Publications by authors named "Mika Sakai"

Embedding two boron atoms into a polycyclic aromatic hydrocarbon (PAH) leads to the formation of a neutral analogue that is isoelectronic to the corresponding dicationic PAH skeleton, which can significantly alter its electronic structure. Based on this concept, we explore herein the identification of near-infrared (NIR)-emissive PAHs with the aid of an in silico screening method. Using perylene as the PAH scaffold, we embedded two boron atoms and fused two thiophene rings to it.

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We studied the photophysical and electroluminescent (EL) characteristics of a series of azaborine derivatives having a pair of boron and nitrogen aimed at the multi-resonance (MR) effect. The computational study with the STEOM-DLPNO-CCSD method clarified that the combination of a BN ring-fusion and a terminal carbazole enhanced the MR effect and spin-orbit coupling matrix element (SOCME), simultaneously. Also, we clarified that the second triplet excited state (T) plays an important role in efficient MR-based thermally activated delayed fluorescence (TADF).

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Two kinds of planarized phenyldithienylboranes, which contain (CH ) C- or CH -bridging moieties, were synthesized. The difference of the bridging moieties affects their packing structures and photophysical properties. In particular, the (CH ) C-bridged derivative exhibits a large Stokes shift, unusual for such planarized compounds, that results from a large structural relaxation in the excited state.

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Catalyst-free 1,2-carboboration of ynamides is presented. Readily available aryldichloroboranes react with alkyl- or aryl-substituted ynamides in high yields with complete regio- and stereoselectivity to valuable β-boryl-β-alkyl/aryl α-aryl substituted enamides which belong to the class of trisubstituted alkenylboronates. The 1,2-carboboration reaction is experimentally easy to conduct, shows high functional group tolerance and broad substrate scope.

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Antibody-modified liposomes, immuno-liposomes, can selectively deliver encapsulated drug 'cargos' to cells via the interaction of cell surface proteins with antibodies. However, chemical modification of both the antibodies and phospholipids is required for the preparation of immuno-liposomes for each target protein using conventional methods, which is time-consuming. In the present study, we demonstrated that high-affinity protein A- (Protein A-R28: PAR28) displaying liposomes prepared by the post-insertion of PAR28-conjugated phospholipid through polyethylene glycol (PEG)-linkers (PAR28-PEG-lipo) can undergo rapid modification of antibodies on their surface, and the liposomes can be delivered to cells based on their modified antibodies.

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Electron-deficient heteroacenes that contain two tricoordinate boron atoms in their acene skeletons and planarized phenyl ether moieties at their periphery were synthesized via the borylation of silicon-bridged precursors. X-ray crystallographic analysis revealed quinoidal structures, which give rise to two-step reversible redox processes for both the reduction and oxidation. These compounds exhibit intense absorption and sharp fluorescence bands with vibronic structures in the near-infrared (NIR) region.

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The synthesis and photophysical properties of a soluble amide-embedded coronene is reported. The key step in this synthesis is the twofold C-H activation of diazaperylene by a rhodium(III)Cp* catalyst. This unprecedented structural motif shows intense fluorescence in the near infrared region with a small Stokes shift and a distinct vibronic structure, which exhibits a slight extent of negative solvatochromism.

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A B,N-diphenyl-5,10-dihydro-dibenzo-1,4-azaborine, in which both phenyl groups on the boron and nitrogen atoms are planarized to generate a carbazole substructure, was synthesized. The structral constraint around the boron and nitrogen atoms alters the π-conjugation mode and thus the photophysical and electrochemical properties. Specifically, this structurally constrained dibenzoazaborine showed an intense blue emission with a narrow full width at half maximum.

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Incorporation of main group elements into the π-conjugated frameworks is a sophisticated strategy to alter the fundamental nature of the parent conjugated π-systems, giving rise to attractive electronic and photophysical properties that are otherwise inaccessible with classic carbon- or metal-based materials. Out of all π-conjugated heterocycles, those that are structurally constrained by tethered aryl substituents surrounding the main group center deserve a great deal of attention because not only do they commonly possess the maximum efficiency of π-conjugation and intermolecular interaction, but they also enjoy remarkable thermal and morphological stabilities that are especially crucial for solid-state performances. In certain cases, elucidation of the behavior of such compounds may additionally provide sufficient perspective toward graphene materials doped with main group elements, which are widely considered as potential next-generation optoelectronic materials.

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To investigate the safety and efficacy of cisplatin(CDDP)treatment after carboplatin(CBDCA)hypersensitivity reactions (CHSR)in gynecologic malignancies, we retrospectively reviewed the clinical records of 544 patients who underwent paclitaxel and CBDCA therapy(TC therapy). CHSR was observed in 18 patients. Eight patients were administered weekly paclitaxel and CDDP therapy(wTP therapy)continuously, to confirm that there was no CDDP hypersensitivity followingintravenous administration of 10 mgCDDP.

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Fourteen beta-agonists were quantitatively analyzed in cattle, chicken and swine liver specimens purchased at 14 wet markets in Selangor State, Malaysia, by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The health risks of ractopamine and clenbuterol residues in the Malaysian population were assessed based on quantitative data and meat consumption statistics in Malaysia. Wastewater samples collected at swine farms (n = 2) and cattle/cow farms (n = 2) in the Kuala Langat district were analyzed for the presence for the 14 compounds.

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Purpose: We tried to clarify the cytotoxic mechanism of VK(3) using the breast cancer cell line MCF-7.

Methods: Cytotoxicity was measured via intracellular esterase activity. DNA fragmentation was assessed by agarose gel electrophoresis.

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This article reports changes in tacrolimus (FK506) blood levels connected with carbamazepine (CBZ). A drug interaction between FK506 and CBZ was investigated in a woman, who was in her 40s, who underwent heart transplantation. Pharmacokinetic parameters were measured, including dose and trough blood levels (C(0)), area under the serum concentration-time curve from 0 to 12 hours (AUC(0-12h)), and apparent clearance of oral FK506 (CL/F) for FK506 alone (about 3 months before starting CBZ) and combined with CBZ (11 days and about 3 months after starting CBZ).

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A genomic PCR fragment of 4581 bp, referred to as PyRE10G, was isolated from the red alga Porphyra yezoensis. PyRE10G contained a putative open reading frame encoding gag, protease, integrase, reverse transcriptase (RT), and RNase H, but one stop codon was present in the integrase region. Southern blot analysis revealed that PyRE10G exists as a single copy in the genome.

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Four DNA fragments encoding a reverse transcriptase (RT)-like gene related to that of long terminal repeat (LTR) retrotransposons were isolated from the red alga Porphyra yezoensis by genomic PCR. Southern blot analysis suggested that one clone exists as a single copy per genome. Its full-length cDNA (PyRE2A) contained RT/RNase H-like sequences, which are most closely related to those of the Volvox LTR retrotransposon, although two stop codons were present within the RT region.

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