A catalytic oxidation of benzene under mild conditions is one of the most important and difficult reactions. In order to develop a hydroxylation catalyst for benzene, we have designed and synthesized some new copper(II) complexes with 1,1-bis(N-propyl-2-benzimidazolyl)propane and its derivatives, which are a bidentate ligand to provide the reaction space easily accessible for exogenous substrate, can easily synthesized, and are not easily decomposed in the reaction with H2O2. These complexes reacted catalytically with benzene in the presence of excess H2O2 under mild conditions in aqueous MeCN solution to give phenol and quinone.
Quantum dots (QDs) have been used to study the effects of fluorescent probes for biomolecules and cell imaging. Adipose tissue-derived stem cells, which carry a relatively lower donor site morbidity, while yielding a large number of stem cells at harvest, were transduced with QDs using the octa-arginine (R8) cell-penetrating peptide (CPP). The concentration ratio of QDs:R8 of 1×104 was optimal for delivery into ASCs. No cytotoxicity was observed in ASCs transduced with less than 16 nM of QDs655. In addition, most of the cells could be labeled within 1 h and the fluorescent intensity was maintained at least for 2 weeks. The ASCs labeled with QDs using R8 were further transplanted subcutaneously into the backs of mice or into mice through the tail vein. The labeled ASCs could be imaged with good contrast using the Maestro in vivo imaging system. These data suggested that QDs labeling using R8 could be utilized for the imaging of ASCs.
The sentinel lymph node (SLN) is defined as the first node that receives lymph flow from each organ. During lymph node metastasis, cancer cells first reach the SLN via lymph flow. In patients with cancer, lymph node dissection is typically not performed if cancer cells are not detected in the SLN. Minimally invasive SLN biopsy (SLNB) is the most commonly accepted surgical procedure, followed by selective removal of cancerous lymph nodes. To perform SLNB effectively, it is important that cancer cells are detected with high sensitivity in SLN connected to the tumor site. Recently, fluorescent nanoparticles known as quantum dots (QDs) have received attention as lymph tracers. Compared with currently utilized conventional agents such as dyes and radioactive tracers, QDs have more suitable particle size (15–20 nm) for transversal of the lymph network and have nearinfrared bright fluorescence for real-time observation. Previous studies using mice and pigs have succeeded in detecting SLNs in breast, skin and some digestive systems with QDs; however, these studies did not analyze the tissue structure of SLNs at the single particle level, and detailed histological information relating to lymph node metastasis could not be obtained by their methods. We have been developing single particle imaging with QDs in cell culture and in mice. Here, we apply our imaging method to the gastrointestinal SLNB in pigs. Digestive systems generally have a more multidirectional and complicated lymphatic network than breast or skin tissues. Thus, it is difficult to precisely detect SLNs in the digestive system SLNB. By imaging QD distribution in lymph networks using two original optical systems (laparoscope and confocal microscopy), we have succeeded in precisely identifying the stomach SLN and visualizing the micro-structure in the SLN. We have also developed a method that detects specific cells in the SLN with cellular marker-conjugated QDs that could be utilized to detect cancer cells in SLNs using tumor-specific molecule conjugated QDs. The use of QDs to detect SLNs has the potential to significantly increase discovery rates of cancer metastasis and make SLNB a more widespread practice in various cancer surgeries.
Artificial cell vesicles, or liposomes, are enclosed with phospholipid bilayer membranes, the properties of which are very similar to those of real living cells. For recent decades, in particular, giant unilamellar vesicles (GUVs), which are around 1 - 100 μm in diameter, have been often employed for investigation on the cell membrane behavior including interactions between bilayers and proteins, the effects on membrane protein functions, etc. Previously, we demonstrated GUVs could be prepared that contained a biological system of transcription/translation (gene expression) with its function intact. Furthermore, we also demonstrated recombinant transmembrane protein (one of G protein coupled receptors, GPCRs), which, using a baculovirus/insect gene expression system, were expressed on the enveloped budded virus (BV) particles from the complementary DNA sequence, could be reconstituted on GUV membranes through the BV-GUV membrane fusion. By combining the above protocols, artificial vesicles with functions of signal transduction pathways might be available.
We fabricated a rechargeable molecular cluster battery (MCB), using molecular clusters such as Mn12 (Mn12O 12(CH3COO)16(H2O)4) clusters as a cathode active material. This is the first demonstration that molecular cluster species have the ability to act as cathode active materials. In order to modify a cycle performance and a charging/ discharging rate of MCB, we prepared molecular cluster-nanocarbon hybrid materials and applied them for cathode materials.
We report the observation of a remarkably strong coupling between light and a multinode-type exciton. The observed radiative decay time reaches the order of 100 fs, which is much faster than the dephasing process of nonradiative scattering. In this high-speed superradiance, the light wave and the excitonic wave in a high-quality thin film form a harmonized wave-wave coupling over a range of multiple wavelengths. So, we observed the signal of the excitonic state with large radiative width up to room temperature. This mechanism contradicts the conventional physical description of light-matter interaction based on the long-wavelength approximation.
Optical properties: Localized plasmon resonance (LPR) due to collective oscillation of free electrons in noble metal nanoparticles (NPs) by light irradiation has been studied extensively for various applications such as photoluminescence, SERS, and other chemical reactions. LPR is known to be sensitive to shape, size, and physical environment of NPs. Therefore, our attention to the coupled plasmon resonance is attracted by the possibilities of LPR tuning. Recently, we have reported the first direct observation of coupled plasmon mode of Au nanoparticle dimer. Catalytic properties: (Ga1-xZnx)(N1-xOx) solid solution modified with Rh/Cr2O3 (core/shell) nanoparticles exhibits high photocatalytic activity for overall water splitting under visible light. The particle size of Rh, which is an important factor for the activity, is not controllable by the conventional photodeposition method. We have demonstrated that chemically-synthesized monodisperse 1.7 nm Rh nanoparticles as cores of cocatalysts improved the photocatalytic activity. Here, we report a new modification method of size-tuned Rh nanoparticles onto the solid solution and the correlations between the Rh size and photocatalytic activity. We have also evaluated the loading effect of oxygen evolution site. Manganese oxide nanoparticles, which are known to have catalytic activity for water oxidation, were loaded onto the (Ga1-xZnx)(N1-xOx) together with a cocatalyst for H2 evolution, and used for the photocatalytic reaction. The photoelectrochemical and photocatalytic measurements revealed that the manganese oxide nanoparticles work as cocatalysts for O2 evolution, and that both H2 and O2 evolution rates were remarkably improved.