Synthesis and optical properties of WS2 nanotubes with relatively small diameters.

Tungsten disulfide (WS2) nanotubes exhibit various unique properties depending on their structures, such as their diameter and wall number. The development of techniques to prepare WS2 nanotubes with the desired structure is crucial for understanding their basic properties. Notably, the synthesis and characterization of multi-walled WS2 nanotubes with small diameters are challenging. This study reports the synthesis and characterization of small-diameter WS2 nanotubes with an average inner diameter of 6 nm. The optical absorption and photoluminescence (PL) spectra of the as-prepared nanotubes indicate that a decrease in the nanotube diameter induces a red-shift in the PL, suggesting that the band gap narrowed due to a curvature effect, as suggested by theoretical calculations.

Semiconducting Transition Metal Dichalcogenide Heteronanotubes with Controlled Outer-Wall Structures.

Transition metal dichalcogenide (TMDC) nanotubes exhibit unique physical properties due to their nanotube structures. The development of techniques for synthesizing TMDC nanotubes with controlled structures is very important for their science and applications. However, structural control efforts have been made only for the homostructures of TMDC nanotubes and not for their heterostructures that provide an important platform for their two-dimensional counterparts. In this study, we synthesized heterostructures of TMDC nanotubes, MoS2/WS2 heteronanotubes, and demonstrated a technique for controlling features of their structures, such as diameters, layer numbers, and crystallinity. The diameter of the heteronanotubes could be tuned with inner nanotube templates and was reduced by using small-diameter WS2 nanotubes. The layer number and crystallinity of the MoS2 outer wall could be controlled by controlling their precursors and synthesis temperatures, resulting in the formation of high-crystallinity TMDC heteronanotubes with specific chirality. This study can expand the research of van der Waals heterostructures.

RACE1, a Japanese Blumeria graminis f. sp. hordei isolate, is capable of overcoming partially mlo-mediated penetration resistance in barley in an allele-specific manner.

Loss-of-function mutation of the MILDEW RESISTANCE LOCUS O (Mlo) gene confers durable and broad-spectrum resistance to powdery mildew fungi in various plants, including barley. In combination with the intracellular nucleotide-binding domain and leucine-rich repeat receptor (NLR) genes, which confer the race-specific resistance, the mlo alleles have long been used in barley breeding as genetic resources that confer robust non-race-specific resistance. However, a Japanese Blumeria graminis f. sp. hordei isolate, RACE1, has been reported to have the potential to overcome partially the mlo-mediated penetration resistance, although this is yet uncertain because the putative effects of NLR genes in the tested accessions have not been ruled out. In this study, we examined the reproducibility of the earlier report and found that the infectious ability of RACE1, which partially overcomes the mlo-mediated resistance, is only exerted in the absence of NLR genes recognizing RACE1. Furthermore, using the transient-induced gene silencing technique, we demonstrated that RACE1 can partially overcome the resistance in the host cells with suppressed MLO expression but not in plants possessing the null mutant allele mlo-5.

Photodynamic activity of C70 caged within surface-cross-linked liposomes.

[70]Fullerene (C(70)) encapsulated into a surface-cross-linked liposome, a so-called cerasome, was prepared by an exchange reaction incorporating C(70)gamma-cyclodextrin complexes into lipid membranes. Fullerene exchange in a cerasome-incorporated C(70) (CIC(70)), as well as in a lipid-membrane-incorporated C(70) (LMIC(70)), was completed within 1 min with stirring at 25 degrees C. CIC(70) was more resistant to lysis than LMIC(70) towards lysing agents such as surfactants. Furthermore, the photodynamic activity of CIC(70) in HeLa cells was similar to that of LMIC(70), indicating that C(70) can act as a photosensitizing drug (PS) without release from cerasome membranes. Thus, in contrast with general drug-delivery systems (DDSs), which require the drug to be released from the interior of liposomes, carriers for PSs for use in photodynamic therapy (PDT) do not necessarily need to release the drug. These results indicate that DDSs with high morphological stability can increase the residence time in blood and achieves tumor-selective drug delivery by the enhanced permeability and retention (EPR) effect.

Intracellular uptake and photodynamic activity of water-soluble [60]- and [70]fullerenes incorporated in liposomes.

Water-soluble fullerenes have attracted attention as promising compounds that have been used to forge new paths in the field of photo-biochemistry. To prepare water-soluble fullerenes, we employed lipid-membrane-incorporated fullerenes (LMICx; x=60 or 70) by using the fullerene exchange method from a gamma-cyclodextrin (gamma-CD) cavity to vesicles. LMIC60 have low toxicity in the dark and engender cell death by photoirradiation (lambda>350 nm). Furthermore, the photodynamic activity of LMIC70 is 4.7-fold that of LMIC60 for the same photon flux (lambda>400 nm). One of the reasons for the higher phototoxicity of LMIC70 is the higher generation of singlet oxygen (1O2) in LMIC70 than in LMIC60. The difference between LMIC60 and LMIC70 is considered to be simply derived from the amount of light absorption in the 400-700 nm region that is suitable for photodynamic therapy (PDT). To the best of our knowledge, this is the first case in which biological activity of C70 and its derivatives toward HeLa cells has been assayed.

Changes in PKB/Akt and calcineurin signaling during recovery in atrophied soleus muscle induced by unloading.

Protein kinase B [PKB, also known as Akt (PKB/Akt)] and calcineurin (CaN) are postulated to play important roles in integrating intracellular signaling in skeletal muscle in response to disuse and increased muscle loading. These experiments investigated changes in signal transduction of the downstream pathways of PKB/Akt and CaN during recovery following disuse-induced muscle atrophy. A 10-day period of hindlimb unloading (HLU) via tail suspension (male rats) was used to produce soleus muscle atrophy. Muscle recovery was achieved by returning animals to normal ambulation for 3-10 days. HLU resulted in significant muscle atrophy and a slow-to-fast fiber transition as revealed by appearance of type IId/x and IIb myosin heavy chain (MHC) isoforms. Muscle mass in HLU animals recovered to control (Con) levels after 10 days of reloading, but the fast-to-slow shift in muscle MHC was incomplete, as indicated by the continued presence of type IId/x MHC. Ten days of HLU resulted in a significant decrease (-43%) in muscle levels of phosphorylated PKB/Akt. In contrast, muscle levels of phosphorylated PKB/Akt were greater (+56%) in HLU than in Con animals early after the onset of reloading (3 days). Soleus levels of phosphorylated p70S6K were significantly higher (+26%) in HLU animals after 3 days of muscle reloading. Muscle levels of phosphorylated PKB/Akt and phosphorylated p70S6K returned to Con levels by day 10 of recovery. Moreover, muscle CaN levels were significantly higher than Con levels after 10 days of muscle reloading. These findings are consistent with the hypothesis that PKB/Akt and its downstream mediators are active in the regrowth of muscle mass during the early periods of recovery from muscle atrophy. Our data support the concept that CaN is involved in muscle remodeling during the later phases of recovery from disuse muscle atrophy.