Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.2.1.1 (ACS)
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Cisplatin (CDDP) was incorporated inside single-wall carbon nanohorns with holes opened (SWNHox) by a nanoprecipitation method that involved dispersion of CDDP and SWNHox in a solvent followed by the solvent evaporation. The incorporated CDDP quantity increased from the previously reported value of 15 to 46%, and the total released quantity of CDDP also increased from 60 to 100% by changing the solvent from dimethylformamide to water. Concurrently, in vitro anticancer efficiency of CDDP@SWNHox increased to 4-6 times greater than that of the intact CDDP. In vivo, CDDP@SWNHox intratumorally injected to transplanted tumors of mice suppressed the tumor growth more than the intact CDDP. We observed that CDDP@SWNHox adhered to the cell surfaces in vitro and stayed within the tumor tissues in vivo. Therefore, we think that the CDDP released from SWNHox realized high concentrations locally at the cells in vitro and in the tissues in vivo and could efficiently attack the tumor cells. We also found that SWNHox itself had an in vivo anticancer effect, which might increase the anticancer activities of CDDP@SWNHox.
ACS Nano 2008 Oct 28
PMID:Enhancement of in vivo anticancer effects of cisplatin by incorporation inside single-wall carbon nanohorns. 1920 52

The preorganized bis(polypseudorotaxane) (approximately 20 nm long) formed by the multiple metallo-bridged poly(beta-cyclodextrin)s has been successfully converted to the lengthened bis(molecular tube) (approximately 200 nm long) through the intermolecular joining of approximately 10 discrete bis(polypseudorotaxane) units and the subsequent removal of the polymer templates. The obtained bis(molecular tube), which is quite soluble in water, dimethylformamide, and dimethyl sulfoxide, has been comprehensively characterized by NMR, gel permeation chromatography, static light scattering, X-ray powder diffraction, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and scanning tunneling microscopy. Further investigations demonstrate that this bis(molecular tube) can capture C(60) through interaction with its many pi-electron-rich biquinolino groups.
ACS Nano 2008 Mar
PMID:Construction of a long cyclodextrin-based bis(molecular tube) from bis(polypseudorotaxane) and its capture of C60. 1920 82

The discovery of the metallopeptide Ni(Cysteine-Glycine-Cysteine)(2-), Ni(CGC)(2-), in the A-cluster active site of Acetyl CoA Synthase has prompted the synthesis of many small molecule models which employ M(N(2)S(2)) complexes as metalloligands. In vitro studies have shown that nickel incorporates into the N(2)S(2) binding pocket even when copper is in the enzyme growth medium, while copper is preferentially taken up in the proximal site, displacing the catalytically active nickel. (Darnault, C.; Volbeda, A.; Kim, E.J.; Legrand, P.; Vernede, X.; Lindahl, P.A.; Fontecilla-Camps, J.C. Nat. Struct. Biol. 2003, 10, 271-279.) The work herein has been designed to address the chemical viability of copper(II) within the tripeptide N(2)S(2) ligand set. To this end, a series of CuN(2)S(2)(2-) complexes, the resin-bound, O-Cu(CGC)(2-) (A) and free Cu(CGC)(2-) (B) complexes, as well as Cu(ema)(2-) (C) and Cu(emi)(2-) (D) dianions, have been characterized by UV-vis, electron paramagnetic resonance (EPR), and electrospray ionization mass spectrometry (ESI-MS) spectroscopies, cyclic voltammetry (CV), and, where appropriate, X-ray diffraction studies, and compared to the Ni(II) congeners. EPR spectroscopic results have indicated that, in frozen N,N-dimethylformamide (DMF) solution, the copper complexes are distorted square planar structures with nitrogen and sulfur donors. This is consistent with X-ray diffraction measurements which also show copper(II) in a distorted square planar environment that is bereft of CuN(2)S(2)(2-) intermolecular interactions. Density-functional theory (DFT) calculations resulted in optimized structures that are consistent with crystallographic data and indicated highest occupied molecular orbital (HOMO)-singly occupied molecular orbital (SOMO) gaps of 5.01 and 4.68 eV for C and D, respectively. Optimized structures of Ni(ema)(2-) and Ni(emi)(2-) share the same basic characteristics as the copper(II) congeners. Electrochemical characterization of C and D resulted in a reversible Cu(III/II) couple at -1.20 V and - 1.40 V, respectively. Reactivity studies with Rh(CO)(2)(+) show similar donor capabilities for complexes A-D. Analysis of A shows that transmetalation does not occur. From competitive metal uptake studies on immobilized tripeptide it is concluded that the N(2)S(2)(4-) ligating unit has a slight preference for Cu(2+) over Ni(2+) and that the biosynthetic pathway responsible for constructing the distal site of ACS must be selective for nickel insertion or copper exclusion, or both.
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PMID:Chemical issues addressing the construction of the distal Ni[cysteine-glycine-cysteine]2- site of acetyl CoA synthase: why not copper? 1925 85

We report bistable non-volatile memory devices based on polystyrene derivatives containing pendent electron-donating mono-, di-, and tri(9,9-dihexylfluorene), which are denoted as poly(St-Fl), poly(St-Fl(2)), and poly(St-Fl(3)), respectively. The effects of the oligofluorene chain lengths and polymer surface structures on the memory characteristics were explored. Poly(St-Fl)-, poly(St-Fl(2))-, and poly(St-Fl(3))-based devices exhibited a flash memory characteristic with different turn-on threshold voltages of 2.8, 2.0, and 1.8 V, respectively, which was on the reverse trend with the highest occupied molecular orbital levels of -5.86, -5.80, and -5.77 eV. Moreover, the memory device showed a high ON/OFF current ratio of 2.5 x 10(4) and a long retention time of 10(4) s. The possible mechanism of the switching behavior was explained by the space-charge-limited-current theory and filamentary conduction. The larger aggregation domain size of the polymer thin film processed from the mixed solvent of chlorobenzene/N,N-dimethylformamide probably promoted the diffusion of the Al atoms into the polymer film and formed the conduction channel. Thus, it significantly reduced the turn-on threshold voltage on the studied polymer memory devices. The present study suggested that the polymer memory characteristics could be efficiently tuned through the pendent conjugated chain length and surface structures.
ACS Appl Mater Interfaces 2009 Sep
PMID:Non-volatile memory devices based on polystyrene derivatives with electron-donating oligofluorene pendent moieties. 2035 22

We describe the use of hydrophobic poly(aryl ether) dendrons to peripherally functionalize hydrophilic amine-containing superparamagnetic iron oxide microspheres (SPIO-NH2) in one step via imine formation. The reversible formation of imine bonds in the absence/presence of water renders dynamic control of the hydrophilicity and hydrophobicity of the microspheres (SPIO-Gn). The dynamic nature of the imine-containing dendronized microspheres (SPIO-Gn) can be "fixed" by locking the reversible 2,6-diiminopyridyl moieties with metal cations (Zn2+, Co2+, and Ni2+) to afford kinetically stable dendronized microspheres (SPIO-Gn-M). Isolation of these microspheres is facilitated by convenient magnetic separation by an externally applied magnetic field. Characterization of these novel organic-inorganic hybrid microspheres has been performed by various techniques using UV/visible absorption and Fourier transform infrared spectroscopies, transmission electron microscopy, thermogravimetric analysis, and a vibrating sample magnetometer. We have demonstrated the stability and reversible switching of hydrophilicity/hydrophobicity by contact-angle measurements. In particular, the hydrophilic SPIO-NH2 microspheres demonstrated a contact angle of 42 +/- 2 degrees when a drop of water was added to a SPIO-NH2-coated mica surface. On the other hand, the hydrophobic SPIO-Gn-M dendronized microspheres demonstrated a contact angle of 85 +/- 2 degrees , an observation that involves an increase of the contact angle of over 40 degrees . Furthermore, when a drop of water was placed on a dynamic SPIO-Gn-coated mica surface, the contact angle of the water droplet decreased in time. Comparatively, the rate of decrease of the contact angle is H2O > 1% Co(OAc)2/H2O > N,N'-dimethylformamide/H2O (1:1).
ACS Appl Mater Interfaces 2009 Sep
PMID:Reversible switching between hydrophilic and hydrophobic superparamagnetic iron oxide microspheres via one-step supramolecular dynamic dendronization: exploration of dynamic wettability. 2035 26

We report on the formation of self-supporting, double stimuli-responsive ultrafiltration membranes via the non-solvent-induced phase separation (NIPS) process. The polymers, polystyrene-block-poly(N,N-dimethylaminoethyl methacrylate) (PS-b-PDMAEMA), were synthesized via living anionic polymerization in THF using sec-butyllithium as initiator. Two amphiphilic diblock copolymers were used, S(81)D(19)(75) and S(68)D(32)(100). The membranes were cast from mixtures of THF and DMF. The influence of the solvent composition, the "open-time" before immersion into the coagulation bath, and the casting film thickness onto the membrane morphology were thoroughly investigated, and flux values obtained for the different membrane systems were compared. The higher content in hydrophilic polymer for S(68)D(32)(100) resulted in a better compatibility with the nonsolvent bath consisting of water, leading to a slower precipitation and thus an improved control of the phase separation occurring. Under certain conditions, ordered microphase-separated porous morphologies were observed in parts of the membrane cross-section. Further, the "smart" properties of those novel materials are shown for two representative systems. It could be demonstrated that both stimuli for PDMAEMA, pH and temperature, can be reversibly and independently applied in order to significantly change the transmembrane water flux.
ACS Appl Mater Interfaces 2009 Jul
PMID:Double stimuli-responsive ultrafiltration membranes from polystyrene-block-poly(N,N-dimethylaminoethyl methacrylate) diblock copolymers. 2035 53

A direct approach for fabricating nanoporous polymer fibers via electrospinning has been demonstrated. Polystyrene (PS) fibers with micro- and nanoporous structures both in the core and/or on the fiber surfaces were electrospun in a single process by varying solvent compositions and solution concentrations of the PS solutions. The porous structures of the fibrous mats were characterized by field emission scanning electron microscopy and Brunauer-Emmett-Teller measurements to confirm that they could be accurately controlled by tuning vapor pressure of tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) solvent mixtures and PS concentrations in the solutions. As the solution concentration decreased, the average fiber diameter decreased, whereas the bead density increased dramatically to show a beads-on-string morphology. Both the specific surface area and pore volume of the fibrous mats showed a unimodal distributions centered at 1/3 THF /DMF mix ratio. Fibers formed from 5 wt % PS in the 1/3 THF and DMF mixtures had the largest specific surface area of 54.92 m(2) g(-1) and a pore volume of 0.318 cm(3)g(-1), respectively.
ACS Appl Mater Interfaces 2010 Feb
PMID:Direct fabrication of highly nanoporous polystyrene fibers via electrospinning. 2035

Ionic liquid (IL)-coated iron oxide nanoparticles (IONs) were synthesized by the thermal decomposition of Fe(CO)(5) in an IL/DMF solvent system in the absence of stabilizing surfactants at 90 degrees C for 1 h. The IL, [omim][BF(4)], could regulate the shape and allow the preparation of anisotropic IONs, such as barlike and wirelike nanoparticles. The barlike IONs prepared using this method showed good superparamagnetic behavior in a magnetic field and a MR contrast enhancement effect in a MR scanner.
ACS Appl Mater Interfaces 2010 Mar
PMID:Synthesis of iron oxide nanoparticles with control over shape using imidazolium-based ionic liquids. 2035 77

New nanocomposites composed of cellulose nanofibers or "whiskers" and an epoxy resin were prepared. Cellulose whiskers with aspect ratios of approximately 10 and approximately 84 were isolated from cotton and sea animals called tunicates, respectively. Suspensions of these whiskers in dimethylformamide were combined with an oligomeric difunctional diglycidyl ether of bisphenol A with an epoxide equivalent weight of 185-192 and a diethyl toluenediamine-based curing agent. Thin films were produced by casting these mixtures and subsequent curing. The whisker content was systematically varied between 4 and 24% v/v. Electron microscopy studies suggest that the whiskers are evenly dispersed within the epoxy matrix. Dynamic mechanical thermoanalysis revealed that the glass transition temperature (T(g)) of the materials was not significantly influenced by the incorporation of the cellulose filler. Between room temperature and 150 degrees C, i.e., below T(g), the tensile storage moduli (E') of the nanocomposites increased modestly, for example from 1.6 GPa for the neat polymer to 4.9 and 3.6 GPa for nanocomposites comprising 16% v/v tunicate or cotton whiskers. The relative reinforcement was more significant at 185 degrees C (i.e., above T(g)), where E' was increased from approximately 16 MPa (neat polymer) to approximately 1.6 GPa (tunicate) or approximately 215 MPa (cotton). The mechanical properties of the new materials are well-described by the percolation model and are the result of the formation of a percolating whisker network in which stress transfer is facilitated by strong interactions between the whiskers.
ACS Appl Mater Interfaces 2010 Apr
PMID:Cellulose whisker/epoxy resin nanocomposites. 2042 28

Poly(vinylidene difluoride)/organically modified montmorillonite (PVDF/OMMT) composite nanofibers were prepared by electrospinning the solution of PVDF/OMMT precursor in DMF. Wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) show that in the bulk of the PVDF/OMMT precursor OMMT platelets are homogeneously dispersed in PVDF and can be both intercalated and exfoliated. It is found that the diameter of the PVDF/OMMT composite nanofibers is smaller than that of the neat PVDF fibers because the lower viscosity of PVDF/OMMT solution, which is attributed to the possible adsorption of PVDF chains on OMMT layers and thus reduction in number of entanglement. The crystal structure of the composite nanofibers was investigated using WAXD and Fourier transform infrared (FT-IR) and compared with that of thin film samples. The results show that the nonpolar alpha phase is completely absent in the electrospun PVDF/OMMT composite nanofibers, whereas it is still present in the neat PVDF electrospun fibers and in the thin films of PVDF/OMMT nanocomposites. The cooperative effect between electrospinning and nanoclay on formation of polar beta and gamma crystalline phases in PVDF is discussed. The IR result reveals that electrospinning induces formation of long trans conformation, whereas OMMT platelets can retard relaxation of PVDF chains and stabilize such conformation due to the possible interaction between the PVDF chains and OMMT layers. This cooperative effect leads to extinction of nonpolar alpha phase and enhances the polar beta and gamma phases in the electrospun PVDF/OMMT composite nanofibers.
ACS Appl Mater Interfaces 2010 Jun
PMID:Cooperative effect of electrospinning and nanoclay on formation of polar crystalline phases in poly(vinylidene fluoride). 2048 44


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