A novel Bi12TiO20/g-C3N4 hybrid catalyst with a bionic granum configuration for enhanced photocatalytic degradation of organic pollutants.

A facile synthesis method was used to produce a novel, multi-layer hybrid carbon nitride with a granum microstromatolite structure (g-C3N4MS). This was combined with Bi12TiO20 (BTO) to produce a catalyst that was useful for decomposing hazardous pollutants. The microstructural investigation of the catalyst showed that the stacked-layer stromatolites of the g-C3N4MS were covered with BTO nanoplates to form the granum-like structures. The coupling between the BTO {310} and the g-C3N4MS {002} facets produced a heterostructure with a large contact area that efficiently separated the photo-generated electrons and holes by a reduction in the CB potential of g-C3N4MS. The photocatalytic performance of this novel catalyst was found to exhibit an optimum efficiency of 97% for the degradation of RhB within 50 min and it had a degradation rate constant that was 11.8 times better than bare BTO and 4.2 times better than g-C3N4MS. Moreover, the synthesized photocatalysts demonstrated good reusability and stability. Based on electron spin resonance results for the novel catalyst, O2- radicals were identified as the main active species in the photocatalytic reaction. A new Z-scheme heterogeneous structure was proposed that reasonably explained the photocatalytic reaction mechanism of the novel catalyst.

Fluorescence resonance energy transfer of CaF2: Eu2+, Tb3+ applied to dye-sensitized solar cells.

CaF2: Eu2+, Tb3+ introduced into dye-sensitized solar cells (DSSCs) were studied to examine the influence of luminescent materials on photoanodes using a simple method. The emission spectra of CaF2: Eu2+, Tb3+ included the blue light of Eu2+ (4f → 5d) at 430 nm and green emission of Tb3+ (5D4 → 7F5) at 542 nm under the monitoring wavelengths at 398 nm, which matched well the absorption range of the N719 dye in DSSCs. Energy transfer (ET) was verified between Eu2+ and Tb3+ ions and the efficiency of ET found to increase with Tb3+ concentration. Both the fluorescence resonance and luminescence-mediated ETs between phosphor and N719 dye were observed as the main contribution in improving photocurrent and power conversion efficiency (PCE) of these DSSCs. The PCE of DSSCs doped with phosphors was greatly increased by 5.16, to 43.3%, which was comparable to cells made of pure TiO2 photoanodes. Moreover, CaF2: Eu2+, Tb3+ enlarged the surface area of TiO2 photonaodes, which helped the adsorption performance of the TiO2 film.

Synergistic anticancer properties of docosahexaenoic acid and 5-fluorouracil through interference with energy metabolism and cell cycle arrest in human gastric cancer cell line AGS cells.

AIM: To explore the synergistic effect of docosahexaenoic acid (DHA)/5-fluorouracil (5-FU) on the human gastric cancer cell line AGS and examine the underlying mechanism. METHODS: AGS cells were cultured and treated with a series of concentrations of DHA and 5-FU alone or in combination for 24 and 48 h. To investigate the synergistic effect of DHA and 5-FU on AGS cells, the inhibition of cell proliferation was determined by MTT assay and cell morphology. Flow cytometric analysis was also used to assess cell cycle distribution, and the expression of mitochondrial electron transfer chain complexes (METCs) I, II and V in AGS cells was further determined by Western blot analysis. RESULTS: DHA and 5-FU alone or in combination could markedly suppress the proliferation of AGS cells in a significant time and dose-dependent manner. DHA markedly strengthened the antiproliferative effect of 5-FU, decreasing the IC50 by 3.56-2.15-fold in an apparent synergy. The morphological changes of the cells were characterized by shrinkage, cell membrane blebbing and decreased adherence. Cell cycle analysis showed a shift of cells into the G0/G1 phase from the S phase following treatment with DHA or 5-FU (G0/G1 phase: 30.04% ± 1.54% vs 49.05% ± 6.41% and 63.39% ± 6.83%, respectively, P < 0.05; S phase: 56.76% ± 3.14% vs 34.75% ± 2.35% and 25.63% ± 2.21%, respectively, P < 0.05). Combination treatment of DHA and 5-FU resulted in a significantly larger shift toward the G0/G1 phase and subsequent reduction in S phase (G0/G1 phase: 69.06% ± 2.63% vs 49.05% ± 6.41% and 63.39% ± 6.83%, respectively, P < 0.05; S phase: 19.80% ± 4.30% vs 34.75% ± 2.35% and 25.63% ± 2.21%, respectively, P < 0.05). This synergy was also reflected in the significant downregulation of the expression of METCs in AGS cells. CONCLUSION: Synergistic anticancer properties of DHA and 5-FU may involve interference with energy production of AGS cells via downregulation of METCs and cell cycle arrest.

Yeast NDI1 improves oxidative phosphorylation capacity and increases protection against oxidative stress and cell death in cells carrying a Leber's hereditary optic neuropathy mutation.

G11778A in the subunit ND4 gene of NADH dehydrogenase complex is the most common primary mutation found in Leber's hereditary optic neuropathy (LHON) patients. The NDI1 gene, which encodes the internal NADH-quinone oxidoreductase in Saccharomyces cerevisiae, was introduced into the nuclear genome of a mitochondrial defective human cell line, Le1.3.1, carrying the G11778A mutation. In transformant cell lines, LeNDI1-1 and -2, total and complex I-dependent respiration were fully restored and largely resistant to complex I inhibitor, rotenone, indicating a dominant role of NDI1 in the transfer of electrons in the host cells. Whereas the original mutant Le1.3.1 cell grows poorly in medium containing galactose, the transformants have a fully restored growth capacity in galactose medium, although the ATP production was not totally recovered. Furthermore, the increased oxidative stress in the cells carrying the G11778A mutation was alleviated in transformants, demonstrated by a decreased reactive oxygen species (ROS) level. Finally, transformants were also shown to be desensitized to induction to apoptosis and also exhibit greater resistance to paraquat-induced cell death. It is concluded that the yeast NDI1 enzyme can improve the oxidative phosphorylation capacity in cells carrying the G11778A mutation and protect the cells from oxidative stress and cell death.

[Therapeutic effect of dietary boron supplement on retinoic acid-induced osteoporosis in rats].

OBJECTIVE: To observe the therapeutic efficacy of dietary boron supplement on retinoic acid-induced osteoporosis in rats, so as to provide experimental evidence for clinical management of osteoporosis with boron. METHODS: Thirty-two SD rats were randomized into normal control group (8 rats) and osteoporotic group (24 rats), and osteoporosis was induced in rats of the latter group by intragastric retinoic acid administration at the daily dose of 80 mg/kg for 15 consecutive days. The osteoporotic rats were subdivided into control group (8 rats) without treatment, boron treatment group (8 rats) and estradiol treatment group (8 rats). After 30 days of treatment, the serum contents of Ca, P, boron and the activities of alkaline phosphatase (AKP) and tartrate-resistant acid phosphatase (TRAP) in the rats were assayed, the bone mineral density (BMD) of the whole body, lumbar vertebrae and tibia were determined, and the morphological changes of the femurs were observed. RESULTS: The serum contents of Ca and P in the rats of the 4 groups differed scarcely, but the content of boron in boron treatment group was markedly higher than that in the other three groups. In the osteoporotic control group, the activities of serum AKP and TRAP, the masses of spongy bone and cortical bone of the femurs, and the quantity of the osteoclasts were increased, with the BMD of the lumbar vertebrae and tibia decreased, suggesting osteoporotic conditions. The mean trabecular plate density and thickness, trabecular bone volume and cortical bone volume of the femurs in the osteoporotic rats treated with boron or estradiol were significantly increased, but the active osteoclast quantity in the spongy bone and serum TRAP activities were obviously decreased, and the bone quality was comparable with that of the normal group. In addition, the serum AKP activity and the active osteoblast quantity in the spongy bone were obviously increased in boron treatment group. CONCLUSION: The dietary boron supplement can increase the serum content of boron of osteoporotic rats to stimulate bone formation and inhibit bone resorption, producing therefore obvious therapeutical effect against osteoporosis.

[The effect of retinoic acid on induction of osteoporotic model rats and the possible mechanism].

OBJECTIVE: To observe the effect of retinoic acid on induction of osteoporotic model in rats and analyze the mechanism therein involved. METHODS: SD rats were treated with retinoic acid 80 mg/(kg x d) by gastrogavage for 15 days to induce osteoporosis and were killed in batches at 0, 30 and 60 days after drug withdrawal. The levels of Ca, P, BGP, E2, IGF-1, AKP and TRAP in serum were assayed, the collagen and proteoglycan contents of bone and bone mineral density (BMD) were determined, and the morphological changes in cancellous and cortical bone and growth plate cartilage (GPC) of femurs from the experimental rats were observed. RESULTS: After 15 days of induction by retinoic acid, the serum E2 and BGP contents of rats were obviously decreased, the activities of AKP and TRAP were significantly increased, and the levels of BMD were lowered. The masses of spongy bone and cortical bone of femurs from the rats were decreased, and the number of chondrocytes in GPC was reduced. At 30 days, after drug withdrawal, the masses of spongy bone and cortical bone of femurs from the osteoporotic model rats still showed reduction; the activities of AKP in serum were lower than those at 15 days after drug redrawal, but were still higher than those of normal group rats; the chondrocytes in GPC were increased, the serum BGP and Ca contents were increased. At 60 days, after drug withdrawal, only the masses of femoral spongy bone of the osteoporotic model rats continuously showed obvious reduction, the other indices, including BGP, E2, AKP, TRAP and the masses of cortical bone, showed no significant difference between the two groups. CONCLUSION: The short-term effect of retinoic acid on induction of rat's osteoporotic model was noticeable, but the long-term effect was not so good, and the bone loss of spongy bone existed longer and was more obvious than that of cortical bone.