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It is still a great challenge to develop electrocatalysts for CO2 reduction with high product selectivity and energy conversion efficiency. In this work, Bi nanoparticles supported on polymeric carbon nitride (Bi/CN) have been prepared for CO2 electrocatalytic conversion. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analyses confirm the existence of Bi2O3 on Bi particle surface, forming Bi/Bi2O3 nanoparticles. CN, as the support, has been found not only to improve the dispersibility of Bi/Bi2O3 nanoparticles, but also to enhance the CO2 adsorption on Bi/CN surface owing to the existence of amino and cyano groups. The electronic structure of Bi/CN has been optimized by the interaction between CN and Bi: the electron transfer from Bi to CN results in electron-deficient Bi sites which stabilize CO2-, HCOO- intermediates and accelerate the formation rate of HCOOH. As a result, the maximum Faradaic efficiency of HCOOH reaches 98% at -1.3 to -1.5 V versus reversible hydrogen electrode (vs. RHE) and remains over 91% in a wide potential window of about 500 mV (-1.1 âˆ¼ -1.6 V vs. RHE). The as-obtained Bi/CN in this work shows superior performance to most of the previously reported Bi-based electrocatalysts.

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The electroreduction of CO2 into the highly value-added fuel formic acid (HCOOH) has been considered an ideal approach to convert renewable energy and mitigate environmental crisis. SnO2 electrode is one of the promising candidates to electrocatalytically convert CO2 to HCOOH, but its poor stability limits its future development and application. In this study, highly stable SnO2 /Bi2 O3 oxide catalysts are obtained by distributing SnO2 nanoparticles on the surface of Bi2 O3 sheets. The XPS spectra revealed an interfacial electronic transportation from Bi2 O3 sheets to SnO2 nanoparticles, which made SnO2 rich of electrons. The strong interfacial interaction protected the active sites of SnO2 from self-reduction in CO2 electroreduction reaction (CO2 RR), stabilizing SnO2 species in the composite catalyst even after long-term usage. Calculations based on density functional theory signified that the presence of Bi2 O3 favored the adsorption of HCOO* intermediate, improved the CO2 conversion into HCOOH on SnO2 /Bi2 O3 interface. As a result, the SnO2 /Bi2 O3 catalyst attained high performance on CO2 RR (the highest FE C 1 value of 90 % at -1.0 V vs. RHE), suppressing H2 evolution reaction (HER) at high potentials. In particular, the selectivity of HCOOH remained above 76 % in a wide potential window (from -1.0 to -1.4 V vs. RHE) and a long duration (12 h).

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Developing highly efficient photocatalysts is of crucial importance to solve the energy crisis and global warming issues. In this work, a P-doped polymeric carbon nitride (CN) photocatalyst was synthesized by one-step copolymerization of guanidine hydrochloride and phosphonitrilic chloride trimer. The doping of P in CN was found to alter the electronic structure, enhance the charge separation and transfer, and promote the CO2 adsorption and activation, making it an efficient CO2 photoreduction catalyst. At the optimized P dose, the CO evolution amount on P-doped CN reached 0.349 µmol (30 mg, 3 h), which was 3.5 times that of pure CN. The process of CO2 photoreduction on P-doped CN was investigated by in situ FTIR analysis, revealing that P doping could promote the formation of a CO2- intermediate. A possible mechanism has been proposed, which may provide new insights into the effect of non-metal element doping in CN on its CO2 photocatalytic reduction performance.

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Electrochemical conversion of CO2 into liquid fuels by efficient and earth-abundant catalysts is of broad interest but remains a great challenge in renewable energy production and environmental remediation. Herein, a Sn particle-decorated polymeric carbon nitride (CN) electrocatalyst was successfully developed for efficient, durable, and highly selective CO2 reduction to formic acid. High-resolution X-ray photoelectron spectroscopy confirmed that the metallic Sn particles and CN matrix are bound by strong chemical interaction, rendering the composite catalyst a stable structure. More notably, the electronic structure of Sn was well tuned to be highly electron-rich due to the electron transfer from N atoms of CN to Sn atoms via metal-support interactions, which favored the adsorption and activation of CO2 molecules, promoted charge transport, and thus enhanced the electrochemical conversion of CO2 . The composite electrocatalyst demonstrated an excellent Faradaic efficiency of formic acid (FEHCOOH ) up to 96±2 % at the potential of -0.9 V vs. reversible hydrogen electrode, which remained at above 92 % during the electrochemical reaction of 10 h, indicating that the present Sn particle-decorated polymeric carbon nitride electrocatalyst is among the best in comparison with reported Sn-based electrocatalysts.

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The vacancy defects of semiconductor photocatalysts play key roles in enhancing their photocatalytic CO2 reduction activity. In this work, CeO2 was chosen as a model catalyst and oxygen vacancies were introduced on its surface by a facile and mild oxalic acid treatment followed by moderate heating in N2. Such a treatment resulted in a much increased ratio of Ce3+/Ce4+ in CeO2, and the oxygen vacancy-enriched CeO2 showed remarkably enhanced photocatalytic activity in CO2 reduction, with CO being the dominant reduction product, whose yield was about 8 times that on the pristine CeO2. In situ FT-IR spectra showed that the abundant oxygen vacancies substantially improved the CO2 adsorption/activation on the surface of CeO2, which facilitated the subsequent reduction of CO2. However, the carbonates strongly adsorbed on the photocatalyst surface might be the main obstacle to maintaining the high CO2 reduction activity and stability of CeO2 with O vacancies.

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The emerging metal single-atom catalyst has aroused extensive attention in multiple fields, such as clean energy, environmental protection, and biomedicine. Unfortunately, though it has been shown to be highly active, the origins of the activity of the single-atom sites remain unrevealed to date owing to the lack of deep insight on electronic level. Now, partially oxidized Ni single-atom sites were constructed in polymeric carbon nitride (CN), which elevates the photocatalytic performance by over 30-fold. The 3d orbital of the partially oxidized Ni single-atom sites is filled with unpaired d-electrons, which are ready to be excited under irradiation. Such an electron configuration results in elevated light response, conductivity, charge separation, and mobility of the photocatalyst concurrently, thus largely augmenting the photocatalytic performance.

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Porous activated carbons (PACs) are promising candidates to capture CO2 through physical adsorption because of their chemical stability, easy-synthesis, cost-effectiveness and good recyclability. However, their low CO2 adsorption capacity, especially low CO2/N2 selectivity, has limited their practical applications. In this work, an optimized PAC with a large specific surface area, a small micropore size, and a large micropore volume has been synthesized by one-step carbonization/activation of casein using K2CO3 as a mild activation agent. It showed a remarkably enhanced CO2 adsorption capacity as high as 5.78 mmol g-1 and an excellent CO2/N2 selectivity of 144 (25 °C, 1 bar). Based on DFT calculations and experimental results, the coexistence of adjacent pyridinic N and -OH/-NH2 species was proposed for the first time to make an important contribution to the ultra-high CO2 adsorption performance, especially CO2/N2 selectivity. This work provides effective guidance to design PAC adsorbents with high CO2 adsorption performance. The content of pyridine N combined with -OH/-NH2 was further elevated by additional nitrogen introduction, resulting in a further enhanced CO2 adsorption capacity up to 5.96 mmol g-1 (25 °C, 1 bar). All these results suggest that, in addition to the well-defined pore structure, pyridinic N with neighboring OH or NH2 species played an important role in enhancing the CO2 adsorption performance of PACs, thus providing effective guidance for the rational design of CO2 adsorbents.

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INTRODUCTION: Mesenchymal stem cells (MSCs) represent a heterogeneous cell population that is promising for regenerative medicine. The present study was designed to assess whether VCAM-1 can be used as a marker of MSC subpopulation with superior angiogenic potential. METHODS: MSCs were isolated from placenta chorionic villi (CV). The VCAM-1(+/-) CV-MSCs population were separated by Flow Cytometry and subjected to a comparative analysis for their angiogenic properties including angiogenic genes expression, vasculo-angiogenic abilities on Matrigel in vitro and in vivo, angiogenic paracrine activities, cytokine array, and therapeutic angiogenesis in vascular ischemic diseases. RESULTS: Angiogenic genes, including HGF, ANG, IL8, IL6, VEGF-A, TGFß, MMP2 and bFGF, were up-regulated in VCAM-1(+)CV-MSCs. Consistently, angiogenic cytokines especially HGF, IL8, angiogenin, angiopoitin-2, µPAR, CXCL1, IL-1ß, IL-1α, CSF2, CSF3, MCP-3, CTACK, and OPG were found to be significantly increased in VCAM-1(+) CV-MSCs. Moreover, VCAM-1(+)CV-MSCs showed remarkable vasculo-angiogenic abilities by angiogenesis analysis with Matrigel in vitro and in vivo and the conditioned medium of VCAM-1(+) CV-MSCs exerted markedly pro-proliferative and pro-migratory effects on endothelial cells compared to VCAM-1(-)CV-MSCs. Finally, transplantation of VCAM-1(+)CV-MSCs into the ischemic hind limb of BALB/c nude mice resulted in a significantly functional improvement in comparison with VCAM-1(-)CV-MSCs transplantation. CONCLUSIONS: VCAM-1(+)CV-MSCs possessed a favorable angiogenic paracrine activity and displayed therapeutic efficacy on hindlimb ischemia. Our results suggested that VCAM-1(+)CV-MSCs may represent an important subpopulation of MSC for efficient therapeutic angiogenesis.

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Lipocalin 2 (LCN2), a multifunctional secretory protein known as neutrophil gelatinase-associated lipocalin (NGAL), is expressed in a variety of cancers. However, little is known about the biological functions of NGAL in the development of lung adenocarcinoma. In the present study, we primarily found that NGAL expression was up-regulated in human lung adenocarcinoma tissues. Additionally, depletion of NGAL expression decreased the ability of cell proliferation and induced cell apoptosis. Furthermore, with the addition of N-acetylcysteine, a scavenger of reactive oxygen species (ROS), it was found that NGAL depletion was sufficient to cause apoptosis of lung adenocarcinoma cells by generating ROS through the inhibition of the nuclear factor E2-related factor 2/heme oxygenase-1 anti-oxidant pathway. Finally, the effect of NGAL down-regulation on the growth of human lung adenocarcinoma was determined in BALB/c nude mice. These findings demonstrate that NGAL may be a potential therapy target for patients with lung adenocarcinoma.

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BACKGROUND: The Notch signaling pathway is implicated in a broad range of developmental processes, including cell fate decisions. This study was designed to determine the role of Notch signaling in adipogenic differentiation of human bone marrow derived MSCs (BM-MSCs). METHODS: The Notch signaling was inhibited by the γ-secretase inhibitor N-[N-(3,5-difluor- ophenacetyl-L-alanyl)]-S-phenylglycine t-butylester (DAPT). The markers involving adipogenic differentiation of MSCs, the relative pathway PTEN-PI3K/Akt/mTOR and autophagy activation were then analyzed. Furthermore, the autophagy inhibitor chloroquine (CQ) and 3-methyladenine (3-MA) were used to study the role of autophagy in the DAPT-induced the adipogenic differentiation of MSCs. RESULTS: We first confirmed the down -regulation of Notch gene expression during MSCs adipocyte differentiation, and showed that the inhibition of Notch signaling significantly enhanced adipogenic differentiation of MSCs. Furthermore, Notch inhibitor DAPT induced early autophagy by acting on PTEN-PI3K/Akt/mTOR pathway. The autophagy inhibitor CQ and 3-MA dramatically abolished the effects of DAPT-induced autophagy and adipogenic differentiation of MSCs. CONCLUSION: Our results indicate that inhibition of Notch signaling could promote MSCs adipogenesis mediated by autophagy involving PTEN-PI3K/Akt/mTOR pathway. Notch signaling could be a novel target for regulating the adipogenic differentiation of MSCs.

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