Interaction between cationic, anionic, and non-ionic surfactants with ABA block copolymer Pluronic PE6200 and with BAB reverse block copolymer Pluronic 25R4

The interaction in aqueous solution between either the normal block copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide): Pluronic PE6200 [(EO)(11)-(PO)(28)-(EO)(11)], or the reverse block copolymer poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide): Pluronic 25R4 [(PO)(19)-(EO)(33)-(PO)(19)] and the surfactants sodium decylsulfate, C(10)OS, decyltrimethyl ammonium bromide, C(10)TAB, and pentaethylene glycol monodecyl ether, C(10)E(5), was investigated and the aggregation behavior of these surfactants with Pluronics was compared. Surface tension measurements show that Pluronics in their non-aggregated state better interact with the anionic surfactant C(10)OS than with cationic and non-ionic ones. The presence of the two Pluronics induces the same lowering of the aggregation number of C(10)OS as shown by fluorescence quenching measurements. The number of polymer chains necessary to bind each C(10)OS aggregate has been estimated to be approximately 6 for PE6200 and approximately 2 for 25R4. Furthermore, this surfactant also induces the same increment in the gyration radius of the polymers as revealed by viscosimetry. Calorimetric results have been reasonably reproduced by applying a simple equilibrium model to the aggregation processes.     

Dissolution of Nickel Ferrite in Aqueous Solutions Containing Oxalic Acid and Ferrous Salts

The dissolution of nickel ferrite in oxalic acid and in ferrous oxalate-oxalic acid aqueous solution was studied. Nickel ferrite was synthesized by thermal decomposition of a mixed tartrate; the particles were shown to be coated with a thin ferric oxide layer. Dissolution takes place in two stages, the first one corresponding to the dissolution of the ferric oxide outer layer and the second one being the dissolution of Ni(1.06)Fe(1.96)O(4). The kinetics of dissolution during this first stage is typical of ferric oxides: in oxalic acid, both a ligand-assisted and a redox mechanism operates, whereas in the presence of ferrous ions, redox catalysis leads to a faster dissolution. The rate dependence on both oxalic acid and on ferrous ion is described by the Langmuir-Hinshelwood equation; the best fitting corresponds to K(1)(ads)=25.6 mol(-1) dm(-3) and k(1)(max)=9.17x10(-7) mol m(-2) s(-1) and K(2)(ads)=37.1x10(3) mol(-1) dm(-3) and k(2)(max)=62.3x10(-7) mol m(-2) s(-1), respectively. In the second stage, Langmuir-Hinshelwood kinetics also describes the dissolution of iron and nickel from nickel ferrite, with K(1)(ads)=20.8 mol(-1) dm(3) and K(2)(ads)=1.16x10(5) mol(-1) dm(3). For iron, k(1)(max)=1.02x10(-7) mol of Fe m(-2) s(-1) and k(2)(max)=2.38x10(-7) mol of Fe m(-2) s(-1); for nickel, the rate constants k(1)(max) and k(2)(max) are 2.4 and 1.79 times smaller, respectively. The factor 1.79 agrees nicely with the stoichiometric ratio, whereas the factor 2.4 implies the accumulation of some nickel in the residual particles. The rate of nickel dissolution in oxalic acid is higher than that in bunsenite by a factor of 8, whereas hematite is more reactive by a factor of 9 (in the absence of Fe(II)) and 27 (in the presence of Fe (II)). It may be concluded that oxalic acid operates to dissolve iron, and the ensuing disruption of the solid framework accelerates the release of nickel. Copyright 2000 Academic Press.     

Dynamic elasticity of triblock copolymer of poly(ethylene oxide) and poly(propylene oxide) on a water surface

Dilatational viscoelasticity of adsorbed and spread films of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer at the air-water interface is studied by the capillary waves and oscillating barrier techniques. At the surface pressure below 10 mN/m, dynamic surface properties of these films coincide with those of poly(ethylene oxide). At higher surface pressures, the results obtained indicate the desorption of poly(propylene oxide) segments from the monolayer and their interaction with poly(ethylene oxide) segments in an aqueous phase. At a surface pressure close to 19 mN/m, the behavior of adsorbed and spread poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) films becomes different. The real part of dynamic surface elasticity of spread films tends toward its maximum value (20 mN/m) and, upon further compression, films begin to dissolve. At the same time, the surface elasticity of adsorbed films decreases nearly twofold upon the achievement of the maximum value that testifies the formation of looser structure of the surface layer.     

不同极性微量选择性溶剂对聚合物膜表面浸润性的控制

通过在双亲性三嵌段共聚物( PEO-PDMS-PEO)的溶液中加入不同极性的微量选择性溶剂, 分别制得胶束和反胶束微粒, 不同组分的溶液涂膜后显示出明显的浸润性差异. 采用透射电镜、原子力显微镜和X射线光电子能谱分别对胶束和反胶束微粒在溶液中和成膜后的结构以及表面化学组成进行了表征, 结果表明, 不同选择性溶剂所形成的胶束和反胶束微粒的结构差异, 导致了涂膜的表面化学组成的不同, 最终影响其表面浸润性.     

Photoisomerization of a carbocyanine derivative in the reverse phases of a block copolymer: evidence for the existence of water droplets

In an attempt to understand the nature of water present in the reverse phases of aggregates formed with the triblock copolymer poly(ethylene oxide)(20)-poly(propylene oxide)(70)-poly(ethylene oxide)(20) (P123) and also investigate how these confined environments influence the rates of photoisomerization, fluorescence lifetimes and quantum yields of a carbocyanine derivative--3,3'-diethyloxadicarbocyanine iodide (DODCI)--were measured in these systems over the temperature range of 293-318 K. Three different copolymer-oil-water compositions were chosen such that the mole ratio of water to copolymer (W) spans the range of 50-150. In these systems, butyl acetate was used as the oil or the nonpolar component. It has been noticed that in all three systems the fluorescence decays of DODCI comprise a long component whose contribution is 85-90%, and this has been ascribed to the fraction of solute solubilized in the core region where hydrated poly(ethylene oxide) units are present. A short-decay component is associated with the remaining fraction, and its values match with those measured in water, indicating that the water present in these reverse phases is in the form of droplets. The photoisomerization rate constants of DODCI located in the core regions of the reverse phases are identical in the three systems at a given temperature and similar to the ones obtained in normal phases of P123. The reasons for the observed behavior have been discussed.     

Thermodynamics of

Formation of cobalt(II)-thiocyanato complexes in nonionic surfactant solutions of poly(ethylene oxide) type with varying poly(ethylene oxide) chain lengths of 7.5 (Triton X-114), 30 (Triton X-305), and 40 (Triton X-405) has been studied by titration spectrophotometry and calorimetry at 298 K. Data were analyzed by assuming formation of a series of ternary complexes Co(NCS)(n)Y(m)((2-n)+) (Y=surfactant) with an overall formation constant beta(nm). In all the surfactant systems examined, data obtained can be explained well in terms of formation of Co(NCS)(+) and Co(NCS)(2) in an aqueous phase (aq), and Co(NCS)(4)Y(2-) in micelles, and their formation constants, enthalpies, and entropies have been determined. The beta(41)/beta(20) ratio increases and the corresponding enthalpy becomes significantly less negative with an increasing number of ethylene oxide groups. This suggests that micelles of these nonionic surfactants have a heterogeneous inner structure consisting of ethylene oxide and octylphenyl moieties. Indeed, on the basis of molar volumes of ethylene oxide and octylphenyl groups, intrinsic thermodynamic parameters have been extracted for the reaction Co(NCS)(2)(aq)+2NCS(-)(aq)=Co(NCS)(4)Y(2-) (Delta(r)G degrees, Delta(r)H degrees, and Delta(r)S degrees ) at each moiety. The Delta(r)G degrees, Delta(r)H degrees, and Delta(r)S degrees values are -16 kJ mol(-1), -15 kJ mol(-1), and 3 J K(-1) mol(-1), respectively, for the ethylene oxide moiety, and -15 kJ mol(-1), -70 kJ mol(-1), and -183 J K(-1) mol(-1) for octylphenyl. Significantly less negative Delta(r)H degrees and Delta(r)S degrees values for ethylene oxide imply that the hydrogen-bonded network structure of water is extensively formed at the ethylene oxide moiety, and the structure is thus broken around the Co(NCS)(4)(2-) complex with weak hydrogen-bonding ability. Copyright 2001 Academic Press.     

5' modification of duplex DNA with a ruthenium electron donor-acceptor pair using solid-phase DNA synthesis

Incorporation of metalated nucleosides into DNA through covalent modification is crucial to measurement of thermal electron-transfer rates and the dependence of these rates with structure, distance, and position. Here, we report the first synthesis of an electron donor-acceptor pair of 5' metallonucleosides and their subsequent incorporation into oligonucleotides using solid-phase DNA synthesis techniques. Large-scale syntheses of metal-containing oligonucleotides are achieved using 5' modified phosporamidites containing [Ru(acac)(2)(IMPy)](2+) (acac is acetylacetonato; IMPy is 2'-iminomethylpyridyl-2'-deoxyuridine) (3) and [Ru(bpy)(2)(IMPy)](2+) (bpy is 2,2'-bipyridine; IMPy is 2'-iminomethylpyridyl-2'-deoxyuridine) (4). Duplexes formed with the metal-containing oligonucleotides exhibit thermal stability comparable to the corresponding unmetalated duplexes (T(m) of modified duplex = 49 degrees C vs T(m) of unmodified duplex = 47 degrees C). Electrochemical (3, E(1/2) = -0.04 V vs NHE; 4, E(1/2) = 1.12 V vs NHE), absorption (3, lambda(max) = 568, 369 nm; 4, lambda(max) = 480 nm), and emission (4, lambda(max) = 720 nm, tau = 55 ns, Phi = 1.2 x 10(-)(4)) data for the ruthenium-modified nucleosides and oligonucleotides indicate that incorporation into an oligonucleotide does not perturb the electronic properties of the ruthenium complex or the DNA significantly. In addition, the absence of any change in the emission properties upon metalated duplex formation suggests that the [Ru(bpy)(2)(IMPy)](2+)[Ru(acac)(2)(IMPy)](2+) pair will provide a valuable probe for DNA-mediated electron-transfer studies.     

Periodic mesoporous organosilicas with multiple bridging groups and spherical morphology

Bi- and trifunctional periodic mesoporous organosilicas (PMOs) with phenylene, thiophene, and ethane bridging groups were synthesized using 1,2-bis(triethoxysilyl)ethane (BTEE), 1,4-bis(triethoxysilyl)benzene (BTEB), and 2,5-bis(triethoxysilyl)thiophene (BTET) organosilica precursors and a poly(ethylene oxide)-poly(D,L-lactic acid-co-glycolic acid)-poly(ethylene oxide) (PEO-PLGA-PEO) triblock copolymer template under low acidic conditions. The PMO samples with different concentrations of organic bridging groups were obtained in the form of spherical particles having average diameters of 2-3 mum and 2D hexagonal (p6m) mesostructure with pore diameters of 7.3-8.4 nm. The particle morphology and chemistry of pore walls were tailored using different mixtures of organosilica precursors. Adsorption and structural properties of the aforementioned PMOs have been studied by nitrogen adsorption and small-angle X-ray scattering, whereas their framework chemistry was quantitatively analyzed by solid-state 13C and 29Si MAS NMR.     

Effect of "inverse melting transition" of aqueous triblock copolymer solutions on solute rotational dynamics

Rotational dynamics of two structurally similar hydrophobic solutes, 2,5-dimethyl-1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DMDPP) and 1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DPP), has been investigated in 30% wv aqueous solution of triblock copolymer, poly(ethylene oxide)(20)-poly(propylene oxide)(70)-poly(ethylene oxide)(20) as a function of temperature. This study has been undertaken in an attempt to explore how the dynamics of a solute molecule solubilized in a copolymer solution is influenced when it undergoes sol-to-gel transition. It has been observed that the anisotropy decays of both DMDPP and DPP can be described by biexponential functions in the sol as well as in the gel phase. This observation has been rationalized on the basis of the probe molecule undergoing two different kinds of motion rather than being located in two different regions of the micelle. Even in the gel phase, which results as a consequence of micelle-micelle entanglement due to an increase in their volume fraction, the rotational relaxation of the solutes is similar to that observed in the micellar solution. The outcome of this work indicates that even though these gels have very high macroscopic viscosities and hence do not flow, the microenvironments experienced by the solutes are akin to that of a micellar solution.     

Theoretical Study and Luminescence Properties of the Cyclic Cu(3)(dppm)(3)OH(2+) Cluster. The First Luminescent Cluster Host at Room Temperature

The [Cu(3)(dppm)(3)OH](BF(4))(2) cyclic cluster host is found to be luminescent at 298 K (lambda(max) = 540 nm; tau(e) = 89 +/- 9 &mgr;s; Phi(e) = 0.14 +/- 0.01) in degassed ethanol solutions and at 77 K (lambda(max) = 480 nm; tau(e) = 170 +/- 40 &mgr;s; Phi = 0.73 +/- 0.07) also in ethanol. The nature of the lowest energy excited states has been addressed theoretically using density functional theory and experimentally using UV-visible, luminescence, and polarized luminescence spectroscopy and is found to be (1,3)A(2) arising from the.(18e)(4)(7a(2))(1)(13a(1))(1) electronic configuration. The excited state geometry optimization for the model Cu(3)(PH(3))(6)OH(2+) compound in its T(1) state ((3)A(2)) has been performed using density functional theory and compared to its ground state structure. The Cu.Cu bond length is expected to decrease greatly in the excited state (calculated DeltaQ approximately 0.47 ?), in agreement with the d(10) electronic configuration. The perturbation of the photophysical properties by the addition of two guest carboxylate anions has been investigated. From the Stern-Volmer plots, the quenching constants, k(q), are 1.65 x 10(8) and 5.10 x 10(8) M(-)(1) s(-)(1) for acetate and 4-aminobenzoate, respectively, which are also proportional to the relative binding strengths of the substrates with Cu(3)(dppm)(3)OH(2+) (i.e., acetate < 4-aminobenzoate).     

Determination of ruthenium and osmium in each other's presence in chloride solutions by direct and third-order derivative spectrophotometry

Ruthenium and osmium (up to 20 mug Ru(Os) ml(-1)) can be determined in chloride solutions directly after absorption of RuO(4) and OsO(4) in hydrochloric acid. In 9 M HCl, RuO(4) and OsO(4) are quantitatively converted into RuCl(6)(2-) (lambda(max) = 480.0 nm, epsilon = 4.8 x 10(3) l mol(-1) cm(-1)) and OsCl(6)(2-) (lambda(max) = 334.8 nm, epsilon = 8.4 x 10(3) l mol(-1) cm(-1)) respectively. Osmium does not interfere with the determination of ruthenium in the form of the RuCl(6)(2-) complex by direct spectrophotometry. The absorbance of the obtained solution at lambda(max) = 480.0 nm corresponds only to the concentration of ruthenium. A derivative spectrophotometric method using numerical calculation of absorption spectra of the RuCl(6)(2-) and OsCl(6)(2-) complexes has been developed for the determination of osmium in a mixture with ruthenium. The interfering effect of ruthenium on the determination of osmium can be eliminated by measuring the value of a third-order derivative spectrum of the OsCl(6)(2-) complex at 350.0 nm ("zero-crossing point" of ruthenium). Simple and rapid determination of ruthenium and osmium in a calibration standard solution of the noble metals (Ru, Rh, Pd, Os, Ir, Pt and Au) for plasma spectroscopy using the proposed methods has been achieved.     

两亲聚合物表面的反相气相色谱分析

采用反相气相色谱探针技术研究了苯乙烯－氧乙烯－苯乙烯三嵌段两亲聚合物的表面物理化学性质。包括表面吸附热力学函数,表面能的色散分量以及表面分子链与探针的分子间相互作用,。探讨了共聚物中亲油性链段聚苯乙烯（PS）和亲水性链段聚氧乙烯（PEO）的组成比例与其表面性质的关系。结果表明共聚物表面组成中随PEO含量的增加,其表面能增大,表面分子链与探针分子的相互作用增强,表面吸附能力也增强。     

(Pyridine)pentaamminechromium(III). Synthesis, Characterization, and Photochemistry

The Cr(NH(3))(5)(py)(3+) ion has been obtained by metathesis of Cr(NH(3))(5)(Me(2)SO)(3+) in pyridine, isolated as the perchlorate salt, and characterized by absorption (lambda(max) at 467, 352, and 260 nm) and emission spectra (lambda(max) at 668 nm, tau = 2.0 &mgr;s at 20 degrees C in water) and by the py aquation rate (k = 5 x 10(-)(4) s(-)(1) at 80 degrees C). Ligand-field (LF) band irradiation in acid aqueous solution (10(-)(2) M HClO(4)) induces photoaquation of py (Phi = 0.26) and NH(3) (Phi = 0.16). HPLC indicates that the latter reaction gives rise to both cis- and trans-Cr(NH(3))(4)(py)(H(2)O)(3+), with the predominance of the cis isomer. This is the first Cr(NH(3))(5)X(z+)() species where Phi(x) > Phi(NH)3: the result is compared with the predictions of various photolysis models and is taken as chemical evidence for pi-acceptance by the py ligand. The photostereochemistry is also discussed. The phosphorescence is totally quenched by Cr(C(2)O(4))(3)(3)(-) (k(q) = 2.7 x 10(9) M(-)(1) s(-)(1)), while the photoreactions are only in part. On 470-nm excitation, the Phi(py)/Phi(NH)()3 ratio is approximately 1 and approximately 2 for the unquenchable and the quenchable contributions, respectively. Such a difference, suggesting at least two reactive precursors, can be interpreted in terms of the photochemistry proceeding from either the lowest doublet and quartet excited states or, alternatively, from the (4)E and (4)B(2) states. Irradiation of the very distinct absorption of coordinated pyridine results in both doublet-state emission and loss of py and NH(3). Comparison of this photobehavior with the LF results gives an efficiency of 0.7 for conversion of the py-localized pipi states into the Cr-localized LF states, confirmed by the wavelength dependence of the relative emission yields. Some py release (Phi = 0.03) is concluded to originate in the pipi states.     

Two-photon absorption properties of 2,6-bis(styryl)anthracene derivatives: effects of donor-acceptor substituents and the pi center

A series of 2,6- and 2,7-bis(styryl)anthracene derivatives with the donors at the styryl group and acceptors at the 9,10-positions have been synthesized, and their two-photon cross sections (Phidelta(max)) were determined. These compounds exhibit a peak two-photon absorptivity (delta(max)) in the range of 700-2500 GM at 780-1030 nm. Values of lambda(max) and Stokes shifts increase as the acceptor is changed to a stronger one. There is also a parallel increase in lambda(2)max and delta(max) with the same variation of the chromophore structure. Both lambda (2)(max)and Phidelta(max) have been optimized by introducing donor-substituted styryl groups at the 2,6-positions and p-cyanophenyl groups at the 9,10-positions, respectively. The effect of a pi center on the two-photon absorption properties has been assessed by comparing the existing data for a variety of D-pi-D derivatives.     

Micellisation of triblock copolymers of ethylene oxide and 1,2-butylene oxide: effect of B-block length

We have used pyrene fluorescence spectroscopy and isothermal titration calorimetry (ITC) to investigate the effect of hydrophobic-block length on values of the critical micelle concentration (cmc) for aqueous solutions of triblock poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) block copolymers (B(n)E(m)B(n), where m and n denote the respective block lengths) with hydrophobic block lengths in the range n=12-21. Combined with results from previous work on B(n)E(m)B(n) copolymers with shorter B blocks, plots of log(10)(cmc) (cmc in molar units and reduced to a common E-block length) against total number of B units (n(t)=n for diblock or n(t)=2n for triblock copolymers) display transitions in the slopes of the two plots, which indicate changes in the micellisation equilibrium. These occur at values of n(t)which can be assigned to the onset and completion of collapse of the hydrophobic B blocks, an effect not previously observed for reverse triblock copolymers. The results are compared with related data for diblock E(m)B(n) copolymers.     

Preparation of monoliths from single crosslinking monomers for reversed-phase capillary chromatography of small molecules

Highly cross-linked networks resulting from single crosslinking monomers were found to enhance the concentrations of mesopores in, and the surface areas of, polymeric monoliths. Four crosslinking monomers, i.e., bisphenol A dimethacrylate (BADMA), bisphenol A ethoxylate diacrylate (BAEDA, EO/phenol=2 or 4) and pentaerythritol diacrylate monostearate (PDAM), were used to synthesize monolithic capillary columns for reversed phase liquid chromatography (RPLC) of small molecules. Tetrahydrofuran (THF) and decanol were chosen as good and poor porogenic solvents for BAEDA-2 and BAEDA-4 monoliths. For the formation of the BADMA monolith, THF was replaced with dimethylformamide (DMF) to improve the column reproducibility. Appropriate combinations of THF, isopropyl alcohol and an additional triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) or PPO-PEO-PPO porogen were found to be effective in forming rigid PDAM monoliths with the desired porosities. Selection of porogens for the BADMA and PDAM monoliths was investigated in further detail to provide more insight into porogen selection. Isocratic elution of alkyl benzenes at a flow rate of 0.3 μL/min was conducted for BADMA and PDAM monoliths. The peaks showed little tailing on both monoliths without addition of acid to the mobile phase. The column efficiency measured for pentylbenzene using the BADMA monolithic column was 60,208 plates/m (k=7.9). Gradient elution of alkyl benzenes and alkyl parabens was achieved with high resolution. Optimized monoliths synthesized from all four crosslinking monomers showed high permeability, and demonstrated little swelling or shrinking in different polarity solvents. Column preparation was highly reproducible; relative standard deviation (RSD) values were less than 1.2% and 7.5% based on retention times and peak areas, respectively, of alkyl benzenes.     

Cuprophilic interactions in luminescent copper(I) clusters with bridging bis(dicyclohexylphosphino)methane and iodide ligands: spectroscopic and structural investigations

Polynuclear copper(I) complexes with bridging bis(dicyclohexylphosphino)methane (dcpm) and iodide ligands, [Cu(2)(dcpm)(2)(CH(3)CN)(2)](BF(4))(2) (1), [Cu(2)(dcpm)(2)](BF(4))(2) (2), [(CuI)(3)(dcpm)(2)] (3), [(CuI)(4)(dcpm)(2)] (4), and [(CuI)(2)(dcpm)(2)] (5) were prepared and their structures determined by X-ray crystal analysis. The shortest Cu--Cu distance found in these complexes is 2.475(1) A for 3. Powdered samples of 1, 3, 4, and 5 display intense and long-lived phosphorescence with lambda(max) at 460, 626, 590, and 456 nm and emission quantum yields of 0.26, 0.11, 0.12, and 0.56 at room temperature, respectively. In the solid state, 2 displays both a weak emission at 377 and an intense one at 474 nm with an overall emission yield 0.42. The difference in emission properties among complexes 1-5 suggests that both Cu--Cu interaction and coordination around the copper(I) center affect the excited state properties. A degassed solution of 2 in acetone gives a bright red emission with lambda(max) at 625 nm at room temperature. The difference absorption spectra of the triplet excited states of 1-5 in acetonitrile show broad absorption peaks at 340-410 and 850-870 nm.     

PEO-PPO-PEO水溶液体系胶束化及凝胶化行为的耗散粒子动力学模拟

采用耗散粒子动力学(Dissipative particle dynamics, DPD)模拟方法研究了三嵌段共聚物聚氧乙烯-聚氧丙烯-聚氧乙烯(PEO-PPO-PEO)的胶束化和凝胶化行为. 通过模拟得到了F127(EO₉₉PO₆₅EO₉₉)水溶液的临界胶束浓度和临界凝胶浓度. 结果发现, 在298 K、 质量分数低于40%时, F127水溶液中形成的胶束形状均为球形. 此外,进一步研究了亲水嵌段长度对胶束结构及凝胶形成浓度的影响, 结果发现, 亲水嵌段越短, 越有利于长椭球状胶束的形成, 而临界凝胶浓度随着亲水嵌段PEO长度的增加而降低.     

Determination of human IgG by solid substrate room temperature phosphorescence immunoassay based on an antibody labeled with nanoparticles containing Rhodamine 6G luminescent molecules

Luminescent silicon dioxide nanoparticles (R-SiO2) with size of 50 nm containing Rhodamine 6G (R) were synthesized by sol-gel method. In the presence of Pb(Ac)2 as a heavy atom perturber, the particle can emit intense and stable room temperature phosphorescence signal of R, respectively, on polyamide membrane, with the lambda(ex)(max)/lambda(em)(max) = 470/635 nm for R. Our research indicates that the specific immune reaction between goat-anti-human IgG antibody labeled with R-SiO2 and human IgG can be carried on polyamide membrane quantitatively, and the phosphorescence intensity was enhanced after the immunoreactions. Thus, a new method of solid substrate room temperature phosphorescence immunoassay (SS-RTP-IA) for the determination of human IgG was established basing on antibody labeled with the nanoparticles containing binary luminescent molecules. The linear range of this method is 0.0624-20.0 pg spot(-1) of human IgG (corresponding concentration, 0.156-50.0 ng mL(-1); sample volume, 0.40 microL spot(-1)). The regression equations of working curves are delta I(p) = 88.16. + 16.79 m(IgG) (pg spot(-1)) (485/646 nm, r = 0.9997). Detection limits calculated by 3Sb/k are 0.017 pg spot(-1). For samples containing 0.156 and 50.0 ng mL(-1) of IgG, we measured repeatedly for 11 times, RSDs are 3.9 and 2.8%, respectively. This method is sensitive, accurate and of high precision.     

Amphiphilic ABC triblock copolymer-assisted synthesis of core/shell structured CdTe nanowires

A new type of amphiphilic ABC triblock copolymer, poly(acrylic acid)(33)-poly(styrene)(47)-poly(ethylene oxide)(113) (PAA(33)-PS(47)-PEO(113)), was designed to assist the synthesis of core/shell structured CdTe nanowires via a one-step synthetic route. The PAA block was adopted to capture cadmium ions as the precursor of CdTe. Due to the bivalent coordination of Cd(2+), the copolymer in dioxane/H(2)O formed micelles with Cd(2+)-polychelate cores. Then CdTe nanocrystals were obtained within the micelles after introduction of NaHTe into the micelle solution. Transmission electron microscopy experiments revealed that the CdTe nanocrystals obtained simultaneously formed "pearl-necklace" aggregates in solution possibly driven by dipole interactions between neighboring particles, and then single crystalline CdTe nanowires upon reflux. Accompanying this morphology change, a phase transition from cubic zinc blende to wurtzite structure was observed by selected-area electron diffraction. The aggregation of the PS block in dioxane with a certain amount of H(2)O enabled the PS blocks to form a densely packed shell on the CdTe nanowires whose typical size is 700-800 nm in length and 15-20 nm in width. The third block of PEO was employed to render the finally formed CdTe nanowires dispersibility.