Ratiometric detection of I- using a dysprosium-based metal-organic framework with a single emission center.

In this study, a dysprosium-based metal-organic framework (MOF) sensor (Dy-MOF) was developed for the ratiometric detection of I- in aqueous medium. Upon excitation at 230 nm, Dy-MOF shows two dominant emission bands at 464 nm and 574 nm assigned to (4F, 4D)5/2 → 6H9/2 + 6F11/2 and 4F9/2 → 6H13/2 transition of Dy3+, respectively, which have different sensitivities toward iodide ions. The introduction of I- slightly weakened the blue emission at 464 nm and significantly quenched the yellow emission at 574 nm. Thus, ratiometric sensing for iodide was realized using the yellow-to-blue intensity ratio of Dy3+. Dy-MOF exhibits superior sensing behavior towards I- with high selectivity, sensitivity and low detection limit (24 nM). This study also provides a strategy for the construction of a ratiometric sensor with dual-emission bands originating from only one emission center.

A ratiometric luminescence sensing platform based on lanthanide-based silica nanoparticles for selective and sensitive detection of Fe3+ and Cu2+ ions.

Detection of Fe(III) and Cu(II) in water is highly desirable because their abnormal levels can cause serious harm to human health and environmental safety. In this work, a ratiometric luminescence sensing platform based on lanthanide-based silica nanoparticles was constructed for the detection of Fe3+ and Cu2+ ions. The terbium-silica nanoparticles (named SiO2@Tb) with dual-emission signals were successfully prepared by grafting Tb3+ ions onto trimellitic anhydride (TMA) functionalized silica nanospheres. It can serve as a ratiometric fluorescent probe for the detection of Fe3+ and Cu2+ ions in water with the green emission of Tb3+ ions as a response signal and the blue emission of silica nanospheres as the reference signal. Significantly, an easy-to-differentiate color change for visual detection was also realized. SiO2@Tb shows high sensitivity even in very low concentration regions towards the sensing of Fe3+ and Cu2+ with low detection limits of 0.75 µM and 0.91 µM, respectively. Moreover, the mechanism for the luminescence quenching of SiO2@Tb was systematically investigated, and was attributed to the synergetic effect of the absorption competition quenching (ACQ) mechanism and cation exchange. This study demonstrates that SiO2@Tb can be employed as a promising fluorescent probe for the detection of Fe3+ and Cu2+ ions, and the combination of lanthanide ions with silica nanoparticles is an effective strategy to construct a ratiometric fluorescent sensing platform for the determination of analytes in environmental detection.

An europium(III) metal-organic framework as a multi-responsive luminescent sensor for highly sensitive and selective detection of 4-nitrophenol and I- and Fe3+ ions in water.

A luminescence sensor based on an europium(III)-based lanthanide-organic framework, [Eu(BCB)(DMF)]·(DMF)1.5(H2O)2 (1), was synthesized via a solvothermal method using 4,4',4''-benzenetricarbonyltribenzoic acid (H3BCB) as a bridging ligand. Single-crystal X-ray diffraction indicates that Eu centers are eight-coordinated with a trigonal dodecahedron and a square antiprismatic configuration, and adjacent Eu atoms are bridged by BCB organic linkers to form a 3D rod-packing structure. Photoluminescence studies show that compound 1 emits bright red luminescence and behaves as a multi-responsive luminescent sensor toward 4-nitrophenol (4-NP) and I- and Fe3+ ions in water with high sensitivity, selectivity and low detection limits. Furthermore, the possible luminescence sensing mechanisms were also investigated by PXRD analysis, UV-vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The recognition mechanism for 4-NP and I- ions can be attributed to the competition absorption and that for Fe3+ ions is considered to be a multi-quenching mechanism dominated by competition absorption. This study demonstrates that the lanthanide-based MOF might be a promising candidate for the detection of 4-NP and I- and Fe3+ ions in aqueous medium.

A terbium(III) lanthanide-organic framework as a selective and sensitive iodide/bromide sensor in aqueous medium.

A potent luminescent sensor for the detection of iodide ions was developed based on a terbium(iii)-based lanthanide-organic framework [Tb(cpia)(H2O)2]n·nH2O (1), which was prepared under hydrothermal conditions using the 5-(4-carboxyphenoxy)isophthalic acid (H3cpia) bridging ligand. Compound 1 exhibits superior luminescence quenching behavior towards I- with high sensitivity and selectivity among various anions and shows real-time response. Moreover, the mechanism of the selective luminescence quenching response for I- can be mainly explained by the absorption competition between 1 and I-. According to this quenching mechanism, we find that compound 1 can also detect Br- by adjusting the excitation wavelength. Significantly, this work could serve as a general guidance for the design and synthesis of pollutant sensors.

Three new flavonoids from Penthorum chinense Pursh and their docking studies.

Three new flavonoids, pinocembrin-7-O-[3″-O-galloyl]-ß-D-glucose (1), pinocembrin-7-O-[2″-O-galloyl-4″,6″-hexahydroxydiphenoyl]-ß-D-glucose (2), 2',6'-dihydroxydihydrochalcone-4'-O-[2″-O-galloyl-4″,6″-hexahydroxydiphenoyl]-ß-D-glucopyranoside (3), and 12 known compounds (4-15) were isolated from Penthorum Chinense Pursh. The structures of all compounds were established mainly by NMR and MS experiments as well as the necessary chemical evidence. The anti-hyperlipidemic activities of the three new flavonoids were predicted by molecular docking.

Discovery of a natural PI3Kδ inhibitor through virtual screening and biological assay study.

Phosphoinositide-3-kinase-δ (PI3Kδ) is a key regulator in the process of IgE mediated mast cell degranulation, which directly induces allergic diseases, such as asthma. This study is aimed at discovery of natural PI3Kδ inhibitors from Chinese medicine and evaluating their anti-mast cell degranulation activity. A combined virtual screening based on 3D pharmacophore model and molecular docking was used to screen for bioactive ingredients directly targeting PI3Kδ. Then, an in vitro kinase inhibition assay was conducted to evaluate the PI3Kδ inhibitory activity of the virtual screening hits. Subsequently, a ß-hexosaminidase release assay was performed to verify the anti-mast cell degranulation activity of the active compounds. Finally, ginkgoneolic acid was identified as a PI3Kδ inhibitor (IC50 = 2.49 µM) and exhibited anti-mast cell degranulation activity in vitro (IC50 = 2.40 µM). Docking studies showed that Glu826, Val827 and Val828 were key amino acid residues for PI3Kδ inhibitory activity. Ginkgoneolic acid may be a potential lead compound for developing effective and safe PI3Kδ-inhibiting drugs.

The rational search for PDE10A inhibitors from Sophora flavescens roots using pharmacophore­ and docking­based virtual screening.

Phosphodiesterase 10A (PDE10A) has been confirmed to be an important target for the treatment of central nervous system (CNS) disorders. The purpose of the present study was to identify PDE10A inhibitors from herbs used in traditional Chinese medicine. Pharmacophore and molecular docking techniques were used to virtually screen the chemical molecule database of Sophora flavescens, a well­known Chinese herb that has been used for improving mental health and regulating the CNS. The pharmacophore model generated recognized the common functional groups of known PDE10A inhibitors. In addition, molecular docking was used to calculate the binding affinity of ligand­PDE10A interactions and to investigate the possible binding pattern. Virtual screening based on the pharmacophore model and molecular docking was performed to identify potential PDE10A inhibitors from S. flavescens. The results demonstrated that nine hits from S. flavescens were potential PDE10A inhibitors, and their biological activity was further validated using literature mining. A total of two compounds were reported to inhibit cyclic adenosine monophosphate phosphodiesterase, and one protected against glutamate­induced oxidative stress in the CNS. The remaining six compounds require further bioactivity validation. The results of the present study demonstrated that this method was a time­ and cost­saving strategy for the identification of bioactive compounds from traditional Chinese medicine.

Preparation of magnetic dummy molecularly imprinted polymers for selective extraction and analysis of salicylic acid in Actinidia chinensis.

Compounds with strong intramolecular hydrogen bonds (e.g., salicylic acid) have weak intermolecular hydrogen bonding interactions between them and functional monomers in the imprinting process. Consequently, the corresponding molecularly imprinted polymers (MIPs) have no specific adsorption ability. Here, the first magnetic dummy MIPs (MDMIPs) based on benzonic acid as dummy template are successfully developed and evaluated with respect to the applications in selective enrichment and analysis of salicylic acid from complex mixtures. Various parameters affecting absorption/desorption were evaluated for achieving optimal recovery and reducing nonspecific interactions. The prepared MDMIPs showed high adsorption capacity, good selectivity, rapid kinetic binding (40 min) and magnetic separation (5 s), high reproducibility (RSD< 4 % for batch-to-batch evaluation), and stability (only 4 % decrease after 6 cycles). Owing to the efficacy in specific binding and removal of interference, trace level salicylic acid was quantified (0.2 µg/g of fresh mass) in Actinidia chinensis by high-performance liquid chromatography.

A three-dimensional supramolecular framework of silver(I), 2-phenylquinoline-4-carboxylate and 4,4'-bipyridine.

A novel supramolecular framework, catena-poly[[[aqua(2-phenylquinoline-4-carboxylato-κO)silver(I)]-µ-4,4'-bipyridine-κ(2)N:N'] dihydrate], {[Ag(C16H10NO2)(C10H8N2)(H2O)]·2H2O}n, has been synthesized and structurally characterized. The Ag(I) centres are four-coordinated and bridged by 4,4'-bipyridine (4,4'-bipy) ligands to form a one-dimensional Ag-bipy chain. The Ag-bipy chains are further linked together by intermolecular O-H···O and O-H···N hydrogen-bonding interactions between adjacent chains, resulting in a three-dimensional framework.

[Manipulative reduction and internal fixation by percutaneous locking compression plate for the treatment of mid-distal tibiofibula shaft fractures].

OBJECTIVE: To investigate the clinical effects of manipulative reduction and percutaneous locking compression plate internal fixation for the treatment of mid-distal tibiofibula shaft fractures. METHODS: From January 2006 to October 2009,46 patients suffering from mid-distal tibiofibula shaft fractures were treated with closed manipulative reduction and LCP, involved 27 males and 19 females with an average age of 39 years old ranging from 17 to 56 years. According to AO classification, there were 12 cases of type A, 24 of type B, 10 of type C. The duration of visiting hospital were from 2 hours to 3 days after being injured for these patients. The injured limbs of the patients were swollen and painful,even with bony crepitus. The wound, function of the injured limb and union of fractures were observed after operation. RESULTS: All the patients were followed up from 12 to 18 months (averaged 15 months). It was found that the wound of all patients had primary healing without any infection. The fracture healing time was 12 to 18 weeks (means 14 weeks). The results were excellent in 40 cases,good in 4 and fair in 2. CONCLUSION: Less invasive, more stable fixation, shorter healing time and better functional rehabilitation are observed in the treatment of mid-distal tibiofibula shaft fractures after manipulative reduction and percutaneous locking compression plate internal fixation.

Porphyrin-containing polyaspartamide gadolinium complexes as potential magnetic resonance imaging contrast agents.

Porphyrin-containing polyaspartamide ligands (APTSPP-PHEA-DTPA) were synthesized by the incorporation of diethylenetriaminepentaacetic acid (DTPA) and 5-(4'-aminophenyl)-10,15,20-tris(4'-sulfonatophenyl) porphyrin, trisodium salt (APTSPP) into poly-α,ß-[N-(2-hydroxyethyl)-l-aspartamide] (PHEA). These ligands were further reacted with gadolinium chloride to produce macromolecule-gadolinium complexes (APTSPP-PHEA-DTPA-Gd). Experimental data of (1)H NMR, IR, UV and elemental analysis evidenced the formation of the polyaspartamide ligands and gadolinium complexes. In vitro and in vivo property tests indicated that APTSPP-PHEA-DTPA-Gd possessed noticeably higher relaxation effectiveness, less toxicity to HeLa cells, and significantly higher enhanced signal intensities (SI) of the VX2 carcinoma in rabbits with lower injection dose requirement than that of Gd-DTPA. Moreover, APTSPP-PHEA-DTPA-Gd was found to greatly enhance the contrast of MR images of the VX2 carcinoma, providing prolonged intravascular duration, and distinguished the VX2 carcinoma and normal tissues in rabbits according to MR image signal enhancements. These porphyrin-containing polyaspartamide gadolinium complexes can be used as the candidates of contrast agents for targeted MRI to tumors.

One-dimensional ferromagnetically coupled bimetallic chains constructed with trans-[Ru(acac)2(CN)2]-: syntheses, structures, magnetic properties, and density functional theoretical study.

Four cyano-bridged 1D bimetallic polymers have been prepared by using the paramagnetic building block trans-[Ru(acac)(2)(CN)(2)](-) (Hacac=acetylacetone): {[{Ni(tren)}{Ru(acac)(2)(CN)(2)}][ClO(4)].CH(3)OH}(n) (1) (tren=tris(2-aminoethyl)amine), {[{Ni(cyclen)}{Ru(acac)(2)(CN)(2)}][ClO(4)].CH(3)OH}(n) (2) (cyclen=1,4,7,10-tetraazacyclododecane), {[{Fe(salen)}{Ru(acac)(2)(CN)(2)}]}(n) (3) (salen(2-)=N,N'-bis(salicylidene)-o-ethyldiamine dianion) and [{Mn(5,5'-Me(2)salen)}(2){Ru(acac)(2)(CN)(2)}][Ru(acac)(2)(CN)(2)].2CH(3)OH (4) (5,5'-Me(2)salen=N,N'-bis(5,5'-dimethylsalicylidene)-o-ethylenediimine). Compounds 1 and 2 are 1D, zigzagged NiRu chains that exhibit ferromagnetic coupling between Ni(II) and Ru(III) ions through cyano bridges with J=+1.92 cm(-1), zJ'=-1.37 cm(-1), g=2.20 for 1 and J=+0.85 cm(-1), zJ'=-0.16 cm(-1), g=2.24 for 2. Compound 3 has a 1D linear chain structure that exhibits intrachain ferromagnetic coupling (J=+0.62 cm(-1), zJ'=-0.09 cm(-1), g=2.08), but antiferromagnetic coupling occurs between FeRu chains, leading to metamagnetic behavior with T(N)=2.6 K. In compound 4, two Mn(III) ions are coordinated to trans-[Ru(acac)(2)(CN)(2)](-) to form trinuclear Mn(2)Ru units, which are linked together by pi-pi stacking and weak Mn...O* interactions to form a 1D chain. Compound 4 shows slow magnetic relaxation below 3.0 K with phi=0.25, characteristic of superparamagnetic behavior. The Mn(III)...Ru(III) coupling constant (through cyano bridges) and the Mn(III)...Mn(III) coupling constant (between the trimers) are +0.87 and +0.24 cm(-1), respectively. Compound 4 is a novel single-chain magnet built from Mn(2)Ru trimers through noncovalent interactions. Density functional theory (DFT) combined with the broken symmetry state method was used to calculate the molecular magnetic orbitals and the magnetic exchange interactions between Ru(III) and M (M=Ni(II), Fe(III), and Mn(III)) ions. To explain the somewhat unexpected ferromagnetic coupling between low-spin Ru(III) and high-spin Fe(III) and Mn(III) ions in compounds 3 and 4, respectively, it is proposed that apart from the relative symmetries, the relative energies of the magnetic orbitals may also be important in determining the overall magnetic coupling in these bimetallic assemblies.

trans-[Os(III)(salen)(CN)(2)](-): a new paramagnetic building block for the construction of molecule-based magnetic materials.

A novel dicyanoosmium(III) complex, trans-Ph(4)P[Os(III)(salen)(CN)(2)].CH(2)Cl(2).H(2)O (1; Ph(4)P(+) = tetraphenylphosphonium cation, salen(2-) = N,N'-ethylenebis(salicylideneaminato) dianion), has been synthesized and structurally characterized. Reactions of 1 with [Cu(Me(3)tacn)(H(2)O)(2)](ClO(4))(2) (Me(3)tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane) under different conditions produce the 1-D ferromagnetic zigzag chains [Os(salen)(CN)(2)](2)[Cu(Me(3)tacn)].CH(3)OH (2) and [Os(salen)(CN)(2)][Cu(Me(3)tacn)].ClO(4) (3).

[The hemodynamic effect of dobutamine stress on myocardial bridging-mural coronary artery].

OBJECTIVE: Patient with myocardial bridging (MB) usually has a benign prognosis, but some MB patients might experience myocardial ischemia, infarction and sudden cardiac death, especially during active physical activities. The purpose of the study was to study the stress-induced blood flow changes of the mural coronary artery in MB patients determined by intracoronary Doppler. METHODS: In 8 patients with MB, the basic average peak velocity (bAPV), hyperemic average peak velocity (hAPV) of blood flow, coronary flow reverse (CFR) proximal and distal to the mural coronary artery were measured before and during intravenously dobutamine (10 microg kg-1 min-1, then add 10 microg kg-1 min-1 at 3 min interval till 40 microg kg-1 min-1) by intracoronary Doppler. RESULTS: The baseline mural coronary diameter reduction was (51.7+/-21.4)% and significantly increased to (90.0+/-12.7)% (P<0.01) during dobutamine infusion. bAPV on the segments proximal and distal to the mural coronary artery significantly increased from (19.83+/-5.84) cm/s and (20.75+/-4.91) cm/s to (31.52+/-10.93) cm/s and (30.46+/-9.01) cm/s (all P<0.05 vs. baseline) respectively post dobutamine infusion. CFR measured at proximal and distal to myocardial bridging also significantly decreased from (2.91+/-0.62) and (2.46+/-0.82) to (2.17+/-0.66) and (1.83+/-0.51) (all P<0.01). CONCLUSION: Stress can significantly increase the compression of intramural coronary artery and reduce CFR on coronary segments both proximal and distal to the MB. Thus, active exercise might induce myocardial ischemia in patients with myocardial bridging.