1. Produkte aus Industrie und Landwirtschaft

Ohne Zusammenfassung     

A Simple Analytical Model for Predicting the Detectable Ion Current in Ion Mobility Spectrometry Using Corona Discharge Ionization Sources

Corona discharge ionization sources are often used in ion mobility spectrometers (IMS) when a non-radioactive ion source with high ion currents is required. Typically, the corona discharge is followed by a reaction region where analyte ions are formed from the reactant ions. In this work, we present a simple yet sufficiently accurate model for predicting the ion current available at the end of this reaction region when operating at reduced pressure as in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) or most IMS-MS instruments. It yields excellent qualitative agreement with measurement results and is even able to calculate the ion current within an error of 15%. Additional interesting findings of this model are the ion current at the end of the reaction region being independent from the ion current generated by the corona discharge and the ion current in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) growing quadratically when scaling down the length of the reaction region.

Open image in new window

Graphical Abstract ?

     

Fabrication of Defined Polydopamine Nanostructures by DNA Origami‐Templated Polymerization

A versatile, bottom‐up approach allows the controlled fabrication of polydopamine (PD) nanostructures on DNA origami. PD is a biosynthetic polymer that has been investigated as an adhesive and promising surface coating material. However, the control of dopamine polymerization is challenged by the multistage‐mediated reaction mechanism and diverse chemical structures in PD. DNA origami decorated with multiple horseradish peroxidase‐mimicking DNAzyme motifs was used to control the shape and size of PD formation with nanometer resolution. These fabricated PD nanostructures can serve as “supramolecular glue” for controlling DNA origami conformations. Facile liberation of the PD nanostructures from the DNA origami templates has been achieved in acidic medium. This presented DNA origami‐controlled polymerization of a highly crosslinked polymer provides a unique access towards anisotropic PD architectures with distinct shapes that were retained even in the absence of the DNA origami template.     

MaxSynBio: Avenues Towards Creating Cells from the Bottom Up

A large German research consortium mainly within the Max Planck Society (“MaxSynBio”) was formed to investigate living systems from a fundamental perspective. The research program of MaxSynBio relies solely on the bottom‐up approach to synthetic biology. MaxSynBio focuses on the detailed analysis and understanding of essential processes of life through modular reconstitution in minimal synthetic systems. The ultimate goal is to construct a basic living unit entirely from non‐living components. The fundamental insights gained from the activities in MaxSynBio could eventually be utilized for establishing a new generation of biotechnological processes, which would be based on synthetic cell constructs that replace the natural cells currently used in conventional biotechnology.     

Atomically Precise Nanocluster Assemblies Encapsulating Plasmonic Gold Nanorods

The self‐assembled structures of atomically precise, ligand‐protected noble metal nanoclusters leading to encapsulation of plasmonic gold nanorods (GNRs) is presented. Unlike highly sophisticated DNA nanotechnology, this strategically simple hydrogen bonding‐directed self‐assembly of nanoclusters leads to octahedral nanocrystals encapsulating GNRs. Specifically, the p‐mercaptobenzoic acid (pMBA)‐protected atomically precise silver nanocluster, Na₄[Ag₄₄(pMBA)₃₀], and pMBA‐functionalized GNRs were used. High‐resolution transmission and scanning transmission electron tomographic reconstructions suggest that the geometry of the GNR surface is responsible for directing the assembly of silver nanoclusters via H‐bonding, leading to octahedral symmetry. The use of water‐dispersible gold nanoclusters, Au_≈250(pMBA)_n and Au₁₀₂(pMBA)₄₄, also formed layered shells encapsulating GNRs. Such cluster assemblies on colloidal particles are a new category of precision hybrids with diverse possibilities.     

A contribution to pharmaceutical biology of freshwater sponges

In vitro anti-tumour and anti-radical activities of the acetone extract of the freshwater sponge Ochridaspongia rotunda were the subject of this study. The extract was found to be highly cytotoxic to human lung tumour cell line A-549 reaching IC₅₀ value of 5.01 ± 0.21 μg/mL. Indeed, it displayed only 2-fold less anti-tumour activity than doxorubicin (IC₅₀ value 2.42 ± 0.13 μg/mL) used as a positive control. The same extract was also found to be almost 37-fold more selective against A-549 vs. MRC-5 (normal) lung cells, in difference to weak selectivity of doxorubicin (less than 3-fold). Its profound anti-DPPH radical activity comparable to that of quercetin (IC₅₀ values 3.68 ± 0.19 and 3.14 ± 0.09 μg/mL, respectively) coupled with no signs of genotoxicity in the comet assay (MRC-5 cell line, vs. doxorubicin) has actually implicated the importance of this animal bioresource in searching for pharmaceutically useful bioactive compounds of natural origin.     

The Solvent-Like Nature of Silica Particles in Organic Solvents

 Kamlet-Taft’s α (hydrogen bond donor acidity) and π^* (dipolarity/polarizability) values of various silica batches measured in various solvents are presented. The α and π^* parameters for the various solid acids are analyzed by means of Fe(phen)₂(CN)₂ (cis-dicyano-bis-(1,10)-phenanthroline-iron(II), 1), Michler’s ketone (4,4′-bis-(dimethylamino)-benzophenone, 2), and two hydrophilic derivatives of 2, (4-(dimethylamino)-4′-(di-2-hydroxyethyl)-amino-benzophenone (3a) and 4,4′-bis-(di-(2-hydroxyethyl)-amino)-benzophenone (3b) as well as coumarin 153 (4) as solvatochromic surface polarity indicators. Apparent β (hydrogen bond acceptor basicity) parameters for bare silica have been evaluated by means of an aminobenzodifuranone dye (5) as solvatochromic probe. The chemical interpretation of the α and π^* parameters and the nature of the solvent/surface interaction which they reflect are discussed. It can be shown that an increase of the HBA (hydrogen bond accepting) capacity of the solvent significantly decreases the HBD (hydrogen bond donating) capacity of the surface environment, whereas the dipolarity/polarizability value of the silica/solvent interface is a composite of many effects. The classification of the polarity of silica particles in organic solvents compared to pure liquids is outlined.     

Radiation‐grafted ion‐exchange membranes: Influence of the initial matrix on the synthesis and structure

A series of commercial fluoropolymer films was irradiated with an electron beam, grafted with styrene, and sulfonated. The influence of the initial fluoropolymer on the grafting yields and the properties of the grafted and sulfonated membranes were investigated. The same synthesis procedure can be followed for most fluoropolymers and samples with a similar degree of grafting, and a homogenous polystyrene distribution can be prepared by varying the absorbed dose. The main difference among different fluoropolymer‐based membranes is the water uptake from liquid water that has a roughly linear dependence on the crystallinity of the sample. The more amorphous the initial material, the greater the water uptake. Mechanical properties of the membranes at 50% relative humidity differ less than those of the starting materials and are comparable to those of Nafion® 105. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3008–3017, 2001