Metallophthalocyanine as ideal antibiotics without light: Mechanisms and applications.

The urgent global health problem of antimicrobial resistance (AMR) calls for the discovery of new antibiotics with innovative modes of action while considering the low toxicity to mammalian cells. This paper proposes a novel strategy for designing antibiotics with selective bacterial toxicity by exploiting the positional differences of electron transport chains (ETC) in bacterial and mammalian cells. The focus is on cytochrome c (cyt C) and its maturation system in E. coli. The catalytic oxidative activity of metallophthalocyanine (MPc), which have a distinctive M-N4 structure, is being investigated. Unlike previous applications based on light-activated reactive oxygen species (ROS) generation, this study exploits the ability of MPcs to oxidize Fe2+ to Fe3+ in cyt C and catalyze the formation of disulfide bonds between cysteine residues to interfere with cyt C maturation, disrupt the bacterial respiratory chain and selectively kills bacteria. In contrast, in mammalian cells, these MPcs are located in the lysosomes and cannot access the ETC in the mitochondria, thus achieving selective bacterial toxicity. Two MPcs that showed effective antibacterial activity in a wound infection model were identified. This study provides a valuable reference for the design of novel antibiotics based on M-N4-based metal complex molecules.

Elevated CO2 and temperature under future climate change increase severity of rice sheath blight.

Sheath blight (ShB), caused by Rhizoctonia solani, is one of the major threats to rice (Oryza sativa L.) production. However, it is not clear how the risk of rice ShB will respond to elevated CO2 and temperature under future climate change. Here, we conducted, field experiments of inoculated R. solani under combinations of two CO2 levels (ambient and enriched up to 590 µmol mol-1) and two temperature levels (ambient and increased by 2.0°C) in temperature by free-air CO2 enrichment (T-FACE) system for two cultivars (a susceptible cultivar, Lemont and a resistant cultivar, YSBR1). Results indicate that for the inoculation of plants with R. solani, the vertical length of ShB lesions for cv. Lemont was significantly longer than that for cv. YSBR1 under four CO2 and temperature treatments. The vertical length of ShB lesions was significantly increased by elevated temperature, but not by elevated CO2, for both cultivars. The vertical length of ShB lesions under the combination of elevated CO2 and elevated temperature was increased by 21-38% for cv. Lemont and by -1-6% for cv. YSBR1. A significant increase in MDA level was related to a significant increase in the vertical length of ShB lesions under the combination of elevated CO2 and elevated temperature. Elevated CO2 could not compensate for the negative effect of elevated temperature on yield of both cultivars under future climate change. Rice yield and biomass were further decreased by 2.0-2.5% and 2.9-4.2% by an increase in the severity of ShB under the combination of elevated CO2 and elevated temperature. Thus, reasonable agronomic management practices are required to improve both resistance to ShB disease and grain yield for rice under future climate change.

The potential role of sucrose transport gene expression in the photosynthetic and yield response of rice cultivars to future CO2 concentration.

The metabolic basis for observed differences in the yield response of rice to projected carbon dioxide concentrations (CO2 ) is unclear. In this study, three rice cultivars, differing in their yield response to elevated CO2 , were grown under ambient and elevated CO2 conditions, using the free-air CO2 enrichment technology. Flag leaves of rice were used to determine (1) if manipulative increases in sink strength decreased the soluble sucrose concentration for the 'weak' responders and (2), whether the genetic expression of sucrose transporters OsSUT1 and OsSUT2 was associated with an accumulation of soluble sugars and the maintenance of photosynthetic capacity. For the cultivars that showed a weak response to additional CO2 , photosynthetic capacity declined under elevated CO2 and was associated with an accumulation of soluble sugars. For these cultivars, increasing sink relative to source strength did not increase photosynthesis and no change in OsSUT1 or OsSUT2 expression was observed. In contrast, the 'strong' response cultivar did not show an increase in soluble sugars or a decline in photosynthesis but demonstrated significant increases in OsSUT1 and OsSUT2 expression at elevated CO2 . Overall, these data suggest that the expression of the sucrose transport genes OsSUT1 and OsSUT2 may be associated with the maintenance of photosynthetic capacity of the flag leaf during grain fill; and, potentially, greater yield response of rice as atmospheric CO2 increases.

Europium(III) complexes/silica hybrid nanospheres synthesized in microemulsion.

Eu(DBM)3Phen/silica nanospheres with a uniform diameter of approximately 40 nm and the characteristic fluorescence of Eu3+ ions have been synthesized by a microemulsion method. SEM and TEM analysis indicate that the hybrid nanospheres are core/shell structures with fine spherical surfaces and that Eu(DBM)3Phen has been successfully enveloped in the SiO2 spheres as chromophore cores. IR absorption spectra and photoluminescence spectra suggest that the hybrid nanoparticles are promising materials for bioassay.

A novel approach from infrared to ultraviolet emission enhancement in Yb3+, Er3+:CaF2 nanofilms.

Under 978 nm excitation, we explored the infrared-to-ultraviolet upconversion properties in the nanofilms with the nanoparticles of Yb3+, Er3+ codoped calcium fluoride (CaF2:Yb3+, Er3+). The strong enhancement of ultraviolet emission was observed. The result is attributed to the optical performance characteristics of the nanostructure materials. Furthermore, a novel upconversion approach explains well the UV-enhanced emission.

Multicolor up-conversion emissions of Tm3+/Er3+/Yb3+ tri-doped YF3 phosphors.

Tm3+/Er3+/Yb3+ tri-doped yttrium fluoride (YF3) phosphors were prepared by a facile hydrothermal method. X-ray topographic analysis found that the phosphors were crystallized products. Their sizes and morphologies were characterized by scanning electron microscopy (SEM, Hitachi S-4800), which indicated that most of the YF3 phosphors were hundreds of nanometers in size. Up-conversion (UC) spectra were recorded under 980-nm diode laser excitation at room temperature with a fluorescence spectrometer (Hitachi F-4500). Plenty of UC emissions of Tm3+ and Er3+ were observed from ultraviolet to red. For Tm3+ ions, a five-photon process (approximately 291 nm and approximately 347 nm), a four-photon process (approximately 362 nm and approximately 452 nm), and a three-photon process (approximately 475 nm) were identified in the UC spectra. The UC emissions from the Er3+ were: approximately 380 nm, approximately 408 nm, approximately 521 nm, approximately 537 nm, and approximately 652 nm. Therefore, cyan-white light can be observed by the naked eye at 980-nm excitation, even under low excitation power density. By comparing the UC spectra of the phosphors annealed at different temperatures, we found that the intensity of the UC luminescence increased as annealing temperature increased. Furthermore, the spectral dependencies on Tm3+ doped concentrations were studied. The energy transfer processes and fluorescence dynamics in the tri-doped system are currently being investigated.

Self-assembly of Yb3+-Tm3+ co-doped YF3 elongated nanocrystals into nanobundles of straw and up-conversion fluorescence.

The hierarchical self-assembly of Yb3+ and Tm3+ co-doped YF3 elongated nanocrystals (NCs) into nanobundles of straw were synthesized through a facile hydrothermal route. The formational mechanisms of regular aggregates of the building blocks were studied. Ultraviolet (UV)-blue upconversion emissions of Tm3+ were recorded under 980-nm excitation by the Yb3+ sensitizer. The relatively bright blue emission indicated that the bundles have the potential for applications such as short-wavelength solid-state lasers and display devices.

Synthesis and photophysical properties of core-shell Eu(DBM)3phen/TiO2 nanohybrids.

The core-shell titania (TiO2) hybrid spheres embedded with tris(dibenzoylmethanato)phenanthroline [Eu-(DBM)3phen] complex clusters were fabricated by a modified Stöber method. Under ultraviolet excitation (355 nm), the hybrid spheres exhibit the characteristic luminescence of the Eu3+ ions. The experimental results indicate that the titanic shell has different influences on the two fluorescent centers of Eu3+ ions. The emission from the centers on the complex surfaces was greatly enhanced when incorporated into titania spheres.

[A novel red phosphor (La3PO7:Eu3+) prepared by solid state method].

Novel red phosphor, Eu3+ -doped oxyphosphate (La3 PO7:Eu3+), was synthesized by a solid state method under high temperature. All the starting materials were analytical grade. La2O3, EuO3 and (NH4)2HPO4 weighed in appropriated molar ratios and ground in an agate mortar. Then the powder was treated under 1000 degrees C. The crystal phase of La3PO7:Eu3+ was investigated by X-ray diffraction (XRD) using a Cu target radiation resource (lamda = 1.54078 ?) and exhibited prominent peaks accordant with JCPDS standard card (33-0720) of La3PO7 in monoclinic phase. Emission and excitation spectra of La3PO7:Eu3+ were recorded at room temperature using a fluorescence spectrometer (Hitachi F-4500). Under 254 nm excitation, intense red fluorescence was observed from La3PO7:Eu3+, which was assigned to the (5)D0-->(7)F2 transition of Eu3+ ions. The intensity of the (5)D0-->(7)F2 transition is stronger than that of the (5)D0-->(7)F1 transition, showing that the Eu3+ ions were in the non-centrosym-metric sites in La3PO7. The CommissionIn-ternational DeL" Eclairage (CIE) coordinate of La3PO7:Eu3+ is (0.63,0.37) in the red area of CIE1931 XY chromaticity coordinate graph and close to that of Y2o3:Eu3+, but the cost of La3PO7 host is lower. This novel material may have potential applications in plasma display panels and Hg-free fluorescent lamps in the future.