Fumarate induces LncRNA-MIR4435-2HG to regulate glutamine metabolism remodeling and promote the development of FH-deficient renal cell carcinoma.

Fumarate hydratase (FH) deficient renal cell carcinoma (RCC) is a type of tumor with definite metabolic disorder, but the mechanism of metabolic remodeling is still unclear. LncRNA was reported to closely correlate with cancer metabolism, however the biological role of LncRNA in the development of progression of FH-deficent RCC was not well studied either. FH-deficient RCC samples were collected in my hospital and used for RNA-sequencing and Mass spectrometry analysis. FH-deficient RCC cell line UOK262 and control pFH cells were used for in vitro experiments, including proliferation assay, transwell assay, western-blot, mass spectrometry and so on. PDX mouse model was used for further drug inhibition experiments in vivo. In this study, we analyzed the profiles of LncRNA and mRNA in FH-deficienct RCC samples, and we found that the LncRNA-MIR4435-2GH was specifically highly expressed in FH-deficient RCC compared with ccRCC. In vitro experiments demonstrated that MIR4435-2HG was regulated by Fumarate through histone demethylation, and the deletion of this gene could inhibit glutamine metabolism. RNA-pulldown experiments showed that MIR4435-2HG specifically binds to STAT1, which can transcriptionally activate GLS1. GLS1 inhibitor CB-839 could significantly suppress tumor growth in PDX tumor models. This study analyzed the molecular mechanism of MIR4435-2HG in regulating metabolic remodeling of FH-deficient RCC in clinical samples, cells and animal models by combining transcriptional and metabolic methods. We found that that GLS1 was a therapeutic target for this tumor, and MIR4435-2HG can be used as a drug sensitivity marker.

Intercalated architecture of MA2Z4 family layered van der Waals materials with emerging topological, magnetic and superconducting properties.

The search for new two-dimensional monolayers with diverse electronic properties has attracted growing interest in recent years. Here, we present an approach to construct MA2Z4 monolayers with a septuple-atomic-layer structure, that is, intercalating a MoS2-type monolayer MZ2 into an InSe-type monolayer A2Z2. We illustrate this unique strategy by means of first-principles calculations, which not only reproduce the structures of MoSi2N4 and MnBi2Te4 that were already experimentally synthesized, but also predict 72 compounds that are thermodynamically and dynamically stable. Such an intercalated architecture significantly reconstructs the band structures of the constituents MZ2 and A2Z2, leading to diverse electronic properties for MA2Z4, which can be classified according to the total number of valence electrons. The systems with 32 and 34 valence electrons are mostly semiconductors. Whereas, those with 33 valence electrons can be nonmagnetic metals or ferromagnetic semiconductors. In particular, we find that, among the predicted compounds, (Ca,Sr)Ga2Te4 are topologically nontrivial by both the standard density functional theory and hybrid functional calculations. While VSi2P4 is a ferromagnetic semiconductor and TaSi2N4 is a type-I Ising superconductor. Moreover, WSi2P4 is a direct gap semiconductor with peculiar spin-valley properties, which are robust against interlayer interactions. Our study thus provides an effective way of designing septuple-atomic-layer MA2Z4 with unusual electronic properties to draw immediate experimental interest.

Chemical vapor deposition of layered two-dimensional MoSi2N4 materials.

Identifying two-dimensional layered materials in the monolayer limit has led to discoveries of numerous new phenomena and unusual properties. We introduced elemental silicon during chemical vapor deposition growth of nonlayered molybdenum nitride to passivate its surface, which enabled the growth of centimeter-scale monolayer films of MoSi2N4 This monolayer was built up by septuple atomic layers of N-Si-N-Mo-N-Si-N, which can be viewed as a MoN2 layer sandwiched between two Si-N bilayers. This material exhibited semiconducting behavior (bandgap ~1.94 electron volts), high strength (~66 gigapascals), and excellent ambient stability. Density functional theory calculations predict a large family of such monolayer structured two-dimensional layered materials, including semiconductors, metals, and magnetic half-metals.

Layer-dependent dielectric and optical properties of centimeter-scale 2D WSe2: evolution from a single layer to few layers.

Two-dimensional (2D) materials usually exhibit interesting layer-dependent dielectric and optical properties, which play important roles in structure optimization and performance improvement of related devices. Recently, 2D WSe2 has attracted considerable attention in atomically thin electronics and optoelectronics, due to its exotic photoelectric properties. In this paper, high-quality, continuous, and centimeter-scale 2D WSe2 with different layers on a sapphire substrate are prepared by an ultrafast ambient-pressure chemical vapor deposition method. We comprehensively investigate the evolution of the layer-dependent dielectric and optical properties of 2D WSe2 from a single layer to five layers by spectroscopic ellipsometry over an ultra-broad energy range (0.73-6.42 eV). We identify the critical points (CPs) in the dielectric function spectra of 2D WSe2 with different layers, and reveal physical origins of the corresponding optical transitions at these CPs by the CP analysis method and first-principles calculations. Results demonstrate that the center energies of these CPs exhibit intriguing layer-dependencies, which can be interpreted as the alternative domination of the decreasing exciton binding energy and the striking band renormalization. For the first time, we found that the imaginary part of the dielectric function of WSe2 at these CPs exhibits a valley-like shape versus the layer number, and the bottom appears at 3-layers. This non-monotonic evolution is explained as a competition between the layer-dependent decrease of the exciton effect and the layer-dependent increase of the joint density of states.

A Double Support Layer for Facile Clean Transfer of Two-Dimensional Materials for High-Performance Electronic and Optoelectronic Devices.

Clean transfer of two-dimensional (2D) materials grown by chemical vapor deposition is critical for their application in electronics and optoelectronics. Although rosin can be used as a support layer for the clean transfer of graphene grown on Cu, it has not been usable for the transfer of 2D materials grown on noble metals or for large-area transfer. Here, we report a poly(methyl methacrylate) (PMMA)/rosin double support layer that enables facile ultraclean transfer of large-area 2D materials grown on different metals. The bottom rosin layer ensures clean transfer, whereas the top PMMA layer not only screens the rosin from the transfer conditions but also improves the strength of the transfer layer to make the transfer easier and more robust. We demonstrate the transfer of monolayer WSe2 and WS2 single crystals grown on Au as well as large-area graphene films grown on Cu. As a result of the clean surface, the transferred WSe2 retains the intrinsic optical properties of the as-grown sample. Moreover, it does not require annealing to form good ohmic contacts with metal electrodes, enabling high-performance field effect transistors with mobility and ON/OFF ratio ∼10 times higher than those made by PMMA-transferred WSe2. The ultraclean graphene film is found to be a good anode for flexible organic photovoltaic cells with a high power conversion efficiency of ∼6.4% achieved.

High-Performance Sub-Micrometer Channel WSe2 Field-Effect Transistors Prepared Using a Flood-Dike Printing Method.

Printing technology has potential to offer a cost-effective and scalable way to fabricate electronic devices based on two-dimensional (2D) transition metal dichalcogenides (TMDCs). However, limited by the registration accuracy and resolution of printing, the previously reported printed TMDC field-effect transistors (FETs) have relatively long channel lengths (13-200 µm), thus suffering low current-driving capabilities (≤0.02 µA/µm). Here, we report a "flood-dike" self-aligned printing technique that allows the formation of source/drain metal contacts on TMDC materials with sub-micrometer channel lengths in a reliable way. This self-aligned printing technique involves three steps: (i) printing of gold ink on a WSe2 flake to form the first gold electrode, (ii) modifying the surface of the first gold electrode with a self-assembled monolayer (SAM) to lower the surface tension and render the surface hydrophobic, and (iii) printing of gold ink close to the SAM-treated first electrode at a certain distance. During the third step, the gold ink would first spread toward the edge of the first electrode and then get stopped by the hydrophobic SAM coating, ending up forming a sub-micrometer channel. With this printing technique, we have successfully downscaled the channel length to ∼750 nm and achieved enhanced on-state current densities of ∼0.64 µA/µm (average) and high on/off current ratios of ∼3 × 105 (average). Furthermore, with our high-performance printed WSe2 FETs, driving capabilities for quantum-dot light-emitting diodes (LEDs), inorganic LEDs, and organic LEDs have been demonstrated, which reveals the potential of using printed TMDC electronics for display backplane applications.

Ultrafast Growth of High-Quality Monolayer WSe2 on Au.

The ultrafast growth of high-quality uniform monolayer WSe2 is reported with a growth rate of ≈26 µm s-1 by chemical vapor deposition on reusable Au substrate, which is ≈2-3 orders of magnitude faster than those of most 2D transition metal dichalcogenides grown on nonmetal substrates. Such ultrafast growth allows for the fabrication of millimeter-size single-crystal WSe2 domains in ≈30 s and large-area continuous films in ≈60 s. Importantly, the ultrafast grown WSe2 shows excellent crystal quality and extraordinary electrical performance comparable to those of the mechanically exfoliated samples, with a high mobility up to ≈143 cm2 V-1 s-1 and ON/OFF ratio up to 9 × 106 at room temperature. Density functional theory calculations reveal that the ultrafast growth of WSe2 is due to the small energy barriers and exothermic characteristic for the diffusion and attachment of W and Se on the edges of WSe2 on Au substrate.