Unveiling the role of proton concentration in dinuclear metal complexes for boosting photocatalytic CO2 reduction.

The reaction kinetics of photocatalytic CO2 reduction is highly dependent on the transfer rate of electrons and protons to the CO2 molecules adsorbed on catalytic centers. Studies on uncovering the proton effect in catalysts on photocatalytic activity of CO2 reduction are significant but rarely reported. In this paper, we, from the molecular level, revealed that the photocatalytic activity of CO2 reduction is closely related to the proton availability in catalysts. Specifically, four dinuclear Co(II) complexes based on Robson-type ligands with different number of carboxylic groups (-nCOOH; n = 0, 2, 4, 6) were designed and synthesized. All these complexes show photocatalytic activity for CO2 reduction to CO in a water-containing system upon visible-light illumination. Interestingly, the CO yields increase positively with the increase of the carboxylic-group number in dinuclear Co(II) complexes. The one containing -6COOH shows the best photocatalytic activity for CO2 reduction to CO, with the TON value reaching as high as 10,294. The value is 1.8, 3.4, and 7.8 times higher than those containing -4COOH, -2COOH, and -0COOH, respectively. The high TON value also makes the dinuclear Co(II) complex with -6COOH outstanding among reported homogeneous molecular catalysts for photocatalytic CO2 reduction. Control experiments and density functional theory calculation indicated that more carboxylic groups in the catalyst endow the catalyst with more proton relays, thus accelerating the proton transfer and boosting the photocatalytic CO2 reduction. This study, at a molecular level, elucidates that more carboxylic groups in catalysts are beneficial for boosting the reaction kinetics of photocatalytic CO2 reduction.

A Planar-Structured Dinuclear Cobalt(II) Complex with Indirect Synergy for Photocatalytic CO2-to-CO Conversion.

Dinuclear metal synergistic catalysis (DMSC) has been proved an effective approach to enhance catalytic efficiency in photocatalytic CO2 reduction reaction, while it remains challenge to design dinuclear metal complexes that can show DMSC effect. The main reason is that the influence of the microenvironment around dinuclear metal centres on catalytic activity has not been well recognized and revealed. Herein, we report a dinuclear cobalt complex featuring a planar structure, which displays outstanding catalytic efficiency for photochemical CO2-to-CO conversion. The turnover number (TON) and turnover frequency (TOF) values reach as high as 14457 and 0.40 s-1 respectively, 8.6 times higher than those of the corresponding mononuclear cobalt complex. Control experiments and theoretical calculations revealed that the enhanced catalytic efficiency of the dinuclear cobalt complex is due to the indirect DMSC effect between two CoII ions, energetically feasible one step two-electron transfer process by Co2 I,I intermediate to afford Co2 II,II(CO2 2-) intermediate and fast mass transfer closely related with the planar structure.

Cited2 inhibited hypoxia-induced proliferation and migration of PASMCs via the TGF-ß1/Cited2/PPARγ pathway.

Objectives: Proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) contribute to hypoxia-induced pulmonary hypertension (HPH). The transcription factor Cbp/p300-interacting transactivator with Glu/Asp-rich carboxy-terminal domain 2 (Cited2) has been implicated in the control of tumor cells and mesenchymal stem cell (MSC) and cardiomyocyte growth or migration. Whether Cited2 is involved in the proliferation and migration of PASMCs and the underlying mechanisms deserve to be explored. Materials and Methods: Cited2 expression was detected in rat PASMCs under hypoxia conditions and HPH rat models. The effect of Cited2 on the proliferation and migration of PASMC was detected by overexpression or knockdown of the Cited2 gene. After PAMSCs were treated with recombinant TGF-ß1 and the lentivirus vector overexpressing Cited2, expression of peroxisome proliferator-activated receptor gamma (PPARγ) was examined by western blotting. Results: We revealed that hypoxia down-regulated the expression of Cited2 in PASMCs and rat pulmonary arteries. Cited2 overexpression inhibited the proliferation and migration of PASMCs under hypoxia, while Cited2 knockdown induced the proliferation and migration of PASMCs. Cited2 inhibits the negative regulation of the TGF-ß1 pathway on PPARγ to inhibit the proliferation and migration of PASMCs. Conclusion: These findings suggest that increased Cited2 expression contributes to the inhibition of PASMCs proliferation and migration by regulating TGF-ß1-mediated target gene expression in HPH and provides a new target for molecular therapy of HPH.

Efficacy of radiofrequency ablation combined with sorafenib for treating liver cancer complicated with portal hypertension and prognostic factors.

BACKGROUND: Patients with liver cancer complicated by portal hypertension present complex challenges in treatment. AIM: To evaluate the efficacy of radiofrequency ablation in combination with sorafenib for improving liver function and its impact on the prognosis of patients with this condition. METHODS: Data from 100 patients with liver cancer complicated with portal hypertension from May 2014 to March 2019 were analyzed and divided into a study group (n = 50) and a control group (n = 50) according to the treatment regimen. The research group received radiofrequency ablation (RFA) in combination with sorafenib, and the control group only received RFA. The short-term efficacy of both the research and control groups was observed. Liver function and portal hypertension were compared before and after treatment. Alpha-fetoprotein (AFP), glypican-3 (GPC-3), and AFP-L3 levels were compared between the two groups prior to and after treatment. The occurrence of adverse reactions in both groups was observed. The 3-year survival rate was compared between the two groups. Basic data were compared between the survival and non-surviving groups. To identify the independent risk factors for poor prognosis in patients with liver cancer complicated by portal hypertension, multivariate logistic regression analysis was employed. RESULTS: When comparing the two groups, the research group's total effective rate (82.00%) was significantly greater than that of the control group (56.00%; P < 0.05). Following treatment, alanine aminotransferase and aspartate aminotransferase levels increased, and portal vein pressure decreased in both groups. The degree of improvement for every index was substantially greater in the research group than in the control group (P < 0.05). Following treatment, the AFP, GPC-3, and AFP-L3 levels in both groups decreased, with the research group having significantly lower levels than the control group (P < 0.05). The incidence of diarrhea, rash, nausea and vomiting, and fatigue in the research group was significantly greater than that in the control group (P < 0.05). The 1-, 2-, and 3-year survival rates of the research group (94.00%, 84.00%, and 72.00%, respectively) were significantly greater than those of the control group (80.00%, 64.00%, and 40.00%, respectively; P < 0.05). Significant differences were observed between the survival group and the non-surviving group in terms of Child-Pugh grade, history of hepatitis, number of tumors, tumor size, use of sorafenib, stage of liver cancer, histological differentiation, history of splenectomy and other basic data (P < 0.05). Logistic regression analysis demonstrated that high Child-Pugh grade, tumor size (6-10 cm), history of hepatitis, no use of sorafenib, liver cancer stage IIIC, and previous splenectomy were independent risk factors for poor prognosis in patients with liver cancer complicated with portal hypertension (P < 0.05). CONCLUSION: Patients suffering from liver cancer complicated by portal hypertension benefit from the combination of RFA and sorafenib therapy because it effectively restores liver function and increases survival rates. The prognosis of patients suffering from liver cancer complicated by portal hypertension is strongly associated with factors such as high Child-Pugh grade, tumor size (6-10 cm), history of hepatitis, lack of sorafenib use, liver cancer at stage IIIC, and prior splenectomy.