8 research outputs found

    Fast Syntheses of MOFs Using Nanosized Zeolite Crystal Seeds In Situ Generated from Microsized Zeolites

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    Herein, we report a seeded growth methodology using zeolite crystal seeds for the rapid hydrothermal syntheses of MOFs. Common microsized zeolite crystals without surface modification are added to the hydrothermal synthesis systems of MOFs and break into nanosized zeolite crystal seeds under the MOF hydrothermal synthesis conditions. Nanosized zeolite seeds can offer enormous surface areas to nucleate MOFs and the in situ generation way can avoid aggregation and separation troubles relevant to nanosized zeolite production. Fast syntheses of MIL-101­(Cr), MIL-100­(Cr), MIL-104­(Co), and MIL-53­(Fe) were carried out by employing zeolite MOR, Y, or ZSM-5 crystal seeds. Typically, only about 1.3 wt % microsized zeolite MOR crystals relative to the metal and ligand precursors for MIL-101 formation can shorten the crystallization complete time by 75% compared to the conventional MIL-101 crystallization without adding zeolites. This nanosized zeolite seed-assisted growth methodology is an important step toward the industrial scale-up of MOF synthesis. Simultaneously, it builds a bridge between MOFs and zeolites, which may shed light on the preparation of composite materials composed of MOFs and zeolites

    Selective Ethylene Oligomerization with Chromium-Based Metal–Organic Framework MIL-100 Evacuated under Different Temperatures

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    MIL-100­(Cr) was synthesized and evacuated under different temperatures to generate a series of heterogeneous catalysts for ethylene oligomerization. These catalysts showed moderate catalytic activities for ethylene oligomerization but high selectivities to low carbon olefins C6, C8, and C10. Moreover, the oligomer distribution was different depending on the evacuation temperature. The XPS results showed the reduction of some Cr<sup>III</sup> active sites in the MIL-100­(Cr) structure to Cr<sup>II</sup> active sites, which made the catalysts show polymerization activities. The MIL-100­(Cr)-250 catalyst evacuated at 250 °C exhibited the highest oligomerization and polymerization activities up to 9.27 × 10<sup>5</sup> g/(molCr·h) and 0.99 × 10<sup>5</sup> g/(molCr·h) respectively. The oligomerization selectivity to low carbon olefins C6, C8, and C10 was about 99%. The byproduct polymer from MIL-100­(Cr)-250 belonged to linear polyethylene with ultrahigh molecular weight and broad molecular weight distributions. This work demonstrated that MOFs containing coordinatively unsaturated metal sites might be a promising selective catalyst for ethylene slurry oligomerization

    CTCs detected in a blood sample from a liver cancer patient.

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    <p>A total of 10 CTCs were detected in this sample; 3 single migratory biophenotypic epithelial/mesenchymal CTCs, 3 single migratory mesenchymal CTCs and a tumor microembolus containing 4 mesenchymal CTCs were observed (epithelial biomarkers are indicated by red fluorescence; mesenchymal biomarkers are indicated by green fluorescence).</p

    EpCAM, CK8/18/19, vimentin and twist expression in HepG2 tumor cells and leukocytes.

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    <p><b>A</b>: negative control, leukocytes stained for CD45 expression (bright blue fluorescence); <b>B</b>: HepG2 cells stained for EpCAM expression (red fluorescence); <b>C</b>: HepG2 cells stained for CK8 expression(red fluorescence); <b>D</b>: HepG2 cells stained for CK18 expression(red fluorescence); <b>E</b>: HepG2 cells stained for CK19 expression(red fluorescence); <b>F</b>: HepG2 cells stained for vimentin expression (green fluorescence); <b>G:</b> HepG2 cells stained for twist expression(green fluorescence); <b>H:</b> HepG2 cells stained for EpCAM, CK8/18/19, vimentin and twist expression (red/green fluorescence). The cells were analyzed using a 100x oil objective</p

    Thymines in Single-Stranded Oligonucleotides and G‑Quadruplex DNA Are Competitive with Guanines for Binding to an Organoruthenium Anticancer Complex

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    Organometallic ruthenium­(II) complexes [(η<sup>6</sup>-arene)­Ru­(en)­Cl]<sup>+</sup> (arene = e.g., biphenyl (<b>1</b>), dihydrophenanthrene, tetrahydroanthracene) show promising anticancer activity both in vitro and in vivo and are cytotoxic to cisplatin-resistant cancer cells, implying that these monofunctional complexes have a different mechanism of action from that of bifunctional cisplatin. We demonstrate here that complex <b>1</b> binds selectively to the guanine base in the 15-mer single-stranded oligodeoxynucleotides (ODNs) 5′-CTCTCTX<sub>7</sub>G<sub>8</sub>Y<sub>9</sub>CTTCTC-3′ [X = Y = T; X = C, Y = A; X = A, Y = T; X = T, Y = A] to form thermodynamically stable adducts, but thymine bases (T<sub>7</sub>/T<sub>11</sub> or T<sub>6</sub>/T<sub>11</sub>) compete kinetically with guanine for binding to <b>1</b>. The T-bound monoruthenated species eventually convert to diruthenated products via a second step of binding at G or/and to G-bound monoruthenated species through dissociation of the diruthenated adducts. Complex <b>1</b> was further shown to bind preferentially to the middle T in a sequence rather than to a T near the terminus and favor coordination to a 5′-T compared to a 3′-T. Interestingly, the T bases in the human telomeric G-quadruplex sequence (5′-AGGGTTAGGGTTAGGGTTAGGG-3′) were found to be more competitive both kinetically and thermodynamically with G bases for binding to <b>1</b>. These results suggest that thymine bases play a unique role in the pathways of ruthenation of DNA by organoruthenium anticancer complexes and illustrate that kinetic studies can provide new insight into the mechanism of action of metallodrugs in addition to study of the structures and functions of the thermodynamically stable end products
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