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The authors’ recent concept of bioinorganic filtration devices made up of solid-state membranes (SSMs) accommodating ring-shaped, ribonucleic acid (RNA)-stabilized tobacco mosaic virus (TMV) coat protein (CP) assemblies with central 4 nm holes as genetically encoded ‘pore-in-pore’ fittings, to convey size and charge specificity to the membranes’ permeability, has been elaborated. Key developments for simplifying and finishing the unique combination apply to both soft- and hard-matter components: previous SSMs with millions of conical pores demanded sophisticated lithography to achieve a taper trapping the bionanopores upon insertion in a flow. Now focused helium (He) ion beam technology has enabled efficient, fast preparation of silicon nitride templates adapted to the nanorings. Proof-of-concept experiments reveal that negative charges imparted by nucleic acids exposed on the bionanopores might improve electrophoretic implantation further. Suitable peptides installed on the outer nanoring rim had been shown to nucleate spatially confined silica deposition from liquid precursors, which have been optimized in order to seal the annular gaps between bio and inorganic SSM pores by ‘bionic glue’. Finally, two engineered CP variants and a modified scaffold RNA were established for novel TMV nanoring types with altered pore charges, which also allow installing accessory molecules for advanced filtration and conversion tasks.

Measuring the mechanical properties of living tissue is a challenging task due to the small sizes and the fragility of the living organisms. A promising method, which works best on small scales, is the passive microrheology, which observes the motion of tracing beads within the sample. The video imaging method observes this motion by imaging the tracer particles with suitable optics (e.g. a microscope). As living tissue is a complex material, the viscoelastic properties are highly frequency dependent; therefore, a fast high-speed camera is needed to resolve the important frequencies in the 100 to 1000 Hz regime. As the data rate of high-speed cameras exceed the storage speed, only short burst of measurements can be carried out. This leads to a limited dynamic range of frequencies and missed measurement opportunities. It normally is not possible to track all the particles in real time to avoid the storage requirement of the video, as the tracking needs to be very precise and thus has a high computing demand. In this presentation, a combination of a CMOS imaging sensor with an FPGA is presented, which, in combination, allows for virtually unlimited long high-speed tracking of up to eight particles at up to 10 kHz. First, the sensor and the FPGA combinations are laid out. Secondly, the used particle tracking algorithm and its implementation is explained and benchmarked with a known state-of-the-art algorithm. Finally, this integrated sensor solution is mounted on a standard microscope and hour long tracking experiments on living 3T3 fibroblasts are carried out, studying the impact of blebbistatin on the mobility of polystyrene beads within the cell.

A model is presented which describes energy dissipation in a typical SFM-setup. We take into account not only the deflection of the cantilever, but also the local elastic deformation of tip and sample, which to our understanding is a key feature for dissipation. When this model is applied to the scanning motion of the tip, energy dissipation is naturally explained and can be calculated from inter atomic potentials.

A new route will be presented for an all-parallel fabrication of highly flexible, freestanding membranes with well-defined porosity. This fabrication is based on arrays of well-defined Au nanoparticles (NPs) exhibiting a high degree of hexagonal order as obtained in a first step by a proven micellar approach. These NP arrays serve as masks in a second reactive ion etching (RIE) step optimized for etching Si and some important Si compounds (silicon oxide, silicon nitride) on the nanoscale. Application to commercially available silicon nitride membranes of well-defined thickness, delivers a diaphragm with millions of nanopores of intended and controlled size, shape, and areal density with narrow distributions of these parameters. Electrophoretic transport measurements indicated a very low flow resistance of these porous membranes in ionic solutions as expected theoretically. Size-selective separation of protein molecules was demonstrated by real-time fluorescence microscopy.

Nowadays, high-speed video microscopy is used in many applications like microrheology1, 2 or flow cytometry3 to measure mechanical properties of cells or to identify their type. Typically, high-speed cameras use buffering to reach very high frame rates due to the limited bandwidth of the interface to a PC like Ethernet or USB. Additionally, analysis of large data is compute-intense and in many cases difficult to do online. We developed a system that consists of a high speed CMOS image sensor combined with a field programmable gate array (FPGA) and a pulsed LED illumination system. Due to an image transformation that is done on the FPGA, the dimensionality of the data is reduced without loss of important information. This leads to a significant reduction of the amount of data as well as to noise reduction as a side effect. Furthermore, we developed a modular analysis toolkit that can be used to do the whole analysis directly on the same FPGA online so that buffering is not required and measurements can run continuously on high frame rates. Hence, we can analyze a large total number of objects at very high throughput rates in microfluidic devices. We present the analysis of diluted whole blood in a microfluidic system with our device as well as a sorting application that uses multiple regions of interest that are observed simultaneously so that particles can be analyzed before and after a manipulation or gate.

The mechanical characterization of different cell types is important to improve the physiological understanding of cells. Cell types can be differentiated by their elasticity, which is a measure of the amount of deformation under a given stress. Simulations based on the finite element method help us to understand, verify and improve the analysis of deformation-based cell characterization methods such as flow-based cytometry. We achieve efficient computations using a 2D-rotationally symmetric model, based on fluid-structure interaction with a hyper-elastic material. The deformation of a cell along the entirety of a microfluidic channel can be tracked for a variety of elasticities, viscosities, cell sizes, channel geometries and flow rates. The model is even able to simulate soft cells with Young’s modulus of a few hundred pascals in microfluidic channels up to 2 mm in length. Simulations can be carried out in media with constant viscosity as well as in non-Newtonian fluids with shear-dependent viscosity. We have shown that the cell carrier-medium has a strong influence on cell deformation. The position of steady-state deformation dependence on cell properties is investigated. Furthermore, the simulation model can reproduce experimentally observed relaxation of cells, which can then be mapped to actual material parameters to classify and distinguish different cell types.

Droplet‐based microfluidic technology offers several benefits: the integration of multiple laboratory functions into a single microfabricated chip, manual intervention possibilities, minimal sample consumption, and increased analysis speed and data precision. These advantages have boosted the widespread application of this technology in biological and biomedical research. Despite recent progress, considerable challenges remain to be addressed for end‐user applications. This especially concerns the difficulty of creating powerful and easy to implement methods for real‐time analysis and active manipulation of passing droplets. Toward this end, we developed a very sensitive optical device equipped with smart algorithms for real‐time label‐free monitoring and active manipulation of passing droplets. We demonstrate the advanced properties of the developed optical device by measuring different droplet production parameters as well as the label‐free detection of cells in droplets. Moreover, the newly developed technology was connected with a function generator system to allow for subsequent manipulation of the monitored droplets based on the measured parameters. As an example, we performed electric field‐mediated, label‐free sorting of cell‐containing droplets from empty ones. Furthermore, we achieved an efficient size‐based separation of droplets. We envision that the developed optical device will be a useful tool for the online monitoring of passing droplets and will be implemented for the integration and automation of various droplet‐based microfluidic functional units.

Intermediate filament (IF) networks are a major contributor to cell rigidity and thus serve as vital elements to preserve the integrity of entire cell layers. Keratin K8 and K18 IFs are the basic constituents of the cytoskeleton of epithelial cells. The mechanical properties of K8/K18 networks depend on the structural arrangements of individual filaments within the network. This paper investigates the architecture of these networks in vitro under the influence of the monovalent cation potassium and that of the cytolinker protein plectin. Whereas increasing amounts of potassium ions lead to filament bundling, plectin interlinks filaments at filament intersection points but does not lead to bundle formation. The mechanics of the resulting networks are investigated by microrheology with assembled K8/K18 networks. It is shown that bundling induced by potassium ions significantly stiffens the network. Furthermore, our measurements reveal an increase in plectin-mediated keratin network rigidity as soon as an amount corresponding to more than 20% of the plectin present in cells is added to the keratin IF networks. In parallel, we investigated the influence of plectin on cell rigidity in detergent-extracted epithelial vulva carcinoma derived A431 cells in situ. These cytoskeletons, containing mostly IFs, actin filaments and associated proteins, exhibit a significantly decreased stiffness, when plectin is downregulated to ≈10% of the normal value. Therefore, we assume that plectin, via the formation of IF-IF connections and crosslinking of IFs to actin filaments, is an important contributor to cell stiffness.

The condensation of water vapor on a volatile polymeric solution leads to a porous surface after evaporation of both solvent and water. However, the stabilization of the water microdroplet is of great importance, which can be achieved using specific polymer or adding a third substance to the polymer solution. Short chain alcohols (methanol, ethanol, and n-propanol) are utilized to fabricate a self-assembled porous honeycomb film of linear, low molecular weight polystyrene using the breath figure technique. A combination of breath figure processing and the effect of alcohol on a water droplet can stabilize the pattern and make pores on the surface of the polymer film. The quality of the porous honeycomb film is strongly dependent on the type of alcohols and the concentration of polymer. In a specific range of polymer and alcohol concentration, pores cover all the surface of the polymer film. This method offers the possibility of producing a honeycomb structure with no trace of additive residual after the fabrication process and avoiding polymer modification. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 709–718

Two-photon absorption (TPA) and fluorescence intensity have possibilities for application in photodynamic therapy and photonic devices. The nonlinear optical properties of the cationic neutral red dye (NR) encapsulated in nanodroplets were studied using the Z-scan technique. The nanodroplets were prepared with a mixture of water, oils, and anionic Bis (2-ethylhexyl) sulfosuccinate sodium salt (AOT). The TPA and nonlinear refractive (NLR) index were studied in three different systems; NR in nanodroplets, NR in AOT and water, and NR in a different solvent. The results indicated that the TPA and NLR index spectra of NR depend on the droplet size. The TPA of the NR dye in the nanodroplet is enhanced in comparison to the NR/solvent system. Moreover, the second-order hyperpolarizability and fluorescence activity of the NR are affected by the encapsulation in the nanodroplets.

Small-angle X-ray scattering was used to study the mixture of C12E5 (pentaethylene glycol monododecyl ether)/H2O/n-decane microemulsion and polyethylene glycol (PEG). The size, shape and the structure factor of the microemulsion were investigated by adding the polymer (PEG) to the mixture. Attractive depletion potential was induced between the microemulsion droplets by the non-adsorb polymer. The range and strength of the attractive potential were changed by varying the molecular weight and concentration of PEG. The forward scattering, S(0), of the spherical microemulsion, declined gradually as the polymer concentration decreased. For PEG with the molecular weight of Mn = 285−315, the microemulsion morphology remained spherical, but the main peak of the structure factor moved towards a bigger q. When PEG with molecular weights of Mn = 2200 and Mn = 6000 were used, a shape transition from spherical to cylindrical was induced in line with increasing polymer concentration.

Colchicine is an efficient drug for the management of inflammatory diseases, such as gouty arthritis and familial Mediterranean fever. It affects neutrophil activity by interfering with the formation of microtubules. To test the hypothesis that therapeutic concentrations of colchicine modulate the mechanical properties of these cells, we applied a combination of biophysical techniques (optical stretching and microrheology) to analyze cellular deformability. The contribution of the subcellular compartments to the regulation of cell mechanics was determined by fitting a multicomponent model of cellular viscoelasticity to time-dependent deformation curves. Neutrophils were found to be less deformable in response to 10 ng/ml colchicine. The model-based analysis of cellular deformation revealed a decrease in cytoplasmatic elasticity and a substantial increase in both elasticity and viscosity of the cell membrane compartment in response to colchicine. These results correlate with a reduced number of cytoplasmatic microtubules and an increase in subcortical actin filaments. The latter finding was confirmed by microrheology and fluorescence microscopy. Neutrophil migration through small pores requiring substantial cellular deformations, but not through large pores, was significantly impaired by colchicine. These data demonstrate that colchicine determines mechanics of neutrophils and, thereby, motility in confined spaces, which is crucial during extravasation of neutrophils in response to inflammatory stimuli.

The site-specific attachment of nanoparticles is of interest for biomaterials or biosensor applications. Polymer brushes can be used to regulate this adsorption, so the conditions for selective adsorption of phosphonate-functionalized nanoparticles onto micropatterned polymer brushes with different functional groups are optimized. By choosing the strong polyelectrolytes poly(3-sulfopropyl methacrylate), poly(sulfobetaine methacrylate), and poly[2-(methacryloyloxy)ethyl trimethylammonium chloride], it is possible to direct the adsorption of nanoparticles to specific regions of the patterned substrates. A pH-dependent adsorption can be achieved by using the polycarboxylate brush poly(methacrylic acid) (PMAA) as substrate coating. On PMAA brushes, the nanoparticles switch from attachment to the brush regions to attachment to the grooves of a patterned substrate on changing the pH from 3 to 7. In this manner, patterned substrates are realized that assemble nanoparticles in pattern grooves, in polymer brush areas, or substrates that resist the deposition of the nanoparticles. The nanoparticle deposition can be directed in a pH-dependent manner on a weak polyelectrolyte, or is solely charge-dependent on strong polyelectrolytes. These results are correlated with surface potential measurements and show that an optical trap is a versatile method to directly probe interactions between nanoparticles and polymer brushes. A model for these interactions is proposed based on the optical trap measurements.

This study investigates water-in-oil microemulsion stabilised by Aerosol OT (AOT) dispersed in n-decane at water/AOT molar ratio of 6.7. The collective diffusion coefficient of microemulsion and microemulsion/tetrabutylammonium chloride (TBAC) systems was investigated by photon correlation spectroscopy (PCS). In the systems at the constant water/AOT concentration, the collective diffusion decreases with the reduction of oil concentration. Furthermore, PCS experiment revealed that collective diffusion coefficient of AOT/H2O/n-decane microemulsions increased with TBAC added to the microemulsion. We also studied the structural information of pure and salt-mixed AOT microemulsion by small-angle X-ray scattering technique. The structural investigation of our samples shows cylindrical to spherical transition with the reduction of oil concentration.

The mechanical properties of epithelial cells are modulated by structural changes in keratin intermediate filament networks. To investigate the relationship between network architecture and viscoelasticity, we assembled keratin filaments from recombinant keratin proteins 8 (K8) and 18 (K18) in the presence of divalent ions (Mg2+). We probed the viscoelastic modulus of the network by tracking the movement of microspheres embedded in the network during assembly, and studied the network architecture using scanning electron microscopy. Addition of Mg2+ at physiological concentrations (

We study collective diffusion coefficient (Dc) of Water-in-oil nanoemulsions (L2 phase) stabilized by AOT and dispersed in n-Decane oils by dynamic light scattering (DLS). At constant water concentration we vary the oil concentration and there is clear evidence for a changing collective diffusion coefficient of the droplets in AOT nanoemuslion. The collective diffusion coefficient in AOT nanoemulsions is studied from relaxation investigations with dynamic light scattering. Also, we study the collective diffusion coefficient (Dc) of droplets with add the TBAC to the droplets of AOT nanoemulsion. We discuss the results with study structural investigations with small-angle x-ray scattering. The results of this study suggest that the formation of non-spherical aggregates at low concentration of droplets can describe the behavior of the collective diffusion coefficient at AOT nanoemulsion.

he photon correlation spectroscopy and small-angle X-ray scattering is used for study the mixture of C12E5 microemulsion with PEG in order to determine structure and dynamic of the system. Photon correlation spectroscopy experiment showed an exponential relaxation for pure C12E5 microemulsion that come from Brownian motion of oil nano-droplets in water. The shape of the relaxation changed with increasing of PEG concentration in the C12E5 microemulsion, (relaxation becomes non-exponential with the increase of PEG), which demonstrates an increase of cooperatively in the C12E5 microemulsion. The SAXS experiment was used to study the structure of the system, and a model consists of a mixture of core-shell spheres with an Asakura-Oosawa interaction was applied to analyze data.

In the last decades, polymer brush coatings have proven to be excellent anti-fouling materials by preventing protein adhesion. When using this property to restrict cell growth laterally in cell culture, it is crucial to ensure that other cell functions remain unaffected. The present study therefore examines MC3T3-E1 cell growth and morphology on patterned PSBMA brush substrates and probes their proliferation potential at mRNA level. The osteoblastic cells display a more elongated morphology than cells on the control substrates, but show no sign of elevated levels of the apoptosis marker p53 or diminished levels of Ki-67 or H4, which serve as indicators of proliferation. Therefore, patterned polymer brushes do not seem to influence cells in their proliferation state and are suitable cell culture substrates. Nevertheless, the use of polymer brush surfaces in long-term cell culture was found to be limited by their instability in cell culture medium.

The Breath-Figure technique was employed to imprint honeycomb structures in the polymer films via the condensation of water vapor on the surface of an evaporating polymer solution. Generally, the condensed water droplets can be stabilized by an end-functional polymer or by particles added to the polymer solution. In this study, we carried out a systematic experiment on the effect of different stabilizers on the porous honeycomb structure under identical physical conditions. The end-functional polymer produced a large area of regular spherical bubbles, whereas adding particles to the polymer solution leads to smaller arrays of the flattened bottom bubbles. The separation length between pores was larger for polymer/particle sample than that of the end-functional polymer films. In the regular area of polymer/particle film many bubbles were not decorated by particles. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1430–1436, 2011

We present a method for the evaluation of SAXS data of highly oriented semicrystalline polymers, allowing us to determine up to seven structural parameters from the measurements. The utilized samples were polypropylenes with varied distributions of the molecular weight, which were spun with different take-up velocities to alter the spinline stress, thus influencing the structural properties. We were able to determine the degree of orientation, lamella radius, long spacing, lattice distortion, and lamella height simultaneously. The microscopic orientation was compared with the crystalline orientation evaluated by Herman’s orientation function from WAXS.

Micro-voids that evolve during mechanical deformation in polypropylene have been characterized by small-angle X-ray scattering. Such voids can be modelled as randomly distributed cylinders which are oriented along the stretching direction, showing a log-normal size distribution. The model and simulation results are presented here. Advantages and disadvantages of the approach, the validity of the model, and important considerations for data evaluation are discussed. Data analysis of two-dimensional scattering images has been performed using a fully automatedMATLABroutine by direct model fitting to scattering images.

Ded icated to Professor Dieter Vollhardt on the occasion of his 70th birthday. Nacre-type organic/inorganic hybrid multilayers can be fabricated through a continuous polymer­ induced liquid precursor (PILP) layer formed underneath a poly(styrene)-b/ock-poly(acrylic acid) (PS-b-PAA) block copolymer monolayer. Subsequent Layer-by-Layer transfer of block copolymer/pILP films leads to a multilayer with organic-inorganic hybrid architecture. The subsequent annealing pro­ cess transforms the PILP layers into layers of polycrystalline CaC03 • which morphologically resemble that of biogenic nacre.

Journal of applied polymer science 112, 188-199 (2009). doi:10.1002/app.29282, Published by Wiley, New York, NY [u.a.]

The ptychographical iterative engine (PIE) algorithm is examined with both simulated and experimental scanning coherent-diffraction microscopy data. The optimum overlap in terms of image quality, dose on the sample and time of measurements is determined using simulated diffraction data. The validity of the results is supported by experimental helium-neon laser light diffraction data.

Summary Accurate models for the light-scattering form factors of nanoparticles are of crucial importance to characterize the optical properties of the particles and to develop new photonic devices. Analytical or semi-empirical models exist for particles of spherical and cylindrical shape. The angular spectrum of scattering for particles of more complex shape is very complex and can only be obtained by numerical simulations. Moreover, the light scattering of metallic particles depends on many parameters as size, shape, optical constants, substrate and polarization of light. Experimental verification of the differential scattering cross-sections obtained from different calculation methods is always necessary. Measurements done on single nanoparticles are very sensitive to their local properties and the sinal-to-noise ratio may be very poor. Arrays of identical particles illuminated by a planes waves produce Bragg diffraction and the resultant patterns depend on the averaged values of the form factors of the particles. In order to test the validity of models for the scattering form factor, we present an experimental setup capable of measuring Bragg diffraction patterns of arrays of nanoparticles in the visible and near-infrared regions of the spectrum. The approach is similar to that of X-ray diffraction of crystals.

Two-dimensional gratings are generated on poly-carbonate films spin-coated onto thin gold–silver bimetallic layers by two-beam interference method. Sub-micrometer periodic polymer dots and stripes are produced illuminating the poly-carbonate surface by p- and s-polarized beams of a frequency quadrupled Nd:YAG laser, and crossed gratings are generated by rotating the substrates between two sequential treatments. It is shown by pulsed force mode atomic force microscopy that the mean value of the adhesion is enhanced on the dot-arrays and on the crossed gratings. The grating-coupling on the two-dimensional structures results in double peaks on the angle dependent resonance curves of the surface plasmons excited by frequency doubled Nd:YAG laser. The comparison of the resonance curves proves that a surface profile ensuring minimal undirected scattering is required to optimize the grating-coupling, in addition to the minimal modulation amplitude, and to the optimal azimuthal orientation. The secondary minima are the narrowest in presence of linear gratings on multi-layers having optimized composition, and on crossed structures consisting of appropriately oriented polymer stripes. The large coupling efficiency and adhesion result in high detection sensitivity on the crossed gratings. Bio-sensing is realized by monitoring the rotated-crossed grating-coupled surface plasmon resonance curves, and detecting the chemical heterogeneity by tapping-mode atomic force microscopy. The interaction of Amyloid-β peptide, a pathogenetic factor in Alzheimer disease, with therapeutical molecules is demonstrated.

The scattering of light by metallic nanostructures is one of the key phenomena to understand how the light couples to surface plasmons. The local field enhancement and the surface plasmon resonances are two other associated effects of special importance for surface enhanced Raman scattering. The size, shape and material of the structures determine the light scattering efficiency at its angular spectrum, in a very complex way. Only simple shapes have been reasonably well modelled so far. Therefore, measurement of the scattering properties of complex structures, in different illumination conditions, is fundamental to test scattering models. Using an approach analogous to x-ray diffraction, we investigated the light scattering of arrays of nanoparticles using total internal illumination. Arrays of particles of different size, shape and lattice constants were investigated this way. It was observed that the shape of the particle and its material have a strong influence on the distribution of the intensities of the Bragg diffraction patterns. Moreover, the validity of different models of light scattering form factors can be tested by comparison with the measurements. In addition, we built an experimental set-up to measure the dispersion relation of arrays of nanoparticles, or two-dimensional gratings, using total internal illumination.

New metallocene catalysts applied to propylene polymerization expand the range of properties of polypropylene (PP), resulting in semi-crystalline materials having crystallinities below 60% up to X-ray amorphous highly elastic ones. To date the origin of the unique elastic mechanical behavior of such low crystalline PP is not completely understood. Therefore, the microscopic orientation of those PPs due to uniaxial stretching was investigated using wide-(WAXS) and small-angle X-ray scattering (SAXS). The aim of this study was to correlate these orientations or changes in the developed fiber textures with the macroscopic stress–strain behavior. This includes efforts to come closer to the main question of the nature of the physical cross-links in these not chemical cross-linked homopolymers, which is the reason for the high elastic behavior. Therefore, high molecular weight metallocene PPs showing different crystallinities (0–36%) were stretched to several elongations and the structural changes during the deformation were recorded by X-ray scattering. Stress–strain measurements show the great potential of these PPs as a thermoplastic rubber material. For quantitative analysis and discussion of the polymer chain orientations, the orientation functions were calculated. Correlations between the orientation functions and the stress–strain curves allow an interpretation of the macroscopic behavior on a microscopic scale. A higher cross-linking density in elongated samples indicates that the network, which is responsible for the elasticity, mainly built up by strain-induced morphology changes and chain orientations.

Starting from differently substituted boronic acids as versatile building block, new "ortho-aryl" alpha-diimine ligands a-h were synthesized in an easy, high-yielding route. Reaction of the complex precursor diacetylacetonato-nickel(II) with a trityl salt, like [CPh3] [B(C6F5)4] or [CPh3] [SbCl6], in the presence of the diimine ligands afford the monocationic, square planar complexes 2a-g in almost quantitative yields. Suitable crystals (2d',e,f,g) were submitted for X-ray diffraction analysis. A geometry model was developed to describe the orientation of ligand fragments around the nickel(II) center that influence the polymer microstructure. At elevated reaction temperature and pressure, and in the presence of hydrogen, 2a-e catalyze the homopolymerization of ethylene to give branched PE products ranging from HD- to LLD-PE grades. The polymerization results indicate the possibility of precise microstructure control depending on the particular complex substitution. Preliminary investigations on material density and mechanical behavior by uniaxial stretching until failure point toward new material properties that can result from the simple ethylene monomer by catalyst design.

Angular interrogation investigation of the rotated grating-coupled surface plasmon resonance was performed, via exciting plasmons on special sensing layers by a frequency doubled continuous Nd:Yag laser beam in Kretschmann arrangement. NBK7 glass substrates were evaporated by silver and gold layers having appropriate thicknesses to ensure a narrow plasmon resonance peak. Thin poly-carbonate films spin-coated onto the bimetallic layers were patterned by the fourth harmonic of a pulsed mode Nd:Yag laser applying a master grating-based interference method. The pulsed force mode atomic force microscopic investigation has shown the existence of a surface relief grating and a coexistent adhesion modulation having a period of 416 nm. The conditions of the grating-coupling effect were determined for shallow sub-micrometer polymer gratings, and secondary minima were detected on the resonance curves measured in presence of polymer patterns, according to the calculations. The indispensability of a minimal modulation amplitude and the existence of an optimal rotation angle of the grating grooves with respect to the plasmon propagation direction were experimentally proven. The position of the emerged secondary resonance minimum indicated that the average film thickness was decreased caused by material removal during the structure formation. It was shown by tapping-mode AFM that the sub-micrometer adhesion modulation resulted in periodic adherence of streptavidin in the structure’s valleys. The attachment of a small amount of protein was detected based on the shift of the secondary resonance peak. The capability of the polymer grating for sensitivity enhancement was demonstrated, proving that the secondary peak shift is highly sensitive to the protein concentration. The application of the polymer grating covered bimetallic films as transducing layers in novel bio-sensorization method based on rotated grating coupling is proposed.

Using the Digital Pulsed Force Mode (DPFM) approach, the local mechanical properties of living HeLa cells have been examined. The cells were attached to a favorable glass-like substrate. The AFM used for the experiments was a commercial AFM setup by WITec. At every point of the image, approach and retract curves have been performed. The repetition rate of the cycle was 175 Hz. A total of about 500,000 curves has been recorded and completely evaluated for each experiment. The substrate served as an online reference material for calibration purposes. First, the force trajectories were corrected for the viscous drag force in the liquid environment. Second, the curves within the region of the substrate were phase corrected to compensate for the time lag of the signal in the setup assuming a purely elastic response of the reference material. Finally, all the force traces have been corrected by using this information and evaluated according to common continuum-elastic models. The resulting images allow the assignment of values of Young's modulus, local adhesion, hysteretic behavior, etc. at a high lateral resolution all over the cell body. In this paper, we describe the procedure of our measurement and the corresponding signal correction strategy of our automated data evaluation.

The determination of the mechanical properties of polymer-surfaces is a widespread task in the AFM community. The most important step in measuring is the thorough calibration of the measurement setup. Here, we address that problem for the case of Digital Pulsed Force Mode measurements. We show that following our suggestions, one can get reliable and consistent quantitative data on the mechanical properties of polymers such as PMMA or SBR rubber. The influence of the individual cantilevers and their properties, as well as the variations due to the settings of the AFM are widely eliminated.

A new metallocene catalyst applied to propene polymerization provides an expansion of the properties of polypropylene (PP) by generating semi-crystalline materials having 0–60% crystallinity. The purpose of the present study was to investigate such low crystalline elastomeric polypropylene (ePP) samples in order to compile further information on their crystal structure and the related phase transitions in the temperature range of 298–423 K. Calorimetric and stress strain measurements of mentioned ePP in comparison with high crystalline PP ( X c = 62%) confirms the new class of low crystalline PPs. These polymers combine the properties of a thermoplast, like excellent processability and ductility using heat, with those of elastomers. Temperature dependant WAXS investigations were carried out to determine crystallinity, crystalline structure, crystal modifications and crystal size in the temperature range from 298 to 423 K. As a function of temperature, apparent α- and γ-crystalline modifications were correlated and discussed concerning the phase transitions observed calorimetrically. The presented study includes calorimetric, tensile and X-ray scattering measurements of five metallocene PPs with crystallinities of 0%, 5%, 18%, 36% and 62%.

We synthesised P4VP bromides with octyl and dodecyl pendant groups; the bromide anions in these polymer salts were further substituted with dodecylsulfate or bis(2-ethylhexylsuccinate) anions. Direct SFM visualisation of the original P4VP chains, of the macromolecular salts and of their complexes, showed that the attachment of the pendant groups and especially the complexation with the surfactants promotes stretching of the macromolecules while adsorbing on mica substrate. On the other hand, viscosimetry showed that in solution (chloroform) the comb-like chains and their complexes with dodecylsulfate had more compact conformations than those of the original P4VP. The scaling exponents describing the correlation between the contour length and the end-to-end distance of the adsorbed macromolecules were found to be ca. 3/4, which is indicative of 2D self-avoiding walk statistics.

Sub-micrometer periodic structures were prepared on the surface of poly-carbonate films by UV laser treatment methods: a) grating-like structures having a period of 156 nm were induced by ArF excimer laser, b) 416 nm and 833 nm periodic gratings were prepared by two-beam interference realized by the fourth harmonic of a Nd:Yag laser. The sub-micrometer adhesion pattern accompanying the topographical structure was determined by pulsed force mode atomic force microscopy. The difference between the measured adhesion modulation and the adhesion profile calculated based on the topography was explained by the UV laser illumination caused phase and chemical changes. XPS investigations proved that chemical modification of the polymer occurs and the degree of the photo-degradation depends on the treating laser wavelength as well as on the number and fluence of the laser pulses. It was demonstrated by tapping mode atomic force microscopy that bovine serum albumin attaches to surface parts having higher adhesion. The dependence of the protein adherence on the surface treatment conditions was demonstrated based on the C 1s and O 1s spectra and on the proteinaceous nitrogen level.

Two-beam interference method was applied to generate gratings having periods of 416 nm and 833 nm by the forth harmonic of a Nd:Yag laser on thin poly-carbonate films spin-coated onto silver layer-covered substrates. The dependence of the modulation depth on the fluence and number of laser pulses was investigated by atomic force microscopy. A secondary pattern appeared on very thin polymer layers thanks to the “p” polarized laser beam illumination induced self-organized processes. The conditions of the emergence of grating-coupling caused additional plasmon resonance peak were determined for the sub-micrometer periodic polymer gratings. Surface plasmon resonance measurements were performed in attenuated total reflection arrangement to determine the effect of the angle between the plasmon propagation direction and the polymer groves on the grating-coupling. The effect of the modulation depth on the grating-coupling caused additional resonance minimum was also analyzed. We found coupling phenomena according to our calculations, the differences between the measured and theoretically predicted resonance curves were explained by the scattering on the complex surface structure.

Grating-like structures having a period of 416 nm were produced on the surface of poly-carbonate films by two-beam interference realized by the fourth harmonic of Nd:Yag laser. The period of the structures was half of that the applied master grating, the ratio of the width of the valleys to the period was tuned by the intensity, the depth of the modulation was increased by the number of laser pulses. Pulsed force mode atomic force microscopy was applied to study the topography and the adhesion on structured surfaces with sub-micrometer resolution. The adhesion modulation caused by the topography was calculated along line cross-sections of the AFM pictures taking into account the tip and surface geometry. The separation of the effects of the topography and the laser-induced material changes proved that the adhesion is increased at the areas illuminated by laser beam having a fluence above the melting threshold. The laser-induced material changes cause an additional adhesion increase at the valleys of the structure. It was shown that the adherence of albumin results in dense packing on poly-carbonate surface parts having sub-micrometer periodic adhesion modulation.

Sub-micrometer periodic gratings were generated on thin poly-carbonate films spin-coated onto thin flat silver layer covered BK7 substrates by two-beam interference realized with the fourth harmonic of the Nd:Yag laser. The 416 nm period of the laser-induced grating was half of the applied master grating, the modulation depth was increased by the number of laser pulses at a given intensity. Attenuated total reflection measurements were performed in case of plasmon propagation directions parallel and perpendicular to the grooves, and on rotated gratings oriented at angles making the grating coupling effect detectable. Atomic force microscopy (AFM) was applied to determine the modulation depth of the gratings. It was shown that the periodically corrugated polymer surfaces resulted in the coupling of the surface plasmons already when the structure period was very close to the plasmon wavelength. The small shift of the resonance positions proved that the modulation depth cannot be explained by material removal, the material rearrangement plays an important role in the grating formation. These experimental results correlate with our temperature model calculations revealing that there is softening on the upper polymer surface and melting down to the silver layer at the lowest and highest applied laser fluences, respectively.

An atomic force microscopic method to study the incubation states of UV laser irradiated polymer samples is presented. Targets were illuminated by different number of pulses at 5.8 and 8.9mJ∕cm2 fluences. The induced adhesive and morphological changes were investigated simultaneously by an atomic force microscope equipped with a pulsed force mode extension. Importantly, below 100 pulses morphological changes were not observable while significant changes in the adhesion were found as a result of the incubation at 8.9mJ∕cm2 fluence. This method allows the imaging and detection of the whole laser modified area with nanometer resolution.

The scanning force microscope (SFM) was used to investigate the temperature dependent micro mechanical properties of polymethylmethacrylate (PMMA) films with a thickness of 35 nm in the range of the radius of gyration. Force–distance curves were performed in the glass transition range to create permanent nanometric indentations with maximal forces up to 4 μN. Quantitative measurements of the indentation depth during and after application of the force, hysteresis energy and slope of the loading part are carried out as function of sample temperature and applied force. The glass transition of the polymer film can be clearly identified by the change of the mechanical properties of the polymer. Surprisingly, only a small change of elasticity at the glass transition is observed.

A new approach is described to tailor properties of polyketones based on the controlled modification of the block structure by varying the polymerization process. Ethylene–propylene–CO (ECOPCO) terblock copolymers with similar composition but different chain microstructures have been synthesized using either preset polymerization (PSP) or pulsed-feed polymerization (PFP), respectively. Whereas by PSP an ABC-triblock structure is obtained, the PFP results in [AB]n-multiblock structure. In this paper we investigate the influence of the chain microstructure on the mechanical behavior and the surface properties. SFM phase images display a phase-separated bulk morphology where triblock polymers due to the larger block lengths form coarser structures than the multiblock samples. If the ECO content is above 50%, partially crystalline lamellar structures can be found, which in case of the multiblock sample form a continuous network of lamellar-like ECO rich domains. All ECOPCO terpolymers reveal elastomeric behavior with an elastic recovery of at least 82% but tensile strength and elongation vary with the block length of the chain microstructures. Differences in elasticity are explained by the formation of different amounts of cross-links consisting of blocks of parallel-aligned ECO chain segments or crystalline lamellae. It can be shown that the surface morphology differs from bulk morphology, mainly by the point that no distinct phase separation appears but ECO rich domains can be detected. Surface tension measurements enable to correlate the surface energy with surface composition and surface morphology.