Evaluating the Leishmania tarentolae response to inorganic strontium-based oxyfluorides.

The increasing global prevalence of the parasitic vector-borne disease leishmaniasis combined with rising resistance to current therapeutics necessitates the search for novel approaches to combat leishmania. This study evaluates the effects of novel strontium-based oxyfluorides for potential therapeutic use by testing cultures of Leishmania tarentolae, a species of Leishmania found in reptiles, as a model species. Cells were cultured with a range of mixed metal strontium oxyfluoride compounds selected to systematically test the relationship between compound structure and cell viability and enzyme activity over time.

Leishmania tarentolae novel responses to Bi3+-doped strontium aluminum oxyfluorides.

Novel therapeutics for the treatment of leishmaniasis are of interest as the disease not only is becoming more prevalent, but drug resistance is increasing in certain regions of the world. Reported here is the use of Bi3+-doped strontium aluminum oxyfluoride phosphors and protease inhibitors to test in vitro inhibitory activity against cultured promastigote Leishmania tarentolae and effects on L. tarentolae secreted acid phosphatase (SAP) activity. Cell viability did not significantly decrease in the presence of 50 µM anti-perovskite compounds, implying limited cytotoxicity. Yet SAP activity did increase in the cell free preparations with time in the presence of strontium compounds. Of interest was the observation that cell free SAP activity did not increase in the presence of protease inhibitors with or without added strontium compounds. Since secreted proteases may play a role in the maturation of Leishmania SAP and thus be involved with parasite-host infection establishment, this is in further need of evaluation. Nitric oxide production on day 4 post-addition of the strontium compounds was evaluated and showed an approximately 50% decrease in NO production in the presence of two test compounds relative to DMSO control cells. This is the first report of anti-perovskite compound inhibition of NO production by Leishmania.

PANI@UiO-66 and PANI@UiO-66-NH2 Polymer-MOF Hybrid Composites as Tunable Semiconducting Materials.

This investigation explores optimum synthetic conditions for novel polymer-metal organic framework hybrid composites composed of Zr-terephthalate-based MOF UiO-66 and conductive polyaniline (PANI) nanofibers in an effort to optimize conductivity while minimizing MOF structural deformation. Successful syntheses of self-assembled PANI nanofibers in PANI@UiO-66 and PANI@UiO-66-NH2 composites were confirmed using scanning electron microscopy, infrared spectroscopy, and powder X-ray diffraction. The polymer-MOF composites show different bonding synergies to the PANI nanofibers depending on the organic linker used. Electronic properties of the post-synthetically modified PANI@UiO-66 and PANI@UiO-66-NH2 were investigated using UV-vis diffuse reflectance spectroscopy. Sheet resistivity of the self-assembled polymer-MOF composites was determined under an inert atmosphere at room temperature using four-point probe measurements to confirm tunable semiconductivity ranging from 40 to 2 mS/sq. Furthermore, the effects of aniline oxidation on the crystallinity and coordination of UiO-66 and UiO-66-NH2 were determined through analysis of these results.

Structural characterization and photoluminescence in the rare earth-free oxy-fluoride anti-perovskites Sr3-xBi2x/3AlO4F and Sr3-xBi2x/3GaO4F.

The activator Bi3+ has been successfully incorporated into the anti-perovskite oxy-fluoride host lattice Sr3MO4F (M = Al, Ga) to form rare earth-free phosphors of the composition Sr3-xBi2x/3AlO4F, 0 ≤ x ≤ 0.1, and Sr3-xBi2x/3GaO4F, 0 ≤ x ≤ 0.048. These phases absorb in the UV region (λex = 240-326 nm) and exhibit broad emission in the blue region of the visible spectrum (λem = 446.5-455 nm). The optimum compositions for maximum photoluminescent intensity were determined to be Sr2.976Bi0.016AlO4F and Sr2.976Bi0.016GaO4F before concentration quenching occurs. Full structural characterization based upon PXRD and NPD data were performed with DFT calculations suggesting that Bi3+ ions are preferentially incorporated on the ten coordinate Sr(1) site.

Synthesis and characterisation of the quaternary nitride-fluoride Ce2MnN3F(2-delta).

Ce(2)MnN(3)F(2-delta) has been synthesised via low-temperature fluorination of the ternary nitride Ce(2)MnN(3). To the best of our knowledge, Ce(2)MnN(3)F(2-delta) is the first quaternary nitride-fluoride to be reported. The reaction of Ce(2)MnN(3) with 10% F(2)/N(2) at 95-115 degrees C yields the fluorinated phase Ce(2)MnN(3)F(2-delta), with tetragonal symmetry (P4/nmm a = 3.8554(4) A and c = 13.088(4) A based on neutron powder diffraction), accompanied by starting material. Rietveld refinement supports a staged fluorine insertion reaction (into alternate rocksalt layers) to give a product with stoichiometry Ce(2)MnN(3)F(2-delta). A comparison with the formation of Sr(2)TiO(3)F(2) and the isostructural LaSrMnO(4)F indicates that two F(-) anions are inserted but no F(-)/N(3-) substitution takes place. Magnetic susceptibility measurements show a transition from Pauli paramagnetic behaviour, in Ce(2)MnN(3), to paramagnetic behaviour upon fluorination. The effective magnetic moment in Ce(2)MnN(3)F(2-delta), mu(eff) = 5.38 mu(B), is consistent with an intermediate value between that of Mn(3+) (4.9 mu(B)) and Mn(2+) (5.9 mu(B)) supporting the proposed stoichiometry, Ce(2)MnN(3)F(2-delta).