Molecular printboards: versatile platforms for the creation and positioning of supramolecular assemblies and materials

This tutorial review describes the development of molecular printboards, which are tailor-made surfaces functionalized with receptor (host) molecules. Such substrates can be used for the binding of complementary ligand (guest) molecules through multivalent interactions. Supramolecular multivalent interactions are ideal to attain a quantitative and fundamental understanding of multivalency at interfaces. Because of their quantitative interpretation, the focus is on (i) the interaction of cyclodextrin host surfaces with multivalent hydrophobic guest molecules, (ii) the vancomycin-oligopeptide system, and (iii) the multivalent binding of histidine-tagged proteins to NiNTA receptor surfaces. The review will be of interest to researchers in the fields of supramolecular chemistry, chemical biology, surface chemistry, and molecular recognition.     

Phase transfer of CdS nanocrystals mediated by heptamine β-cyclodextrin

A fundamental and systematic study on the fabrication of a supramolecularly assembled nanostructure of an organic ligand-capped CdS nanocrystal (NC) and multiple heptamine β-cyclodextrin ((NH(2))(7)βCD) molecules in aqueous solution has been here reported. The functionalization process of presynthesized hydrophobic CdS NCs by means of (NH(2))(7)βCD has been extensively investigated by using different spectroscopic and structural techniques, as a function of different experimental parameters, such as the composition and the concentration of CD, the concentration of CdS NCs, the nature of the NC surface capping ligand (oleic acid and octylamine), and the organic solvent. The formation of a complex based on the direct coordination of the (NH(2))(7)βCD amine groups at the NC surface has been demonstrated and found responsible for the CdS NC phase transfer process. The amine functional group in (NH(2))(7)βCD and the appropriate combination of pristine capping agent coordinating the NC surface and a suitable solvent have been found decisive for the success of the CdS NC phase transfer process. Furthermore, a layer-by-layer assembly experiment has indicated that the obtained (NH(2))(7)βCD functionalized CdS NCs are still able to perform the host-guest chemistry. Thus, they offer a model of a nanoparticle-based material with molecular receptors, useful for bio applications.     

The Nature and Efficiency of Neurotransmitter Exocytosis also Depend on Physicochemical Parameters

Exocytosis is an important biological process used by cells to deliver messengers or effectors to target cells with high spatial, quantitative, and kinetic precision. This process occurs by interaction and fusion of vesicles containing the (bio)chemical information with the cell membrane to release their contents into the surrounding medium. Because of its importance for life, this mechanism underlies many biological controlling factors, including different families of proteins and enzymes. Tremendous efforts have been made over the last decade toward their determination. However, in parallel, many studies have also shown that the physical and chemical characteristics of the exocytosis actors (vesicle, membrane, and extracellular medium) could directly affect the quantitative or kinetic features of secretion. The major pieces evidence for this influence, which have been reported in the literature, are reviewed herein. It demonstrates undoubtedly that pure biological aspects cannot be segregated from the physicochemical context of living mechanisms.     

SERS and Raman imaging as a new tool to monitor dyeing on textile fibres

Textile fibres containing Ag nanoparticles have been widely explored for a number of antimicrobial fabrics. Moreover, it is well‐known that textile dyeing is a critical stage in the manufacture thereof. This research shows that surface enhanced Raman scattering (SERS) and Raman imaging can be used with advantage in the monitoring of this process. Using Ag containing linen fibres stained with methylene blue (MB), it was possible to map the local distribution of the MB dye in the fibres by Raman imaging. MB was selected as the SERS molecular probe and as a model dye. Composites of linen fibres and Ag nanoparticles were prepared by distinct methods and used as SERS substrates in order to evaluate the effect of the preparative method on the Raman images. Our results demonstrate that by using Raman imaging associated to the presence of Ag nanoparticles, it is possible to distinguish the local distribution of the dye on the textile surface. This investigation allows to foreseeing the use of this technique in terms of quality control of Ag containing fabrics, which is a market in great expansion. Copyright © 2016 John Wiley & Sons, Ltd.     

Hydrolytically stable arabinofuranoside analogs for the synthesis of arabinosyltransferase inhibitors

The first members of two new families of arabinosyltransferase inhibitors, derived from previously reported hybrid compounds covalently associating an iminoalditol with an α-d-arabinofuranoside, have been prepared. In place of the arabinofuranoside moiety, they incorporate in their structure a suitably substituted tetrahydrofuran (C-glycoside family) or a cyclopentane (carba-sugar family) for mimicking the α-d-arabinofuranoside ring.     

Sensitivity-Enhanced 13C-NMR Spectroscopy for Monitoring Multisite Phosphorylation at Physiological Temperature and pH

Abundant phosphorylation events control the activity of nuclear proteins involved in gene regulation and DNA repair. These occur mostly on disordered regions of proteins, which often contain multiple phosphosites. Comprehensive and quantitative monitoring of phosphorylation reactions is theoretically achievable at a residue-specific level using ¹H-¹⁵N NMR spectroscopy, but is often limited by low signal-to-noise at pH>7 and T>293 K. We have developed an improved ¹³Cα-¹³CO correlation NMR experiment that works equally at any pH or temperature, that is, also under conditions at which kinases are active. This allows us to obtain atomic-resolution information in physiological conditions down to 25 μm . We demonstrate the potential of this approach by monitoring phosphorylation reactions, in the presence of purified kinases or in cell extracts, on a range of previously problematic targets, namely Mdm2, BRCA2, and Oct4.     

Generic tropical initial ideals of Cohen-Macaulay algebras

We study the generic tropical initial ideals of a positively graded Cohen-Macaulay algebra R over an algebraically closed field k. Building on work of Römer and Schmitz, we give a formula for each initial ideal, and we express the associated quasivaluations in terms of certain I-adic filtrations. As a corollary, we show that in the case that R is a domain, every initial ideal coming from the codimension 1 skeleton of the tropical variety is prime, so “generic presentations of Cohen-Macaulay domains are well-poised in codimension 1.”