Photoswitching of Conductance of Diarylethene-Gold Nanoparticle Network Based on the Alteration of π-Conjugation.

Diarylethenes, which have same core structures but have different positions of thiol groups that are bound to gold nanoparticles, were prepared. In one diarylethene, which has two thiol groups at the positions equivalent to 5,5'-positions of di(3-thienyl)ethene, the π-connectivity between two thiol groups increases upon photocyclization, but in the other diarylethene, which has two thiol groups at 2- and 5-positions of one of the 3-thenyl group, the π-connectivity decreases upon photocyclization. The gold nanoparticle networks of these diarylethenes were prepared and the change in conductance was measured upon alternate irradiation with UV and visible light. For two diarylethenes, the direction of the photoswitching was opposite, reflecting the difference in the π-connectivity. The result suggests that the topology of π-conjugation between electrodes is the decisive factor in the conductance of gold nanoparticle network.

Controlling Localization and Excretion of Nanoparticles by Click Modification of the Surface Chemical Structures inside Living Cells.

Invited for this month's cover is the group of Drs. Takeo Ito and Kazuhito Tanabe from Kyoto University, Japan. The cover image shows accumulation of silica nanoparticles on the plasma membrane by click modification of the surface in living cells. Read the full text of the article at 10.1002/cplu.201402436.

Controlling Localization and Excretion of Nanoparticles by Click Modification of the Surface Chemical Structures inside Living Cells.

Surface modification of silica nanoparticles (SiNPs) inside living cells was conducted by using the copper-free bioorthogonal click reaction to evaluate the effects of surface chemical structures on dynamic behavior and excretion of SiNPs. The results demonstrated the spatial translocation of intracellular SiNPs to the plasma membrane upon surface modification in situ with phospholipids. Moreover, the extent and kinetics of excretion of the SiNPs from inside the cell were enhanced by modification.

Synthesis and identification of α-cyano bis(indolyl)chalcones as novel anticancer agents.

Microwave-assisted synthesis of 23 α-cyano bis(indolyl)chalcones (6a-w) and their in vitro anticancer activity against three human cancer cell lines have been discussed. Among the synthesized chalcones, compound 6n was found to be the most potent and selective against A549 lung cancer cell line (IC50 = 0.8 µM). In a preliminary mechanism of action studies some α-cyano bis(indolyl)chalcones were found to enhance tubulin polymerization suggesting these compounds could act as microtubule stabilizing agents.

Enzyme-catalyzed conversion of chemical structures on the surface of gold nanorods.

For developing metal nanoparticles of which surface chemical structures could be altered by enzymes in the cells, functional linkers caged by coumaric acids have been synthesized. Synthesized gold nanorod (GNR) conjugates possessing coumaric acid precursors underwent (porcine liver) esterase-catalyzed hydrolysis on their surface to afford GNRs coated with amino-functionalized polyethylene glycol and fluorescent coumarins as reporter molecules for monitoring the conversion. The chemical structural conversion on the GNR surfaces was successfully observed inside cells by fluorescence microscopy when GNR conjugates were incubated with tumor cells.

An uncharacterized member of the ribokinase family in Thermococcus kodakarensis exhibits myo-inositol kinase activity.

Here we performed structural and biochemical analyses on the TK2285 gene product, an uncharacterized protein annotated as a member of the ribokinase family, from the hyperthermophilic archaeon Thermococcus kodakarensis. The three-dimensional structure of the TK2285 protein resembled those of previously characterized members of the ribokinase family including ribokinase, adenosine kinase, and phosphofructokinase. Conserved residues characteristic of this protein family were located in a cleft of the TK2285 protein as in other members whose structures have been determined. We thus examined the kinase activity of the TK2285 protein toward various sugars recognized by well characterized ribokinase family members. Although activity with sugar phosphates and nucleosides was not detected, kinase activity was observed toward d-allose, d-lyxose, d-tagatose, d-talose, d-xylose, and d-xylulose. Kinetic analyses with the six sugar substrates revealed high Km values, suggesting that they were not the true physiological substrates. By examining activity toward amino sugars, sugar alcohols, and disaccharides, we found that the TK2285 protein exhibited prominent kinase activity toward myo-inositol. Kinetic analyses with myo-inositol revealed a greater kcat and much lower Km value than those obtained with the monosaccharides, resulting in over a 2,000-fold increase in kcat/Km values. TK2285 homologs are distributed among members of Thermococcales, and in most species, the gene is positioned close to a myo-inositol monophosphate synthase gene. Our results suggest the presence of a novel subfamily of the ribokinase family whose members are present in Archaea and recognize myo-inositol as a substrate.

Genomic and non-genomic effects of glucocorticoids on allergic rhinitis model in mice.

Glucocorticoids (GCs) are well known for their anti-inflammatory effects, which are elicited through a transcriptional mechanism via a cytosolic glucocorticoid receptor (cGR)-mediated genomic effect. However, recent in vitro studies report that GCs can act as a membrane glucocorticoid receptor (mGR). This study aimed to examine whether mometasone furoate (MF) influences the nasal symptoms induced by histamine, substance P, ATP. Furthermore, the influences of various compounds on MF action were studied in vivo. The mice were intranasally administered with nasal symptom-inciting agents, and the occurrences of sneezing and nasal rubbing were counted. MF repressed the nasal symptoms caused when it was administered 10, 30 and 60min before the induction of nasal symptoms. The repressive effect observed 10min after the administration of MF was inhibited by RU486, a GR antagonist, but not by actinomycin D, a transcriptional inhibitor. In contrast, the repressive effect observed 60min after the administration of MF was inhibited by RU486 and actinomycin D. Therefore, the effects observed 10 and 60min after the MF administration were classified as non-genomic and genomic effects, respectively. The non-genomic effect suppressed the nasal symptoms induced by m-3M3FBS, a phospholipase C (PLC) activator, and was inhibited by U-73122, a PLC inhibitor. The genomic effect was inhibited by N-(p-amylcinnamoyl) anthranilic acid, a phospholipase A2 (PLA2) inhibitor. These results indicate that MF has a non-genomic effect through repression of the activation of PLC via the mGR, and MF has also a genomic effect that was influenced by the inhibition of PLA2 through transcriptional regulation via cGR.

Remarkable photocytotoxicity of a novel triazole-linked cationic porphyrin-ß-carboline conjugate.

Employing a click chemistry approach we have synthesized a novel triazole-linked cationic porphyrin-ß-carboline conjugate which exhibited remarkable photocytotoxicity against the A549 cancer cell line (IC(50) = 60 nM).

αvß3-Integrin-targeting lanthanide complex: synthesis and evaluation as a tumor-homing luminescent probe.

The application of lanthanide complexes in the time-resolved fluorescence imaging of living cells has emerged in the last few decades, providing high-contrast images of cells through detection of the delayed emission. In the present study, we synthesized novel trivalent lanthanide complexes containing the cyclic peptide c(RGDfK) to visualize the α(v)ß(3)-integrin-expressing tumor cells. Conjugation of c(RGDfK) with the macrocyclic bipyridine ligand had little effect on the fluorescence properties of the complex, indicating that the coordinated lanthanide ion was well isolated from the peptide. Bright luminescence images of α(v)ß(3)-integrin-expressing U87-MG cells were successfully obtained by employing the probes.

Synthesis and biological evaluation of indolyl chalcones as antitumor agents.

A series of indolyl chalcones were synthesized and evaluated in vitro for their anticancer activity against three human cancer cell lines. Compounds 3b-d, 3h, 3j, 3l, 3m, 4g, and 4j showed significant cytotoxicity, particularly, indolyl chalcones 3l and 3m were identified as the most potent and selective anticancer agents with IC(50) values 0.03 and 0.09 microM, against PaCa-2 cell line, respectively.