Tandem X-ray absorption spectroscopy and scattering for in situ time-resolved monitoring of gold nanoparticle mechanosynthesis.

Current time-resolved in situ approaches limit the scope of mechanochemical investigations possible. Here we develop a new, general approach to simultaneously follow the evolution of bulk atomic and electronic structure during a mechanochemical synthesis. This is achieved by coupling two complementary synchrotron-based X-ray methods: X-ray absorption spectroscopy (XAS) and X-ray diffraction.

Advances in Nickel Nanoparticle Synthesis via Oleylamine Route.

Nickel nanoparticles are an active research area due to their multiple applications as catalysts in different processes. A variety of preparation techniques have been reported for the synthesis of these nanoparticles, including solvothermal, microwave-assisted, and emulsion techniques. The well-studied solvothermal oleylamine synthesis route comes with the drawback of needing standard air-free techniques and often space-consuming glassware.

Thermally highly stable amorphous zinc phosphate intermediates during the formation of zinc phosphate hydrate.

The mechanisms by which amorphous intermediates transform into crystalline materials are still poorly understood. Here we attempt to illuminate the formation of an amorphous precursor by investigating the crystallization process of zinc phosphate hydrate. This work shows that amorphous zinc phosphate (AZP) nanoparticles precipitate from aqueous solutions prior to the crystalline hopeite phase at low concentrations and in the absence of additives at room temperature.

Processing nanoparticles with A4F-SAXS for toxicological studies: Iron oxide in cell-based assays.

Nanoparticles are not typically ready-to-use for in vitro cell culture assays. Prior to their use in assays, powder samples containing nanoparticles must be dispersed, de-agglomerated, fractionated by size, and characterized with respect to size and size distribution. For this purpose we report exemplarily on polyphosphate-stabilized iron oxide nanoparticles in aqueous suspension.

Online coupling of field-flow fractionation with SAXS and DLS for polymer analysis.

We report on a hyphenated polymer analysis method consisting of asymmetrical flow field-flow fractionation (A4F) coupled online with small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS). A mixture of six poly(styrene sulfonate)s with molar masses in the range of 6.5 × 103 to 1.

The size distribution of 'gold standard' nanoparticles.

The spherical gold nanoparticle reference materials RM 8011, RM 8012, and RM 8013, with a nominal radius of 5, 15, and 30 nm, respectively, have been available since 2008 from NIST. These materials are recommended as standards for nanoparticle size measurements and for the study of the biological effects of nanoparticles, e.g.

1.55 A structure of the ectoine binding protein TeaA of the osmoregulated TRAP-transporter TeaABC from Halomonas elongata.

TeaABC from the moderate halophilic bacterium Halomonas elongata belongs to the tripartite ATP-independent periplasmic transporters (TRAP-T), a family of secondary transporters functioning in conjunction with periplasmic substrate binding proteins. TeaABC facilitates the uptake of the compatible solutes ectoine and hydroxyectoine that are accumulated in the cytoplasm under hyperosmotic stress to protect the cell from dehydration. TeaABC is the only known TRAP-T activated by osmotic stress.

Agglomeration of proteins in acoustically levitated droplets.

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.

Common mode of DNA binding to cold shock domains. Crystal structure of hexathymidine bound to the domain-swapped form of a major cold shock protein from Bacillus caldolyticus.

Bacterial cold shock proteins (CSPs) regulate cellular adaptation to cold stress. Functions ascribed to CSP include roles as RNA chaperones and in transcription antitermination. We present the crystal structure of the Bacillus caldolyticus CSP (Bc-Csp) in complex with hexathymidine (dT(6)) at a resolution of 1.

H-bonding-directed self-assembly of synthetic copolymers containing nucleobases: organization and colloidal fusion in a noncompetitive solvent.

The self-organization of random copolymers composed of a nucleobase monomer (either 1-(4-vinylbenzyl)thymine or 9-(4-vinylbenzyl)adenine) and dodecyl methacrylate (DMA) was studied in dilute chloroform solutions. The balance between the molar fractions of the nucleobase monomer (leading to intermolecular H-bonding) and DMA (soluble moiety in chloroform) in the polymer chains was found to be the parameter that principally influences the self-organization. DMA-rich copolymers are molecularly soluble in chloroform, whereas nucleobase-rich copolymers are insoluble in this solvent.

T-rich DNA single strands bind to a preformed site on the bacterial cold shock protein Bs-CspB.

Bacterial cold shock proteins (CSPs) are involved in cellular adaptation to cold stress. They bind to single-stranded nucleic acids with a KD value in the micro- to nanomolar range. Here we present the structure of the Bacillus subtilis CspB (Bs-CspB) in complex with hexathymidine (dT6) at a resolution of 1.

V-shaped crystalline structures of di-n-alkyl esters of phosphoric acid.

We prepared crystals of di-n-alkyl esters of phosphoric acid with chain lengths of n = 10, 12, 14, 16, and 18. These were characterized by single-crystal X-ray analysis and differential scanning calorimetry (DSC). It was found that the alkyl chains are in an extended all-trans conformation and aligned close to perpendicular, forming V-shaped molecules.

Crystal structure of NblA from Anabaena sp. PCC 7120, a small protein playing a key role in phycobilisome degradation.

Cyanobacterial light-harvesting complexes, the phycobilisomes, are proteolytically degraded when the organisms are starved for combined nitrogen, a process referred to as chlorosis or bleaching. Gene nblA, present in all phycobilisome-containing organisms, encodes a protein of about 7 kDa that plays a key role in phycobilisome degradation. The mode of action of NblA in this degradation process is poorly understood.

Single-stranded DNA bound to bacterial cold-shock proteins: preliminary crystallographic and Raman analysis.

The cold-shock response has been described for several bacterial species. It is characterized by distinct changes in intracellular protein patterns whereby a set of cold-shock-inducible proteins become abundant. The major cold-shock proteins of Bacillus subtilis (Bs-CspB) and Bacillus caldolyticus (Bc-Csp) are small oligonucleotide/oligosaccharide-binding (OB) fold proteins that have been described as binding single-stranded nucleic acids.

Characterization and analysis of posttranslational modifications of the human large cytoplasmic ribosomal subunit proteins by mass spectrometry and Edman sequencing.

The 60S ribosomal proteins were isolated from ribosomes of human placenta and separated by reversed phase HPLC. The fractions obtained were subjected to trypsin and Glu-C digestion and analyzed by mass fingerprinting (MALDI-TOF), MS/MS (ESI), and Edman sequencing. Forty-six large subunit proteins were found, 22 of which showed masses in accordance with the SwissProt database (June 2002) masses (proteins L6, L7, L9, L13, L15, L17, L18, L21, L22, L24, L26, L27, L30, L32, L34, L35, L36, L37, L37A, L38, L39, L41).