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1.
Artigo em Inglês | MEDLINE | ID: mdl-39374169

RESUMO

Transition metal dichalcogenides (TMDs) are 2D materials in which the layers are stacked together by van der Waals forces. Although TMDs are expected to be promising for electronic applications, forming a uniform electrode on them is challenging because of the low adhesion forces between metals and TMDs. This study focuses on improving the quality of metal electrodes by introducing atomic H to create surface defects, using Ni on WS2 as an example. The detailed effects of H etching and subsequent Ni growth were investigated using scanning tunneling microscopy (STM) and synchrotron-based X-ray photoemission (XPS) techniques. Our studies reveal that introducing point defects of ∼3.05 × 1011 cm-2 on the WS2 surface, results in a significant shift in Ni growth from the Volmer-Weber to a near Frank-van der Merwe mode. The origin of the change is the bond formation between the Ni and W atoms, which is expected to realize ohmic contact. The optimization of metal-TMD interfaces offers valuable insights for advanced applications.

2.
Angew Chem Int Ed Engl ; 62(36): e202307157, 2023 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-37450419

RESUMO

Receptor tyrosine kinases (RTKs) are generally activated through their dimerization and/or oligomerization induced by their cognate ligands, and one such RTK hepatocyte growth factor (HGF) receptor, known as MET, plays an important role in tissue regeneration. Here we show the development of ubiquitin (Ub)-based protein ligand multimers, referred to as U-bodies, which act as surrogate agonists for MET and are derived from MET-binding macrocyclic peptides. Monomeric Ub constructs (U-body) were first generated by genetic implantation of a macrocyclic peptide pharmacophore into a structural loop of Ub (lasso-grafting) and subsequent optimization of its flanking spacer sequences via mRNA display. Such U-body constructs exhibit potent binding affinity to MET, thermal stability, and proteolytic stability. The U-body constructs also partially/fully inhibited or enhanced HGF-induced MET-phosphorylation. Their multimerization to dimeric, tetrameric, and octameric U-bodies linked by an appropriate peptide linker yielded potent MET activation activity and downstream cell proliferation-promoting activity. This work suggests that lasso-grafting of macrocycles to Ub is an effective approach to devising protein-based artificial RTK agonists and it can be useful in the development of a new class of biologics for various therapeutic applications.


Assuntos
Fator de Crescimento de Hepatócito , Ubiquitina , Fator de Crescimento de Hepatócito/metabolismo , Ubiquitina/metabolismo , Ligação Proteica , Proteínas Proto-Oncogênicas c-met/metabolismo , Fosforilação , Peptídeos/farmacologia , Peptídeos/metabolismo
3.
Adv Sci (Weinh) ; 10(17): e2300845, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37132589

RESUMO

Plumbene, with a structure similar to graphene, is expected to possess a strong spin-orbit coupling and thus enhances its superconducting critical temperature (Tc ). In this work, a buckled plumbene-Au Kagome superstructure grown by depositing Au on Pb(111) is investigated. The superconducting gap monitored by temperature-dependent scanning tunneling microscopy/spectroscopy shows that the buckled plumbene-Au Kagome superstructure not only has an enhanced Tc with respect to that of a monolayer Pb but also possesses a higher value than what owned by a bulk Pb substrate. By combining angle-resolved photoemission spectroscopy with density functional theory, the monolayer Au-intercalated low-buckled plumbene sandwiched between the top Au Kagome layer and the bottom Pb(111) substrate is confirmed and the electron-phonon coupling-enhanced superconductivity is revealed. This work demonstrates that a buckled plumbene-Au Kagome superstructure can enhance superconducting Tc and Rashba effect, effectively triggering the novel properties of a plumbene.

4.
ACS Appl Mater Interfaces ; 15(12): 16153-16161, 2023 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-36802501

RESUMO

Layered transition metal dichalcogenides (TMDs) are two-dimensional materials exhibiting a variety of unique features with great potential for electronic and optoelectronic applications. The performance of devices fabricated with mono or few-layer TMD materials, nevertheless, is significantly affected by surface defects in the TMD materials. Recent efforts have been focused on delicate control of growth conditions to reduce the defect density, whereas the preparation of a defect-free surface remains challenging. Here, we show a counterintuitive approach to decrease surface defects on layered TMDs: a two-step process including Ar ion bombardment and subsequent annealing. With this approach, the defects, mainly Te vacancies, on the as-cleaved PtTe2 and PdTe2 surfaces were decreased by more than 99%, giving a defect density <1.0 × 1010 cm-2, which cannot be achieved solely with annealing. We also attempt to propose a mechanism behind the processes.

5.
Nanoscale ; 14(39): 14623-14629, 2022 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-36164927

RESUMO

We demonstrate the novel growth of silicene grown on Ag(111) using STM and reveal the mechanism with KMC simulation. Our STM study shows that after the complete formation of the first layer of silicene, it is transformed into bulk Si with the reappearance of the bare Ag surface. This dewetting (DW) during the epitaxial growth is an exception in the conventional growth behavior. Our KMC simulation reproduces DW by taking into account the differences in the activation energies of Si atoms on Ag, silicene, and bulk Si. The growth modes change depending on the activation energy of the diffusion, temperature, and deposition rate, highlighting the importance of kinetics in growing metastable 2D materials.

6.
J Phys Condens Matter ; 32(24): 243001, 2020 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-32069440

RESUMO

Topological materials have become promising materials for next-generation devices by utilizing their exotic electronic states. Their exotic states caused by spin-orbital coupling usually locate on the surfaces or at the edges. Scanning tunneling spectroscopy (STS) is a powerful tool to reveal the local electronic structures of condensed matters. Therefore, STS provides us with an almost perfect method to access the exotic states of topological materials. In this topical review, we report the current investigations by several methods based on the STS technique for layered topological material from transition metal dichalcogenide Weyl semimetals (WTe2 and MoTe2) to two dimensional topological insulators (layered bismuth and silicene). The electronic characteristics of these layered topological materials are experimentally identified.

7.
Chem Asian J ; 9(10): 2891-5, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25056560

RESUMO

A [2.2]paracyclophane-based through-space conjugated oligomer comprising three π-electron systems was designed and synthesized. The arrangement of three π-conjugated systems in an appropriate order according to the energy band gap resulted in efficient unidirectional photoexcited energy transfer by the Förster mechanism. The energy transfer efficiency and rate constants were estimated to be >0.999 and >10(12) s(-1), respectively. The key point for the efficient energy transfer is the orientation of the transition dipole moments. The time-dependent density functional theory (TD-DFT) studies revealed the transition dipole moments of each stacked π-electron system; each dipole moment was located on the long axis of each stacked π-electron system. This alignment of the dipole moments is favorable for fluorescence resonance energy transfer (FRET).

9.
Biotechnol Lett ; 34(10): 1773-9, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22714272

RESUMO

Baculoviral expression systems, including those of Autographa californica multiple nucleopolyhedrovirus Bombyx mori nucleopolyhedrovirus (BmNPV), are used for recombinant protein production. Four B. mori-derived (BmN4, Bm5, Bmc140, and Bme21) cell lines were infected with recombinant BmNPV viruses expressing firefly luciferase or EGFP as reporters under the control of a viral polyhedrin promoter. Bme21 exhibited significantly higher (100-fold) luciferase activity than BmN4 and Bm5. With the EGFP reporter protein, Bme21 cells showed a marked increase in the ratio of EGFP-positive cells, reaching 90 % on day 4 post-infection, while Bm5 and BmN4 cells had a slow increase in the ratio of their EGFP-positive population. The viral titer in a supernatant of Bme21 cell culture increased faster than those of Bm5 and BmN4 cells. This susceptibility indicates that the Bme21 cell line is useful for large-scale protein expression using BmNPV.


Assuntos
Bombyx/genética , Bombyx/virologia , Vetores Genéticos/genética , Nucleopoliedrovírus/genética , Proteínas Recombinantes de Fusão/genética , Animais , Linhagem Celular , Proteínas de Fluorescência Verde/química , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/metabolismo , Células Sf9 , Transfecção
10.
Mol Biotechnol ; 40(2): 180-5, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18543128

RESUMO

The recombinant protein expression by Bombyx mori nucleopolyhedrovirus (BmNPV) infecting silkworm larvae or pupae may endow us with a potent system for the production of large eukaryotic proteins. However, the screening of silkworm strains ideally suited to this method has scarcely been conducted. In the present study, we injected recombinant BmNPV containing a reporter gene, luciferase or DsRed, into hemocoel of fifth instar larvae of selected 12 silkworm strains. Among them, the strain d17 is found to be the highest in reporter expression from the intrinsic polyhedrin promoter of Autographa californica NPV or the silkworm actin A3 promoter. These results suggest that the d17 strain is highly permissive for BmNPV replication and is the most likely candidate of a "factory" for large-scale expression using the BmNPV bacmid system.


Assuntos
Bombyx/metabolismo , Bombyx/virologia , Nucleopoliedrovírus/genética , Nucleopoliedrovírus/fisiologia , Animais , Bombyx/classificação , Bombyx/genética , Expressão Gênica , Genes Reporter/genética , Larva/classificação , Larva/genética , Larva/metabolismo , Larva/virologia
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