Formation of gold-capped silicon nanocolumns on silicon substrate

Gold-capped silicon nanocolumns regularly distributed over silicon substrate were obtained. The columns length was roughly 100?nm; their deviation from perpendicular axis was less than 2°. The diameter of the columns was of the order of 10?nm or below of that. The proposed procedure of nanostructuring included the following main steps: deposition of aluminum thin layer (100?C500?nm) by magnetron sputtering on (100) oriented Si wafers; formation of porous self-ordered alumina structures by electrochemical anodizing of the Al film in oxalic acid; electroless inversion of Au in alumina pores; and reactive ion etching. The obtained Si?CAu structures are of importance as the platforms for biosensing applications, while the gold-free structures are of interest in photovoltaics.     

In‐depth proteomics approach of secretome to identify novel biomarker for sepsis in LPS‐stimulated endothelial cells

Sepsis and septic shock, which are conditions triggered by infection, occur with high incidence in emergency departments and are among the most common causes of death in hospitalized patients worldwide. Therefore, the identification of sepsis biomarkers for the rapid diagnosis is a major goal for researchers in the field of critical care. Endothelial cells play a pivotal role in orchestrating the inflammatory response triggered by sepsis. In this study, we used proteomics to investigate the secretome of EA.hy926 endothelial cells following lipopolysaccharide (LPS) stimulation with 1 μg/mL LPS for 12 or 24 h. SILAC in cell cultures and an online 2D‐LC‐MS/MS system were used to analyze the secretome dynamics in response to LPS. We found that 22 of the 77 secreted proteins identified in both the presence and absence of LPS and that 19 of the secreted proteins were quantified more strongly after LPS treatment for 24 h than after treatment for 12 h. By Gene Ontology and KEGG pathway analyses, we found that proteins related to the regulation of the actin cytoskeleton showed the highest secretion response to LPS stimulation. Out of the 19 candidate proteins, we focused on moesin, which is involved in the function of endothelial cells, and confirmed its amount in cellular lysates and media taken from primary human umbilical vein endothelial cells treated with LPS. To our knowledge, this study provides the first in‐depth analysis of the LPS‐induced secretome in human endothelial cells, and we propose 19 new biomarker candidates for sepsis, including moesin.     

Selection of DNA Aptamers with Affinity for Pro-gastrin-Releasing Peptide (proGRP), a Tumor Marker for Small Cell Lung Cancer

Aptamers are single-strand oligonucleotides that are generated by the systemic evolution of ligands by exponential enrichment (SELEX) technique and that can bind to target molecules specifically. However, only a few aptamers have been developed to date against tumor markers. To utilize aptamers for tumor diagnosis, a variety of aptamers are required. Here, a single-stranded DNA aptamer specific for pro-gastrin-releasing peptide (proGRP), a marker for small cell lung cancer, was selected using SELEX. After selection, identical sequences were found in the DNA library. This sequence was selected and its binding affinity to proGRP was evaluated using surface plasmon resonance.     

Reaction Mechanism for the Dual Gold‐Catalyzed Synthesis of Dibenzopentalene: A DFT Study

A wide range of gold‐catalyzed reactions based on a dual activation mechanism has recently been reported in the literature. Herein, we present a computational investigation of the mechanism for the formation of dibenzopentalenes from 1‐ethynyl‐2‐(phenylethynyl)benzene. Transition states have been found, which substantiate the dual activation mechanism previously published and furthermore point towards a continuous presence of two gold moieties throughout the mechanistic cycle, an observation of high importance for all reactions in the field of dual activation. The initial activation of the diyne has been shown to proceed via an intermolecular transfer of a cationic gold catalyst from the thermodynamically preferred geminal‐σ,π‐acetylide complex to the active non‐geminal analogue. Furthermore, the regioselectivity of a 5‐endo versus a 6‐endo cyclization has been addressed, and the 5‐endo cyclization was found to be most favorable both thermodynamically and with regard to the activation barrier.     

Surface chemical approach to single-step measurement of antibody in human serum using localized surface plasmon resonance biosensor on microtiter plate system

In clinical settings, serum antibody levels serve as markers of pathology. For example, antibodies related to autoimmune diseases are among the conventional targets in laboratory tests. Simple clinical tests can improve the efficacy of laboratory practice. This study describes a single-step, wash-free technique for optically detecting antibodies in human serum through the localized surface plasmon resonance (LSPR) of gold nanoparticles. As a proof-of-concept experiment, the amount of antibiotin dissolved in human serum was measured with a LSPR-based biosensor in a wash-free manner using a conventional 96-well microtiter plate and a plate reader. For an efficient surface modification of biosensors, zwitterionic copolymer was used as a scaffold on the gold nanoparticle surface to immobilize antigen and blocking reagent. Single-step, wash-free measurement of antibiotin in human serum was successfully achieved. In addition, nonspecific responses from serum contents were significantly reduced because both the copolymer and hydrophilic antigen reagent that we employed were composed of poly(ethylene oxide) spacer. Comparative experiments of the antigen-antibody reaction in serum to that in buffered solution revealed that serum is a favorable environment for the biological reaction. In conclusion, our gold-nanoparticle-based LSPR method may provide a rapid and simple way to measure the amount of antibody in serum quantitatively in clinical practice.

Literatur

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Literatur

Ohne Zusammenfassung     

Dispersion und Absorption transversaler Schallwellen im Magnetfeld

The propagation velocity and absorption of transverse ultrasonic waves have bsen measured in a polycristalline metallic probe as functions of a magnetic field parallel to the direction of propagation. In agreement with the macroscopic theory, these measurements showed, that the propagation velocity was increased by the magnetic field for frequencies below a transition frequency characteristic for the medium. In case of high frequencies the magnetic field causes an absorption. In the dispersion region characterized by the transition frequency, the magnetohydrodynamic Reynolds number is of order one and the magnetically induced changes in propagation velocity and absorption are strongly frequency dependent.