Photoswitchable precision glycooligomers and their lectin binding

The synthesis of photoswitchable glycooligomers is presented by applying solid-phase polymer synthesis and functional building blocks. The obtained glycoligands are monodisperse and present azobenzene moieties as well as sugar ligands at defined positions within the oligomeric backbone and side chains, respectively. We show that the combination of molecular precision together with the photoswitchable properties of the azobenzene unit allows for the photosensitive control of glycoligand binding to protein receptors. These stimuli-sensitive glycoligands promote the understanding of multivalent binding and will be further developed as novel biosensors

Le sergent la tulipe

Conjunt de particel·les dels següents instruments: 1r violí, 2n violí, viola, violoncel i contrabaix, flauta o flageolet, 1r clarinet, 2n clarinet, trompes o saxhorns, 1a corneta, 2a corneta, 1r trombó, 2n trombó, trombó baix, figle, bateriaConté publicitat d'altres partitures de l'editorialQuadrill

Successive translocation of the rings in a [3]rotaxane

This research was financially supported by the Netherlands Organization for the Advancement of Research (NOW).A [2]rotaxane, a [3]rotaxane and the corresponding thread containing two succinamide (succ) binding stations and a central redox-active pyromellitimide (pmi) station were studied. Infrared spectroelectrochemical experiments revealed the translocation of the macrocycle between the succinamide station and the electrochemically reduced pmi station (radical anion and dianion). Remarkably, in the [3]rotaxane, the rings can be selectively translocated. One-electron reduction leads to the translocation of one of the two macrocycles from the succinamide to the pyromellitimide station, whereas activation of the shuttle through two-electron reduction results in the translocation of both macrocycles: the dianion, due to its higher electron density and hence greater hydrogen-bond accepting affinity, is hydrogen bonded to both macrocycles. Systems with such an on-command contraction are known as molecular muscles. The relative strengths of the binding between the macrocycle and the imide anions could be estimated from the hydrogen-bond-induced shifts in the C=O stretching frequencies of hydrogen-bond accepting amide groups of the macrocycle.PostprintPeer reviewe

Imaging of morphological and biochemical hallmarks of apoptosis with optimized optogenetic tools

Creation of optogenetic switches for specific activation of cell death pathways can provide insights into apoptosis and could also form a basis for noninvasive, next-generation therapeutic strategies. Previous work has demonstrated that cryptochrome 2 (Cry2)/cryptochrome-interacting β helix–loop–helix (CIB), a blue light–activated protein–protein dimerization module from the plant Arabidopsis thaliana, together with BCL2-associated X apoptosis regulator (BAX), an outer mitochondrial membrane–targeting pro-apoptotic protein, can be used for light-mediated initiation of mitochondrial outer membrane permeabilization (MOMP) and downstream apoptosis. In this work, we further developed the original light-activated Cry2-BAX system (hereafter referred to as OptoBAX) by improving the photophysical properties and light-independent interactions of this optogenetic switch. The resulting optogenetic constructs significantly reduced the frequency of light exposure required for membrane permeabilization activation and also decreased dark-state cytotoxicity. We used OptoBAX in a series of experiments in Neuro-2a and HEK293T cells to measure the timing of the dramatic morphological and biochemical changes occurring in cells after light-induced MOMP. In these experiments, we used OptoBAX in tandem with fluorescent reporters to image key events in early apoptosis, including membrane inversion, caspase cleavage, and actin redistribution. We then used these data to construct a timeline of biochemical and morphological events in early apoptosis, demonstrating a direct link between MOMP-induced redistribution of actin and apoptosis progression. In summary, we created a next-generation Cry2/CIB–BAX system requiring less frequent light stimulation and established a timeline of critical apoptotic events, providing detailed insights into key steps in early apoptosis.ECU Open Access Publishing Support Fun

Photoswitching Using Visible Light: A New Class of Organic Photochromic Molecules

A versatile new class of organic photochromic molecules that offers an unprecedented combination of physical properties including tunable photoswitching using visible light, excellent fatigue resistance, and large polarity changes is described. These unique features offer significant opportunities in diverse fields ranging from biosensors to targeted delivery systems while also allowing non-experts ready synthetic access to these materials

Negatively photochromic organic compounds: Exploring the dark side

The last few years have seen an explosion of interest in traditional photochromic systems not only for their applications in variable transmission devices, which continues to attract commercial interest, but also for the ability of these molecules to undergo structural and electronic reorganisation which has been seized upon by materials scientists for the development of switches, logic gates, photoinduced molecular motions such as rotors and fibrils, and photoregulation of drug availability. This comprehensive review examines, for the first time, the ‘dark side of photochromism’; negatively photochromic systems which are coloured in their ground state and reversibly photobleach upon exposure to electromagnetic radiation with a wavelength over ca. 400 nm i.e. visible light responsive systems. This review is organised by structural class and examines their synthesis, structure, key spectroscopic data for coloured and bleached species, structure – switching relationships and applications. The usefulness of these negatively photochromic systems is only gradually coming to the fore with the advantages of low energy activation c.f. conventional Uv-activated switches, enabling the modulation of a plethora of useful optical and physical properties and the design of new materials with broad ranging applications

Le Cinéma muet, une industrie qui fabrique des inégalités hommes-femmes, un art capable de renverser les hiérarchies de genres

International audienceBehind the camera, inequalities between women and men are significant. When she was asked why she had chosen a « man’s job », Alice Guy explained how difficult it was for her to be accepted as a director, a creator and a producer. The superiority of man is an informal hierarchy which spread and created formal hierarchies leading to the exclusion of women from jobs and politics, and in the end, the impossibility for women to find their place in a society dominated by men.Stereotyped images of women may be the product of a society willing to convey these hierarchies on screens. But fictions may also sometimes reverse these patterns. In movies, women can be deputies, and men take care of children, as shown in Les Femmes députées (1913). Could such fictions have an impact and bring change in society ?This article shows how french cinema in the years between 1895 and 1929 played a part to try and change theses hierarchies between men and women while it also maintained major inequalities in its own business structure.Derrière la caméra, les inégalités entre les femmes et les hommes sont fortes. Alice Guy, à qui l’on a souvent demandé pourquoi elle avait choisi « une carrière si peu féminine », décrit dans son autobiographie les difficultés qu’elle a rencontrées pour s’imposer comme réalisatrice, metteure en scène, directrice de production. La supériorité de l’homme sur la femme est une hiérarchie informelle qui s’insinue partout et fabrique des discriminations normées comme les interdictions aux femmes d’exercer certains métiers, de voter, et finalement d’occuper une place à part entière au sein de la société, qui soit libérée de la domination masculine. Les images stéréoptypées des femmes ne seraient-elles pas induites par la société elle-même, soucieuse de retrouver à l’écran ses caractéristiques et ses traditions ? L’inversion des rôles par la fiction, capable de rendre les femmes députées, et de confier aux hommes la garde des enfants (Les Femmes députées, 1913), peut-elle encourager des changements sociaux ?Cet article tente de voir comment le cinéma français des années 1895-1929 peut renverser les hiérarchies de genre informelles, tout en étant le symbole même, de par son industrie, d’une hiérarchisation très codifiée des genres en défaveur des femmes