Self-organisation of dodeca-dendronized fullerene into supramolecular discs and helical columns containing a nanowire-like core

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Prévalence du portage d'entérobactéries productrices de beta-lactamase à spectre étendu chez les personnes âgées institutionnalisées et facteurs de risques associés.

International audienceL'augmentation de l'incidence des entérobactéries productrices de β-lactamase à spectre étendu (EBLSE) représente un problème majeur de santé publique. La prévention de la transmission croisée nécessite la mise en place de précautions standard mais aussi de précautions complémentaires, s'appuyant notamment sur l'institution d'une stratégie de dépistage adaptée. Dans cet objectif, la connaissance de la prévalence du portage de EBSLE et des facteurs de risque associés s'avère indispensable, donnée toutefois non clairement établie pour les personnes âgées institutionnalisées. Dans notre étude, un écouvillonnage rectal a donc été réalisé pour tous les patients hospitalisés au sein de trois établissements disposant d'unités de soins de longue durée sur une période de deux mois. Parmi les 412 patients inclus, onze étaient porteurs de EBLSE (2,7 %, Intervalle de confiance à 95 % : 1,4-4,8), prévalence de portage faible en comparaison aux données de la littérature. Escherichia coli (54,5 %) était l'espèce majoritairement retrouvée. L'analyse statistique a montré que l'âge, le sexe, les antécédents urinaires et d'antibiothérapie au cours des six mois précédents étaient des facteurs de risque significatifs, le sexe féminin apparaissant comme protecteur. Au final, pour ces patients âgés institutionnalisés, une politique de dépistage ciblé sur les antécédents récents d'antibiothérapie et d'infections urinaires apparaît comme la plus pertinente

Redox switchable daisy chain rotaxanes driven by radical-radical interactions

We report the one-pot synthesis and electrochemical switching mechanism of a family of electrochemically bistable 'daisy chain' rotaxane switches based on a derivative of the so-called 'blue box' (BB4+) tetracationic cyclophane cyclobis(paraquat-p-phenylene). These mechanically interlocked molecules are prepared by stoppering kinetically the solution-state assemblies of a self-complementary monomer comprising a BB4+ ring appended with viologen (V2+) and 1,5-dioxynaphthalene (DNP) recognition units using click chemistry. Six daisy chains are isolated from a single reaction: two monomers (which are not formally 'chains'), two dimers, and two trimers, each pair of which contains a cyclic and an acyclic isomer. The products have been characterized in detail by high-field H-1 NMR spectroscopy in CD3CN-made possible in large part by the high symmetry of the novel BB4+ functionality and the energies associated with certain aspects of their dynamics in solution are quantified. Cyclic voltammetry and spectroelectrochemistry have been used to elucidate the electrochemical switching mechanism of the major cyclic daisy chain products, which relies on spin-pairing interactions between V center dot+ and BB2(center dot+) radical cations under reductive conditions. These daisy chains are of particular interest as electrochemically addressable molecular switches because, in contrast with more conventional bistable catenanes and rotaxanes, the mechanical movement of the ring between recognition units is accompanied by significant changes in molecular dimensions. Whereas the self-complexed cyclic monomer known as a [cl]daisy chain or molecular 'ouroboros'-conveys sphincter-like constriction and dilation of its ultramacrocyclic cavity, the cyclic dimer ([c2]daisy chain) expresses muscle-like contraction and expansion along its molecular length

Gene delivery with polycationic fullerene hexakis-adducts

Polyplexes prepared from DNA and globular compact polycationic derivatives constructed around a fullerene hexakis-adduct core have shown remarkable gene delivery capabilities

A neutral naphthalene diimide [2]rotaxane

A neutral donor-acceptor [2]rotaxane, which has been synthesized using click chemistry, has had its solid-state structure and superstructure elucidated by X-ray crystallography. Both dynamic H-1 NMR spectroscopy and electrochemical investigations have been employed in an attempt to shed light on both geometrical reorganization and redox-switching processes that are occurring or can be induced within the [2]rotaxane.A neutral donor-acceptor [2]rotaxane, which has been synthesized using click chemistry, has had its solid-state structure and superstructure elucidated by X-ray crystallography. Both dynamic (1)H NMR spectroscopy and electrochemical investigations have been employed in an attempt to shed light on both geometrical reorganization and redox-switching processes that are occurring or can be induced within the [2]rotaxane