All-cellulose composites prepared from flax and lyocell fibres compared to epoxy–matrix composites

All-cellulose composites (ACCs) were prepared by partial dissolution in ionic liquid and compared to composites with epoxy matrix. Wide-angle X-ray diffraction and scanning electron microscopy were used to reveal differences in the structure of the composites. In tensile tests, lyocell-fibre based ACCs showed similar strength and stiffness, yet superior extensibility compared to lyocell-epoxy composites. However, when flax fibres were used, tensile properties clearly inferior to flax-epoxy were observed. Dynamic-mechanical and thermogravimetric analysis revealed a favourable behaviour for ACC in terms of more diffuse thermal softening and increased resistance to thermal degradation.     

Selective control of gliding microtubule populations

First lab-on-chip devices based on active transport by biomolecular motors have been demonstrated for basic detection and sorting applications. However, to fully employ the advantages of such hybrid nanotechnology, versatile spatial and temporal control mechanisms are required. Using a thermo-responsive polymer, we demonstrate the selective starting and stopping of modified microtubules gliding on a kinesin-1-coated surface. This approach allows the self-organized separation of multiple microtubule populations and their respective cargoes.     

Environment-dependent generation of photoacoustic waves from plasmonic nanoparticles

Nanoparticle-augmented photoacoustics is an emerging technique for molecular imaging. This study investigates the fundamental process of the photoacoustic signal generation by plasmonic nanoparticles suspended in a weakly absorbing fluid. The photoacoustic signal of gold nanospheres with varying silica shell thicknesses is shown to be dominated by the heat transfer between the nanoparticles and the surrounding environment.     

pH-sensitive capsules as intracellular optical reporters for monitoring lysosomal pH changes upon stimulation

The concept of a long-term sensor for ion changes in the lysosome is presented. The sensor is made by layer-by-layer assembly of oppositely charged polyelectrolytes around ion-sensitive fluorophores, in this case for protons. The sensor is spontaneously incorporated by cells and resides over days in the lysosome. Intracellular changes of the concentration of protons upon cellular stimulation with pH-active agents are monitored by read-out of the sensor fluorescence at real time. With help of this sensor concept it is demonstrated that the different agents used (Monensin, Chloroquine, Bafilomycin A1, Amiloride) possessed different kinetics and mechanisms of action in affecting the intracellular pH values.     

Protein oriented ligation on nanoparticles exploiting O6-alkylguanine-DNA transferase (SNAP) genetically encoded fusion

A bimodular genetic fusion comprising a delivery module (scFv) and a capture module (SNAP) is proposed as a novel strategy for the site-specific covalent conjugation of targeting peptides to nanoparticles. An scFv mutant selective for HER2 tumor antigen is chosen as the targeting ligand. SNAP-scFv is immobilized on magnetofluorescent nanoparticles and its targeting efficiency against HER2-positive cells is assessed by flow cytometry and immunofluorescence.     

Highly permeable and selective pore-spanning biomimetic membrane embedded with aquaporin Z

A highly permeable yet highly selective pore-spanning biomimetic membrane embedded with aquaporin Z is molecularly designed and constructed via a combination of pressure-assisted vesicle adsorption and covalent-conjugation-driven vesicle fusion on a porous support. This approach represents a significant breakthrough in the architecture of biomimetic membranes embedded with aquaporin in a planar form.     

Nano- and microstructuring of graphene using UV-NIL

In this work we demonstrate for the first time the micro-?and nanostructuring of graphene by means of UV-nanoimprint lithography. Exfoliated graphene on SiO(2) substrates, as well as graphene deposited by chemical vapor deposition (CVD) on polycrystalline nickel and copper, and transferred CVD graphene on dielectric substrates, were used to demonstrate that our technique is suitable for large-area patterning (2?×?2?cm(2)) of graphene on various types of substrates. The demonstrated fabrication procedure of micrometer as well as nanometer-sized graphene structures with feature sizes down to 20?nm by a wafer-scale process opens up an avenue for the low-cost and high-throughput manufacturing of graphene-based optical and electronic applications. The processed graphene films show electron mobilities of up to 4.6?×?10(3)?cm(2)?V (-1)?s(-1), which confirms them to exhibit state-of-the-art electronic quality with respect to the current literature.     

Thermally controlled permeation of ionic molecules through synthetic nanopores functionalized with amine-terminated polymer brushes

We present temperature-dependent ionic transport through an array of nanopores (cylindrical and conical) and a single conical nanopore functionalized with amine-terminated poly(N-isopropylacrylamide) [PNIPAAM-NH(2)] brushes. For this purpose, nanopores are fabricated in heavy ion irradiated polyethylene terephthlate (PET) membranes by a controlled chemical track-etching technique, which leads to the generation of carboxyl (COOH) groups on the pore surface. End-functionalized polymer chains are immobilized onto the inner pore walls via a 'grafting-to' approach through the covalent linkage of surface COOH moieties with the terminal amine groups of the PNIPAAM molecules by using carbodiimide coupling chemistry. The success of the chemical modification reaction is corroborated by measuring the permeation flux of charged analytes across the multipore membranes in an aqueous solution, and for the case of single conical pore by measuring the current-voltage (I-V) characteristics, which are dictated by the electrostatic interaction of the charged pore surface with the mobile ions in an electrolyte solution. The effective nanopore diameter is tuned by manipulating the environmental temperature due to the swelling/shrinking behaviour of polymer brushes attached to the inner nanopore walls, leading to a decrease/increase in the ionic transport across the membrane. This process should permit the thermal gating and controlled release of ionic drug molecules through the nanopores modified with thermoresponsive polymer chains across the membrane.     

Automated high resolution measurement of heliostat slope errors

A new optical measurement method that simplifies and optimizes the mounting and canting of heliostats and helps to assure their optical quality before commissioning of the solar field was developed. This method is based on the reflection of regular patterns in the mirror surface and their distortions due to mirror surface errors. The measurement has a resolution of about 1 million points per heliostat with a measurement uncertainty of less than 0.2 mrad and a measurement time of about 1 min per heliostat. The system is completely automated and allows the automatic measurement of an entire heliostat field during one night. It was extensively tested at the CESA-1 heliostat field at the Plataforma Solar de Almería. Comparisons of flux simulations based on the measurement results with real flux density measurements were performed. They showed an excellent agreement and demonstrated in a striking manner the high measurement accuracy and high grade of detail in the simulation achieved by this technique.