Proteins on Supported Lipid Bilayers Diffusing around Proteins Fixed on Acrylate Anchors.

Mobility of proteins and lipids plays a major role in physiological processes. Platforms which were developed to study protein interaction between immobilized and mobile proteins suffer from shortcomings such as fluorescence quenching or complicated fabrication methods. Here we report a versatile platform comprising immobilized histidine-tagged proteins and biotinylated proteins in a mobile phase. Importantly, multiphoton photolithography was used for easy and fast fabrication of the platform and allows, in principle, extension of its application to three dimensions. The platform, which is made up of functionalized polymer structures embedded in a mobile lipid bilayer, shows low background fluorescence and allows for mobility of arbitrary proteins.

Metal Free Reversible-Deactivation Radical Polymerizations: Advances, Challenges, and Opportunities.

A considerable amount of the worldwide industrial production of synthetic polymers is currently based on radical polymerization methods. The steadily increasing demand on high performance plastics and tailored polymers which serve specialized applications is driven by the development of new techniques to enable control of polymerization reactions on a molecular level. Contrary to conventional radical polymerization, reversible-deactivation radical polymerization (RDRP) techniques provide the possibility to prepare polymers with well-defined structures and functionalities. The review provides a comprehensive summary over the development of the three most important RDRP methods, which are nitroxide mediated radical polymerization, atom transfer radical polymerization and reversible addition fragmentation chain transfer polymerization. The focus thereby is set on the newest developments in transition metal free systems, which allow using these techniques for biological or biomedical applications. After each section selected examples from materials synthesis and application to biomedical materials are summarized.

Stimulated Emission Depletion Lithography with Mercapto-Functional Polymers.

Surface reactive nanostructures were fabricated using stimulated emission depletion (STED) lithography. The functionalization of the nanostructures was realized by copolymerization of a bifunctional metal oxo cluster in the presence of a triacrylate monomer. Ligands of the cluster surface cross-link to the monomer during the lithographic process, whereas unreacted mercapto functionalized ligands are transferred to the polymer and remain reactive after polymer formation of the surface of the nanostructure. The depletion efficiency in dependence of the cluster loading was investigated and full depletion of the STED effect was observed with a cluster loading exceeding 4 wt %. A feature size by λ/11 was achieved by using a donut-shaped depletion beam. The reactivity of the mercapto groups on the surface of the nanostructure was tested by incubation with mercapto-reactive fluorophores.

On the Question of Site-Selective Ligand Exchange in Carboxylate-Substituted Metal Oxo Clusters.

Reaction of [Ti4Zr4O6(OBu)4(OMc)16] (OMc = methacrylate) with acetylacetone (acacH) resulted in dissection of the cluster and formation of [Ti(OBu)2(acac)2] and the smaller cluster [Ti2Zr4O4(OMc)16]. In contrast, the same reaction with [Zr6O4(OH)4(OOCR)12]2·6RCOOH (R = Et, CH2CH=CH2) led to site-selective substitution of two carboxylate ligands and formation of isostructural [Zr6O4(OH)4(OOCR)12-x (acac) x ]2·6RCOOH (x ≤ 1).

Retention of the Cluster Core Structure during Ligand Exchange Reactions of Carboxylato-Substituted Metal Oxo Clusters.

The exchange of the carboxylato ligands of Zr4O2(methacrylato)12 in reactions with carboxylic acids proceeds with retention of the composition and structure of the cluster core. This was concluded from exchange/re-exchange experiments and from comparison of the IR bands of the cluster core of the original and ligand-exchanged clusters. The IR bands were assigned on the basis of DFT calculations. Scrambling reactions between two Zr4O2(OOCR)12 clusters with different carboxylato ligands are a new way to prepare mixed-ligand oxo clusters.

Lithium aryloxo magnesiates: an examination of ligand size and donor effects.

The combination of equimolar amounts of LiOAr and Mg(OAr)2 (OAr=aryloxide) in polar media afforded several lithium aryloxomagnesiates. Factors influencing the structural chemistry of the compounds, such as the degree of ligand bulk, type of Lewis base donors, and crystallization solvent, are examined. Structural characterization reveals a discrete, solvent-separated species, [Li(thf)4][Mg(BHT)3].THF (1) (BHT=2,6-tBu2-4-MeC6H2O) and a family of molecular compounds with various Li/Mg stoichimetries, including a 1:1 Li/Mg ratio in [LiMg(Odpp)3(thf)2].0.5PhMe (2) (Odpp=2,6-Ph2C6H3O) and [Li(Et2O)Mg(Odpp)3].0.5PhMe (3), a 2:1 Li/Mg ratio as in [{Li(thf)2}2Mg(OMes)4].2THF (4) (OMes=2,4,6-Me3C6H2O) and [{Li(tmeda)}2Mg(m-Odtp)4].0.5Et2O (5) (m-Odtp=3,5-tBu2C6H3O), and a novel 2:3 Li/Mg ratio in [{Li(thf)2}2Mg3(m-Odtp)8(thf)2].3THF (6). Two new homometallic magnesium bis(aryloxides), Mg(Odpp)2(thf)2 (7) and Mg(Odpp)2(Et2O)2 (8), are also included for the sake of comparison. The solution behavior of the heterobimetallic compounds in arene and polar solvent is analyzed by 1H NMR spectroscopy.