Efficient Purification of Cowpea Chlorotic Mottle Virus by a Novel Peptide Aptamer.

The cowpea chlorotic mottle virus (CCMV) is a plant virus explored as a nanotechnological platform. The robust self-assembly mechanism of its capsid protein allows for drug encapsulation and targeted delivery. Additionally, the capsid nanoparticle can be used as a programmable platform to display different molecular moieties.

Resonance Energy Transfer to Track the Motion of Lanthanide Ions-What Drives the Intermixing in Core-Shell Upconverting Nanoparticles?

The imagination of clearly separated core-shell structures is already outdated by the fact, that the nanoparticle core-shell structures remain in terms of efficiency behind their respective bulk material due to intermixing between core and shell dopant ions. In order to optimize the photoluminescence of core-shell UCNP the intermixing should be as small as possible and therefore, key parameters of this process need to be identified. In the present work the Ln(III) ion migration in the host lattices NaYF and NaGdF was monitored.

Folding DNA into origami nanostructures enhances resistance to ionizing radiation.

We report experimental results on damage induced by ionizing radiation to DNA origami triangles which are commonly used prototypes for scaffolded DNA origami nanostructures. We demonstrate extreme stability of DNA origami upon irradiation, which is caused by (i) the multi-row design holding the shape of the origami even after severe damage to the scaffold DNA and (ii) the reduction of damage to the scaffold DNA due to the protective effect of the folded structure. With respect to damage induced by ionizing radiation, the protective effect of the structure is superior to that of a naturally paired DNA double helix.

Serial femtosecond and serial synchrotron crystallography can yield data of equivalent quality: A systematic comparison.

For the two proteins myoglobin and fluoroacetate dehalogenase, we present a systematic comparison of crystallographic diffraction data collected by serial femtosecond (SFX) and serial synchrotron crystallography (SSX). To maximize comparability, we used the same batch of micron-sized crystals, the same sample delivery device, and the same data analysis software. Overall figures of merit indicate that the data of both radiation sources are of equivalent quality.

Non-ionic surfactants as innovative skin penetration enhancers: insight in the mechanism of interaction with simple 2D stratum corneum model system.

Transdermal drug delivery is a passive diffusion process of an active compound through the skin which is affected by drug solubility in the multilamellar lipidic matrix of the stratum corneum (SC). Widely used non-ionic surfactants (NIS) can be added into transdermal formulations to enhance the penetration of drugs by influencing the packing of the stratum corneum lipidic matrix. Objective of our study was to analyse the interaction between selected NIS and a simple SC lipidic matrix model system using a variety of surface-sensitive techniques based on the application of Langmuir monolayers.

Europium-Doped Ceria-Gadolinium Mixed Oxides: PARAFAC Analysis and High-Resolution Emission Spectroscopy under Cryogenic Conditions for Structural Analysis.

Gadolinium-doped ceria or gadolinium-stabilized ceria (GDC) is an important technical material due to its ability to conduct O ions, e.g., used in solid oxide fuel cells operated at intermediate temperature as an electrolyte, diffusion barrier, and electrode component.

A Platform of Phenol-Based Nitroxide Radicals as an "EPR Toolbox" in Supramolecular and Click Chemistry.

A large number (63) of well-defined nitroxide radicals, all phenol-based TEMPO and PROXYL esters, were synthesized using different strategies based on well-established Steglich esterifications. All of these radicals can be used as spin probes (SPs) and spin labels (SLs) for electron paramagnetic resonance (EPR) spectroscopy of supramolecular systems. Depending on the nature of the functional group(s) on each SP/SL, the synthesized nitroxide radicals serve as polyphilic molecular "toolbox" for the EPR-spectroscopic detection and characterization of specific types of interactions, e.

Multivariate chemometrics as a key tool for prediction of K and Fe in a diverse German agricultural soil-set using EDXRF.

Within the framework of precision agriculture, the determination of various soil properties is moving into focus, especially the demand for sensors suitable for in-situ measurements. Energy-dispersive X-ray fluorescence (EDXRF) can be a powerful tool for this purpose. In this study a huge diverse soil set (n = 598) from 12 different study sites in Germany was analysed with EDXRF.

Electrostatic interactions of alkaline earth cations with 1,2-dimyristoyl-sn-glycero-3-phosphatidic acid (DMPA) model membranes at neutral and acidic pH.

The binding of alkaline earth cations Mg, Ca, and Sr (M) to unilamellar 1,2-dimyristoyl-sn-glycero-3-phosphatidic acid (DMPA) vesicles was analysed by pH potentiometry, differential scanning calorimetry (DSC), isothermal titration calorimetry (ITC) and FT-IR spectroscopy. The binding of alkaline earth cations induces deprotonation of the DMPA headgroup even at very low concentration of divalent cations (~ 100 µM). The amount of deprotonated DMPA was measured by pH potentiometry as a function of divalent cation concentration.

Time-resolved crystallography reveals allosteric communication aligned with molecular breathing.

A comprehensive understanding of protein function demands correlating structure and dynamic changes. Using time-resolved serial synchrotron crystallography, we visualized half-of-the-sites reactivity and correlated molecular-breathing motions in the enzyme fluoroacetate dehalogenase. Eighteen time points from 30 milliseconds to 30 seconds cover four turnover cycles of the irreversible reaction.

Antibody Binding at the Liposome-Water Interface: A FRET Investigation toward a Liposome-Based Assay.

Different signal amplification strategies to improve the detection sensitivity of immunoassays have been applied which utilize enzymatic reactions, nanomaterials, or liposomes. The latter are very attractive materials for signal amplification because liposomes can be loaded with a large amount of signaling molecules, leading to a high sensitivity. In addition, liposomes can be used as a cell-like "bioscaffold" to directly test recognition schemes aiming at cell-related processes.

Strategies for sample delivery for femtosecond crystallography.

Highly efficient data-collection methods are required for successful macromolecular crystallography (MX) experiments at X-ray free-electron lasers (XFELs). XFEL beamtime is scarce, and the high peak brightness of each XFEL pulse destroys the exposed crystal volume. It is therefore necessary to combine diffraction images from a large number of crystals (hundreds to hundreds of thousands) to obtain a final data set, bringing about sample-refreshment challenges that have previously been unknown to the MX synchrotron community.

Vacuum-UV and Low-Energy Electron-Induced DNA Strand Breaks - Influence of the DNA Sequence and Substrate.

DNA is effectively damaged by radiation, which can on the one hand lead to cancer and is on the other hand directly exploited in the treatment of tumor tissue. DNA strand breaks are already induced by photons having an energy below the ionization energy of DNA. At high photon energies, most of the DNA strand breaks are induced by low-energy secondary electrons.

Vacuum-UV induced DNA strand breaks - influence of the radiosensitizers 5-bromouracil and 8-bromoadenine.

Radiation therapy is a basic part of cancer treatment. To increase the DNA damage in carcinogenic cells and preserve healthy tissue at the same time, radiosensitizing molecules such as halogenated nucleobase analogs can be incorporated into the DNA during the cell reproduction cycle. In the present study 8.

Photophysics of "Floppy" Dyads as Potential Biomembrane Probes.

In the study a dyad (C6 probe), constructed of two dyes with highly different hydrophobicities, was investigated by steady-state and time-resolved spectroscopic techniques in chloroform, methanol, and in phospholipid vesicles, respectively. The dyad was built on two dyes: the lipophilic benzo[a]pyrene (BaP) and the hydrophilic sulforhodamine B (SRB). The dyes were linked via a short, but flexible alkyl chain (six C-atoms).

The Physico-Chemical Basis of DNA Radiosensitization: Implications for Cancer Radiation Therapy.

High-energy radiation is used in combination with radiosensitizing therapeutics to treat cancer. The most common radiosensitizers are halogenated nucleosides and cisplatin derivatives, and recently also metal nanoparticles have been suggested as potential radiosensitizing agents. The radiosensitizing action of these compounds can at least partly be ascribed to an enhanced reactivity towards secondary low-energy electrons generated along the radiation track of the high-energy primary radiation, or to an additional emission of secondary reactive electrons close to the tumor tissue.

Rapid Synthesis of Sub-10 nm Hexagonal NaYF-Based Upconverting Nanoparticles using Therminol 66.

We report a simple one-pot method for the rapid preparation of sub-10 nm pure hexagonal (β-phase) NaYF-based upconverting nanoparticles (UCNPs). Using Therminol 66 as a co-solvent, monodisperse UCNPs could be obtained in unusually short reaction times. By varying the reaction time and reaction temperature, it was possible to control precisely the particle size and crystalline phase of the UCNPs.

Low-Energy Electron-Induced Strand Breaks in Telomere-Derived DNA Sequences-Influence of DNA Sequence and Topology.

During cancer radiation therapy high-energy radiation is used to reduce tumour tissue. The irradiation produces a shower of secondary low-energy (<20 eV) electrons, which are able to damage DNA very efficiently by dissociative electron attachment. Recently, it was suggested that low-energy electron-induced DNA strand breaks strongly depend on the specific DNA sequence with a high sensitivity of G-rich sequences.

Intramolecular deactivation processes of electronically excited Lanthanide(III) complexes with organic acids of low molecular weight.

The luminescence of Lanthanide(III) complexes with different model ligands was studied under direct as well as sensitized excitation conditions. The research was performed in the context of studies dealing with deep-underground storages for high-level nuclear waste. Here, Lanthanide(III) ions served as natural analogues for Actinide(III) ions and the low-molecular weight organic ligands are present in clay minerals and furthermore, they were employed as proxies for building blocks of humic substances, which are important complexing molecules in the natural environment, e.

Stability of the Parent Anion of the Potential Radiosensitizer 8-Bromoadenine Formed by Low-Energy (<3 eV) Electron Attachment.

8-Bromoadenine (A) is a potential DNA radiosensitizer for cancer radiation therapy due to its efficient interaction with low-energy electrons (LEEs). LEEs are a short-living species generated during the radiation damage of DNA by high-energy radiation as it is applied in cancer radiation therapy. Electron attachment to A in the gas phase results in a stable parent anion below 3 eV electron energy in addition to fragmentation products formed by resonant exocyclic bond cleavages.

Effect of adsorption kinetics on dissociation of DNA-nucleobases on gold nanoparticles under pulsed laser illumination.

Photothermal therapy is a novel approach to destroy cancer cells by an increase of temperature due to laser illumination of gold nanoparticles (GNPs) that are incorporated into the cells. Here, we study the decomposition of DNA nucleobases via irradiation of gold nanoparticles with ns-laser pulses. The kinetics of the adsorption and decomposition process is described by a theoretical model based on the Langmuir assumptions and correlated with experimentally determined reaction rates revealing a strong influence of the nucleobase specific adsorption.

Sensitizing DNA Towards Low-Energy Electrons with 2-Fluoroadenine.

2-Fluoroadenine ((2F) A) is a therapeutic agent, which is suggested for application in cancer radiotherapy. The molecular mechanism of DNA radiation damage can be ascribed to a significant extent to the action of low-energy (<20 eV) electrons (LEEs), which damage DNA by dissociative electron attachment. LEE induced reactions in (2F) A are characterized both isolated in the gas phase and in the condensed phase when it is incorporated into DNA.

Sequence dependence of electron-induced DNA strand breakage revealed by DNA nanoarrays.

The electronic structure of DNA is determined by its nucleotide sequence, which is for instance exploited in molecular electronics. Here we demonstrate that also the DNA strand breakage induced by low-energy electrons (18 eV) depends on the nucleotide sequence. To determine the absolute cross sections for electron induced single strand breaks in specific 13 mer oligonucleotides we used atomic force microscopy analysis of DNA origami based DNA nanoarrays.

Molecular processes studied at a single-molecule level using DNA origami nanostructures and atomic force microscopy.

DNA origami nanostructures allow for the arrangement of different functionalities such as proteins, specific DNA structures, nanoparticles, and various chemical modifications with unprecedented precision. The arranged functional entities can be visualized by atomic force microscopy (AFM) which enables the study of molecular processes at a single-molecular level. Examples comprise the investigation of chemical reactions, electron-induced bond breaking, enzymatic binding and cleavage events, and conformational transitions in DNA.

Self-assembly of different single-chain bolaphospholipids and their miscibility with phospholipids or classical amphiphiles.

A variety of bolalipids with a single long alkyl chain and two identical headgroups self-assemble in aqueous solutions into helical entangled nanofibers leading to the formation of a hydrogel. An increase in temperature usually leads to the break-up of the fiber structure into micellar aggregates. In this paper the question is addressed whether bolalipids of different lengths or different headgroup structures can form mixed fibers.