Efficient generation of singlet oxygen(1 O_(2)) by an excitonic ene rgy transfer process is highly desired on a semiconductor photocatalyst for selective oxidation of methyl phenyl sulfide(MPS).Herein,it is demonstrat...Efficient generation of singlet oxygen(1 O_(2)) by an excitonic ene rgy transfer process is highly desired on a semiconductor photocatalyst for selective oxidation of methyl phenyl sulfide(MPS).Herein,it is demonstrated that a large amount of 1 O_(2) is produced on pristine graphitic carbon nitride(CN) nanosheet compared with bismuth oxybromide(BiOBr) and comme rcial P25 titanium dioxide(TiO_(2)).This leads to a certain photoactivity of CN for MPS oxidation.The observed ~77% selectivity for CN depends on the competitive results of excitonic energy transfer for 1 O_(2) formation and charge carrier separation for superoxide radical(O_(2)·) production,which are based on the phosphorescence spectra and electron paramagnetic resonance signals,respectively.Moreover,ultrathin CN nanosheets are synthesized by thermal treatment with the cyanuric acid-melamine hydrogen bonded aggregates as precursors.It is confirmed that the amount of produced 1 O_(2) could be increased by decreasing the thickness of resultant CN nanosheets.The optimized ultrathin CN nanosheet(~4 nm) exhibits excellent photoactivity with high selectivity(~99%).It is suggested that the excitonic energy transfer for 1 O_(2) formation is close related to the intrinsic exciton binding energy and the two-dimensional quantum confinement effect.This work establishes a basic mechanistic understanding on the excitonic processes in CN,and develops a feasible route to design CN-based photocatalysts for efficient 1 O_(2) generation.展开更多
AIM: To investigate the hepatoprotective effects and antioxidant activity of caffeic acid phenethyl ester(CAPE) in rats with liver fibrosis. METHODS: A total of 75 male Sprague-Dawley rats were randomly assigned to se...AIM: To investigate the hepatoprotective effects and antioxidant activity of caffeic acid phenethyl ester(CAPE) in rats with liver fibrosis. METHODS: A total of 75 male Sprague-Dawley rats were randomly assigned to seven experimental groups: a normal group(n = 10), a vehicle group(n = 10), a model group(n = 15), a vitamin E group(n = 10), and three CAPE groups(CAPE 3, 6 and 12 mg/kg, n = 10, respectively). Liver fibrosis was induced in rats by injecting CCl4 subcutaneously, feeding with high fat forage, and administering 30% alcohol orally for 10 wk. Concurrently, CAPE(3, 6 and 12 mg/kg) was intraperitoneally administered daily for 10 wk. After that, serum total bilirubin(TBil), aminotransferase(ALT) and aspartate aminotransferase(AST) levels were measured to assess hepatotoxicity. To investigate antioxidant activity of CAPE, malondialdehyde(MDA), glutathione(GSH) levels, catalase(CAT) and superoxide dismutase(SOD) activities in liver tissue were determined. Moreover, the effect of CAPE on α-smooth muscle actin(α-SMA), a characteristic hallmark of activated hepatic stellate cells(HSCs), and NF-E2-related factor 2(Nrf2), a key transcription factor for antioxidant systems, was investigated by immunohistochemistry. RESULTS: Compared to the model group, intraperitoneal administration of CAPE decreased TBil, ALT, and AST levels in liver fibrosis rats(P < 0.05), while serum TBil was decreased by CAPE in a dose-dependent manner. In addition, the liver hydroxyproline contents in both the 6 and 12 mg/kg CAPE groups were markedly lower than that in the model group(P < 0.05 and P < 0.001, respectively). CAPE markedly decreased MDA levels and, in turn, increased GSH levels, as well as CAT and SOD activities in liver fibrosis rats compared to the model group(P < 0.05). Moreover, CAPE effectively inhibited α-SMA expression while increasing Nrf2 expression compared to the model group(P < 0.01). CONCLUSION: The protective effects of CAPE against liver fibrosis may be due to its ability to suppress the activation of HSCs by inhibiting oxidative stress.展开更多
基金NSFC(Nos.U1805255,11804086,21706044,21971057)General Financial Grant from the China Postdoctoral Science Foundation(No.2017M621316)+2 种基金the Natural Science Foundation of Heilongjiang Province,China(No.B2017006)the General Financial Grant from the Postdoctoral Science Foundation of Heilongjiang Province,China(No.LBHZ17187)the General Financial Grant from Heilongjiang Province for returned students from overseas in 2018。
文摘Efficient generation of singlet oxygen(1 O_(2)) by an excitonic ene rgy transfer process is highly desired on a semiconductor photocatalyst for selective oxidation of methyl phenyl sulfide(MPS).Herein,it is demonstrated that a large amount of 1 O_(2) is produced on pristine graphitic carbon nitride(CN) nanosheet compared with bismuth oxybromide(BiOBr) and comme rcial P25 titanium dioxide(TiO_(2)).This leads to a certain photoactivity of CN for MPS oxidation.The observed ~77% selectivity for CN depends on the competitive results of excitonic energy transfer for 1 O_(2) formation and charge carrier separation for superoxide radical(O_(2)·) production,which are based on the phosphorescence spectra and electron paramagnetic resonance signals,respectively.Moreover,ultrathin CN nanosheets are synthesized by thermal treatment with the cyanuric acid-melamine hydrogen bonded aggregates as precursors.It is confirmed that the amount of produced 1 O_(2) could be increased by decreasing the thickness of resultant CN nanosheets.The optimized ultrathin CN nanosheet(~4 nm) exhibits excellent photoactivity with high selectivity(~99%).It is suggested that the excitonic energy transfer for 1 O_(2) formation is close related to the intrinsic exciton binding energy and the two-dimensional quantum confinement effect.This work establishes a basic mechanistic understanding on the excitonic processes in CN,and develops a feasible route to design CN-based photocatalysts for efficient 1 O_(2) generation.
基金Liver Fibrosis Foundation of Wang Bao-En,China,No.20100033Science and Technology Foundation of Shaanxi Province,China,No.2010K01-199
文摘AIM: To investigate the hepatoprotective effects and antioxidant activity of caffeic acid phenethyl ester(CAPE) in rats with liver fibrosis. METHODS: A total of 75 male Sprague-Dawley rats were randomly assigned to seven experimental groups: a normal group(n = 10), a vehicle group(n = 10), a model group(n = 15), a vitamin E group(n = 10), and three CAPE groups(CAPE 3, 6 and 12 mg/kg, n = 10, respectively). Liver fibrosis was induced in rats by injecting CCl4 subcutaneously, feeding with high fat forage, and administering 30% alcohol orally for 10 wk. Concurrently, CAPE(3, 6 and 12 mg/kg) was intraperitoneally administered daily for 10 wk. After that, serum total bilirubin(TBil), aminotransferase(ALT) and aspartate aminotransferase(AST) levels were measured to assess hepatotoxicity. To investigate antioxidant activity of CAPE, malondialdehyde(MDA), glutathione(GSH) levels, catalase(CAT) and superoxide dismutase(SOD) activities in liver tissue were determined. Moreover, the effect of CAPE on α-smooth muscle actin(α-SMA), a characteristic hallmark of activated hepatic stellate cells(HSCs), and NF-E2-related factor 2(Nrf2), a key transcription factor for antioxidant systems, was investigated by immunohistochemistry. RESULTS: Compared to the model group, intraperitoneal administration of CAPE decreased TBil, ALT, and AST levels in liver fibrosis rats(P < 0.05), while serum TBil was decreased by CAPE in a dose-dependent manner. In addition, the liver hydroxyproline contents in both the 6 and 12 mg/kg CAPE groups were markedly lower than that in the model group(P < 0.05 and P < 0.001, respectively). CAPE markedly decreased MDA levels and, in turn, increased GSH levels, as well as CAT and SOD activities in liver fibrosis rats compared to the model group(P < 0.05). Moreover, CAPE effectively inhibited α-SMA expression while increasing Nrf2 expression compared to the model group(P < 0.01). CONCLUSION: The protective effects of CAPE against liver fibrosis may be due to its ability to suppress the activation of HSCs by inhibiting oxidative stress.
