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In the present work, β-SiC/SiO2 coaxial nanocables are synthesized in a large area via direct pyrolysis of polymeric precursor method, in which, polycarbosilane acts the single raw material. The morphology, chemical composition and detailed microstructure of the nanocables are characterized. The core of nanocables are single crystalline β-SiC nanowires with diameter of 30 - 60 nm grown along [111] direction. The uniform coating layer is amorphous SiO2 with thickness of 15 nm. Based on the pyrolysis process of polycarbosilane, the Vapor-Liquid-Solid growth mechanism is discussed. Furthermore, field emission measurements show the turn-on field and the threshold field are 3.2 V/μm and 6.5 V/μm, respectively. This study shows that β-SiC/SiO2 coaxial nanocables are promising for field emission display device and other vacuum electronic devices.

In this study, we have developed the pre-shell-post-core route to synthesize the magnetic rattle-type silica. This method has not only simplified the precursor's process and reduced the reacting time, but also ameliorated the loss of magnetite and made the magnetite content and the inner core size controllable and tunable. The magnetite contents and inner core size can be easily controlled by changing the type and concentration of alkali, reaction system and addition of water. The results show that alkali aqueous solution promotes the escape of the precursor iron ions from the inner space of rattle-type silica and results in the loss of magnetite. In this case, NaOH ethanol solution is better for the formation of magnetite than ammonia because it not only offers an appropriate alkalinity to facilitate the synthesis of. magnetic particles, but also avoids the escape of the iron ions from the mesopores of rattle-type silica. The synthesis process is very simple and efficient, and it takes no more than 2 hours to complete the total preparation and handling of the magnetic rattle-type silica. The end-product Fe3O4@SiO2 nanocomposites also have good magnetic properties which will perform potential application in biomedical science.

The synthesis of SBA-15 with or without ethanol using a one-step method and its porosity were investigated. Well-ordered SBA-15 with a rod like morphology could be obtained from starting mixtures by aging at a low (60 degrees C) or high (80 degrees C) temperature in the presence of an appropriate amount of ethanol. By contrast, mesoporous materials containing aggregates of particles obtained in the absence of ethanol at high aging temperatures (70 or 80 degrees C) had complex poorly ordered structures, indicating that ethanol can affect the structure of mesoporous materials. In addition, the poorly ordered mesoporous materials had unusual desorption characteristics, namely they possessed a two-step desorption branch.

In this work, mesoporous hydroxyapatite-silica (HA-silica) composite materials with four different Si:Ca:P ratios were sol-gel derived through self-assembly using triblock copolymer Pluronics P123 as template. The composition and mesoporous structure formed were characterized by X-ray diffraction and electron microscopy. The XRD patterns indicated that the intensity of the HA phase becomes stronger as the Ca/Si ratio of the composite increases. From nitrogen gas analysis at 77 K, type IV isotherm plots for typical mesoporous materials were observed for all of the samples. However, the mesoporous structure of HA-silica tends to becomes less ordered as the Ca/Si ratio increases. Promising consistency between the pore sizes from the Barrett, Joyner and Halenda (BJH) method, Transmission Electron Microscopy (TEM) and Small Angle X-ray diffraction (SAXRD) was also observed. The formation mechanism of mesoporous HA-silica composites was proposed, where the interaction between the crystallization of HA and the surfactant liquid crystal determines the regularity of the meso-structure. In vitro drug loading and release studies showed that drug loading capacity is dependent on the pore volume of the sample, and the mesoporosity of the samples were responsible for the sustained release of drugs. In vitro cell culture of the samples showed promising biocompatibility where osteosarcoma cells were observed to grow favourably on the synthesized composites.

The electrochemical properties of new homogenous thionine (TH)-doped silica nanoparticles as a mediator were studied. The nanocomposites were synthesized by using sonochemical method. The sonication induced the strong combination between dye molecules and silica in the construction of the composites. By controlling reaction condition, face rougher uniform spheres could be achieved. The as-prepared nanocomposites can be used as the mediator to construct the biosensors with horseradish peroxidase coimmobilized in the gelatine matrix and cross-linked with formaldehyde. The described experimental evidences show the different ratio of ethanol to water can induce the changes in their diameters. As a consequence, the resulting biosensors exhibited amperometric response decreased with the increase of the spherical size. The resulting biosensor mediated by the 100 nm diameter of TH-doped silica nanoparticles exhibited very fast amperometric response, good stability and could be effectively used for the study of the electrocatalytic properties.

For the first time, a new multifunctional nanomaterial which combined the superparamagnetic property of iron oxide nanoparticles with the fluorescent property of morin-Al3+ complex was prepared. Iron oxide nanoparticles were first coated with SiO2 which could isolate them from the complex and the surrounding. Subsequently, Al2O3 . nH2O which provided active aluminum atom were deposited on the silica shell. Finally, morin which would react with the reactive aluminum atom was added into the reaction mixture to prepare the final multifunctional nanomaterial. The obtained product was characterized by X-ray powder diffraction, transmission electron microscopy, fourier transform infrared spectra, photoluminescence spectra, fluorescence microscopy, and vibration sample magnetometer. The characterization results showed that the final samples had an average size of 60 nm with spherical shape. The saturation magnetization of this new synthesized material was about 8.5 emu g(-1). Its excitation and emission wavelengths were 420 and 513 nm, respectively.

Optically transparent and highly ordered mesoporous organosilica thin films functionalized with two different organic groups in various proportions were synthesized by templated-directed cocondensation of tetraethylorthosilicate (TEOS) and a mixture of two distinct and functional organotriethoxysilanes [NC(CH2)3Si(OEt)3 and O=P(OEt)2(CH2)3Si(OEt)3]. The mesostructured films obtained by evaporation induced self-assembly (EISA) approach were deposited on glass or silicon substrates by dip-coating. They were characterized by Grazing Incidence Small Angle X-ray Scattering (GISAXS) and X-ray reflectivity. We showed that whatever the proportion in organic groups, only 2D hexagonal phase having p6m symmetry was observed for all the materials indicating a good compatibility between the organic groups. The bi-functionalization of the internal pores surface by the organotriethoxysilanes groups was clearly evidenced by using micro-Raman spectroscopy.

Through hydrogen reduction of metal precursors in supercritical CO2, Cu, and Pd, nanocrystals were deposited onto SiO2 nanowires to form different types of nanostructured materials, including nanocrystal-nanowire, spherical aggregation-nanowire, shell-nanowire composites, and "mesoporous" metals supported by the framework of nanowires. This supercritical fluid deposition technique is an attractive approach for modifying nanowires because of its generality and simplicity; the modified nanowires could be useful as catalysts and for further fabrication of multifunctional composites.

Silica-polymer nanocomposites have been synthesized via polymerizable bicontinuous microemulsions to disperse functionalized/nonfunctionalized SiO2 nanoparticles uniformly in a polymerized microemulsion system as revealed by transmission electron microscopy. The effect of both types of SiO2 nanoparticles in the polymerized microemulsion increased its glass transition temperature (Tg) from 90 to 128 degrees C. TgS of functionalized silica nanocomposites were about 15 degrees C higher than those of nonfunctionalized samples. As expected, both hardness and modulus of the nanocomposites increased with the loading of both types of silica from 2 to 6 wt%. In the case of nonfunctionalized silica, the improvement of properties may be simply exerted by the conventional filler effect due to the better dispersion of nanoparticles of silica in fluid microemulsion prior to the polymerization. The additional effect for the functionalized silica containing a terminal vinyl group is that It could be grafted to the polymer matrix through cross-polymerization with microemulsion-formed polymer to establish strong nanocomposite networks.

The combination of two silica precursors, tetraethylorthosilicate and phenyltriethoxysilane, were utilized to synthesize organic dye-doped silica nanoparticles. The hydrophobic nature of phenyltriethoxysilane keeps the organic dye in the silica matrix, whereas the hydrophilic tetraethylorthosilicate-formed silica allows the resulting nanoparticles to be dispersed in aqueous solutions. Characterization of the nanoparticles showed that they could be synthesized in the nanometer range with high photostability and minimal dye leakage. The silica matrix of the nanoparticles allows different routes of surface biomolecular modification for biosensor and bioanalysis applications. We have shown different applications of the nanoparticles in bioanalysis and in biosensing. Biotin interaction of avidin-coated nanoparticles can be used for the determination of biotinylated bovine serum albumin, and the immobilization of glutamate dehydrogenase on the nanoparticle surfaces enables the nanoparticles to be used as biosensors for glutamate determination.

In this article, we report a method for cell recognition of system lupus erythematosus (SLE) patients that uses photostable luminescent nanoparticles as biological labels. The luminescent silica nanoparticles are prepared with a water-in-oil microemulsion (W/O) technique. The silica network is produced by the controlled hydrolysis of tetraethylorthosilicate (TEOS) in water nanodroplets with the initiation of ammonia (NH3.H2O). A luminescent compound, tris(2,2'-bipyridyl)dichlororuthenium(II)hexahydrate [Ru(II)(bpy)3]2+, is doped inside as a luminescent signaling element, and the most appropriate dye concentration for the preparation of the nanoparticles with a size of 28 +/- 4 nm has been determined. The luminescent silica nanoparticles are covalently immobilized with goat anti-human immunoglobulin G (IgG), which can recognize SmIgG+ B lymphocytes. We have used antibody-labeled nanoparticles to recognize target SmIgG+ B lymphocytes isolated from the circulating blood of SLE patients. It has been observed that a bioassay based on fluorescent nanoparticles can identify target cells selectively and efficiently. And fluorescent nanoparticle labels also exhibit high photostability. The experiment results have shown that this cell recognition method was an effective one as further proof of the diagnosis of SLE.

Here we describe a new route for the synthesis of nanometric Ni particles embedded in a mesoporous silica material with excellent potential for catalytic applications. Mesoporous silica with a surface area in the range of 202-280 m2/g, with narrow pore size distribution and Ni nanoparticles (particles in the range of 3-41 nm) were obtained in a direct process. A different approach was adopted to process such a nanocomposite. This new approach is based on the formation of a polymer with the silicon oxianion and nickel cation chelated to the macromolecule structure and on the control of the pyrolysis step. The CO/CO2 atmosphere resulting from the pyrolysis of the organic material promotes the reduction of the Ni citrate.

Mesostructured silica-nanoparticle monolithic composites have been synthesized by dispersing prefabricated nanoparticles of gold or zeolite (silicalite) in ethanolic reaction mixtures containing SiCl4 and a Pluronic triblock copolymer template. Whereas silicalite nanoparticles were used directly, surface functionalization of the gold nanoparticles with either primed silicate ions or a discrete 3-5-nm-thick silica shell was required to increase the interfacial compatibility with the hydrophilic poly(ethylene oxide) blocks. Under these conditions, the resulting monoliths consisted of distributed nanoparticles within an ordered mesostructured silica matrix. Removal of the polymer template by calcination produced corresponding mesoporous silica-nanoparticle replicas. The combination of the structure and the porosity of the silica framework with the crystal chemical properties of the embedded nanoparticles suggests that such composites should be useful as multifunctional materials.