Vertical array growth of small diameter single-walled carbon nanotubes

A hot filament chemical vapor deposition method has been developed to grow vertical array single-walled carbon nanotubes (SWNTs). In this study, a hot filament (temperature greater than 2000 degrees C) was used to activate gas mixtures of hydrogen and carbon containing species at sub-atmospheric pressures. Silicon substrates decorated with islands of iron were directly inserted into a preheated furnace in which a hot filament is activating the gas. Vertical arrays of SWNTs are produced with diameters ranging from 0.78 to 1.6 nm. The samples were characterized with Raman and fluorescence spectroscopy and SEM and TEM microscopy.     

Magnetically Assembled Multisegmented Nanowires and Their Applications

Here we report a cost effective and versatile way of synthesizing and assembling multi‐functional (e.g., gold‐polypyrrole‐nickel‐gold) nanowires. Multisegmented nanowires were synthesized using electrodeposition method for precise control over segment dimensions for proper expression of material functionality. The nanowires were integrated on microfabricated electrodes using magnetic dipole interactions between the ferromagnetic segment in the nanowire and the ferromagnetic electrodes. The electrical properties of multisegmented nanowires showed semiconducting behavior with the activation energy of ca. 0.27 eV for the conducting polymer segment of the nanowire. These nanowire devices showed response towards light and exposure to ammonia, demonstrating their potential use as photonic device and gas sensor, respectively.     

Chiral separation of amides of amino acid on a (S)‐N‐(3,5‐dinitrobenzoyl)leucine‐N‐phenyl‐N‐propylamide‐bonded silica using nonaqueous capillary electrochromatography

(S)‐N‐(3,5‐dinitrobenzoyl)leucine‐N‐phenyl‐N‐propylamine‐bonded silica was used as a chiral stationary phase for separation of a set of racemic π‐acidic and π‐basic α‐amino acid amides in electrolyteless ACN‐water eluents by CEC in the RP and polar organic (PO) modes. The effect of the amount of water in the ACN‐water eluent on chiral separation was examined. As water is added to ACN, retention was shortened but resolution and selectivity deteriorated severely. Retention, enantioselectivity, and resolution factors obtained in 100% ACN were compared with those in an n‐hexane‐isopropanol eluent with a small amount of water by normal phase (NP) CEC. Much shorter retention times with comparable enantioselectivities were observed with 100% ACN, demonstrating the advantage of separation on (S)‐N‐(DNB)leucine‐N‐phenyl‐N‐propylamine‐bonded silica in PO‐CEC over NP‐CEC.     

Phenotype-based screening rediscovered benzopyran-embedded microtubule inhibitors as anti-neuroinflammatory agents by modulating the tubulin–p65 interaction

Neuroinflammation is one of the critical processes implicated in central nervous system (CNS) diseases. Therefore, alleviating neuroinflammation has been highlighted as a therapeutic strategy for treating CNS disorders. However, the complexity of neuroinflammatory processes and poor drug transport to the brain are considerable hurdles to the efficient control of neuroinflammation using small-molecule therapeutics. Thus, there is a significant demand for new chemical entities (NCEs) targeting neuroinflammation. Herein, we rediscovered benzopyran-embedded tubulin inhibitor 1 as an anti-neuroinflammatory agent via phenotype-based screening. A competitive photoaffinity labeling study revealed that compound 1 binds to tubulin at the colchicine-binding site. Structure–activity relationship analysis of 1’s analogs identified SB26019 as a lead compound with enhanced anti-neuroinflammatory efficacy. Mechanistic studies revealed that upregulation of the tubulin monomer was critical for the anti-neuroinflammatory activity of SB26019. We serendipitously found that the tubulin monomer recruits p65, inhibiting its translocation from the cytosol to the nucleus and blocking NF-κB-mediated inflammatory pathways. Further in vivo validation using a neuroinflammation mouse model demonstrated that SB26019 suppressed microglial activation by downregulating lba-1 and proinflammatory cytokines. Intraperitoneal administration of SB26019 showed its therapeutic potential as an NCE for successful anti-neuroinflammatory regulation. Along with the recent growing demands on tubulin modulators for treating various inflammatory diseases, our results suggest that colchicine-binding site-specific modulation of tubulins can be a potential strategy for preventing neuroinflammation and treating CNS diseases.Subject terms: Drug discovery, Neurodegeneration     

Visuomotor anomalies in achiasmatic mice expressing a transfer-defective Vax1 mutant

In binocular animals that exhibit stereoscopic visual responses, the axons of retinal ganglion cells (RGCs) connect to brain areas bilaterally by forming a commissure called the optic chiasm (OC). Ventral anterior homeobox 1 (Vax1) contributes to the formation of the OC, acting endogenously in optic pathway cells and exogenously in growing RGC axons. Here, we generated Vax1^AA/AA mice expressing the Vax1^AA mutant, which is incapable of intercellular transfer. We found that RGC axons cannot take up Vax1^AA protein from the Vax1^AA/AA mouse optic stalk (OS) and grow slowly to arrive at the hypothalamus at a late stage. The RGC axons of Vax1^AA/AA mice connect exclusively to ipsilateral brain areas after failing to access the midline, resulting in reduced visual acuity and abnormal oculomotor responses. Overall, our study provides physiological evidence for the necessity of intercellular transfer of Vax1 and the importance of the bilateral RGC axon projection in proper visuomotor responses.Subject terms: Axon and dendritic guidance, Morphogen signalling     

ESIPT-Inspired Dual-Mode Photoswitches with Fast Molecular Isomerization in the Solid State

Photoswitchable materials have attracted considerable attention in various fields. Developing excellent solid-state dual-mode photoswitches is an important but challenging task. Herein, we propose a new strategy to construct an excited-state intramolecular proton transfer (ESIPT) inspired photoswitch ( DiAH-pht ) that possesses aggregation-induced emission (AIE) features and displays a fast molecular isomerization process characterized by dual-mode behavior in the solid state. Mechanistic studies indicate that introduction of a bulky group can create a folded molecular conformation that provides adequate volume to facilitate photoisomerization and the enhanced ESIPT effect can boost the isomerization process. The feasibility of our strategy was further demonstrated by the activated photoisomerization performance of the Schiff base derivatives. Furthermore, DiAH-pht shows good performance in the fields of dual-mode information encryption and high-density data storage.     

Synthesis and electrorheological properties of polyaniline-Na+-montmorillonite suspensions

We synthesized polyaniline-Na⁺-montmorillonite nanocomposite particles using an emulsion intercalation method and prepared electrorheological (ER) fluids by dispersing the synthesized nanocomposite particles in an electrically insulating silicone oil. The conducting polymer (polyaniline) was inserted into the layers of clay, and this insertion of polyaniline was confirmed by X-ray diffraction. For the first time, ER properties were determined via a rotational rheometer equipped with a high voltage generator.     

Janus-Type ESIPT Chromophores with Distinctive Intramolecular Hydrogen-bonding Selectivity

Excited-state intramolecular proton transfer (ESIPT)-based solid luminescent materials with multiple hydrogen bond acceptors (HBAs) remain unexplored. Herein, we introduced a family of Janus-type ESIPT chromophores featuring distinctive hydrogen bond (H-bond) selectivity between competitive HBAs in a single molecule. Our investigations showed that the central hydroxyl group preferentially forms intramolecular H-bonds with imines in imine-modified 2-hydroxyphenyl benzothiazole (HBT) chromophores but tethers the benzothiazole moiety in hydrazone-modified HBT chromophores. Imine-derived HBTs generally exhibit higher fluorescence efficiency, while hydrazone-derived HBTs show a reduced overlap between the absorption and fluorescence bands. Quantum chemical calculations unveiled the molecular origins of the biased intramolecular H-bonds and their impact on the ESIPT process. This Janus-type ESIPT chromophore skeleton provides new opportunities for the design of solid luminescent materials.