DNA architectonics: towards the next generation of bio-inspired materials

The use of DNA in nanobiotechnology has advanced to a stage at which almost any two or three dimensional architecture can be designed with high precision. The choice of the DNA sequences is essential for successful self-assembly, and opens new ways of making nanosized monomolecular assemblies with predictable structure and size. The inclusion of designer nucleoside analogues further adds functionality with addressable groups, which have an influence on the function of the DNA nano-objects. This article highlights the recent achievements in this emerging field and gives an outlook on future perspectives and applications.     

DNA Architectonics: towards the Next Generation of Bio‐inspired Materials

The use of DNA in nanobiotechnology has advanced to a stage at which almost any two or three dimensional architecture can be designed with high precision. The choice of the DNA sequences is essential for successful self‐assembly, and opens new ways of making nanosized monomolecular assemblies with predictable structure and size. The inclusion of designer nucleoside analogues further adds functionality with addressable groups, which have an influence on the function of the DNA nano‐objects. This article highlights the recent achievements in this emerging field and gives an outlook on future perspectives and applications.     

The image of the coefficient space in the universal deformation space of a flat Galois representation of a p-adic field

The coefficient space is a kind of resolution of singularities of the universal flat deformation space for a given Galois representation of some local field. It parametrizes (in some sense) the finite flat models for the Galois representation. The aim of this note is to determine the image of the coefficient space in the universal deformation space.     

Chip-nanoelectrospray quadrupole time-of-flight tandem mass spectrometry of meningioma gangliosides: a preliminary study

A strategy combining high-performance thin layer chromatography (HPTLC), laser densitometry, and fully automated chip-based nanoelectrospray (nanoESIchip) performed on a NanoMate robot coupled to QTOF-MS was developed, optimized, and for the first time applied for mapping and structural identification of gangliosides (GGs) extracted and purified from a human angioblastic meningioma specimen. While HPTLC pattern indicated only seven fractions migrating as GM3, GM2, GM1, GD3, GD1a (nLD1, LD1), GD1b, GT1b, and possibly GD2, due to the high sensitivity, mass accuracy, and ability to ionize minor species in complex mixtures, nanoESIchip-QTOF MS was able to discover significantly more GG species than ever reported in meningioma. Thirty-four distinct glycosphingolipid components of which five asialo, one GM4, nine GM3, two GM2, two GD3, nine GM1, and six GD1 differing in their ceramide compositions were identified. All structures presented long-chain bases with 18 carbon atoms, while the length of the fatty acid was found to vary from C11 to C25. MS screening results indicated also that the diversity of the expressed GM1 structures is higher than expected in view of the low proportions evidenced by densitometric quantification. Simultaneous fragmentation of meningioma-associated GM1 (d18:1/24:1) and GM1 (d18:1/24:0) by MS/MS using CID confirmed the postulated structures of the ceramide moieties and provided data on the glycan core, which document that for each of the GM1 (d18:1/24:1) and GM1 (d18:1/24:0) forms both GM1a and GM1b isomers are expressed in the investigated meningioma tissue.     

SANDWICH-TYPE RESULTS FOR A CLASS OF CONVEX INTEGRAL OPERATORS＊

Let H(U) be the space of analytic functions in the unit disk U.For the integral operator Aφ,(ψ)α,β,γ:K → H(U),with K (C) H(U),defined by Aφ,(ψ)α,β,γ[f](z) =[β+γ/zγφ(z)∫z0fα(t)(ψ)(t)tδ-1 dt]1/β, where α...     

Structural and magnetic behaviour of lead-bismuthate glasses containing rare earth ions

Lead-bismuthate glasses containing rare earth ions in the xR₂O₃(1 − x)[3Bi₂O₃⋅ PbO] (R = Nd, Eu, Er and Gd), xCeO₂(1 − x)[3Bi₂O₃⋅ PbO] and xTb₄O₇(1 − x)[3Bi₂O₃⋅ PbO] vitreous systems with x up to 0.25 were prepared and investigated by density, IR spectroscopy and magnetic susceptibility measurements. Density data show that the gradual addition of the rare earth ions leads not only to a simple incorporation of the rare earth ions in the host glass matrix but also generates structural changes of the vitreous matrix. FTIR data permitted to determine the Bi³⁺/Bi⁶⁺ ratio of the samples and to follow the compositional evolution of the structural changes for the studied systems. Magnetic susceptibility data show that the magnetic rare earth ions appear as isolated species for low rare earth oxide contents (x ≤ 0.03 ÷ 0.05) and as both isolated and magnetically coupled species for higher contents. All the magnetic rare earth ions present a very accentuated clustering tendency. Some of the studied rare earth ions appear in the host glass matrix in a single valence state (neodymium, gadolinium, and erbium), namely the 3+ one. Other rare earth ions appear in two valence states (i.e., cerium, europium and terbium), but the 3+ one is the most stable.     

Time-sharing evolution and sensitivity enhancements in 2D HSQC-TOCSY and HSQMBC experiments

Modifications of time-shared (TS) HSQC-like experiments originally developed by Griesinger and co-workers (Sattler M, Maurer M, Schleucher J, Griesinger C. J. Biomol. NMR 1995; 5: 97) are proposed to extract different types of information from a single NMR pulse scheme. It is shown that simultaneous acquisition of 1H,13C and 1H,15N HSQC-TOCSY and HSQMBC experiments can afford experimental sensitivity enhancements of 20-40% with respect to the separate acquisition of individual 13C or 15N data. In addition, the incorporation of a number of independent editing elements can be easily used for different purposes, for instance, to assign unambiguously 1H, 13C, and 15N chemical shifts, to differentiate directly from relayed cross-peaks, or to measure simultaneously long-range proton-carbon and proton-nitrogen coupling constants. The suggested methodologies can be applied to many different classes of nitrogen-containing compounds and illustrative examples are provided for the peptide cyclosporine as a demonstration of the performance of such experiments.     

Evolution of a total synthesis of (-)-kendomycin exploiting a Petasis-Ferrier rearrangement/ring-closing olefin metathesis strategy

A convergent stereocontrolled total synthesis of (-)-kendomycin (1) has been achieved. The synthesis proceeds with a longest linear sequence of 21 steps, beginning with commercially available 2,4-dimethoxy-3-methylbenzaldehyde (12). Highlights of the synthesis include an effective Petasis-Ferrier union/rearrangement tactic to construct the sterically encumbered tetrahydropyran ring, a ring-closing metathesis to generate the C(4a-13-20a) macrocycle, an effective epoxidation/deoxygenation sequence to isomerize the C(13,14) olefin, and a biomimetic quinone-methide-lactol assembly to complete the synthesis.     

Atropisomeric discrimination in new Ru(II) complexes containing the C(2)-symmetric didentate chiral phenyl-1,2-bisoxazolinic ligand

A new family of Ru(II) complexes containing the tridentate meridional 2,2':6',2'-terpyridine (trpy) ligand, a C(2)-symmetric didentate chiral oxazolinic ligand 1,2-bis[4'-alkyl-4',5'-dihydro-2'-oxazolyl]benzene (Phbox-R, R = Et or iPr), and a monodentate ligand, of general formula [Ru(Y)(trpy)(Phbox-R)](n+) (Y = Cl, H(2)O, py, MeCN, or 2-OH-py (2-hydroxypyridine)) have been prepared and thoroughly characterized. In the solid state the complexes have been characterized by IR spectroscopy and by X-ray diffraction analysis in two cases. In solution, UV/Vis, cyclic voltammetry (CV), and one-dimensional (1D) and two-dimensional (2D) NMR spectroscopy techniques have been used. We have also performed density functional theory (DFT) calculations with these complexes to interpret and complement experimental results. The oxazolinic ligand Phbox-R exhibits free rotation along the phenyloxazoline axes. Upon coordination this rotation is restricted by an energy barrier of 26.0 kcal mol(-1) for the case of [Ru(trpy)(Phbox-iPr)(MeCN)](2+) thus preventing its potential interconversion. Furthermore due to steric effects the two atropisomers differ in energy by 5.7 kcal mol(-1) and as a consequence only one of them is obtained in the synthesis. Subtle but important structural effects occur upon changing the monodentate ligands that are detected by NMR spectroscopy in solution and interpreted by using their calculated DFT structures.