Thermal Stability, Microstructure and Photocatalytic Activity of the Bismuth Oxybromide Photocatalyst

Flake BiOBr was first prepared by a solution method at room temperature. Then, the produced BiOBr was calcined at different temperatures. It was found that BiOBr is not a stable compound. It transforms to plate-like Bi24031Brll at around 750 ℃ and the formed Bi24O31Br11 can further convert to rod-like a-Bi203 at around 850℃. The prepared compounds were characterized with X-ray diffraction （XRD）, N2 physical adsorption, scanning electron microscopy （SEM）, and UV-Vis diffuse reflectance spectra （DRS）, respectively. The photocatalytic activity of the produced bismuth oxybromides was evaluated by photocatalytic decomposition of acid orange Ⅱ under both visible light （λ〉420 nm） and UV light （λ=365 nm） irradiation. Results show that these compounds have different band gaps and different photocatalytic properties. The band gap energies of the as-prepared samples were found to be 2.82, 2.79, 2.60 and 3.15 eV for BiOBr, BiOBr/Bi24O31Br, Bi24O31Br, and a-Bi2O3, respectively. Under both UV light and visible light irradiation, the photocatalytic activity follows the order： BiOBr/Bi24O31Br mixture 〉 BiOBr 〉 Bi24031Br〉a-Bi2O3. The change in photocatalytic activity could be attributed to the different light absorption ability and microstructures of the photocatalysts.

Discovery and characterization of novel small-molecule inhibitors targeting nicotinamide phosphoribosyltransferase

Aim Nicotinamide phosphoribosyltransferase （NAMPT） plays an important role in cardiocerebro-vascu- lar physiopathological process. It is also a promising anticancer target. It is highly desirable to discover novel NAMPT inhibitors as anticancer drug candidates and understand their action mode. Methods We carried out a high throughput screening system on a chemical library of 24434 small-molecules. Anti-proliferative activity were further studied on active compounds. Isothermal titration calorimetry and cellular thermal shift assay were used to confirm the target specificity. Molecular modeling and site-directed mutagenesis studies were taken to investigate the binding mode of NAMPT inhibitor. Results Using high throughput screening system targeting NAMPT, we ob- tained a potent NAMPT inhibitor MS0 （China Patent ZL201110447488.9 ） with excellent in vitro activity （IC50 = 9.87 ± 1.15 nmol · L^-1 ） and anti-proliferative activity against multiple human cancer cell lines including stem-like cancer cells. Structure-activity relationship studies yielded several highly effective analogues. These inhibitors spe- cifically bound NAMPT, rather than downstream NMNAT. We provided the first chemical case using cellular ther- mal shift assay to explain the difference between in vitro and cellular activity; MS7 showed best in vitro activity （ IC50 = 0.93 ± 0.29 nmol · L^-1 ） but worst cellular activity due to poor target engagement in living cells. Site-di- rected mutagenesis studies identified important residues for NAMPT catalytic activity and inhibitor binding. Con- clusions The present study provides a class of novel NAMPT inhibitors for future development of anticancer a- gents. Our findings also contribute to deep understanding the action mode of NAMPT inhibitors and NAMPT basic research in cardiocerebro-vascular system.