Search

Dinemasone C is prepared from cis-tetrahydro-4-hydroxy-6-methyl-2-pyrone by aldol reaction with 2,4-hexadienal, epoxidation followed by cyclization, and epimerization of the ring fusion. Dinemasone C, epi-dinemasone C, anhydrodinemasone BC and nor-dinemasone B are shown to be active against bacteria, which has included Legionella pneumophila Corby, algae and fungi.

A combination of NMR relaxation analysis and molecular dynamics (MD) simulations is used to identify the independent motions of dimerization and FK506 binding proteins (FKBP) domain motions of the homodimeric macrophage infectivity potentiator (Mip) protein from Legionella pneumophila, wherein two Mip monomers are dimerized through an N-terminal helix bundle connected by a long alpha-helix to a C-terminal FKBP domain in each subunit. The MD simulation trajectory reveals a flexible region in the helix that acts as a molecular hinge mediating interdomain motions.

Manipulation of magnetic dipole emission with resonant photonic nanostructures is of great interest for both fundamental research and applications. However, obtaining selective control over the emission properties of magnetic dipole transitions is challenging, as they usually occur within a manifold of spectrally close emission lines associated with different spin states of the involved electronic levels. Here we demonstrate spectrally selective directional tailoring of magnetic dipole emission using designed photonic nanostructures featuring a high quality factor. Specifically, we employ a hybrid nanoscale optical system consisting of a Eu 3+ compound coupled to a designed broken-symmetry TiO 2 metasurface to demonstrate directional color routing of the compound's emission through its distinct electric and magnetic-dominated electronic transition channels. Using low numerical aperture collection optics, we achieve a fluorescence signal enhancement of up to 33.13 for the magnetic-dominated dipole transition at 590 nm when it spectrally overlaps with a spectrally narrow resonance of the metasurface. This makes the, usually weak, magnetic dipole transition the most intense spectral line in our recorded fluorescence spectra. By studying the directional emission properties for the coupled system using Fourier imaging and time-resolved fluorescence measurements, we demonstrate that the high-quality-factor modes in the metasurface enable free-space light routing, where forward-directed emission is established for the magnetic-dominated dipole transition, whereas the light emitted via the electric dipole transition is mainly directed sideways. Our results underpin the importance of magnetic light-matter interactions as an additional degree of freedom in photonic and optoelectronic systems. Moreover, they facilitate the development of spectrometer-free and highly integrated nanophotonic imaging, sensing, and probing devices.

Mie-resonant high-index dielectric nanoparticles and metasurfaces have been suggested as a viable platform for enhancing both electric and magnetic dipole transitions of fluorescent emitters. While the enhancement of the electric dipole transitions by such dielectric nanoparticles has been demonstrated experimentally, the case of magnetic-dipole transitions remains largely unexplored. Here, we study the enhancement of spontaneous emission of Eu 3+ ions, featuring both electric and magnetic-dominated dipole transitions, by dielectric metasurfaces composed of Mie-resonant silicon nanocylinders. By coating the metasurfaces with a layer of an Eu 3+ doped polymer, we observe an enhancement of the Eu 3+ emission associated with the electric (at 610 nm) and magnetic-dominated (at 590 nm) dipole transitions. The enhancement factor depends systematically on the spectral proximity of the atomic transitions to the Mie resonances as well as their multipolar order, both controlled by the nanocylinder size. Importantly, the branching ratio of emission via the electric or magnetic transition channel can be modified by carefully designing the metasurface, where the magnetic dipole transition is enhanced more than the electric transition for cylinders with radii of about 130 nm. We confirm our observations by numerical simulations based on the reciprocity principle. Our results open new opportunities for bright nanoscale light sources based on magnetic transitions.

Hepes-glutamic acid buffer-mediated organic solvent protection effect (HOPE)-fixation has been introduced as an alternative to formalin fixation of clinical samples. Beyond preservation of morphological structures for histology, HOPE-fixation was demonstrated to be compatible with recent methods for RNA and DNA sequencing. However, the suitability of HOPE-fixed materials for the inspection of proteomes by mass spectrometry so far remained undefined. This is of particular interest, since proteins constitute a prime resource for drug research and can give valuable insights into the activity status of signaling pathways. In this study, we extracted proteins from human lung tissue and tested HOPE-treated and snap-frozen tissues comparatively by proteome and phosphoproteome analyses. High confident data from accurate mass spectrometry allowed the identification of 2603 proteins and 3036 phosphorylation sites. HOPE-fixation did not hinder the representative extraction of proteins, and investigating their biochemical properties, covered subcellular localizations, and cellular processes revealed no bias caused by the type of fixation. In conclusion, proteome as well as phosphoproteome data of HOPE lung samples were qualitatively equivalent to results obtained from snap-frozen tissues. Thus, HOPE-treated tissues match clinical demands in both histology and retrospective proteome analyses of patient samples by proteomics.

We study the polarization characteristics of light emission and collection in the near field by the tips of a Dual-SNOM (two scanning near-field optical microscopes) setup. We find that cantilevered fiber probes can serve as emitters of polarized light, or as polarization-sensitive detectors. The polarization characteristics depend on the fiber type used for tip fabrication. In Dual-SNOM measurements, we demonstrate mapping of different field components of the plasmonic dipole pattern emitted by an aperture probe.

The macrophage infectivity potentiator (MIP) protein is a major virulence factor of Legionella pneumophila, the causative agent of Legionnaires' disease. MIP belongs to the FK506-binding proteins (FKBP) and is necessary for optimal intracellular survival and lung tissue dissemination of L. pneumophila. We aimed to identify new small-molecule inhibitors of MIP by starting from known FKBP12 ligands. Computational analysis, synthesis, and biological testing of pipecolic acid derivatives revealed a promising scaffold for new MIP inhibitors.

Dinemasone C was prepared in three steps (8% overall yield) from cis-tetrahydro-4-hydroxy-6-methyl-2-pyrone by aldol reaction with 2,4-hexadienal, epoxidation followed by cyclization, and epimerization of the ring fusion. Dinemasone C, epi-dinemasone C, anhydrodinemasone BC, and nor-dinemasone B are active against bacteria, including Legionella pneumophila Corby, algae, and fungi.