基于Au纳米通道膜的生物分离新方法在蛋白质分离中的应用

采用化学沉积法将Au沉积到聚碳酸酯滤膜(PC-Mem)上,制备了直径为55nm左右的Au纳米通道膜(Au-Mem).以牛血清白蛋白(BSA)和免疫球蛋白G(IgG)抗体为模型分子,研究了Au-Mem以及分别以半胱氨酸和硫氰酸胍修饰的Au-Mem(Cys-Au-Mem,Gua-Au-Mem)对模型分子的分离特性.由于硫氰酸胍具有一定的亲水作用和蛋白质变性作用,BSA在Gua-Au-Mem上的迁移速率比在Au-Mem上增加了30～50倍,而修饰膜对IgG的迁移速率无明显影响.在pH=4.5时分离了BSA和IgG的混合溶液.Gua-Au-Mem和Cys-Au-Mem对混合溶液的分离度分别为31.6和23.1,表明经修饰的Au-Mem具有良好的分离性能.     

Electrodeposition of Au monolayer on Pt(111) mediated by self-assembled monolayers

In-situ scanning tunneling microscopy (STM), cyclic voltammetry (CV), and infrared reflection-adsorption spectroscopy (IRRAS) have been used to examine the electrodeposition of gold onto Pt(111) electrodes modified with benzenethiol (BT) and benzene-1,2-dithiol (BDT) in 0.1 M HClO4 containing 10 microM HAuCl4. Both BT and BDT were attached to Pt(111) via one sulfur headgroup. STM and IRRAS results indicated that the other SH group of BDT was pendant in the electrolyte. Both BT and BDT formed (2 x 2) structures at the coverage of 0.25, and they were transformed into (square root(3) x square root(3))R30 degrees as the coverage was raised to 0.33. These two organic surface modifiers resulted in 3D and 2D gold islands at BT- and BDT-coated Pt(111) electrodes, respectively. The pendant SH group of BDT could interact specifically with gold adspecies to immobilize gold adatoms on the Pt(111) substrate, which yields a 2D growth of gold deposition. Molecular resolution STM revealed an ordered array of (6 x 2 square root(13)) after a full monolayer of gold was plated on the BDT/Pt(111) electrode. Since BDT was strongly adsorbed on Pt(111), gold adatoms only occupied free sites between BDT admolecules on Pt(111). This is supported by a stripping voltammetric analysis, which reveals no reductive desorption of BDT admolecules at a gold-deposited BDT/Pt(111) electrode. It seems that the BDT adlayer acted as the template for gold deposit on Pt(111). In contrast, a BT adlayer yielded 3D gold deposit on Pt(111). This study demonstrates unambiguously that organic surface modifiers could contribute greatly to the electrodeposition of metal adatoms.     

A fundamental study of the effects of modifiers in supercritical fluid chromatography

The effects of organic modifiers on retention and peak shape in packed-column supercritical fluid chromatography were studied. The adsorption behavior of different modifiers was investigated on stationary phases consisting of hydrocarbon monolayers chemically bonded on silica. Adsorption isotherms for several modifiers were recorded using breakthrough measurements. The results were compared with those obtained by a simple method based on the injection of different sample sizes. Modifiers were selected to reflect various types of interactions with the silica support. Isotherms were found to be approximately Langmuirean. Experiments were performed to elucidate the influence of adsorbed molecules on the retention of selected test solutes. The introduction of a solvent modifier can lead to a substantial change in the mobile phase density, the effect of which is comparable with that of an increase in the density of pure carbon dioxide. Our results confirm that the effects of low concentrations of modifiers (between 0 and 2 percent) in packed-column SFC are largely due to deactivation of residual silanol groups on the silica support. The accessibility of the active sites was found to depend strongly on the size and structure of the modifier molecules. The decrease of retention due to the addition of low concentrations of modifiers could be described accurately by a model derived from Langmuir adsorption behavior. Some semi-quantitative rules for the selection of modifiers and the required concentrations for optimum deactivation of the support are discussed.     

TiO2纳米管的模板法制备及表征

TiO2纳米材料在太阳能的储存与利用、光电转换、光致变色及光催化降解大气和水中的污染物等方面具有广阔的应用前景,成为重点研究的课题之一[1～5].目前,以TiO2纳米粉体和纳米膜的研究较为普遍,而TiO2纳米管的报道不多.由于纳米管比纳米膜具有更大的比表面积,因而具有较高的吸附能力,可望提高TiO2的光电转换效率.模板法(包括多孔阳极氧化铝膜(PAA)、光刻蚀制备的纳米模板、聚碳酸酯纳米滤膜等)在制备导电聚合物、金属、碳、无机半导体等纳米管或线型材料方面已得到广泛应用[6～9],在这些模板中,PAA膜具有均匀分布的垂直于表面的相互平行的密集纳米孔,且孔径、孔间距、膜厚可以通过电化学手段加以控制[10～13].     

金纳米通道的研究及其在分析化学中的应用

微纳尺度的研究是微纳米技术的重要组成部分。本文重点对金纳米通道的制备及其在分离分析、传感器等方面的研究和应用作了评述。展望了金纳米通道的应用前景。     

Understanding the role of clay silicate nanoparticles with organic modifiers in thermal curing of cyanate ester resin

The catalytic effect of montmorillonite clay nanoparticles containing organic modifiers such as quaternary phosphonium salts on cure mechanism of cyanate ester resin (RS-9D) was studied by differential scanning calorimetry (DSC) measurements, FT-IR and NMR spectroscopy as well as mass-spectrometry. The results show that the net catalytic effect arises from the presence of moisture associated with nanoclay particles where organic modifiers act as moisture transport agents. Possible mechanisms for cure pathways are discussed.     

Extraction of metal–dye ion-association complexes by thin ether-type polyurethane membranes

The extraction and transport of various gold(III) chloride–organic dye ion-association complexes in aqueous solution through thin ether-type polyurethane membranes have been studied. The effects of the presence of salt, acid, different starting and receiving solution compositions, and temperature on the sorption process were investigated. Methylene Blue, Rhodamine B and Brilliant Green, which represent organic dyes from the thiazine, xanthene, and triphenylmethane groups, respectively, were used for this study. Gold(III) chloride and the individual organic dyes were extracted and transported through the membrane only if the solution conditions favored the formation of a neutral species. The ion-association complexes of gold(III) chloride with Methylene Blue and Rhodamine B were extracted and transported by the polymer only when the formation of the complex was more efficient than the individual extraction and transport of each of the species. The extraction of Brilliant Green under all conditions studied was very high, however, no transport occurred. The overall sorption of this dye was found to be independent of the presence of gold regardless of solution composition. High temperature resulted in a very high rate of transport of the gold(III) chloride–organic dye ion-pair.     

Nanopolaritonics with a continuum of molecules: simulations of molecular-induced selectivity in plasmonics transport through a continuous Y-shape

Using the recent NF (near-field) formulation for electrodynamics on the nanoscale, we simulate transport in a Y-shape gold nanostructure in the presence of 2-level molecules. NF is shown to be easily integrated with the Liouville equation, producing a simple and efficient nanopolaritons (plasmons-excitons) solver, with a large time step. Two cases are considered: coating of the gold structure with molecular layers thinner than the structure, and filling space with aligned molecules. In both cases significant effects on the radiation transport are obtained even for low molecular densities. At low densities the effects are primarily an overall reduction of the plasmonics peak, but at higher densities there is a significant selectivity control by the molecules. A redshift is predicted, especially for the space-filling case. The combined nanopolariton shows qualitative hybridization, and the spectral peaks separate with increasing coupling, i.e., with increasing molecular densities. The results open the way to "control of light by light," i.e., controlling plasmonic light transport by inducing a change in the direction of the guiding molecular dipoles through radiation or other means.     

Immobilization of the nanoparticle monolayer onto self-assembled monolayers by combined sterically enhanced hydrophobic and electrophoretic forces

The immobilization of surface-derivatized gold nanoparticles onto methyl-terminated self-assembled monolayers (SAMs) on gold surface was achieved by the cooperation of hydrophobic and electrophoretic forces. Electrochemical and scanning probe microscopy techniques were utilized to explore the influence of the SAM's structure and properties of the nanoparticle/SAM/gold system. SAMs prepared from 1-decanethiol (DT) and 2-mercapto-3-n-octylthiophene (MOT) were used as hydrophobic substrates. The DT SAM is a closely packed and organized monolayer, which can effectively block the underlying gold and inhibit a variety of solution species including organic and inorganic molecules from penetrating, whereas the MOT monolayer is poorly packed or disorganized (because of a large difference in dimension between the thiophene head and the alkylchain tail) and permeable to many organic probes in aqueous solution but not to inorganic probes. Thus, the MOT monolayer provides a more energetically favorable hydrophobic surface for the penetration and adsorption of organic species than the DT monolayer. This hypothesis is supported by experiments in which the density of hydrophobically immobilized nanoparticles on the MOT SAM is much larger than that on the DT SAM. The results also suggest new approaches for modification of macroscopic surfaces with nanoscopic particles.     

A vapor selectivity study of microsensor arrays employing various functionalized ligand protected gold nanoclusters

We synthesized and tested four different monolayer protected gold nanoclusters (MPCs) as chemically selective interfaces for an organic vapor sensor array. The ligands chosen for capping the nano-Au particles and for selective organic vapor sorption were octanethiol, 2-naphthalenethiol, 2-benzothiazolethiol and 4-methoxythiolphenol. The same set of gold nanoclusters were tested on two different types of sensor platforms, a chemiresistor (CR) and a quartz crystal microbalance (QCM). The sensing properties of both sensor arrays were investigated with 10 organic vapors of various functional groups. Vapor sensing selectivity, dominated by the shell ligand structure of MPC, was demonstrated. The sensitivities of MPC coated CR are better than those of QCM sensors coated with the same material. The average CR/QCM amplification factors are range from 1.9 for 4-methoxythiolphenol MPC to 16.9 for octanethiol MPC. These differences in amplification factors indicate the functional group specific mechanisms for each vapor-MPC pair. The shell penetration mechanism of hydrogen-bonding vapor molecules into the 2-benzothiazolethiol capped MPC reduced the CR/QCM amplification factors. Strong attraction between MPC shell ligands can also reduce the magnitude of resistance changes during vapor sorption.     

Influence of anions on the dimensionality of extended networks based on Cu I cations and 1,4,5,8,9,12-hexaazatriphenylene (HAT) ligands

Reactions of Cu I salts with 1,4,5,8,9,12-hexaazatriphenylene (HAT) afford three types of cationic coordination polymers depending on the anion present in the reaction solution. In the crystal structure of {[Cu(HAT)][BF4]x1/3(C6H6)}infinity, (1), Cu ions and HAT molecules form extended layers that are best described as strongly distorted honeycomb nets. The space between the layers is occupied by [BF4]- anions and solvent molecules. {[Cu(HAT)][PF6]}infinity, (2), crystallizes as a chiral (10,3)-a net with [PF6]- anions residing in the cavities of the three-dimensional metal-organic framework. The crystal structure of {[Cu4(HAT)3][SbF6]4x3C6H6}infinity, (3), is based on unique extended [Cu4(HAT)3]infinity "nanotubules" filled with solvent molecules and [SbF6]- anions.     

Metal-controlled assembly of uranyl diphosphonates toward the design of functional uranyl nanotubules

Two uranyl nanotubules with elliptical cross sections were synthesized in high yield from complex and large oxoanions using hydrothermal reactions of uranyl salts with 1,4-benzenebisphosphonic acid or 4,4'-biphenylenbisphosphonic acid and Cs(+) or Rb(+) cations in the presence of hydrofluoric acid. Disordered Cs(+)/Rb(+) cations and solvent molecules are present within and/or between the nanotubules. Ion-exchange experiments with A(2){(UO(2))(2)F(PO(3)HC(6)H(4)C(6)H(4)PO(3)H)(PO(3)HC(6)H(4)C(6)H(4)PO(3))}·2H(2)O (A = Cs(+), Rb(+)), revealed that A(+) cations can be exchanged for Ag(+) ions. The uranyl phenyldiphosphonate nanotubules, Cs(3.62)H(0.38)[(UO(2))(4){C(6)H(4)(PO(2)OH)(2)}(3){C(6)H(4)(PO(3))(2)}F(2)]·nH(2)O, show high stability and exceptional ion-exchange properties toward monovalent cations, as demonstrated by ion-exchange studies with selected cations, Na(+), K(+), Tl(+), and Ag(+). Studies on ion-exchanged single crystal using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS) provide evidence for chemical zonation in Cs(3.62)H(0.38)[(UO(2))(4){C(6)H(4)(PO(2)OH)(2)}(3){C(6)H(4)(PO(3))(2)}F(2)]·nH(2)O, as might be expected for exchange through a diffusion mechanism.     

Photochemical patterning of a self-assembled monolayer of 7-diazomethylcarbonyl-2,4,9-trithiaadmantane on gold films via Wolff rearrangement

Photolithographic attachment of functional organic molecules via ester or amide linkages to self-assembled monolayers (SAMs) on gold thin films was achieved by employing a novel photoreactive surface anchor, 7-diazomethylcarbonyl-2,4,9-trithiaadmantane. The photoreactive SAM was prepared by the spontaneous physical adsorption of the photoreactive surface anchor onto gold surfaces. The alpha-diazo ketone moiety of the SAM was found to display the classical Wolff rearrangement reactivity to produce a ketene intermediate on the exposed area. Organic molecules such as alcohols and amines can thus be attached to the gold surfaces selectively by the facile in situ formation of ester or amide linkages. The structure and reactivity of the photoreactive surface anchor were characterized by real-time FT-IR, fluorescence, and polarization modulation infrared reflectance absorption spectroscopy (PM-IRRAS). The Wolff rearrangement reactivity of the SAM suggested that a "surface-isolated" carbonylcarbene may be generated when the SAM was exposed to 255-nm irradiation.     

有机改性剂对氯代酚毛细管区带电泳分离的影响

在分离19种氯代酚的过程中,考察了不同的有机添加剂对其毛细管区带电泳分离的影响,发现除了缓冲溶液的pH值外,缓冲溶液添加剂对氯代酚的电泳分离也有较大影响。这种影响与添加剂和氯代酚形成氢键的能力有关。     

Paclitaxel-functionalized gold nanoparticles

Here we describe the first example of 2 nm gold nanoparticles (Au NPs) covalently functionalized with a chemotherapeutic drug, paclitaxel. The synthetic strategy involves the attachment of a flexible hexaethylene glycol linker at the C-7 position of paclitaxel followed by coupling of the resulting linear analogue to phenol-terminated gold nanocrystals. The reaction proceeds under mild esterification conditions and yields the product with a high molecular weight, while exhibiting an extremely low polydispersity index (1.02, relative to linear polystyrene standards). TGA analysis of the hybrid nanoparticles reveals the content of the covalently attached organic shell as nearly 67% by weight, which corresponds to approximately 70 molecules of paclitaxel per 1 nanoparticle. The presence of a paclitaxel shell with a high grafting density renders the product soluble in organic solvents and allows for detailed (1)H NMR analysis and, therefore, definitive confirmation of its chemical structure. High-resolution TEM was employed for direct visualization of the inorganic core of hybrid nanoparticles, which were found to retain their average size, shape, and high crystallinity after multiple synthetic steps and purifications. The interparticle distance substantially increases after the attachment of paclitaxel as revealed by low-magnification TEM, suggesting the presence of a larger organic shell. The method described here demonstrates that organic molecules with exceedingly complex structures can be covalently attached to gold nanocrystals in a controlled manner and fully characterized by traditional analytical techniques. In addition, this approach gives a rare opportunity to prepare hybrid particles with a well-defined amount of drug and offers a new alternative for the design of nanosized drug-delivery systems.     

High-performance liquid chromatographic and capillary electrophoretic enantioseparation of plant growth regulators and related indole compounds using macrocyclic antibiotics as chiral selectors

Enantioseparation of plant growth regulators, such as 3-(3-indolyl)-butyric acid, abscisic acid and structurally related molecules including a variety of substituted tryptophan compounds, has been achieved by HPLC and/or CE. The covalently bonded macrocyclic antibiotics, teicoplanin, ristocetin A and vancomycin, were used as chiral stationary phases (CSPs) in HPLC. Most of the racemates were baseline resolved in the reversed-phase mode (EtOH-H2O) using the teicoplanin CSP. The chiral recognition mechanism is discussed in regard to the structure of the analytes. In CE, the three aforementioned macrocyclic antibiotics were used as chiral additives in a phosphate run buffer. The effect of pH and the concentration of the organic modifiers were considered. The results obtained by HPLC and CE were compared.     

Investigation of Electrosorption of Organic Molecules onto Gold and Nickel Electrodes Using an Electrochemical Quartz Crystal Microbalance

The adsorption behaviors of two organic molecules, benzoic acid (BA) and 2-butyne-1,4-diol (BD), on metal electrodes have been studied using an electrochemical quartz crystal microbalance (EQCM) combined with the cyclic voltammetry technique. In the range of potentials studied, BA molecules were adsorbed onto an electrodeposited gold electrode with a saturation concentration of 5.0 × 10¹⁴ molecules/cm². It was found that the Frumkin isotherm model was most suitable to depict the electrosorption behavior. The isotherm parameters by nonlinear fitting, which agreed with the literature values, implied BA was chemisorbed on the gold surface. For BD on an electrodeposited nickel electrode, the equivalent molar mass of the reaction species was calculated on the basis of the voltammetry curve and mass curve, which were obtained simultaneously during the potential scan. The analysis of EQCM data for the electrosorption of BD on gold and nickel electrodes showed an irreversible characteristic; the latter effectively inhibited the hydrogen evolution reaction.     

Ligand-stabilized aromatic three-membered gold rings and their sandwichlike complexes

Electronic structure calculations (DFT) suggest that ligand-stabilized three-membered gold(I) rings constituting the core structure in a series of cyclo-Au3L(n)H(3-n) (L = CH3, NH2, OH and Cl; n = 1, 2, 3) molecules exhibit aromaticity, which is primarily due to 6s and 5d cyclic electron delocalization over the triangular Au3 framework (s- and d-orbital aromaticity). The aromaticity of the novel triangular gold(I) isocycles was verified by a number of established criteria of aromaticity. In particular, the nucleus-independent chemical shift, NICS(0), the upfield changes in the chemical shifts for Li+, Ag+, and Tl+ cations over the Au3 ring plane, and their interaction with electrophiles (e.g., H+, Li+, Ag+, and Tl+) are indicative for the aromaticity of the three-membered gold(I) rings. Interestingly, unlike the respective substituted derivatives of cyclopropenium cation and the bora-cyclopropene carbacyclic analogues, the aromatic Au3 rings, although exhibit comparable diatropicity, react with electrophiles in a different way affording 1:1 and 2:1 sandwichlike complexes. The bonding in the three-membered gold(I) rings is characterized by a common ring-shaped electron density, more commonly seen in aromatic organic molecules and in "all-metal" aromatics, such as the cyclo-[Hg3]4- tetraanion. Moreover, the cation-pi interactions in the 1:1 and 1:2 sandwichlike complexes formed upon reacting the Au3 rings with electrophiles, depending on the nature of the cation, are predicted to be predominantly electrostatic (Li+, Tl+) or covalent (H+, Ag+). The 1:2 complexes constitute a new class of sandwichlike complexes, which are expected to have novel properties and applications.     

Mapping the nanoparticle-coating monolayer with NMR pseudocontact shifts

Lanthanide ions Yb(3+) and Tb(3+), once bound to the monolayer of organic molecules coating the surface of gold nanoparticles, induce pseudo-contact shifts on the signals of nearby nuclear spins. This not only allows the investigation of the average structure of the ligands in the monolayer but also the mapping of the position of organic molecules bound to it.     

Self-assembled gold nanoparticles on functionalized gold (111) studied by scanning tunneling microscopy

Nanogold colloidal solutions are prepared by the reduction of HAuClO4 with sodium citrate and sodium borohydride.4-Aminothiophenol (ATP) self-assembled monolayers (SAMs) are formed on gold(111) surface,on which gold nanopartides are immobilized and a sub-monolayer of the particles appears.This sub-monolayer of gold nanopartides is characterized with scanning tunneling microscopy (STM),and a dual energy barrier tunneling model is proposed to explain the imageability of the gold nanopartides by STM.This model can also be used to construct multiple energy barrier structure on solid/ liquid interface and to evaluate the electron transport ability of some organic monolayers with the aid of electrochemical method.