Two nickel complexes, [Ni(tpen)](ClO4)2.0.5CH3COCH3 ( 1 ) and [Ni(tpbn)](ClO4)2 ( 2 ), of tetrapyridyl ligands N,N,N′,N′-tetrakis(2-pyridyl-methyl)-1,2-ethanediamine (tpen) and N,N,N′,N′-tetrakis(2-pyridyl-methyl)-1,4-butanediamine (tpbn) were prepared and their catalysis for water oxidation reaction (WOR) studied. In 0.1 M phosphate buffer solution (PBS) of pH 8.0, complex 1 is a homogeneous molecular catalyst with an overpotential of ~440 mV and a Faradaic efficiency of 89%. At pH ≥ 9.0, complex 1 degraded gradually during the catalytic process and formed NiOx composite (nickel oxide with general formula NixOyHz) active for WOR. In contrast, complex 2 deteriorated under measured conditions (pH 8.0–12.0) and formed NiOx composite active for WOR. The NiOx composite derived from 1 in 0.1 M PBS at pH 11.0 showed an activity with an overpotential of ~500 mV, a Tafel slope of ~90 mV/decade and a Faradaic efficiency of 97%. Mechanisms were proposed for water oxidation catalyzed by 1 and 2 . This work revealed that the catalytic activity of the nickel complexes was related to the flexibility of the tetrapyridyl ligands and the adaptability of the coordination sphere of the nickel(II) center. 相似文献
The aim of this work was to further investigate the anticancer potential of Juglans mandshurica Maxim, including the separation of active constituents and their anti-proliferative effects with underlying mechanism of action. Five alkaloids (1–5) were isolated from the bark of J. mandshurica. Among them, 1 showed the highest cytotoxic activities against Hep3B and HepG2 cells with an IC50 values of 61.80 and 56.24 μM, respectively. Therefore, the cellular mechanism involved 1 was subsequently studied. Our results showed that 1 markedly caused apoptosis and autophagy, but without cell cycle arrest in HepG2 cells. Interestingly, only autophagic cell death was induced in 1-treated Hep3B cells. It is concluded that the isolated alkaloids exerted a certain anti-hepatoma potential, and our results may provide a basis for the further investigation of the alkaloids extracted from J. mandshurica. 相似文献
Biomaterial scaffolds are the cornerstone to supporting 3D tissue growth. Optimized scaffold design is critical to successful regeneration, and this optimization requires accurate knowledge of the scaffold's interaction with living tissue in the dynamic in vivo milieu. Unfortunately, non‐invasive methods that can probe scaffolds in the intact living subject are largely underexplored, with imaging‐based assessment relying on either imaging cells seeded on the scaffold or imaging scaffolds that have been chemically altered. In this work, the authors develop a broadly applicable magnetic resonance imaging (MRI) method to image scaffolds directly. A positive‐contrast “bright” manganese porphyrin (MnP) agent for labeling scaffolds is used to achieve high sensitivity and specificity, and polydopamine, a biologically derived universal adhesive, is employed for adhering the MnP. The technique was optimized in vitro on a prototypic collagen gel, and in vivo assessment was performed in rats. The results demonstrate superior in vivo scaffold visualization and the potential for quantitative tracking of degradation over time. Designed with ease of synthesis in mind and general applicability for the continuing expansion of available biomaterials, the proposed method will allow tissue engineers to assess and fine‐tune the in vivo behavior of their scaffolds for optimal regeneration. 相似文献
Despite its high morbidity and mortality, contrast‐induced acute kidney injury (CIAKI) remains a diagnostic dilemma because it relies on in vitro detection of insensitive late‐stage blood and urinary biomarkers. We report the synthesis of an activatable duplex reporter (ADR) for real‐time in vivo imaging of CIAKI. ADR is equipped with chemiluminescence and near‐infrared fluorescence (NIRF) signaling channels that can be activated by oxidative stress (superoxide anion, O2.?) and lysosomal damage (N‐acetyl‐β‐d ‐glucosaminidase, NAG), respectively. By virtue of its high renal clearance efficiency (80 % injected doses after 24 h injection), ADR detects sequential upregulation of O2.? and NAG in the kidneys of living mice prior to a significant decrease in glomerular filtration rate (GFR) and tissue damage in the course of CIAKI. ADR outperforms the typical clinical assays and detects CIAKI at least 8 h (NIRF) and up to 16 h (chemiluminescence) earlier. 相似文献
Three ruthenium(II) polypyridyl complexes with 5-amino-1,10-phenanthroline ligands have been successfully designed and synthesized. They have been fully characterized by ESI-MS, ESI-HRMS, 1H NMR, and elemental analyses. The photophysical and electrochemical properties of the three complexes have been investigated in organic solvent. The geometrical configuration and the electron density distribution in the frontier molecular orbitals of the three complexes have been studied. The three complexes show metal-to-ligand charge transfer (1MLCT) absorption at 445 nm, and intense triplet metal-to-ligand (3MLCT) emission at around 619 nm in fluid solution at 298 K and 580 nm in low-temperature glass. Electrochemical studies of the three complexes are consistent with one RuIII/II reversible couple at around 1.31 V accompanied by three ligand-centered reduction couples.