Enhanced Raman Scattering of Rhodamine 6G Films on Two-Dimensional Transition Metal Dichalcogenides Correlated to Photoinduced Charge Transfer

We studied the surface-enhanced Raman scattering of an organic fluoropore (Rhodamine 6G, R6G) monolayer adsorbed onto graphene and two-dimensional (2D) molybedenium disulfides (MoS₂) phototransistors and compared the results with the Raman scattering of R6G on 2D tungsten diselenides system (WSe₂). The Raman enhancement factor of the R6G film adsorbed onto WSe₂ was comparable to the corresponding value on graphene at 1365 cm^–1 and was approximately twice this value at 615 cm^–1. The amplitude of the charge transfer was estimated in situ by measuring the photocurrent produced in a hybrid system consisting of physisorbed R6G layer and the 2D materials. We found that the enhanced Raman scattering of R6G adsorbed onto the 2D materials was closely correlated with the charge transfer between the adsorbed molecules and the 2D materials. We also revealed that the intensity of Raman scattering generally decreased as the layer number of the 2D materials increased. For the R6G on the MoS₂ nanosheet, a single layer system provided a maximum Raman enhancement factor, and this value decreased pseudolinearly with the number of layers. By contrast, the Raman enhancement factor of the R6G on WSe₂ was greatest for both the mono- and bilayers, and it decreased dramatically as the number of layers increased. We provide qualitative theoretical explanations for these trends based on the electric field enhancement for the multile Fresnel phases and energy band diagrams of both systems

Digital 3D Local Growth of Iron Oxide Micro- and Nanorods by Laser-Induced Photothermal Chemical Liquid Growth

We introduce laser growth of iron oxide micro and nanorods by the photothermal chemical liquid growth method at low temperature, ambient pressure, and solution environment. By focusing a 532 nm continuous-wave laser on a Pt substrate immersed in iron oxide precursor solution, vertically aligned iron oxide micro- and nanorods are successfully fabricated with the length up to >100 μm, whereas the length can be easily controlled by changing the laser power or the illumination time. It is also found that the direction of the laser ray determines the growth direction of the iron oxide micro- and nanorods, which is the property that makes this process suitable for the fabrication of complex 3D structures as confirmed by making an iron oxide junction and kinked iron oxide microrod structure. Moreover, the resultant iron oxide microrod is applied as a microtemplate for the growth of nanostructure to show that this process can be further integrated to other 3D structures to achieve trans-scale hierarchical structures

Mobilization of Endogenous Bone Marrow Derived Endothelial Progenitor Cells and Therapeutic Potential of Parathyroid Hormone after Ischemic Stroke in Mice

<div><p>Stroke is a major neurovascular disorder threatening human life and health. Very limited clinical treatments are currently available for stroke patients. Stem cell transplantation has shown promising potential as a regenerative treatment after ischemic stroke. The present investigation explores a new concept of mobilizing endogenous stem cells/progenitor cells from the bone marrow using a parathyroid hormone (PTH) therapy after ischemic stroke in adult mice. PTH 1-34 (80 µg/kg, i.p.) was administered 1 hour after focal ischemia and then daily for 6 consecutive days. After 6 days of PTH treatment, there was a significant increase in bone marrow derived CD-34/Fetal liver kinase-1 (Flk-1) positive endothelial progenitor cells (EPCs) in the peripheral blood. PTH treatment significantly increased the expression of trophic/regenerative factors including VEGF, SDF-1, BDNF and Tie-1 in the brain peri-infarct region. Angiogenesis, assessed by co-labeled Glut-1 and BrdU vessels, was significantly increased in PTH-treated ischemic brain compared to vehicle controls. PTH treatment also promoted neuroblast migration from the subventricular zone (SVZ) and increased the number of newly formed neurons in the peri-infarct cortex. PTH-treated mice showed significantly better sensorimotor functional recovery compared to stroke controls. Our data suggests that PTH therapy improves endogenous repair mechanisms after ischemic stroke with functional benefits. Mobilizing endogenous bone marrow-derived stem cells/progenitor cells using PTH and other mobilizers appears an effective and feasible regenerative treatment after ischemic stroke.</p></div

Highly Sensitive and Stretchable Multidimensional Strain Sensor with Prestrained Anisotropic Metal Nanowire Percolation Networks

To overcome the limitation of the conventional single axis-strain sensor, we demonstrate a multidimensional strain sensor composed of two layers of prestrained silver nanowire percolation network with decoupled and polarized electrical response in principal and perpendicular directional strain. The information on strain vector is successfully measured up to 35% maximum strain with large gauge factor (>20). The potential of the proposed sensor as a versatile wearable device has been further confirmed

Highly Stretchable and Transparent Supercapacitor by Ag–Au Core–Shell Nanowire Network with High Electrochemical Stability

Stretchable and transparent electronics have steadily attracted huge attention in wearable devices. Although Ag nanowire is the one of the most promising candidates for transparent and stretchable electronics, its electrochemical instability has forbidden its application to the development of electrochemical energy devices such as supercapacitors. Here, we introduce a highly stretchable and transparent supercapacitor based on electrochemically stable Ag–Au core–shell nanowire percolation network electrode. We developed a simple solution process to synthesize the Ag–Au core–shell nanowire with excellent electrical conductivity as well as greatly enhanced chemical and electrochemical stabilities compared to pristine Ag nanowire. The proposed core–shell nanowire-based supercapacitor still possesses fine optical transmittance and outstanding mechanical stability up to 60% strain. The Ag–Au core–shell nanowire can be a strong candidate for future wearable electrochemical energy devices

Recovery of local cerebral blood flow in the ischemic cortex.

<p>Local cerebral blood flow was measured using the PeriScans laser image scanner 14 days after stroke. <b>A</b>. Laser scanning images of LCBF in stroke/saline mice and stroke/PTH treatment mice before, during and 14 days after MCA occlusion. B. Sketch of the mouse skull showing the imaging area (square frame with arrow) for LCBF. The total scan area was 5.76 mm². <b>C</b>. Quantification of LCBF measurements using the laser Doppler scanner. In this focal ischemia model of barrel cortex stroke, LCBF could largely recover 14 days after stroke. A greater recovery was seen with PTH treatment. N = 8 animals in each group; * <i>P</i><0.05 vs. stroke control.</p

On-Demand Modulation of Bacterial Cell Fates on Multifunctional Dynamic Substrates

This paper reports unprecedented dynamic surfaces based on zwitterionic low-density self-assembled monolayers (LDSAMs) of alkanethiolates on gold, which integrate three interconvertible statesbacteria-adherable, bactericidal, and nonfouling statesthrough electrical modulations. The conformations of alkanethiolates were electrically modulated to generate zwitterionic, anionic, and cationic surfaces, which responded differently to bacteria and determined the fate of bacteria. Furthermore, the reversible switching of multifunctions of the surface was realized for killing bacteria and subsequently releasing dead bacteria from the surface. For practical application of our strategy, we examined the selective antibacterial effect of our surface for eradication of mycoplasma contaminants in contaminated mammalian cell cultures

PTH increased the endothelial progenitor cells in the peripheral blood.

<p>Six days after stroke with PTH or saline treatment, blood samples were collected. FITC-conjugated CD34 and PE-conjugated VEGFR2/Flk1/KDR labeled cell populations were measured by BD FACSCalibur flow cytometer. <b>A</b>–<b>C</b>. Representative results of Fluorescence Activated Cell Sorting (FACS) are shown in A (sham control), B (stroke plus saline), and C (stroke plus PTH). <b>D</b>. The bar graph shows quantified data with a significant increase in CD34+/Flk1+ cells in stroke plus PTH group. N = 5 animals in each of the three groups; * <i>P</i><0.05 vs. sham and stroke controls.</p

PTH treatment promoted functional recovery after stroke.

<p>The adhesive-removal test was performed to evaluate sensorimotor deficits of the mice before, and 7 to 21 days after focal cerebral ischemia. <b>A</b>. All mice showed impaired function in this test (increased time to detect) after stroke. Mice that received PTH, however, exhibited significantly improved sensorimotor activity (faster detection of the sticky dot) at all time points tested. <b>B</b>. The time to removal of the sticky dot from the affected left paw was significantly increased in all stroke animals at 7 days after stroke. PTH treatment, however, improved this sensorimotor activity so that the time to removal was significantly shorter 14 days after stroke. N = 11–20 animals, * <i>P</i><0.05, ** <i>P</i><0.01 vs. stroke controls at the same time point.</p

PTH enhanced angiogenesis at the peri-infarct region 14 days after stroke.

<p>Fourteen days after stroke, endothelial cells and cell proliferation at the peri-infarct region was inspected using immunohistochemical methods. <b>A</b> and <b>B</b>. Representative Glut-1 (green) staining of vascular endothelial cells in the brain section from stroke/saline and stroke/PTH mice. <b>C</b>. The area of Glut-1 fluorescent reactivity in stroke/saline and stroke/PTH groups. <b>D</b> to <b>I</b>. Fluorescent labeling of Glut-1+ (green) and BrdU+ (red) cells. F and I are 3-D images showing co-localized labeling of Glut-1 and BrdU, indicative of angiogenesis. <b>J</b>. Quantified data of fluorescent reactivity of Glut-1/BrdU double positive cells; PTH treatment significantly promoted angiogenesis. N = 6; ** <i>P</i><0.01 vs. stroke control.</p