless deposition on a non-conductive substrate, while the second one is electrodeposited on the adsorbed carbon powder. This “sandwich” does not only y...

Golden viruses: The rodlike tobacco mosaic virus and citrate-covered gold nanoparticles of 6-nm diameter self-assemble into a metal-virus nanodumbbell. The gold nanoparticles selectively bind to the ends of the rods, and can be enlarged by electroless deposition to yield gold-virus-gold dumbbells (see picture).

Clusters built from metals, semiconductors and dielectric materials, whether they are bare or coated by ligand molecules, interact in many different ways with soft matter. The ensuing phenomena are of great relevance for technical problems such as metal/polymer interfaces, but also to fundamental questions such as controlled charging of single clus...

Simple electrochemical deposition techniques can produce highly defined metal nanostructures in templates. Electroless deposition (ELD) can be effectively used for depositing metals on insulators such as biological or plastic surfaces. With biomolecular templates, metallization methods are often restricted to mild reductions, and the deposition of...

SiGe islands grown by deposition of 10 monolayers of Ge on Si(0 0 1) at 740 °C were investigated by using a combination of selective wet chemical etching and atomic force microscopy. The used etchant, a solution consisting of ammonium hydroxide and hydrogen peroxide, shows a high selectivity of Ge over SixGe1−x and is characterized by relatively sl...

Cadmium sulfide / Nanocrystals / Metal clusters / Microcontact printing / Nanostructures / Template synthesis Near-spherical dendrimers can be used as templates for bot-tom-up syntheses of semiconductor clusters. Starting from methanolic solutions of Cd 2+ , sulfide, and poly(amidoamine) dendrimers, CdS clusters precipitate at the dendrimers. A pre...

Biomolecules are vitally important elements in nanoscale science and also in future nanotechnology. Their shape and their chemical and physical functionality can give them a big advantage over inorganic and organic substances. While this becomes most obvious in proteins and peptides, with their complicated, but easily controlled chemistry, other bi...