WO₃/Conducting Polymer Heterojunction Photoanodes for Efficient and Stable Photoelectrochemical Water Splitting

An efficient and stable heterojunction photoanode for solar water oxidation was fabricated by hybridization of WO₃ and conducting polymers (CPs). Organic/inorganic hybrid photoanodes were readily prepared by the electropolymerization of various CPs and the codeposition of tetraruthenium polyoxometalate (Ru₄POM) water-oxidation catalysts (WOCs) on the surface of WO₃. The deposition of CPs, especially polypyrrole (PPy) doped with Ru₄POM (PPy:Ru₄POM), resulted in a remarkably improved photoelectrochemical performance by the formation of a WO₃/PPy p–n heterojunction and the incorporation of efficient Ru₄POM WOCs. In addition, there was also a significant improvement in the photostability of the WO₃-based photoanode after the deposition of the PPy:Ru₄POM layer due to the suppression of the formation of hydrogen peroxide, which was responsible for corrosion. This study provides insight into the design and fabrication of novel photosynthetic and photocatalytic systems with excellent performance and stability through the hybridization of organic and inorganic materials

Antituberculosis Activity of a Naturally Occurring Flavonoid, Isorhamnetin

Isorhamnetin (<b>1</b>) is a naturally occurring flavonoid having anticancer and anti-inflammatory properties. The present study demonstrated that <b>1</b> had antimycobacterial effects on <i>Mycobacterium tuberculosis</i> H₃₇Rv, multi-drug- and extensively drug-resistant clinical isolates with minimum inhibitory concentrations of 158 and 316 μM, respectively. Mycobacteria mainly affect the lungs, causing an intense local inflammatory response that is critical to the pathogenesis of tuberculosis. We investigated the effects of <b>1</b> on interferon (IFN)-γ-stimulated human lung fibroblast MRC-5 cells. Isorhamnetin suppressed the release of tumor necrosis factor (TNF)-α and interleukin (IL)-12. A nontoxic dose of <b>1</b> reduced mRNA expression of TNF-α, IL-1β, IL-6, IL-12, and matrix metalloproteinase-1 in IFN-γ-stimulated cells. Isorhamnetin inhibited IFN-γ-mediated stimulation of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase and showed high-affinity binding to these kinases (binding constants: 4.46 × 10⁶ M^–1 and 7.6 × 10⁶ M^–1, respectively). The 4′-hydroxy group and the 3′-methoxy group of the B-ring and the 5-hydroxy group of the A-ring of <b>1</b> play key roles in these binding interactions. A mouse <i>in vivo</i> study of lipopolysaccharide-induced lung inflammation revealed that a nontoxic dose of <b>1</b> reduced the levels of IL-1β, IL-6, IL-12, and INF-γ in lung tissue. These data provide the first evidence that <b>1</b> could be developed as a potent antituberculosis drug