Amyloid fibrils are polymers formed by proteins under specific conditions and in many cases they are related to pathogenesis, such as Parkinson’s and Alzheimer’s diseases. Their hallmark is the presence of a β-sheet structure. High resolution structural data on these systems as well as information gathered from multiple complementary analytical techniques is needed, from both a fundamental and a pharmaceutical perspective. Here, a previously reported de novo designed, pH-switchable coiled coil-based peptide that undergoes structural transitions resulting in fibril formation under physiological conditions has been exhaustively characterized by transmission electron microscopy (TEM), cryo-TEM, atomic force microscopy (AFM), wide-angle X-ray scattering (WAXS) and solid-state NMR (ssNMR). Overall, a unique 2-dimensional carpet-like assembly composed of large coexisiting ribbon-like, tubular and funnel-like structures with a clearly resolved protofilament substructure is observed. Whereas electron microscopy and scattering data point somewhat more to a hairpin model of β-fibrils, ssNMR data obtained from samples with selectively labelled peptides are in agreement with both, hairpin structures and linear arrangements.

The helical coiled coil is a well-studied folding motif that can be used for the design of nanometer-sized bioinspired fibrous structures with potential applications as functional materials. A two-component system of coiled coil based model peptides is investigated, which forms, under acidic conditions, uniform, hundreds of nanometers long, and ~2.6 nm thick trimeric α-helical fibers. In the absence of the other component and under the same solvent conditions, one model peptide forms β-sheet-rich amyloid fibrils and the other forms stable trimeric α-helical coiled coils, respectively. These observations reveal that the complementary interactions driving helical folding are much stronger here than those promoting the intermolecular β-sheet formation. The results of this study are important in the context of amyloid inhibition but also open up new avenues for the design of novel fibrous peptidic materials.

Levitated droplets can model spray drying, a process which is poorly X-ray understood despite its industrial importance. Monitoring the drying process by simultaneous synchrotron X-ray scattering and Raman spectroscopy provides insights into the processes starting from the molecular species up to larger crystalline particles forming the stable system. In this study, slurries of two different phosphate-containing ammonium iron molybdates with different Fe/Mo ratios which are used as precursors for catalysts were exemplarily studied. Next to the phases containing highly condensed Keggin anions other phases of less condensed molybdates and phosphates were formed during the drying depending on the composition of the slurry and the drying time. To validate the capability of this experimental approach, the stable samples obtained after the drying in the levitator were compared with samples obtained after conventional spray drying and filtration of the precipitates. The results of comprehensive characterization (X-ray diffraction (XRD), Raman, attenuated total reflection Fourier transformation infrared spectroscopy (ATR-FTIR), inductively coupled plasma optical emission spectroscopy (ICP-OES)) indicate that the setup can be used to acquire reliable information on the processes during spray drying of complex oxides by using minimal amounts of material with volumes of several micro liters.

During the mineralisation of metal carbonates MCO3 (M=Ca, Sr, Ba, Mn, Cd, Pb) liquid-like amorphous intermediates emerge. These intermediates that form via a liquid/liquid phase separation behave like a classical emulsion and are stabilized electrostatically. The occurrence of these intermediates is attributed to the formation of highly hydrated networks whose stability is mainly based on weak interactions and the variability of the metal-containing pre-critical clusters. Their existence and compositional freedom are evidenced by electrospray ionization mass spectrometry (ESI-MS). Liquid intermediates in non-classical crystallisation pathways seem to be more common than assumed.

The impact of the ovo proteins ovalbumin and lysozyme—present in the first stage of egg shell formation—on the homogeneous formation of the liquid amorphous calcium carbonate (LACC) precursor, was studied by a combination of complementing methods: in situ WAXS, SANS, XANES, TEM, and immunogold labeling. Lysozyme (pI = 9.3) destabilizes the LACC emulsion whereas the glycoprotein ovalbumin (pI = 4.7) extends the lifespan of the emulsified state remarkably. In the light of the presented data: (a) Ovalbumin is shown to behave commensurable to the 'polymer-induced liquid precursor' (PILP) process proposed by Gower et al. Ovalbumin can be assumed to take a key role during eggshell formation where it serves as an effective stabilization agent for transient precursors and prevents undirected mineralization of the eggshell. (b) It is further shown that the emulsified LACC carries a negative surface charge and is electrostatically stabilized. (c) We propose that the liquid amorphous calcium carbonate is affected by polymers by depletion stabilization and de-emulsification rather than 'induced' by acidic proteins and polymers during a so-called polymer-induced liquid-precursor process. The original PILP coating effect, first reported by Gower et al., appears to be a result of a de-emulsification process of a stabilized LACC phase. The behavior of the liquid amorphous carbonate phase and the polymer-induced liquid-precursor phase itself can be well described by colloid chemical terms: electrostatic and depletion stabilization and de-emulsification by depletion destabilization.

Molecular masses and end groups of polystyrene (PS) formed in a novel container-less polymerization strategy, based on levitated droplets in an acoustic trap, were determined by Gel Permeation Chromatography (GPC) and Matrix-assisted Laser Desorption/Ionization Time of Flight Mass spectrometry (MALDI-TOF MS).

A combination of two analytical methods, time-resolved X-ray diffraction (XRD) and Raman spectroscopy, is presented as a novel tool for crystallization studies. An acoustic levitator was employed as sample environment. This setup enables the acquisition of XRD and Raman data in situ simultaneously within a 20 s period and hence permits investigation of polymorphic phase transitions during the crystallization process in different solvents (methanol, ethanol, acetone, dichloromethane, acetonitrile). These real time measurements allow the determination of the phase content from the onset of the first crystalline molecular assemblies to the stable system. To evaluate the capability of this approach, the setup was applied to elucidate the crystallization process of the polymorphic compound nifedipine. The results indicate the existence of solvent-dependent transient phases during the crystallization process. The quality of the data allowed the assignment of the lattice constants of the hitherto unknown crystal structure of the beta-polymorph.

As a model for spray drying the early stages of crystallization of complex molybdate catalyst precursors were monitored online in droplets levitated acoustically. Synchron X-ray scattering techniques were applied to study the drying process of a typical molybdate catalysts precursor prepared from Ni-,Fe-,Bi-nitrate, ammonium heptamolybdate and H3PO4. Comparison with diffraction patterns obtained from sessile droplets shows significant differences in the crystal growth, whereas the final crystal structure – including a Keggin-type anion – is identical in both cases. The levitated samples exhibit a decelerated growth with a large number of small crystallites at the beginning of the crystallization, whereas in case of the sessile droplets a small number of large crystallites were observed after a few minutes. The acoustic levitation using an ultrasonic trap proves to be an elegant tool to mimic spray drying and offers new possibilities in relation to the understanding of the drying process.

A new setup is presented which enables simultaneous wide- and small-angle X-ray scattering (WAXS/SAXS) and Raman spectroscopic experiments during the synthesis of Mo-based mixed oxide catalyst precursors at the μ-spot beamline at the Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung (BESSY). Furthermore, we report about the separate monitoring of the same reactions under comparable conditions by simultaneous combined ATR/UV–vis/Raman spectroscopic measurements. For testing the performance of both experimental setups two syntheses were described comprising the precipitation of metal molybdates by mixing solutions of metal nitrates and ammonium heptamolybdate. Additionally, the effect of H3PO4 admixture on precipitation was investigated. The combined evaluation of spectroscopic and WAXS/SAXS data allows the discrimination between different molybdate species appearing in solution and precipitate. Furthermore, these molybdate species could be assigned to separate phases of different crystallinity.

Zeitschrift für anorganische und allgemeine ChemieVolume 634, Issue 11 p. 2015-2015 Short Communication New Insights into the Crystallization Process of Calcium Carbonate by a Contact-Free in situ Scattering Technique using a Levitating Drop Method Stephan E. Wolf, Stephan E. Wolf Johannes Gutenberg-University of Mainz, Institute of Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55099 MainzSearch for more papers by this authorJork Leiterer, Jork Leiterer Johannes Gutenberg-University of Mainz, Institute of Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55099 MainzSearch for more papers by this authorMichael Kappl, Michael Kappl Johannes Gutenberg-University of Mainz, Institute of Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55099 MainzSearch for more papers by this authorFranziska Emmerling, Franziska Emmerling Johannes Gutenberg-University of Mainz, Institute of Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55099 MainzSearch for more papers by this authorWolfgang Tremel, Corresponding Author Wolfgang Tremel tremel@uni-mainz.de Johannes Gutenberg-University of Mainz, Institute of Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55099 MainzJohannes Gutenberg-University of Mainz, Institute of Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55099 MainzSearch for more papers by this author Stephan E. Wolf, Stephan E. Wolf Johannes Gutenberg-University of Mainz, Institute of Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55099 MainzSearch for more papers by this authorJork Leiterer, Jork Leiterer Johannes Gutenberg-University of Mainz, Institute of Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55099 MainzSearch for more papers by this authorMichael Kappl, Michael Kappl Johannes Gutenberg-University of Mainz, Institute of Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55099 MainzSearch for more papers by this authorFranziska Emmerling, Franziska Emmerling Johannes Gutenberg-University of Mainz, Institute of Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55099 MainzSearch for more papers by this authorWolfgang Tremel, Corresponding Author Wolfgang Tremel tremel@uni-mainz.de Johannes Gutenberg-University of Mainz, Institute of Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55099 MainzJohannes Gutenberg-University of Mainz, Institute of Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55099 MainzSearch for more papers by this author First published: 28 August 2008 https://doi.org/10.1002/zaac.200870015AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume634, Issue11September 2008Pages 2015-2015 RelatedInformation

Acoustic levitation is used as a new tool to study concentration‐dependent processes in fluorescence spectroscopy. With this technique, small amounts of liquid and solid samples can be measured without the need for sample supports or containers, which often limits signal acquisition and can even alter sample properties due to interactions with the support material. We demonstrate that, because of the small sample volume, fluorescence measurements at high concentrations of an organic dye are possible without the limitation of inner‐filter effects, which hamper such experiments in conventional, cuvette‐based measurements. Furthermore, we show that acoustic levitation of liquid samples provides an experimentally simple way to study distance‐dependent fluorescence modulations in semiconductor nanocrystals. The evaporation of the solvent during levitation leads to a continuous increase of solute concentration and can easily be monitored by laser‐induced fluorescence.

An in situ study of the contact-free crystallization of calcium carbonate in acoustic levitated droplets is reported. The levitated droplet technique allows an in situ monitoring of the crystallization while avoiding any foreign phase boundaries that may influence the precipitation process by heterogeneous nucleation. The diffusion-controlled precipitation of CaCO3 at neutral pH starts in the initial step with the homogeneous formation of a stable, nanosized liquid-like amorphous calcium carbonate phase that undergoes in a subsequent step a solution-assisted transformation to calcite. Cryogenic scanning electron microscopy studies indicate that precipitation is not induced at the solution/air interface. Our findings demonstrate that a liquid-liquid phase separation occurs at the outset of the precipitation under diffusion-controlled conditions (typical for biomineral formation) with a slow increase of the supersaturation at neutral pH.

An ultrasonic trap (acoustic levitator) was used as an analytical tool to allow container-free handling of proteins in small sample volumes. This trap was combined for the first time with synchrotron small-angle X-ray scattering (SAXS) for structure analysis of biological macromolecules in a solution. The microfocus beamline at BESSY was used as a source of intense X-ray radiation. Apoferritin (APO) was used as a model protein, and its aggregation behavior in a levitator was followed from a diluted solution to the solid state. Different stages of APO agglomeration were observed without solid container walls, which may influence aggregation behavior and produce a parasitic scattering background. Starting with a volume of 5 μL we analyzed the concentration dependence of APO structure factors in the range from 5 to 1,200 mg/mL (solid protein). The solution was stirred automatically due to convection inside the droplet caused by the ultrasonic field. SAXS data recording of APO was performed in time intervals of 60 s during an aggregation experiment of 30 to 60 min.

Crystallization processes under different conditions are of fundamental interest in chemistry, pharmacy, and medicine. Therefore, we have studied the formation of micro- and nanosized crystals using water-caffeine (1,3,7-trimethyl-1 H-purine-2,6(3 H,7 H)-dione) solutions under ambient conditions as a relevant model system. When droplets of an aqueous caffeine solution evaporate and eventually dry on surfaces (glass, polystyrene, and polyester), stable "coffee tabletop" rings with a perimeter of typically 3 mm are formed after 20 to 50 min. Using a micro focus X-ray beam available at the BESSY muSpot-beamline, the fine structure of different caffeine needles can be distinguished. Unexpectedly, both crystal modifications (alpha- and beta-caffeine) are present, but locally separated in these rings. Furthermore, AFM studies reveal the presence of even smaller particles on a nanometer length scale. To eliminate influences of surface irregularities from the crystallization process, acoustic levitation of liquid samples was employed. Such levitated droplets are trapped in a stable position and only surrounded by air. The solvent in an ultrasonically levitated drop evaporates completely, and the resulting crystallization of caffeine was followed in situ by synchrotron X-ray diffraction. In this case, the diffraction pattern is in accordance with pure alpha-caffeine and does not indicate the formation of the room temperature polymorph beta-caffeine. Hence, our investigations open new vistas that may lead to a controlled formation of cocrystals and novel polymorphs of micro- and nanocrystalline materials, which are of relevance for fundamental studies as well as for pharmaceutical and medical applications.

Zeitschrift für anorganische und allgemeine ChemieVolume 632, Issue 12-13 p. 2132-2132 Poster Characterisation of levitated samples for modelling of condensed matter Jork Leiterer, Corresponding Author Jork Leiterer Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, D-12489 BerlinFederal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, D-12489 BerlinSearch for more papers by this authorFranziska Emmerling, Franziska Emmerling Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, D-12489 BerlinSearch for more papers by this authorAndreas F. Thünemann, Andreas F. Thünemann Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, D-12489 BerlinSearch for more papers by this authorUlrich Panne, Ulrich Panne Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, D-12489 BerlinSearch for more papers by this author Jork Leiterer, Corresponding Author Jork Leiterer Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, D-12489 BerlinFederal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, D-12489 BerlinSearch for more papers by this authorFranziska Emmerling, Franziska Emmerling Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, D-12489 BerlinSearch for more papers by this authorAndreas F. Thünemann, Andreas F. Thünemann Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, D-12489 BerlinSearch for more papers by this authorUlrich Panne, Ulrich Panne Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, D-12489 BerlinSearch for more papers by this author First published: 23 August 2006 https://doi.org/10.1002/zaac.200670112Citations: 5AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume632, Issue12-13September 2006Pages 2132-2132 RelatedInformation

For the investigation of small sample volumes, the use of an acoustic levitator was tested as a `sample holder' for hovering droplets in a synchrotron beam. It might be advantageous to use levitated droplets instead of samples confined in solid holders, especially for the study of crystallization processes where the influence of containing walls has to be minimized. In a first experiment, the crystallization of sodium chloride in a small droplet of aqueous solution has been followed with a time resolution of 30 s. The collected diffraction peaks are compared with data in the ICSD database.

This paper intends to develop a measurement system to characterize photomasks for 193 nm lithography applications. Based on the VUV spectrophotometer at the Fraunhofer IOF institute, some modifications have been addressed to fulfil these special measurements. Characterizations on photomasks have been successfully carried out, which show good correlations to simulations.