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The blood levels of microRNA-122 (miR-122) is associated with the severity of cardiovascular disorders, and targeting it with efficient and safer miR inhibitors could be a promising approach. Here, we report the generation of a γ-peptide nucleic acid (γPNA)-based miR-122 inhibitor (γP-122-I) that rescues vascular endothelial dysfunction in mice fed a high-fat diet. We synthesized diethylene glycol-containing γP-122-I and found that its systemic administration counteracted high-fat diet (HFD)-feeding-associated increase in blood and aortic miR-122 levels, impaired endothelial function, and reduced glycemic control. A comprehensive safety analysis established that γP-122-I affects neither the complete blood count nor biochemical tests of liver and kidney functions during acute exposure. In addition, long-term exposure to γP-122-I did not change the overall adiposity, or histology of the kidney, liver, and heart. Thus, γP-122-I rescues endothelial dysfunction without any evidence of toxicity in vivo and demonstrates the suitability of γPNA technology in generating efficient and safer miR inhibitors.

van der Waals heterostructures (vdWHs) of metallic (m-) and semiconducting (s-) transition-metal dichalcogenides (TMDs) exhibit an ideal metal/semiconductor (M/S) contact in a field-effect transistor. However, in the current two-step chemical vapor deposition process, the synthesis of m-TMD on pregrown s-TMD contaminates the van der Waals (vdW) interface and hinders the doping of s-TMD. Here, NbSe 2 /Nb-doped-WSe 2 metal-doped-semiconductor (M/d-S) vdWHs are created via a one-step synthesis approach using a niobium molar ratio-controlled solution-phase precursor. The one-step growth approach synthesizes Nb-doped WSe 2 with a controllable doping concentration and metal/doped-semiconductor vdWHs. The hole carrier concentration can be precisely controlled by controlling the Nb/(W + Nb) molar ratio in the precursor solution from ∼3 × 10 11 /cm 2 at Nb-0% to ∼1.38 × 10 12 /cm 2 at Nb-60%; correspondingly, the contact resistance R C value decreases from 10 888.78 at Nb-0% to 70.60 kΩ.μm at Nb-60%. The Schottky barrier height measurement in the Arrhenius plots of ln( I sat / T 2 ) versus q / K B T demonstrated an ohmic contact in the NbSe 2 /W x Nb 1- x Se 2 vdWHs. Combining p-doping in WSe 2 and M/d-S vdWHs, the mobility (27.24 cm 2 V -1 s -1 ) and on/off ratio (2.2 × 10 7 ) are increased 1238 and 4400 times, respectively, compared to that using the Cr/pure-WSe 2 contact (0.022 cm 2 V -1 s -1 and 5 × 10 3 , respectively). Together, the R C value using the NbSe 2 contact shows 2.46 kΩ.μm, which is ∼29 times lower than that of using a metal contact. This method is expected to guide the synthesis of various M/d-S vdWHs and applications in future high-performance integrated circuits.

Two-dimensional transition metal dichalcogenides (TMDs) offer numerous advantages over silicon-based application in terms of atomically thin geometry, excellent opto-electrical properties, layer-number dependence, band gap variability, and lack of dangling bonds. The production of high-quality and large-scale TMD films is required with consideration of practical technology. However, the performance of scalable devices is affected by problems such as contamination and patterning arising from device processing; this is followed by an etching step, which normally damages the TMD film. Herein, we report the direct growth of MoSe 2 films on selective pattern areas via a surface-mediated liquid-phase promoter using a solution-based approach. Our growth process utilizes the promoter on the selective pattern area by enhancing wettability, resulting in a highly uniform MoSe 2 film. Moreover, our approach can produce other TMD films such as WSe 2 films as well as control various pattern shapes, sizes, and large-scale areas, thus improving their applicability in various devices in the future. Our patterned MoSe 2 field-effect transistor device exhibits a p-type dominant conduction behavior with a high on/off current ratio of ∼10 6 . Thus, our study provides general guidance for direct selective pattern growth via a solution-based approach and the future design of integrated devices for a large-scale application.

Two-dimensional (2D) layered materials with properties such as a large surface-to-volume ratio, strong light interaction, and transparency are expected to be used in future optoelectronic applications. Many studies have focused on ways to increase absorption of 2D-layered materials for use in photodetectors. In this work, we demonstrate another strategy for improving photodetector performance using a graphene/MoS 2 heterojunction phototransistor with a short channel length and a tunable Schottky barrier. The channel length of sub-30 nm, shorter than the diffusion length, decreases carrier recombination and carrier transit time in the channel and improves phototransistor performance. Furthermore, our graphene/MoS 2 heterojunction phototransistor employed a tunable Schottky barrier that is only controlled by light and gate bias. It maintains a low dark current and an increased photocurrent. As a result, our graphene/MoS 2 heterojunction phototransistor showed ultrahigh responsivity and detectivity of 2.2 × 10 5 A/W and 3.5 × 10 13 Jones, respectively. This is a considerable improvement compared to previous pristine MoS 2 phototransistors. We confirmed an effective method to develop phototransistors based on 2D materials and obtained ultrahigh performance of our phototransistor, which is promising for high-performance optoelectronic applications.

Piezoelectricity of transition metal dichalcogenides (TMDs) under mechanical strain has been theoretically and experimentally studied. Powerful strain sensors using Schottky barrier variation in TMD/metal junctions as a result of the strain-induced lattice distortion and associated ion-charge polarization were demonstrated. However, the nearly fixed work function of metal electrodes limits the variation range of a Schottky barrier. We demonstrate a highly sensitive strain sensor using a variable Schottky barrier in a MoS 2 /graphene heterostructure field effect transistor (FET). The low density of states near the Dirac point in graphene allows large modulation of the graphene Fermi level and corresponding Schottky barrier in a MoS 2 /graphene junction by strain-induced polarized charges of MoS 2 . Our theoretical simulations and temperature-dependent electrical measurements show that the Schottky barrier change is maximized by placing the Fermi level of the graphene at the charge neutral (Dirac) point by applying gate voltage. As a result, the maximum Schottky barrier change (ΔΦ SB ) and corresponding current change ratio under 0.17% strain reach 118 meV and 978, respectively, resulting in an ultrahigh gauge factor of 575 294, which is approximately 500 times higher than that of metal/TMD junction strain sensors (1160) and 140 times higher than the conventional strain sensors (4036). The ultrahigh sensitivity of graphene/MoS 2 heterostructure FETs can be developed for next-generation electronic and mechanical-electronic devices.

In this report, a screening-engineered carbon nanotube (CNT) network/MoS 2 /metal heterojunction vertical field effect transistor (CNT-VFET) is fabricated for an efficient gate modulation independent of the drain voltage. The gate field in the CNT-VFET transports through the empty space of the CNT network without any screening layer and directly modulates the MoS 2 semiconductor energy band, while the gate field from the Si back gate is mostly screened by the graphene layer. Consequently, the on/off ratio of CNT-VFET maintained 10 3 in overall drain voltages, which is 10 times and 1000 times higher than that of the graphene (Gr) VFET at V sd = 0.1 (ratio = 81.9) and 1 V (ratio = 3), respectively. An energy band diagram simulation shows that the Schottky barrier modulation of CNT/MoS 2 contact along the sweeping gate bias is independent of the drain voltage. On the other hand, the gate modulation of Gr/MoS 2 is considerably reduced with increased drain voltage because more electrons are drawn into the graphene electrode and screens the gate field by applying a higher drain voltage to the graphene/MoS 2 /metal capacitor.