Observation of Collective Photoswitching in Free‐Standing TATA‐Based Azobenzenes on Au(111)

Light‐induced transitions between the trans and cis isomer of triazatriangulenium‐based azobenzene derivatives on Au(111) surfaces were observed directly by scanning tunneling microscopy, allowing atomic‐scale studies of the photoisomerization kinetics. Although the azobenzene units in these adlayers are free‐standing and spaced at uniform distances of 1.26 nm, their photoswitching depends on the isomeric state of the surrounding molecules and, specifically, is accelerated by neighboring cis isomers. These collective effects are supported by ab initio calculations indicating that the electronic excitation preferably localizes on the n–π* state of trans isomers with neighboring cis azobenzenes.     

Efficient Conversion of Light to Chemical Energy: Directional,Chiral Photoswitches with Very High Quantum Yields

Photochromic systems have been used to achieve a number of engineering functions such as light energy conversion, molecular motors, pumps, actuators, and sensors. Key to practical applications is a high efficiency in the conversion of light to chemical energy, a rigid structure for the transmission of force to the environment, and directed motion during isomerization. We present a novel type of photochromic system (diindane diazocines) that converts visible light with an efficiency of 18 % to chemical energy. Quantum yields are exceptionally high with >70 % for the cis–trans isomerization and 90 % for the back‐reaction and thus higher than the biochemical system rhodopsin (64 %). Two diastereomers (meso and racemate) were obtained in only two steps in high yields. Both isomers are directional switches with high conversion rates (76–99 %). No fatigue was observed after several thousands of switching cycles in both systems.     

Protein Interactions with Polymer Coatings and Biomaterials

Protein adsorption is considered to be the most important factor of the interaction between polymeric biomaterials and body fluids or tissues. Water‐mediated hydrophobic and hydration forces as well as electrostatic interactions are believed to be the major factors of protein adsorption. A systematic analysis of various monolayer systems has resulted in general guidelines, the so‐called “Whitesides rules”. These concepts have been successfully applied for designing various protein‐resistant surfaces and are being studied to expand the understanding of protein–material interactions beyond existing limitations. Theories on the mechanisms of protein adsorption are constantly being improved due to the fast‐developing analytical technologies. This Review is aimed at improving these empirical guidelines with regard to present theoretical and analytical advances. Current analytical methods to test mechanistic hypotheses and theories of protein–surface interactions will be discussed. Special focus will be given to state‐of‐the‐art bioinert and biospecific coatings and their applications in biomedicine.     

Core‐Modified Rubyrins Containing Dithienylethene Moieties

Two stable core‐modified rubyrins bearing one and two dithienylethene (DTE) units ( 1 and 2 ) have been synthesized. With one “closed‐form” DTE unit, 1 shows aromaticity associated with its conjugated circuit of 26 π‐electrons. In contrast, rubyrin 2 containing one “open‐form” DTE unit has nonaromatic properties.     

Mussel‐Inspired Dendritic Polymers as Universal Multifunctional Coatings

A rapid and universal approach for multifunctional material coatings was developed based on a mussel‐inspired dendritic polymer. This new kind of polymer mimics not only the functional groups of mussel foot proteins (mfps) but also their molecular weight and molecular structure. The large number of catechol and amine groups set the basis for heteromultivalent anchoring and crosslinking. The molecular weight reaches 10 kDa, which is similar to the most adhesive mussel foot protein mfp‐5. Also, the dendritic structure exposes its functional groups on the surface like the folded proteins. As a result, a very stable coating can be prepared on virtually any type of material surface within 10 min by a simple dip‐coating method, which is as fast as the formation of mussel byssal threads in nature.     

A candidate reference measurement procedure for Cyclosporine A in whole blood

Monitoring of Cyclosporine A (CsA) concentrations in whole blood is widely performed due to the narrow therapeutic index of the drug. Required standardisation for routine analysis of CsA is still missing. The candidate reference measurement procedure presented here is designated for the assignment of CsA values in hemolysed blood associated with expanded measurement uncertainty. Separate stock solutions for calibration and control materials were prepared by spiking hemolysed blood with CsA under gravimetric control. The essential sample pretreatment step was protein precipitation. Analysis was performed using isotope dilution LC-MS/MS with online solid phase extraction. Interference by matrix components was investigated. Using [²H₄]-CsA as the internal standard, no interference from the investigated matrices were detected. Measurement repeatability using three pools of whole blood as samples revealed coefficients of variation (CV) ranging from 1.0 % to 1.6 %. Intermediate measurement precision was determined by repeated analysis of self-prepared control materials taken from different stock solutions of pooled whole blood. CVs were between 0.8 % and 2.4 %. Measurement accuracy was checked using three control materials prepared from three different stock solutions. The recoveries of the mean of mean values obtained on four measurement days ranged from 99.4 % to 101.3 %. The combined expanded uncertainty of measurement based on 5 days of measurement and was evaluated according to the GUM as U = 2.0 % (k = 2).     

Functionalized diamond nanopowder for phosphopeptides enrichment from complex biological fluids

Diamond is known for its high affinity and biocompatibility towards biomolecules and is used exclusively in separation sciences and life science research. In present study, diamond nanopowder is derivatized as Immobilized Metal Ion Affinity Chromatographic (IMAC) material for the phosphopeptides enrichment and as Reversed Phase (C-18) media for the desalting of complex mixtures and human serum profiling through MALDI-TOF-MS. Functionalized diamond nanopowder is characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Diamond-IMAC is applied to the standard protein (β-casein), spiked human serum, egg yolk and non-fat milk for the phosphopeptides enrichment. Results show the selectivity of synthesized IMAC-diamond immobilized with Fe³⁺ and La³⁺ ions. To comprehend the elaborated use, diamond-IMAC is also applied to the serum samples from gall bladder carcinoma for the potential biomarkers. Database search is carried out by the Mascot program (www.matrixscience.com) for the assignment of phosphorylation sites. Diamond nanopowder is thus a separation media with multifunctional use and can be applied to cancer protein profiling for the diagnosis and biomarker identification.     

Linear spaces on the intersection of cubic hypersurfaces

Upper bounds for the number of variables necessary to imply the existence of anm-dimensional linear variety on the intersection ofr cubic hypersurfaces over local and global fields are given. D. J. Lewis was partially supported by a National Science Foundation grant. Rainer Schulze-Pillot was supported by a Deutsche Forschungsgemeinschaft Stipendium.