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1.
Katsuya Hyodo Yoshinori Arisaka Satoshi Yamaguchi Tetsuya Yoda Nobuhiko Yui 《Macromolecular bioscience》2019,19(4)
Modulation of material properties and growth factor application are critical in constructing suitable cell culture environments to induce desired cellular functions. Sulfonated polyrotaxane (PRX) surfaces with immobilized vascular endothelial growth factors (VEGFs) are prepared to improve network formation in vascular endothelial cells. Sulfonated PRXs, whereby sulfonated α‐cyclodextrins (α‐CDs) are threaded onto a linear poly(ethylene glycol) chain capped with bulky groups at both terminals, are coated onto surfaces. The molecular mobility of sulfonated PRX surfaces is modulated by tuning the number of threading α‐CDs. VEGF is immobilized onto surfaces with varying mobility. Low mobility and VEGF‐immobilization reinforce cell proliferation, yes‐associated protein activity, and rhoA, pdgf, ang‐1, and pecam‐1 gene expression. Highly mobile surfaces and soluble VEGF weakly affect these cell responses. Network formation is strongly stimulated in vascular endothelial cells only on low‐mobility VEGF‐immobilized surfaces, suggesting that molecular mobility and VEGF immobilization synergistically control cell function. 相似文献
2.
Dongshuang Wu Kohei Kusada Tomokazu Yamamoto Takaaki Toriyama Syo Matsumura Ibrahima Gueye Okkyun Seo Jaemyung Kim Satoshi Hiroi Osami Sakata Shogo Kawaguchi Yoshiki Kubota Hiroshi Kitagawa 《Chemical science》2020,11(47):12731
We report the synthesis of high-entropy-alloy (HEA) nanoparticles (NPs) consisting of five platinum group metals (Ru, Rh, Pd, Ir and Pt) through a facile one-pot polyol process. We investigated the electronic structure of HEA NPs using hard X-ray photoelectron spectroscopy, which is the first direct observation of the electronic structure of HEA NPs. Significantly, the HEA NPs possessed a broad valence band spectrum without any obvious peaks. This implies that the HEA NPs have random atomic configurations leading to a variety of local electronic structures. We examined the hydrogen evolution reaction (HER) and observed a remarkably high HER activity on HEA NPs. At an overpotential of 25 mV, the turnover frequencies of HEA NPs were 9.5 and 7.8 times higher than those of a commercial Pt catalyst in 0.05 M H2SO4 and 1.0 M KOH electrolytes, respectively. Moreover, the HEA NPs showed almost no loss during a cycling test and were much more stable than the commercial Pt catalyst. Our findings on HEA NPs may provide a new paradigm for the design of catalysts.RuRhPdIrPt high-entropy-alloy nanoparticles with a broad and featureless valence band spectrum show high hydrogen evolution reaction activity. 相似文献
3.
Direct Introduction of a Dimesitylboryl Group Using Base‐Mediated Substitution of Aryl Halides with Silyldimesitylborane 下载免费PDF全文
Dr. Eiji Yamamoto Kiyotaka Izumi Ryosuke Shishido Prof. Dr. Tomohiro Seki Noriaki Tokodai Prof. Dr. Hajime Ito 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(49):17547-17551
The first dimesitylboryl substitution of aryl halides with a silylborane bearing a dimesitylboryl group in the presence of alkali‐metal alkoxides is described. The reactions of aryl bromides or iodides with Ph2MeSi?BMes2 and Na(OtBu) afforded the desired aryl dimesitylboranes in good to high yields and with high borylation/silylation ratios. Selective reaction of the sterically less‐hindered C?Br bond of dibromoarenes provided monoborylated products. This reaction was used to rapidly construct a D‐π‐A aryl dimesityl borane with a non‐symmetrical biphenyl spacer. 相似文献
4.
5.
Synthesis of a Pentacene‐Type Silaborin via Double Dehydrogenative Cyclization of 1,4‐Diboryl‐2,5‐disilylbenzene 下载免费PDF全文
Tatsuya Hirofuji Dr. Toshiaki Ikeda Prof. Dr. Takeharu Haino Prof. Dr. Yohsuke Yamamoto Prof. Dr. Atsushi Kawachi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(28):9734-9739
A new pentacene‐type silaborin, in which three benzene rings are bridged by silicon and boron atoms, has been synthesized and characterized by using NMR spectroscopy and X‐ray crystallographic analysis. The precursor, 1,4‐bis(dimesitylboryl)‐2,5‐bis(phenylsilyl)benzene ( 4 ), was prepared by stepwise introduction of a silyl group and a boryl group to a benzene ring starting from 1,4‐dibromobenzene. Double cyclization of 4 proceeds by a H‐Mes exchange and a B‐H/C‐H dehydrogenative condensation to afford pentacene‐type silaborin 5 . X‐ray crystal structure analysis reveals that 5 adopts a bent structure rather than a planar one. UV/Vis spectra and DFT calculations for 5 reveal a lowering of the LUMO energy level compared with corresponding anthracene‐type 3 . 相似文献
6.
Takashi Machida Dr. Takeshi Iwasa Prof. Dr. Tetsuya Taketsugu Prof. Dr. Kazuki Sada Dr. Kenta Kokado 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(36):8028-8034
Aggregation-induced emission (AIE) is a fascinating phenomenon because of the applications of luminescent materials in the aggregated state, which exploit the large structural changes of the molecules in the excited state. Recently, it was reported that triphenylphosphane derivatives show AIE behavior in which they undergo potentially large structural changes in the excited state. Inspired by this report, photoinduced pyramidal inversion behavior of phosphanes was investigated. In photochemical experiments, the prepared P-stereogenic phosphanes exhibited photoracemization in dilute solution, and a negative correlation was observed between the photoracemization and the AIE phenomenon. Theoretical computations revealed that the inversion barrier in the excited state was much smaller than that in the ground state. This is the first report on the photoinduced pyramidal inversion behavior of phosphanes, which will provide new and unexplored applications. 相似文献
7.
Dr. Takeshi Matsumoto Risa Yamamoto Dr. Masanori Wakizaka Dr. Akinobu Nakada Prof. Dr. Ho-Chol Chang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(43):9609-9619
The global demand for energy and the concerns over climate issues renders the development of alternative renewable energy sources such as hydrogen (H2) important. A high-spin (hs) FeII complex with o-phenylenediamine (opda) ligands, [FeII(opda)3]2+ (hs- [6R] 2+), was reported showing photochemical H2 evolution. In addition, a low-spin (ls) [FeII(bqdi)3]2+ (bqdi: o-benzoquinodiimine) (ls- [0R] 2+) formation by O2 oxidation of hs- [6R] 2+, accompanied by ligand-based six-proton and six-electron transfer, revealed the potential of the complex with redox-active ligands as a novel multiple-proton and -electron storage material, albeit that the mechanism has not yet been understood. This paper reports that the oxidized ls- [0R] [PF6]2 can be reduced by hydrazine giving ls-[FeII(opda)(bqdi)2][PF6]2 (ls- [2R] [PF6]2) and ls-[FeII(opda)2(bqdi)][PF6]2 (ls- [4R] [PF6]2) with localized ligand-based proton-coupled mixed-valence (LPMV) states. The first isolation and characterization of the key intermediates with LPMV states offer unprecedented molecular insights into the design of photoresponsive molecule-based hydrogen-storage materials. 相似文献
8.
Yuta Yamamoto Shogo Nakano Fumio Seki Yasuteru Shigeta Sohei Ito Hiroaki Tokiwa Makoto Takeda 《Molecules (Basel, Switzerland)》2021,26(5)
Infection of hosts by morbilliviruses is facilitated by the interaction between viral hemagglutinin (H-protein) and the signaling lymphocytic activation molecule (SLAM). Recently, the functional importance of the n-terminal region of human SLAM as a measles virus receptor was demonstrated. However, the functional roles of this region in the infection process by other morbilliviruses and host range determination remain unknown, partly because this region is highly flexible, which has hampered accurate structure determination of this region by X-ray crystallography. In this study, we analyzed the interaction between the H-protein from canine distemper virus (CDV-H) and SLAMs by a computational chemistry approach. Molecular dynamics simulations and fragment molecular orbital analysis demonstrated that the unique His28 in the N-terminal region of SLAM from Macaca is a key determinant that enables the formation of a stable interaction with CDV-H, providing a basis for CDV infection in Macaca. The computational chemistry approach presented should enable the determination of molecular interactions involving regions of proteins that are difficult to predict from crystal structures because of their high flexibility. 相似文献
9.
Optical Review - This paper proposes a novel steganography method to show an aerial image that is formed with aerial imaging by retro-reflection by use of dual transparent balls made of acrylic... 相似文献
10.
Prof. Dr. Erika Nakashima Prof. PhD Hisashi Yamamoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(35):e202103989
Since the global peptide drug market demand has been predicted to increase, highly efficient and inexpensive mass scale peptides are required. However, the production process raises questions about the cost of energy input, scale-up production, raw materials, and solvents treatment. This paper introduces 2 methods for the 2–4 mer oligopeptides bond formation for batch reaction utilizing 50–100 mol% of a mild Brønsted acid under the mild condition. One of the methods has been capably adapted to flow synthesis at room temperature using organic solvents with boiling points below 100 °C. The method applies the tert-butoxycarbonyl amino methoxy group, forming the desired dipeptide without solvent at mild temperatures. Furthermore, the conversion of the carboxylic acid leaving the group to phenyl ester promotes peptide bond formation, and the reaction were applied to di, tri, and tetrapeptide bond formation in excellent yield without notable racemization at ambient temperature (up to >99 % yield and 99 : 1 dr). Finally, this study proposes this new production method to overcome the limited scale-up production by reaction device scale: liquid phase biomimetic catalytic peptide flow synthesis utilizing a mild Brønsted acid. 相似文献