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Protein aggregation is a hallmark of several severe neurodegenerative disorders such as Huntington's, Parkinson's, or Alzheimer's disease. Metal ions play a profound role in protein aggregation and altered metal-ion homeostasis is associated with disease progression. Here we utilize \(\mu\)-X-ray fluorescence imaging in combination with rapid freezing to resolve the elemental distribution of phosphorus, sulfur, potassium, and zinc in huntingtin exon-1-mYFP expressing HeLa cells. Using quantitative XRF analysis, we find a threefold increase in zinc and a 10-fold enrichment of potassium that can be attributed to cellular stress response. While the averaged intracellular ion areal masses are significantly different in aggregate-containing cells, a local intracellular analysis shows no different ion content at the location of intracellular inclusion bodies. The results are compared to corresponding experiments on HeLa cells forming pseudoisocyanine chloride aggregates. As those show similar results, changes in ion concentrations are not exclusively linked to huntingtin exon-1 amyloid formation.

Biofouling on surfaces in contact with sea- or brackish water can severely impact the function of devices like reverse osmosis modules. Single species laboratory assays are frequently used to test new low fouling materials. The choice of bacterial strain is guided by the natural population present in the application of interest and decides on the predictive power of the results. In this work, the analysis of the bacterial community present in brackish water from Mashabei Sadeh, Israel was performed and Rheinheimera sp. was detected as a prominent microorganism. A Rheinheimera strain was selected to establish a short-term accumulation assay to probe initial bacterial attachment as well as biofilm growth to determine the biofilm-inhibiting properties of coatings. Both assays were applied to model coatings, and technically relevant polymers including laser-induced graphene. This strategy might be applied to other water sources to better predict the fouling propensity of new coatings.

Amphiphilic polymer coatings combining hydrophilic elements, in particular zwitterionic groups, and hydrophobic elements comprise a promising strategy to decrease biofouling. However, the influence of the content of the hydrophobic component in zwitterionic coatings on the interfacial molecular reorganization dynamics and the anti-fouling performance is not well understood. Therefore, coatings of amphiphilic copolymers of sulfobetaine methacrylate 3-[N-2'-(methacryloyloxy)ethyl-N,N-dimethyl]-ammonio propane-1-sulfonate (SPE) are prepared which contain increasing amounts of hydrophobic n-butyl methacrylate (BMA). Their fouling resistance is compared to that of their homopolymers PSPE and PBMA. The photo-crosslinked coatings form hydrogel films with a hydrophilic surface. Fouling by the proteins fibrinogen and lysozyme as well as by the diatom Navicula perminuta and the green algae Ulva linza is assessed in laboratory assays. While biofouling is strongly reduced by all zwitterionic coatings, the best fouling resistance is obtained for the amphiphilic copolymers. Also in preliminary field tests, the anti-fouling performance of the amphiphilic copolymer films is superior to that of both homopolymers. When the coatings are exposed to a marine environment, the reduced susceptibility to silt incorporation, in particular compared to the most hydrophilic polyzwitterion PSPE, likely contributes to the improved fouling resistance.

X-ray-based analytics are routinely applied in many fields, including physics, chemistry, materials science, and engineering. The full potential of such techniques in the life sciences and medicine, however, has not yet been fully exploited. We highlight current and upcoming advances in this direction. We describe different X-ray-based methodologies (including those performed at synchrotron light sources and X-ray free-electron lasers) and their potentials for application to investigate the nano-bio interface. The discussion is predominantly guided by asking how such methods could better help to understand and to improve nanoparticle-based drug delivery, though the concepts also apply to nano-bio interactions in general. We discuss current limitations and how they might be overcome, particularly for future use in vivo.

X-ray-based analytics are routinely applied in many fields, including physics, chemistry, materials science, and engineering. The full potential of such techniques in the life sciences and medicine, however, has not yet been fully exploited. We highlight current and upcoming advances in this direction. We describe different X-ray-based methodologies (including those performed at synchrotron light sources and X-ray free-electron lasers) and their potentials for application to investigate the nano-bio interface. The discussion is predominantly guided by asking how such methods could better help to understand and to improve nanoparticle-based drug delivery, though the concepts also apply to nano-bio interactions in general. We discuss current limitations and how they might be overcome, particularly for future use in vivo.

Combining high hydrophilicity with charge neutrality, polyzwitterions are intensely explored for their high biocompatibility and low-fouling properties. Recent reports indicated that in addition to charge neutrality, the zwitterion's segmental dipole orientation is an important factor for interacting with the environment. Accordingly, a series of polysulfobetaines with a novel architecture was designed, in which the cationic and anionic groups of the zwitterionic moiety are placed at equal distances from the backbone. They were investigated by in vitro biofouling assays, covering proteins of different charges and model marine organisms. All polyzwitterion coatings reduced the fouling effectively compared to model polymer surfaces of poly(butyl methacrylate), with a nearly equally good performance as the reference polybetaine poly(3-(N-(2-(methacryloyloxy)ethyl)-N,N-dimethylammonio)propanesulfonate). The specific fouling resistance depended on the detailed chemical structure of the polyzwitterions. Still, while clearly affecting the performance, the precise dipole orientation of the sulfobetaine group in the polyzwitterions seems overall to be only of secondary importance for their antifouling behavior.

A new Rococo 2 X-ray fluorescence detector was implemented into the cryogenic sample environment at the Hard X-ray Micro/Nano-Probe beamline P06 at PETRA III, DESY, Hamburg, Germany. A four sensor-field cloverleaf design is optimized for the investigation of planar samples and operates in a backscattering geometry resulting in a large solid angle of up to 1.1 steradian. The detector, coupled with the Xspress 3 pulse processor, enables measurements at high count rates of up to 10\(^{6}\) counts per second per sensor. The measured energy resolution of ∼129 eV (Mn \(\Kappa\alpha\) at 10000 counts s\(^{−1}\)) is only minimally impaired at the highest count rates. The resulting high detection sensitivity allows for an accurate determination of trace element distributions such as in thin frozen hydrated biological specimens. First proof-of-principle measurements using continuous-movement 2D scans of frozen hydrated HeLa cells as a model system are reported to demonstrate the potential of the new detection system.

The widespread occurrence of zwitterionic compounds in nature has incited their frequent use in designing biomimetic materials. Therefore, zwitterionic polymers are a thriving field. A particular interest for this particular polymer class has currently focused on their use in establishing neutral, low-fouling surfaces. After highlighting strategies to prepare model zwitterionic surfaces as well as those that are more suitable for practical purposes relying strongly on radical polymerization methods, we present recent efforts to diversify the structure of the hitherto quite limited variety of zwitterionic monomers and of the derived polymers. We identify key structural variables, consider their influence on essential properties such as overall hydrophilicity and long-term stability, and discuss promising targets for the synthesis of new variants.

The widespread occurrence of zwitterionic compounds in nature has incited their frequent use for designing biomimetic materials. Hence, zwitterionic polymers are a thriving field. A particular interest for this particular polymer class has currently focused on their use in establishing "neutral", low-fouling surfaces. After highlighting strategies to prepare model zwitterionic surfaces as well as such that are more suitable for practical purposes relying strongly on radical polymerization methods, we present recent efforts to diversify the structure of the hitherto quite limited variety of zwitterionic monomers, and of the derived polymers. We identify key structural variables, consider their influence on essential properties such as overall hydrophilicity and long-term stability, and discuss promising targets for the synthesis of new variants.

Optics express 26(2), 1237 - 1254 (2018). doi:10.1364/OE.26.001237, Coherent X-ray ptychography is a tool for highly dose efficient lensless nano-imaging of biological samples. We have used partially coherent soft X-ray synchrotron radiation to obtain a quantitative image of a laterally extended, dried, and unstained fibroblast cell by ptychography. We used data with and without a beam stop that allowed us to measure coherent diffraction with a high-dynamic range of 1.7·10$^6$. As a quantitative result, we obtained the refractive index values for two regions of the cell with respect to a reference area. Due to the photon energy in the water window we obtained an extremely high contrast of 53% at 71 nm half-period resolution. The dose applied in our experiment was 9.5·10$^4$ Gy and is well below the radiation damage threshold. The concept for dynamic range improvement for low dynamic range detectors with a beam stop opens the path for high resolution nano-imaging of a variety of samples including cryo-preserved, hydrated and unstained biological cells., Published by OSA, Washington, DC

Quick and reliable testing is crucial for the development of new fouling release (FR) coatings. Exposure of these coatings to natural multispecies communities is essential in evaluating their efficacy. To this end, we present a rotating disk setup for dynamic field exposure. To achieve a well-defined flow on the surface of the disk, an easy to use sample mounting system was developed that provides a smooth and even surface. We related the angular velocity of the disk to the wall shear stress on the surface with a hydrodynamic model. The wall shear stress was adjusted to values previously found to be suitable to discriminate dynamic diatom attachment on different coating chemistries in the lab. The effect of the dynamic conditions was shown by comparing polystyrene slides under static and dynamic exposure. Using a set of self-assembled monolayers, the discrimination potential of the assay in a multispecies environment was demonstrated.

Interaction of zoospores of Ulva linza with cationic, arginine-rich oligopeptide self-assembled monolayers (SAMs) is characterized by rapid settlement. Some spores settle (ie permanently attach) in a ‘normal’ manner involving the secretion of a permanent adhesive, retraction of the flagella and cell wall formation, whilst others undergo ‘pseudosettlement’ whereby motile spores are trapped (attached) on the SAM surface without undergoing the normal metamorphosis into a settled spore. Holographic microscopy was used to record videos of swimming zoospores in the vicinity of surfaces with different cationic oligopeptide concentrations to provide time-resolved insights into processes associated with attachment of spores. The data reveal that spore attachment rate increases with increasing cationic peptide content. Accordingly, the decrease in swimming activity in the volume of seawater above the surface accelerated with increasing surface charge. Three-dimensional trajectories of individual swimming spores showed a ‘hit and stick’ motion pattern, exclusively observed for the arginine-rich peptide SAMs, whereby spores were immediately trapped upon contact with the surface.

Holographic 3D tracking was applied to record and analyze the swimming behavior of \(\textit {Pseudomonas aeruginosa}\). The obtained trajectories allow to qualitatively and quantitatively analyze the free swimming behavior of the bacterium. This can be classified into five distinct swimming patterns. In addition to the previously reported smooth and oscillatory swimming motions, three additional patterns are distinguished. We show that \(\textit {Pseudomonas aeruginosa}\) performs helical movements which were so far only described for larger microorganisms. Occurrence of the swimming patterns was determined and transitions between the patterns were analyzed.

Imaging of biological samples in the water window offer high chemical contrast between Oxygen and Carbon. To avoid resolution limitations due to lens based microscopy techniques the coherent diffractive imaging (CDI) method is favourable for high resolution imaging. In order to measure extended samples the ptychographic coherent diffractive imaging technique (PCDI) is applied. Images of a test pattern and a fossil diatom are reconstructed with the extended ptychographic iterative engine (ePIE) at 55 nm and 286 nm resolution respectively.

We present a method to characterize the spatial coherence of soft X-ray radiation from a single diffraction pattern. The technique is based on scattering from non-redundant arrays (NRA) of slits and records the degree of spatial coherence at several relative separations [1]. Using NRAs we measured the spatial coherence of the X-ray beam at the XUV X-ray beamline P04 of the PETRA III storage ring [2] and at the U49/2 PGM1 beamline of the BESSY II synchrotron [3]. In both cases, the spatial coherence was measured for different beam parameters, including the photon energy and the monochromator exit slits separation (see Fig.1). We demonstrated that a rapid high-throughput analysis of the beam spatial coherence prior to any experiment utilizing coherence is possible. We also foresee that NRA method could become a viable tool for single pulse coherence characterization measurements at X-ray free-electron lasers [4, 5].References:[1] Y. Mejía et al., Opt. Commun. 273, 428 (2007).[2] P. Skopintsev et al., J. Synchrotron Rad. (2014) (accepted).[3] P. Skopintsev et al. (2014) (in preparation)[4] I.A. Vartanyants et al., Phys. Rev. Lett. 107, 144801 (2011).[5] A. Singer et al., Opt. Express 20(16), 17480 (2012).

The growth and structure of ultrathin silver films (1-5 ML) deposited on a reconstructed V(100)-(5x1) surface are studied by use of STM, AES, and RPES. To model the structure of the system we have also performed first principles calculations. It has been established that due to the annealing of deposited silver uniform films are formed and that the vanadium reconstruction is completely removed. As found from STM measurements and supported by ab initio calculations in the in-plane direction silver follows the structure of the V(100)-(1x1) lattice and is tetragonally distorted in the direction perpendicular to the surface. The ab initio results predicted the adsorption energies of individual silver layers and the work function of Ag/V(100) in accordance with experiments.

Growth of copper and vanadium on a thin Al2O3-fil on Ni3Al(111).

Scanning tunneling microscopy (STM) is used to characterise different states of the V(100) surface during the cleaning procedure in an ultrahigh vacuum apparatus, starting with the "as received" sample and finishing with an almost perfectly clean surface. We show, for the first time, STM images of the clean V(100) surface and with atomic resolution.

Scanning tunneling microscopy is used to characterize different states of the V(100) surface during the cleaning procedure in an ultrahigh vacuum apparatus, starting with the "as received" sample and finishing with an almost perfectly clean surface. We show, for the first time, STM images of the clean V(100) surface and with atomic resolution., Primijenili smo skenirajući tunelirajući mikroskop (STM) za topografsku karakterizaciju površine V(100) prije i tijekom čišćenja u aparaturi za ultravisok vakuum, počevši s “dobivenim” uzorkom i nakon pojedinih postupaka čišćenja. Po prvi puta se pokazuju slike potpuno čiste površine V(100) s atomskim razlučivanjem, snimljene STM-om.

ACS nano 15(3), 3754 - 3807 (2021). doi:10.1021/acsnano.0c09563, X-ray-based analytics are routinely applied in many fields, including physics, chemistry, materials science, and engineering. The full potential of such techniques in the life sciences and medicine, however, has not yet been fully exploited. We highlight current and upcoming advances in this direction. We describe different X-ray-based methodologies (including those performed at synchrotron light sources and X-ray free-electron lasers) and their potentials for application to investigate the nano–bio interface. The discussion is predominantly guided by asking how such methods could better help to understand and to improve nanoparticle-based drug delivery, though the concepts also apply to nano–bio interactions in general. We discuss current limitations and how they might be overcome, particularly for future use in vivo., Published by Soc., Washington, DC