Fabrication of histidine-tagged fusion protein arrays for surface plasmon resonance imaging studies of protein-protein and protein-DNA interactions

The creation and characterization of histidine-tagged fusion protein arrays using nitrilotriacetic acid (NTA) capture probes on gold thin films for the study of protein-protein and protein-DNA interactions is described. Self-assembled monolayers of 11-mercaptoundecylamine were reacted with the heterobifunctional linker N-succinimidyl S-acetylthiopropionate (SATP) to create reactive sulfhydryl-terminated surfaces. NTA capture agents were immobilized by reacting maleimide-NTA molecules with the sulfhydryl surface. The SATP and NTA attachment chemistry was confirmed with Fourier transform infrared reflection absorption spectroscopy. Oriented protein arrays were fabricated using a two-step process: (i) patterned NTA monolayers were first formed through a single serpentine poly(dimethylsiloxane) microchannel; (ii) a second set of parallel microchannels was then used to immobilize multiple His-tagged proteins onto this pattern at discrete locations. SPR imaging measurements were employed to characterize the immobilization and specificity of His-tagged fusion proteins to the NTA surface. SPR imaging measurements were also used with the His-tagged fusion protein arrays to study multiple antibody-antigen binding interactions and to monitor the sequence-specific interaction of double-stranded DNA with TATA box-binding protein. In addition, His-tagged fusion protein arrays created on gold surfaces were also used to monitor antibody binding with fluorescence microscopy in a sandwich assay format.     

The Effect of Oxygen on Phase Equilibria in the Ti-V System: Impacts on the AM Processing of Ti Alloys

Oxygen is always a constituent in “real” titanium alloys including titanium alloy powders used for powder-based additive manufacturing (AM). In addition, oxygen uptake during powder handling and printing is hard to control and, hence, it is important to understand and predict how oxygen is affecting the microstructure. Therefore, oxygen is included in the evaluation of the thermodynamic properties of the titanium-vanadium system employing the CALculation of PHAse Diagrams method and a complete model of the O-Ti-V system is presented. The β-transus temperature is calculated to increase with increasing oxygen content whereas the extension of the α-Ti phase field into the binary is calculated to decrease, which explains the low vanadium solubilities measured in some experimental works. In addition, the critical temperature of the metastable miscibility gap of the β-phase is calculated to increase to above room temperature when oxygen is added. The effects of oxygen additions on phase fractions, martensite and ω formation temperatures are discussed, along with the impacts these changes may have on AM of titanium alloys.     

Zirconium and hafnium in Bulgarian coals

A study of the geochemical behaviour of zirconium (Zr) and afnium (Hf) in several Bulgarian coal deposits has shown that the content of these elements varies considerably, the highest concentrations being found in fragments of coalified woods included in sandstones. Zr and Hf content of the lithotypes of the coals is lower than that of the corresponding whole coal samples. The Zr/Hf ratio for xylain and vitrain is always lower than that for whole coal samples. Zr and Hf are mainly associated with the inorganic matter of the coals and Zr_org and Hf_org dominate only in the low ash coals of some deposits. It is assumed that Zr_org and Hf_org were leached from the terrigenous minerals supplied to the peat swamp and fixed by the organic matter. These processes result in a slight separation of both elements.     

Widespread natural perchlorate in unsaturated zones of the southwest United States

A substantial reservoir (up to 1 kg ha(-1)) of natural perchlorate is present in diverse unsaturated zones of the arid and semi-arid southwestern United States. The perchlorate co-occurs with meteoric chloride that has accumulated in these soils throughout the Holocene [0 to 10-15 ka (thousand years ago)] and possibly longer periods. Previously, natural perchlorate widely believed to be limited to the Atacama Desert, now appears widespread in steppe-to-desert ecoregions. The perchlorate reservoir becomes sufficiently large to affect groundwater when recharge from irrigation or climate change flushes accumulated salts from the unsaturated zone. This new source may help explain increasing reports of perchlorate in dry region agricultural products and should be considered when evaluating overall source contributions.     

Mild and Effective Polymerization of Dopamine on Keratin Films for Innovative Photoactivable and Biocompatible Coated Materials

Mussel‐inspired polydopamine (PD) coating represents a promising route for constructing functional materials and finely tuning or completely changing their surface properties. In this work, a mild and effective method to realize the deposition of PD on keratin‐based films is reported. Reactive oxygen species (ROS), generated by keratin films doped with a photosensitizer, e.g., Azure A (AzA), upon UV–vis and vis‐near IR irradiation, are exploited to obtain the PD coating. Interestingly, the use of vis‐near IR irradiation leads to an increased production of ROS by AzA resulting in a greater PD deposition. Compared to uncoated keratin films, the PD‐keratin coated materials show a granular but homogeneous surface and an increased hydrophilicity, maintaining the ROS generation ability of AzA. This work demonstrates a useful method to effectively and rapidly functionalize with PD materials that are sensitive to temperature, pH and UV light, such as keratin. The proposed strategy allows obtaining new multifunctional biomaterials of potential interest in tissue engineering and drug delivery; in particular, the use of PD‐keratin films for near IR laser bonding of ophthalmic tissue, which is a representative case in wound healing purpose, is shown.     

Targeted synthesis and environmental applications of oxide nanomaterials

Oxide nanomaterials are indispensable building blocks for a future nanotechnology, because they offer an infinite variety of structural motifs that lead to their widespread technical application. Therefore, flexible and tunable preparative strategies are required to convert this large family of materials onto the nanoscale. Although hydrothermal syntheses have proven especially suitable for this purpose, their reaction pathways and mechanisms often remain unknown so that they can be difficult to control. In the following, we summarize our comprehensive approach towards nanostructured functional oxides that is based on synthetic parameter optimizations, mechanistic in situ investigations and the characterization of environmentally relevant properties, e.g. in photocatalysis or sensor technology. The connection between preparative morphology control and the resulting materials properties is demonstrated for selected tungstate systems and bismuth-containing oxides. Furthermore, different methods for the in situ monitoring of hydrothermal processes are discussed.     

Application of lean six sigma business practices to an Air Purifying Respirator process

Chemical and metallurgical operations involving hazardous materials (plutonium, other nuclear materials, beryllium, and corrosive liquids) account for most activities performed at nuclear research facilities. When engineering controls are not feasible, excursions of these contaminants into the operator's breathing zone are prevented through the use of personal protective equipment, including Air Purifying Respirators (APRs). Lean Manufacturing and Six Sigma (LSS) business practices effectively improve the APR process. Designing the APR process management system increases effectiveness, while adopting streamlined and cost effective activities that meet nuclear research worker needs. This paper discusses the application of LSS business practices to an APR process and demonstrates how management uses the results to make decisions.     

A comparison of spherical and cylindrical microparticles composed of nanoparticles for pulmonary application

Nano-embedded microparticles represent promising carrier systems to tackle the challenges of nanoparticle delivery into the lungs by inhalation. While spray drying is widely used for the incorporation of nanoparticles into microparticles, the template-assisted technique is a novel method to prepare aspherical, cylindrical microparticles composed of nanoparticles. In this work, both techniques were applied to produce both spherical and cylindrical nano-embedded microparticles. For both geometries particles consisting of gelatin nanoparticles, mannitol and leucine were prepared in three different sizes each. Cylindrical microparticles could be prepared with defined dimensions and narrow size distributions, allowing to target a wide range of aerodynamic diameters. The size of spherical microparticles was influenced by the spraying feed concentration, yielding only small differences in geometric and aerodynamic diameters and broad particle size distributions. Regarding the redispersibility of the nano-embedded microparticles, spherical particles showed better disintegration behavior and higher nanoparticle release in comparison to cylindrical particles upon contact with water. The template-assisted technique yielded higher nanoparticle content in contrast to spray drying. In summary, cylindrical particles represent a promising drug delivery system with high potential for later application. However, further improvements in the preparation method are required to enable higher yields and a possible later scale-up.

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