Layer by layer assembly of DNA film via Zr(Ⅳ) ion and its intercalation property

In order to study the molecular recognition ability of DNA and different behavior of dyes incorporated into the base pairs, DNA molecule was assembled layer by layer via a Zr(Ⅳ) ion. The UV absorption spectra showed the uniform layer assembly of the DNA film. The fabricated DNA film was water-insoluble and maintained the native B-form structure. UV and CD measurements showed that the DNA film could interealate ethidium bromide (EtBr).     

The interaction of a novel ruthenium (II) complex with self‐assembled DNA film on silicon surface

Calf thymus DNA (ct‐DNA) films were immobilized onto patterned silicon wafers through electrostatic self‐assembly technology and interacted with a novel dinuclear ruthenium (II) complex, [(bpy)₂Ru(H₂bpi)Ru(bpy)₂](ClO₄)₄, which were demonstrated by using a confocal optical microscope. The morphology of the DNA film was measured by atomic force microscopy and the results show that the DNA strands have been folded into coiled conformations and aggregated into circles with diameters between 18 and 55 nm. The interaction process was also monitored by UV‐visible and fluorescence spectra and investigated by X‐ray photoelectron spectra. The results show that the Ru (II) complex interacts with ct‐DNA by the intercalative mode as it behaves in aqueous solutions. Copyright © 2006 John Wiley & Sons, Ltd.     

复合发光材料[Eu（phen）2（NO3^-）]^2＋-MT的插层组装研究

合成了铕的邻菲罗啉配合物,并通过离子交换法将其配阳离子插层组装到了蒙脱土的片层间,制备出了一种超分子复合发光材料[Eu(phen)2(NO3-)]2 -MT。通过红外光谱、X射线衍射、热分析等手段对其进行了表征,并对其荧光性质进行了研究。结果表明,复合材料保持了蒙脱土良好的层柱结构特征,其单位质量稀土配合物的相对荧光强度较相应纯配合物有显著改善,复合材料片层间稀土配合物的热稳定性也较纯稀土配合物有所提高。     

Palladium(II)-mediated assembly of biotinylated ion channels

Simple synthetic methodology has been used to create biotinylated pyridyl cholate lipids that can undergo multiple self-assembly events when inserted into phospholipid vesicles; Pd(II) links cholates into transmembrane lipids, while avidin laterally clusters these complexes together and concomitantly assembles the vesicles into aggregates. The transmembrane assembly of cholates by Pd(II) "opened" the ion channels, whereas avidin addition produced vesicle aggregates, giving a system that mimicked both transmembrane transport and cellular adhesion. Complexation of these Pd(II)-linked cholates by avidin gave a measurable decrease in ion flow, suggesting some channels became blocked or were prevented from adopting the optimum geometry for ion conduction. This reflects the importance of spatially appropriate preorganisation when generating active supramolecular assemblies.     

Model building and molecular mechanics calculations of mitoxantrone-deoxytetranucleotide complexes: Molecular foundations of DNA intercalation as cytostatic active principle

Summary Several intercalation complexes of the antitumor-active drug mitoxantrone with base paired tetranucleotides were constructed by molecular modeling using computer graphics and molecular mechanics calculations. The mitoxantrone molecule favours DNA binding into CG intercalation site. The two side chains of the drug are orientated into the major groove and fixed by hydrogen bonds with the nucleotide bases. This molecular study can be helpful for understanding the mode of action of cytostatically active compounds and to design new structurally related compounds of the anthraquinone drug type.Dedicated to Prof. Dr. Dr. h.c. mult.H. Oelschläger on the occasion of his 75^th birthday     

Functional membranes prepared by layer‐by‐layer assembly and its metal ions adsorption property

PVDF/(PEI‐C/PAA)_n functional membranes were prepared by layer‐by‐layer (LbL) assembly, and their heavy metal ions adsorption capability was investigated. The changes in the chemical compositions of membrane surfaces were determined by X‐ray photoelectron spectroscopy (XPS). XPS results show that the surface of the PVDF membrane can be alternatively functionalized by PEI‐C and PAA. The membrane surface hydrophilicity was evaluated through water contact angle measurement. Contact angle results show that the surface hydrophilicity of the membrane surface depends on the outermost deposited layer. Morphological changes of membrane surfaces were observed by scanning electron microscopy (SEM). The water fluxes for these membranes were elevated after modification. The performances of the PVDF/(PEI‐C/PAA)_n membranes on the adsorption of copper ions (Cu²⁺) from aqueous solutions were investigated by inductively coupled plasma (ICP). The results indicate that the PVDF/(PEI‐C/PAA)_n functional membranes show high copper ions adsorption ability. Copyright © 2010 John Wiley & Sons, Ltd.     

LDHs薄膜基纳米荧光传感器的制备及其研究进展

层状复合氢氧化物(LDHs)是一种层板金属元素和层间离子可调的无机层状材料,利用其独特的插层组装特性,基于静电、氢键、范德华力等相互作用力,功能性荧光客体分子可与LDHs纳米片复合构筑多功能荧光薄膜材料.LDHs薄膜基荧光材料用于荧光传感器,在有机挥发性气体(VOCs)、温度、压力、重要生物分子等的检测中显示了良好性能.本文总结了LDHs复合薄膜的制备方法以及近年来其在纳米荧光传感领域的进展,并对其未来发展做出了展望.     

Synthesis and characterization of Mn(II), Au(III) and Zr(IV) hippurates complexes

Mn(II), Au(III) and Zr(III) complexes with N-benzoylglycine (hippuric acid) (abbreviation hipH) were synthesized and characterized by elemental analysis, molar conductivity, magnetic measurements, spectral methods (mid-infrared, (1)H NMR, mass, X-ray powder diffraction and UV/vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. The molar conductance measurements proved that all hippuric acid complexes are non-electrolytes. The electronic spectra and magnetic susceptibility measurements were used to infer the structures. The IR spectra of the ligand and its complexes are used to identify the type of bonding. The kinetic thermodynamic parameters such as: E*, DeltaH*, DeltaS* and DeltaG* are estimated from the DTG curves. The free ligand and its complexes have been studied for their possible biological antifungal activity.     

Theoretical study of the interaction between a high-valent manganese porphyrin oxyl-(hydroxo)-Mn(IV)-TMPyP and double-stranded DNA

Cationic porphyrin derivatives such as meso-tetrakis(4-N-methylpyridinium)porphyrin, TMPyP, have been shown to interact with double-stranded DNA. The manganese derivative, Mn(III)-TMPyP, activated by an oxygen donor like potassium monopersulfate, provides an efficient DNA-cleaving system. Previous experimental work1 has shown that DNA cleavage by the Mn(III)-TMPyP/KHSO(5) system was due to an oxidative attack, within the minor groove of B-DNA, at the C5' or C1' carbons of deoxyribose units. The aim of this study was to use molecular modeling to elucidate the specificity of the interactions between the transient active species oxyl-Mn(IV)-TMPyP and the DNA target. Geometric parameters, charges, and force field constants consistent with the AMBER 98 force field were calculated by DFT methods. Molecular modeling (mechanics and dynamic simulations) were performed for oxyl-(hydroxo)-Mn(IV)-TMPyP bound in the minor groove of the dodecamer d(5'-TCGTCAAACCGC)-d(5'-GCGGTTTGACGA). Geometry, interactions, and binding energy of the metalloporphyrin located at the A.T triplet region of the dodecamer were analyzed. These studies show no significant structural change of the DNA structure upon ligand binding. Mobility of the metalloporphyrin in the minor groove was restrained by the formation of a hydrogen bond between the hydroxo ligand trans to the metal-oxyl and a DNA phosphate, restricting the access of the oxyl group to the (pro-S) H atom at C5'.     

A label-free colorimetric platform for DNA via target-catalyzed hairpin assembly and the peroxidase-like catalytic of graphene/Au-NPs hybrids

A target-catalyzed hairpin assembly (CHA) and graphene/Au-NPs hybrids-based platform has been developed for the determination of DNA. This new sensor not only avoided any labeling but also reduced the background signal. In the absence of target, the assembly of H1 and H2 couldn't be triggered. The catalytic activity of graphene/Au-NPs hybrids was inhibited by adsorption of H1 and H2, leading to the “inactive” hybrids unable to catalyze the oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB). However, with the addition of target DNA, the target-catalyzed hairpin assembly was initiated and produced plenty of H1–H2 duplex, which had a weak binding affinity with the graphene/Au-NPs. Thus, the protected interface of graphene/Au-NPs hybrids became active and catalyzed the oxidation reaction of TMB accompanied with a colorless to-blue color change. This approach exhibited good sensitivity and specificity for target DNA with a detection limit of 5.74 × 10⁻¹¹ M, and realized the assay of target DNA in human serum samples. Besides, this sensor could be further expanded to detect viruses or proteins by adapting the corresponding aptamers, showing great potential in biochemical detections.     

Mechanical property and corrosion resistance of zirconia/polydopamine nanocomposite multilayer films fabricated via a novel non‐electrostatic layer‐by‐layer assembly technique

Zirconia/polydopamine (ZrO₂/PDA) nanocomposite multilayer films were constructed on Si substrate via a novel nonelectrostatic layer‐by‐layer (NELBL) assembly technique. The building block of this technique is the newly reported dopamine molecule, which can be attached to almost all material surfaces and undergo oxidation‐polymerization to form PDA layers; more importantly, the outer hydroxyl groups of the PDA layer can chelated with certain inorganic oxide nanoparticles to generate oxide films. Thus, ZrO₂/PDA nanocomposite multilayer films were fabricated by sequential NELBL deposition of PDA and ZrO₂ nanoparticles. The formation of the ZrO₂/PDA nanocomposite multilayer films was monitored by the water contact angle (WCA) and ellipsometric thickness measurements, while the microstructure of the fabricated films was analyzed by means of atomic force microscope (AFM), field emission scanning electron microscope (FESEM), X‐ray photoelectron spectrum (XPS), and X‐ray diffraction (XRD) analysis. The mechanical and anticorrosion behaviors of the annealed ZrO₂/PDA nanocomposite multilayers were found to be greatly enhanced as compared with that of the annealed homogeneous ZrO₂ film. The better mechanical and anticorrosion behaviors of the annealed ZrO₂/PDA nanocomposite multilayers than the annealed homogeneous ZrO₂ film may be closely related to their special microstructure. Namely, the organic–inorganic hybrid microstructure of the annealed ZrO₂/PDA nanocomposite multilayers may largely account for the increased nanohardness and corrosion resistance. Copyright © 2010 John Wiley & Sons, Ltd.     

Study of Anti-Apoptotic mechanism of Ruthenium (II)Polypyridyl Complexes via RT-PCR and DNA binding

A set of novel mononuclear polypyridyl complexes of Ru (II) with N – N donar ligands 1, 10 phenanthroline (phen), 2, 2′ bipyridine (bpy), 4, 4′-dimethyl 2, 2′ bipyridine (dmb) and an intercalating ligand (bnpip = 2-(4-butoxy-3-nitrophenyl)-1H-imidazo [4,5-f] [1,10] phenanthroline) have been synthesized and characterized by various spectral methods. The RT - PCR assays suggest that ruthenium (II) complexes inhibit MCF-7, breast cancer cell line by inducing apoptosis via inhibition of cell cycle check points cyclin D, cyclin E and also upregulation of caspase 8 (protein involved in late Apoptosis). Further the binding potency of Ru (II) complexes were investigated using various spectroscopic techniques like UV–visible, fluorescence and viscosity studies. The complex binds to DNA in an intercalative mode as confirmed by viscosity data with differential binding strength. All complexes show cleavage of the pBR322 DNA through a singlet oxygen production. Theoretical evidence via docking of the complex with DNA reveals the significant residues of binding as guanine.     

Poly(styrene-block-isoprene) nanocomposites: Kinetics of intercalation and effects of copolymer on intercalation behaviors

In addition to phase morphology, diffusion, and dynamics in the bulk, the behavior of block copolymers in the confined state has been of great interest. Although random and graft copolymers have been used in polymer-layered silicate nanocomposites, well-defined block copolymers have received relatively little attention. In this study, the kinetics of intercalation of a series of poly(styrene-b-isoprene) block copolymers into a layered silicate were examined via X-ray diffraction. Intercalation was observed even when the copolymer was in the ordered state, with no discontinuity around the order–disorder transition of the copolymer. As the size of the polystyrene block was increased, slower intercalation kinetics were observed, possibly because of the increased glass-transition temperature of the polystyrene segment. Finally, the clearing temperature of the copolymer in the nanocomposites as measured by small-angle X-ray scattering showed a large heating-rate dependence suggesting that the nanoparticles act as kinetics barriers to the disordering of the copolymer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3264–3271, 2003     

Preparation of bismuth telluride thin film by electrochemical atomic layer epitaxy (ECALE)

Thin-layer electrochemical studies of the underpotential deposition (UPD) of Bi and Te on cold rolled silver substrate have been performed. The voltammetric analysis of underpotential shift demonstrates that the initial Te UPD on Bi-covered Ag and Bi UPD on Te-covered Ag fitted UPD dynamics mechanism. A thin film of bismuth telluride was formed by alternately depositing Te and Bi via an automated flow deposition system. X-ray diffraction indicated the deposits of Bi₂Te₃. Energy Dispersive X-ray Detector quantitative analysis gave a 2: 3 stoichiometric ratio of Bi to Te, which was consistent with X-ray Diffraction results. Electron probe microanalysis of the deposits showed a network structure that results from the surface defects of the cold rolled Ag substrate and the lattice mismatch between substrate and deposit. Translated from Chinese Journal of Applied Chemistry, 2005, 22 (11) (in Chinese)     

用焙烧复原法插层组装有机层柱双氢氧化物

有机酸根插层双氢氧化物(简记为:LDHs OA)是制备具有特殊性质和功能的层柱材料的一类重要前驱体[1 3]。本文以Mg6Al2(OH)16CO2-3·6H2O(简记为MgAl CO2-3)和Zn6Al2(OH)16CO2-3·4H2O(简记为ZnAl CO2-3)为前体,用焙烧复原法将十四酸根(简记为14A)和十八酸根(简记为18A)分别插层组装到了MgAl LDHs和ZnAl LDHs层板间而制得了具有大的层间距、良好的结晶度和规整的层状结构的14A(18A)插层LDHs层柱材料(分别简记为MgAl 14A,mgAl 18A,ZnAl 14A,ZnAl 18A),用XRD谱、IR谱表征了插层交换产物的结构。1　实验部分1.1　仪…     

Characterization of oxidoreductase-redox polymer electrostatic film assembly on gold by surface plasmon resonance spectroscopy and Fourier transform infrared-external reflection spectroscopy

The electrostatic assembly of nanocomposite thin films consisting of alternating layers of an organometallic redox polymer (RP) and oxidoreductase enzymes, glucose oxidase (GOX), lactate oxidase (LOX) and pyruvate oxidase (PYX), was investigated. Multilayer nanostructures were fabricated on gold surfaces by the deposition of an anionic self-assembled monolayer of 11-mercaptoundecanoic acid, followed by the electrostatic attachment of a cationic RP, poly(vinylpyridine Os(bis-bipyridine)₂Cl-co-allylamine) (PVP-Os-AA), and anionic oxidoreductase enzymes. Surface plasmon resonance (SPR) spectroscopy, Fourier transform infrared external reflection spectroscopy (FT-IR-ERS) and electrochemistry were employed to characterize the assembly of these nanocomposite films. The surface concentration of GOX was found to be 2.4 ng/mm² for the first enzyme layer and 1.96 ng/mm² for the second enzyme layer, while values of 10.7 and 1.3 ng/mm² were obtained for PYX and LOX, respectively. The apparent affinity constant for GOX adsorption was found to be 8×10⁷ M⁻¹. FT-IR-ERS was used to verify the incorporation of GOX and its conformational stability inside of these nanocomposite thin films. An SPR instrument with a flow-through cell was modified by additions of Ag/AgCl reference and Pt counter electrodes, with the gold-coated SPR surface film serving as the working electrode. This enabled real-time observation of the assembly of sensing components and immediate, in situ electrochemical verification of substrate-dependent current upon the addition of enzyme to the multilayer structure. A glucose-dependant amperometric response with sensitivity of 0.197 μA/cm²/mM for a linear range of 1-10 mM of glucose was obtained. The SPR and FT-IR-ERS studies also showed no desorption of polymer or enzyme from the nanocomposite RP-GOX structure when stored in aqueous environment occurred over the period of 3 weeks, suggesting that decreasing substrate sensitivity with time was due to loss of enzymatic activity rather than loss of film compounds from the nanostructure.     

Probing local electronic and geometric changes of hydrated calcium vanadium oxide (CaxV2O5·yH2O) upon Zn ion intercalation

Abstract

An interesting nanostructured non-stoichiometric vanadium oxide bronze (Ca_xV₂O₅?yH₂O) is incorporated as the active material in an aqueous zinc-ion intercalation device. Simple solvothermal synthesis route produces highly crystalline and strongly oriented nanobelt structures as characterized by microscopy. Upon cycling, the cathode materials are recovered for an X-ray absorption investigation of local electronic and geometric changes for both the host vanadium oxide and the intercalated zinc ion as a function of voltage. This multi-edge study presents changes in Zn–O coordination and suggests Zn-ion occupancy site through theoretical calculations. The layered vanadium host shows gradual oxidation state reduction from charge density donation during intercalation while the Zn ion maintains the +2 oxidation state. The findings add understanding to the mechanisms involved in aqueous electrochemical storage devices.     

2-(2-吡啶基)苯并噻唑的Cu(Ⅱ),Ni(Ⅱ),Cd(Ⅱ)金属配合物的合成以及与DNA相互作用的研究

以金属Cu(Ⅱ),Ni(Ⅱ),Cd(Ⅱ)为中心离子,分别合成2-(2-吡啶基)苯并噻唑为配体的配合物,其中得到了以Cu(Ⅱ)为中心离子的晶体,并培养出了单晶.该配合物是五配位的三斜晶系,上述金属配合物都能与DNA结合,并能有效断裂DNA链,可以通过与癌症细胞的DNA发生解旋DNA的作用从而引起癌症细胞DNA的损伤,使癌细胞的DNA在复制和转录的过程中受到阻碍,从而阻止癌细胞的生长和分裂,并导致癌细胞的死亡.为其在药物开发和分子生物学中的应用提供了有价值的信息.     

四环素-铜(Ⅱ)配合物与DNA相互作用的吸收光谱研究

用紫外光谱方法研究了四环素(TC) Cu(II)配合物与DNA的相互作用.吸收光谱研究表明,DNA能与四环素(TC)及Cu(II)形成的配合物发生反应,配合物与DNA的作用方式随着配合物类型及DNA浓度的不同而不尽相同:当四环素与铜形成1∶1型配合物时,较低浓度的DNA能与配合物以嵌插方式相互作用,而较高浓度的DNA与该配合物除了发生嵌插作用外,还存在另外的作用方式;当四环素与铜形成1∶2型配合物时,DNA与该配合物则主要以嵌插方式相互作用,并且这两种配合物与DNA的嵌插作用均是通过四环素配体插入的.