2’,7’-二氯-5(6)-羧基荧光素的合成及其荧光性能研究

以偏苯三酸酐、4-氯间苯二酚为原料,在ZnCl2催化下反应得到2',7'-二氯-5(6)-羧基荧光素混合物,并用柱色谱进行异构体分离.对取代基团对其荧光性能影响的研究发现,顶环上引入氯使其最大荧光激发波长和荧光发射波长发生红移,荧光强度有所增加;底环上引入羧基,其Stokes位移和荧光量子产率略有降低,但该活性基团的引入将更有利于对生物体进行检测.由此表明,2',7'-二氯-5(6)-羧基荧光素有望用于荧光探针.     

Durable Mesenchymal Stem Cell Labelling by Using Polyhedral Superparamagnetic Iron Oxide Nanoparticles

Small polyhedral superparamagnetic iron oxide (SPIO) nanoparticles (<10 nm) coated with a thin layer of silica were prepared (SPIO@SiO₂ and SPIO@SiO₂‐NH₂). Surface modification of the small polyhedral silica‐coated SPIO nanoparticles with amines led to substantially higher mesenchymal stem cell (MSC) labelling efficiency without the use of additional transfecting agents. Therefore, amine surface‐modified nanoparticles (SPIO@ SiO₂‐NH₂) appeared to be the preferred candidate for MSC labelling. In vitro studies demonstrated that controlled labelling of SPIO@SiO₂ and SPIO@SiO₂‐NH₂ did not cause MSC death or proliferation inhibition. MSCs labelled with SPIO@SiO₂‐NH₂ nanoparticles retained differentiation potential and showed osteogenic, adipogenic and chondrogenic differentiations. The noncytotoxic polyhedral SPIO@SiO₂‐NH₂ nanoparticle‐labelled MSCs were successfully implanted in rabbit brain and erector spinae muscle, and demonstrated long‐lasting, durable MRI labelling efficacy after 8–12 weeks.     

Controlled synthesis of ZnO with adjustable morphologies from nanosheets to microspheres

The synthesis of ZnO with different morphologies (hexagonal prisms, nanosheets, microspheres and quasi-flowers) was realized through a solvothermal method. During the synthetic procedure, the decomposition of hexamethylenetetramine at the temperature ≥100 °C provided (OH)⁻¹ ions at the rate of good distribution, and sodium dodecyl sulfate was used as templates. By adjusting the basicity in the synthetic system, ZnO nanosheets, or microspheres with nanosheet assemblies were obtained. Adjusting the concentration of surfactant, ZnO hexagonal crystals were formed; by adjusting the synthetic temperature, ZnO quasi-flowers with some nanosheet assemblies were produced. Based on experimental observation and analysis, the forming mechanism was discussed.     

Influence of combustion reagent and microwave drying method on the characteristics of nano-sized Nd<Superscript>3+</Superscript>:YAG powders synthesized by the gel combustion method

Nanosized Nd³⁺ doped Y₃Al₅O₁₂ (Nd³⁺:YAG) powders have been synthesized by the gel combustion method using different combustion reagent such as citric acid, ethylene diamine tetraacetic acid (EDTA), glycine, glycol and the combination of citric acid and EDTA with different ratio. The pure YAG phase was obtained at relatively low temperature around 950 °C for citric acid or EDTA and 1,050 °C for glycine or glycol as combustion reagent, respectively by the gel combustion method. It was found that citric acid and EDTA are the better combustion reagents and yield rather homogeneous and well dispersed club-shape Nd³⁺:YAG samples, and the particle size synthesized by EDTA is larger than that by citric acid. Moreover, the particle size of Nd:YAG was enlarged when the ratio of EDTA was increased in the combination reagent, and the better dispersion of YAG was obtained when the ratio of citric acid to EDTA was 1:1 compared to that of other ratios and pure one as combustion reagent. On the other hand, the results showed that the microwave assisted in drying process of gel to xerogel produced more smaller Nd³⁺:YAG particles in size, and more homogeneous dispersion of the Nd³⁺:YAG particles than that of the traditional dry method.     

Microwave-assisted Synthesis of Pyrazolo[4,3-f]quinolin-7-one Derivatives via Multi-component Reactions

A series of new pyrazolo[4,3‐f]quinolin‐7‐one derivatives were synthesized by multi‐component reactions of equimolar amount of aromatic aldehydes with 2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione and 1H‐indazol‐5‐amine in ethylene glycol without catalyst under microwave irradiation. This one‐pot protocol has the advantage of good yields, simple workup procedure and shorter reaction time.     

Highly selective molecular recognition and high throughput detection of melamine based on molecularly imprinted sol-gel film

Multimode reader has been generally applied in immunoassay, and in the proposed paper, the 96 well micro-plate was modified with molecularly imprinted melamine sol-gel film, based on which the highly selective and high throughput detection of melamine was achieved. Melamine was imprinted into silica sol-gel films directly using phenyltrimethoxysilane and methyltrimethoxysilane as functionalized organosilicon precursors. The binding characteristic of the imprinted film to melamine was evaluated by equilibrium binding experiments and the morphology was studied by scanning electronic microscope (SEM). Scatchard analysis was carried out to estimate the binding parameters of the imprinted film. The proposed method exhibited excellent selectivity because of specific recognition of MM by molecularly imprinted film. Under the optimum conditions, the chemiluminescence (CL) intensity had a linear relationship against the concentration of melamine over the range of 0.1-50 μg mL⁻¹ with a lower detection limit of 0.02 μg mL⁻¹.     

Synthesis and characterization of the water-soluble silica-coated ZnS:Mn nanoparticles as fluorescent sensor for Cu ions

Silica-coated ZnS:Mn nanoparticles were synthesized by coating hydrophobic ZnS:Mn nanoparticles with silica shell through microemulsion. The core–shell structural nanoparticles were confirmed by X-ray diffraction (XRD) patterns, high-resolution transmission electron microscope (HRTEM) images and energy dispersive spectroscopy (EDS) measurements. Results show that each core–shell nanoparticle contains single ZnS:Mn nanoparticle within monodisperse silica nanospheres (40 nm). Photoluminescence (PL) spectroscopy and UV–vis spectrum were used to investigate the optical properties of the nanoparticles. Compared to uncoated ZnS:Mn nanoparticles, the silica-coated ZnS:Mn nanoparticles have the improved PL intensity as well as good photostability. The obtained silica-coated ZnS:Mn nanoparticles are water-soluble and have fluorescence sensitivity to Cu²⁺ ions. Quenching of fluorescence intensity of the silica-coated nanoparticles allows the detection of Cu²⁺ concentrations as low as 7.3 × 10⁻⁹ mol L⁻¹, thus affording a very sensitive detection system for this chemical species. The possible quenching mechanism is discussed.     

One-pot synthesis of 4,4-difluoro-3-oxo-2-(triphenylphosphoranylidene)-δ-lactones by Reformatsky reaction

In th presence of zinc and a catalytic amount of cuprous chloride, ethyl 4-bromo-4,4-difluoro-3-oxo-2-(triphenylphosphoranylidene)butanoate 1 reacted with carbonyl compounds to give the gem-difluoromethylenated 2-(triphenylphosphoranylidene)-δ-lactones 4 in moderate to high yields.     

Phase controllable synthesis of unusual -Ga2O3 single crystals with promising luminescence property

A new synthetic approach to unusual -Ga₂O₃ with improved luminescence properties was developed by taking advantage of a microwave-assisted synthesis followed by calcinations at appropriate temperatures. Upon control of crystallinities of GaOOH precursors and the followed calcination temperature, the single crystalline -Ga₂O₃ nanorods can be synthesized in a large scale. The resulting products were characterized by transmission electron microscopy, powder X-ray diffraction, and cathodoluminescence. The luminescence property of this unusual Ga₂O₃ phase was investigated for the first time.     

Chaos control of new Ikeda–Lorenz systems by GYC partial region stability theory

A new strategy to achieve chaos control by GYC partial region stability theory is proposed. By using the GYC partial region stability theory, the Lyapunov function is a simple linear homogeneous function of error states, the controllers are more simple and have less simulation error because they are in lower degree than that of traditional controllers. Simulation results for a new Ikeda–Lorenz system show the effectiveness of this strategy. Copyright © 2008 John Wiley & Sons, Ltd.