Search

In the present work, europium oxide was successfully developed as a newly active photocatalyst and used for H2 evolution with Eosin Y (EY)-sensitized photocatalytic water splitting under visible light irradiation. A series of Pt nanoclusters (NCs) deposited on europium oxide photocatalysts was fabricated by an in-situ chemical deposition method. Electrochemical analysis showed that the conduction band potential of Eu2O3 was −0.82 V (vs NHE), which was more negative than the reduction potential of H2O/H2. High-resolution transmission electron microscopy revealed that the Pt NCs had excellent dispersion and ultrasmall size (~1.81 nm). The optimal photocatalytic H2 evolution activity could be obtained by EY-sensitized 5 wt% Pt/Eu under visible light and reached 807.4 μmol in 2 h. In addition, a reasonable mechanism for the enhancing photocatalytic H2 evolution activity has been investigated and presented. This research indicates that lanthanide oxides with dye sensitization could be very promising photocatalysts for the reduction of water to H2.

Mixed cyclic tetramerization of 5,6-dicyano-2-(4,5-bis(amylthio)-1,3-dithio-2-ylidene)-benzo[d]-1,3-dithiole and 1,2-dicyanobenzene with half-sandwich complex Eu(Pc)(acac) as template in the presence of DBU in refluxing n-pentanol led to the formation and isolation of a series of unprecedented tetrathiafulvalene(TTF)-fused heteroleptic bis(phthalocyaninato) europium double-deckers Eu(Pc)[Pc(TTF)n] (n = 1–4) (1, 2-cis, 2-trans, 3, and 4). Electronic absorption spectroscopic results reveal the effect of fusing TTF onto the phthalocyanine chromophore of double-decker on the electronic structure of the target compounds. ESR together with the IR and electronic absorption spectra disclose the existence of unpaired electron in the newly prepared heteroleptic complexes. In particular, in addition to the Pc-chromophore based one-electron redox processes, one-electron, two-electron, three-electron, and four electron oxidation processes were clearly revealed by the electrochemical technique for the one-TTF, two-TTF, three-TTF, and four-TTF moiety-fused double-decker 1, 2-cis and 2-trans, 3, and 4, respectively, indicating the significant influence of the TTF moieties fused to the double-decker electronic structure. In particular, theoretical calculations over 0 and 4 in combination with the electronic absorption spectroscopy reveal the significant influence of the fused-TTF units to the electronic structure.

Phenanthroline-fused unsymmetrical phthalocyanine (2-H) and its zinc complex (2-Zn) were treated with Re(CO)5Cl to give rhenium(I) tricarbonyl chloride chelates 1-H and 1-Zn respectively, which represent the first example of phthalocyanines with peripherally appended rhenium(I) complex units. The molecular structure of 1-Zn was determined by single crystal X-ray diffraction analysis. The electronic absorption, magnetic circular dichroism, and steady-state and time-resolved fluorescence spectra and the singlet oxygen (1O2) generation efficiencies of 1-H and 1-Zn were measured and compared with those of phenanthroline-fused unsymmetrical phthalocyanines 2-H and 2-Zn, and the corresponding symmetrical phthalocyanines 3-H and 3-Zn as well. The electrochemical properties of 1-H and 1-Zn were also studied by cyclic voltammetry and compared with those of 2-H and 2-Zn. The effects of unsymmetrical phenanthroline fusing and rhenium(I) chelating on the photophysical and electrochemical behaviors of phthalocyanines were highlighted based on the above investigations.

Little is known about mechanisms of membrane fission in bacteria despite their requirement for cytokinesis. The only known dedicated membrane fission machinery in bacteria, FisB, is expressed during sporulation in Bacillus subtilis and is required to release the developing spore into the mother cell cytoplasm. Here we characterized the requirements for FisB-mediated membrane fission. FisB forms mobile clusters of ~12 molecules that give way to an immobile cluster at the engulfment pole containing ~40 proteins at the time of membrane fission. Function mutants revealed that binding to acidic lipids and homo-oligomerization are both critical for targeting FisB to the engulfment pole and membrane fission. Our results suggest that FisB is a robust and unusual membrane fission protein that relies on homo-oligomerization, lipid-binding and likely the unique membrane topology generated during engulfment for localization and membrane scission, but surprisingly, not on lipid microdomains or negative-curvature lipids.

DNA-PAINT is an increasingly popular super-resolution microscopy method that can acquire high-fidelity images at nanometer resolution. It suffers, however, from high background and very slow imaging speed, both of which can be attributed to the presence of unbound fluorophores in solution. We present a fluorogenic DNA-PAINT probe that solves these problems and demonstrate 3D imaging without the need for optical sectioning and a 26-fold increase in imaging speed over regular DNA-PAINT.

Single-molecule localization microscopy methods such as DNA-PAINT (point accumulation for imaging in nanoscale topography), utilize successive localizations of single molecules over time to reveal of biological structures with photon-limited resolution1,2. However, visualization of sub-diffracted discrete bimolecular assemblies still remains a challenge. “DNA origami” has emerged as powerful nano-templating technique capable of generating stable self-assembled scaffold for positioning of molecular species of interest with nanometer precision3,4. Recent studies of DNA-PAINT have focused on imaging different molecular species, such as fluorophores and proteins, positioned on synthetic grid-like DNA nanostructures1,4. These grids are well suited for determining the resolution limit of sparsely labelled points (e.g. one fluorophore per 5x5 nm2). However, biological structures often have a much higher local density and complex structure, making imaging more challenging. In this study, as a proof-of-concept, we explored imaging of circular “ring-like” DNA-origami nanostructures of dimension mimicking small bio-molecular structures (25-50 nm inner diameter), like membrane receptors, ion channels etc. Using a TIRF-based imaging technique, we have optimized the fluorophores density and its positioning on DNA-origami rings to reconstruct “doughnut” shaped images and have been able to resolve inner diameter of ∼25 to 50 nm. We have carried out these analyses on glass surfaces and also on supported bilayers. Our study utilizing DNA rings provides challenging targets for DNA-PAINT technology and underscores the use of size-templated nanostructures, as approximates for bio-molecular complexes, to optimize imaging and analysis protocols independent of biological sample preparation.1. Dai et al. (2016) Nat. Nanotechnol. 11:798-807.2. Baddeley, D. (2015) Nat. Methods 12:1019-1020.3. Yang et al. (2016) Nat. Chem. 8:476-483.4. Schlichthaerle et al. (2016) Curr. Opin. Biotechnol. 39: 41-47.