The role and mechanism of hydrogen sulfide in liver fibrosis.

Hydrogen sulfide (H2S) is the third new gas signaling molecule in the human body after the discovery of NO and CO. Similar to NO, it has the functions of vasodilation, anti-inflammatory, antioxidant, and regulation of cell formation. Enzymes that can produce endogenous H2S, such as CSE, CSB, and 3-MST, are common in liver tissues and are important regulatory molecules in the liver. In the development of liver fibrosis, H2S concentration and expression of related enzymes change significantly, which makes it possible to use exogenous gases to treat liver diseases. This review summarizes the role of H2S in liver fibrosis and its complications induced by NAFLD and CCl4, and elaborates on the anti-liver fibrosis effect of H2S through the mechanism of reducing oxidative stress, inhibiting inflammation, regulating autophagy, regulating glucose and lipid metabolism, providing theoretical reference for further research on the treatment of liver fibrosis with H2S.

Catalytic Degradation of Triphenylmethane Dyes with an Iron Porphyrin Complex as a Cytochrome P450 Model.

The organic dyes used in printing and dyeing wastewater have complex components, diverse structures and strong chemical stability, which make them not suitable for treatment and difficult to degrade in the environment. Porphyrins are macromolecules with 18 π electrons formed by four pyrrole molecules connected with a methylene bridge that has a stable structure. Porphyrin combines with iron to form an active intermediate with a structure similar to the cytochrome P450 enzyme, so they are widely used in the biomimetic field. In the current study, 5,10,15,20-tetra (4-carboxyphenyl) porphine ferric chloride (III) (Fe(III)TCPP) was used as a catalyst and iodosobenzene was used as an oxidant to explore the catalytic degradation of triphenylmethane dyes, such as rhodamine B (RhB) and malachite green (MG). The results of UV-Vis spectral analysis have shown that the conversion rate of the rhodamine B was over 90% when the amount of Fe(III)TCPP was 0.027 mM and the amount of iodosobenzene was eight equivalents. When the catalyst was 0.00681 mM and the amount of the oxidant was five equivalents, the conversion rate of the malachite green reached over 95%. This work provides a feasible method for the degradation of triphenylmethane dyes.

Metal organic framework derived one-dimensional porous Fe/N-doped carbon nanofibers with enhanced catalytic performance.

The aggregation of metal nanoparticles and collapse of precursor metal organic frameworks (MOFs) structure during the carbonization process largely hamper the catalytic performance of MOFs-derived carbon catalysts. Here, we report hollow and porous one-dimensional Fe/N-doped carbon nanofibers (Fe/NCNFs) for activating peroxymonosulfate (PMS), which was obtained by immobilizing Fe-MIL-101 on polyacrylonitrile (PAN) nanofibers via electrospinning technique followed by pyrolysis. The presence of one-dimensional PAN channel suppresses the agglomeration tendency of metal particles during the carbonisation process of Fe-MIL-101, resulting in a uniform dispersion of nanoparticles and an increase of catalytic active sites. The resultant Fe/NCNFs-9 possesses unique hierarchical architecture, large active surface area, well-dispersed Fe species, and abundant Fe-N active sites. These superiorities contributed to the better catalytic performance of Fe/NCNFs-9 compared with PAN derived carbon (PAN-C-9) and Fe-MIL-101 derived carbon (Fe-C-9). Through a series of inhibitor experiments and electrochemical tests, the radical pathway is dominant on BPA removal with the participation of the non-radical pathway in the multi-sites Fe/NCNFs-9/PMS/BPA system. Surprisingly, this strategy could successfully disperse Fe species and effectively reduce the Fe leaching. This work supplies a novel method to design efficient MOFs-derived carbon catalysts toward micropollutants removal.

Singlet oxygen-dominated non-radical oxidation process for efficient degradation of bisphenol A under high salinity condition.

The degradation of organic contaminants under high salinity condition is still a challenge for environmental remediation due to the inhibiting effect resulted from the side reactions between radicals and anions. Here, we demonstrate the non-radical oxidation process via peroxymonosulfate (PMS) activation by metal-free carbon catalyst for efficiently decomposing bisphenol A (BPA) in saline water. The nitrogen-doped graphitic carbon (NGC700) exhibits excellent catalytic activity for depredating BPA at acid and neutral pH. Based on the scavenger experiments and electron paramagnetic resonance (EPR) analyses, the mechanism of catalytic oxidation was elucidated as the non-radical pathway, and singlet oxygen was identified as the primary reactive species. Experiments on the influence of anions (5-500 mM) further show that the inhibiting effect was overcame due to the non-radical process. Interestingly, Cl- markedly facilitated the catalytic performance by generating HOCl in the catalytic process. The results highlight leveraging the non-radical pathway dominated by singlet oxygen to conquer the inhibitory effect of anions in NGC700/PMS system, which represents a crucial step towards environmental remediation under high salinity condition.