Palladium-catalyzed C–S bond formation by using N-amido imidazolium salts as ligands

N-Amido imidazolium salt was employed as a ligand in the palladium-catalyzed cross-coupling reaction of aryl halides and thiols, and showed good activity in the formation of thioether. The best combination for the coupling with aryl bromides was N-amido imidazolium salt 2 and NaHMDS, and that for the coupling with aryl iodides was N-amido imidazolium salt 1 and KO^tBu. The coupling reactions were conducted in the presence of Pd(OAc)₂ (1 mol %) in DMSO at 80 °C for 12 h.     

Quantitative determination of duloxetine and its metabolite in rat plasma by HPLC‐MS/MS

The major metabolite of duloxetine is a glucuronide conjugate of 4‐hydroxy duloxetine (4‐HD). However, interestingly, there have been no reports determining concentrations of 4‐HD and no fully validated method has been established for measuring duloxetine and 4‐HD in rat plasma. We developed a method for the simultaneous quantification of duloxetine and its metabolite in rat plasma using high‐performance liquid chromatography tandem mass spectrometry. Duloxetine and 4‐HD were analyzed on a reverse‐phase C₁₈ analytical column after protein precipitation of the plasma sample with methanol, using carbamazepine as an internal standard. The isocratic mobile phase of 5 mm ammonium acetate–methanol (4:6, v/v) was eluted at 0.4 mL/min. Quantification was performed on a triple‐quadrupole mass spectrometer using electrospray ionization, and the ion transition monitored in selective reaction monitoring mode. The coefficient of variation for assay precision was <18.0%, and the accuracy was 84.0–118.0%. This method was successfully used to measure the concentrations of duloxetine and its metabolite in plasma following the oral administration of a single 40 mg/kg dose in rats. Copyright © 2013 John Wiley & Sons, Ltd.     

Novel silicon-based alternating copolymers: synthesis,photophysical properties,and tunable EL colors

We synthesized novel silicon-based alternating copolymers for tunable electroluminescent (EL) colors by Heck synthetic method. Their thermal, photophysical and electroluminescent properties were studied. Most of them exhibited a blue-green EL color at the operating voltage of lower than 12 V. Unusually, we observed the white EL color from a EL device based on SiPhPVK. From photophysical studies and the time-resolved PL spectroscopies, it might be attributed to the formation of stabilized excited state in SiPhPVK. Furthermore, in order to reduce the operating voltage of their LED with increasing the electron affinity of the main chain in silicon-based alternating copolymers, we synthesized the silicon-based copolymers containing electron transporting oxadiazole units in main chain. We also studied their photophysical and electroluminescent properties.     

Interleukin-1beta stimulates matrix metalloproteinase-2 expression via a prostaglandin E2-dependent mechanism in human chondrocytes

IL-1beta is known promote cyclooxygenase-2 (COX- 2) and matrix metalloproteinase-2 (MMP-2) expression. This study focuses on the characterization of the signaling cascade associated with IL-1beta-induced matrix metalloproteinase-2 (MMP-2) regulation in human chondrocytes. The decrease in collagen levels in the conditioned media was prevented by a broad spectrum MMP inhibitor, suggesting that IL-1beta promotes the proteolytic process leading to MMP-2 activation. IL-1beta-related MMP-2 expression was found to be dependent on prostaglandin E2 (PGE2) production. In addition, the induction of COX-2 and MMP-2 was inhibited by the pretreatment of chondrocytes with a SB203580 or Ro 31-8220, indicating the involvement of protein kinase C (PKC) or p38 mitogen-activated protein kinase (MAPK). However, there is no cross-talk between PKC and p38 MAPK in the IL-1beta-induced MMP-2 activation. Taken together, these results demonstrated that IL-1beta induces MMP-2 expression through the PGE2-dependent mechanism in human chondrocytes.     

An ultraviolet-curable mold for sub-100-nm lithography

We describe a novel UV-curable mold that is stiff enough for replicating dense sub-100-nm features even with a high aspect ratio. It also allows for flexibility when the mold is prepared on a flexible support such that large area replication can be accomplished. The composite material of the mold is inert to chemicals and solvents. The surface energy is made low with a small amount of releasing agent such that the mold can be removed easily and cleanly after patterning. In addition, the material allows self-replication of the mold. These unique features of the mold material should make the mold quite useful for various patterning purposes.     

Effect of plasma etching on photoluminescence of SnO(x)/Sn nanoparticles deposited on DOPC lipid membrane

The photoluminescence characteristic of the SnO(x)/Sn nanoparticles deposited on a solid supported liquid-crystalline phospholipid (1,2-dioleoyl-sn-glycero-3-phosphocholine) membrane was probed after plasma etching the nanoparticle monolayer. It was shown that the plasma etching of the nanoparticle surface greatly altered the particle morphology and enhanced the PL effect, especially when the particle size was below 10 nm in spite of strong presence of surrounding carbon. The enhancement mainly stemmed from the growth of a new PL peak due to the additional defect states produced on the nanoparticle surface by the plasma etching. It was also shown that hydrating the SnO(x)/Sn nanoparticles similarly improved the PL response of the nanoparticles as the hydration produced an additional oxygen-rich oxide layer on the particle surface.     

Aspirin-induced Bcl-2 translocation and its phosphorylation in the nucleus trigger apoptosis in breast cancer cells

Here, we report that B-cell lymphoma 2 (Bcl-2) is a novel target molecule of aspirin in breast cancer cells. Aspirin influenced the formation of a complex by Bcl-2 and FKBP38 and induced the nuclear translocation of Bcl-2 and its phosphorylation. These events inhibited cancer cell proliferation and subsequently enhanced MCF-7 breast cancer cell apoptosis. Bcl-2 knockdown using small interfering RNA (siRNA) delayed apoptotic cell death, which correlated with increased proliferation following aspirin exposure. In contrast, Bcl-2 overexpression enhanced the onset of aspirin-induced apoptosis, which was also associated with a significant increase in Bcl-2 phosphorylation in the nucleus. Therefore, this study may provide novel insight into the molecular mechanism of aspirin, particularly its anticancer effects in Bcl-2- and estrogen receptor-positive breast cancer cells.