Mesoporous Silica Encapsulating Upconversion Luminescence Rare-Earth Fluoride Nanorods for Secondary Excitation
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Mesoporous silica encapsulating upconversion luminescence NaYF(4) nanorods with uniform core-shell structures have been successfully synthesized by the surfactant-assistant sol-gel process. The thickness of ordered mesoporous silica shells can be adjusted from 50 to 95 nm by varying the amount of hydrolyzed silicate oligomer precursors from tetraethyl orthosilicate (TEOS), which further influences the BET surface area, pore volume, and the luminescence intensity. After coated with mesoporous silica shells, the hydrophobic nanorods is rendered to hydropholic simultaneously. The obtained beta-NaYF(4)@SiO(2)@mSiO(2) core-shell nanorods possess high surface area (71.2-196 m(2) g(-1)), pore volume (0.07-0.17 cm(3) g(-1)), uniform pore size distribution (2.3 nm), and accessible channels. Furthermore, the uniform core-shell nanorods show strong upconversion luminescence property similar to the hexagonal upconversion cores. The open mesopores can not only provide convenient transmission channels but also offer the huge location for accommodation of large molecules, such as fluorescent dyes and quantum dots. The secondary-excitation fluorescence of Rhodamine B is generated from the upconversion rare-earth fluoride nanorods cores to the fluorescent dyes loaded in the mesoporous silica shells.Keywords:
Nanorod
Photon Upconversion
An efficient enzyme-responsive controlled release carrier system was successfully fabricated using single-stranded DNA encapsulated functional mesoporous silica nanoparticles. Mesoporous silica nanoparticles were initially fabricated through hydrolysis of tetraethyl orthosilicate (TEOS) in cetyltrimethylammonium chloride (CTAC) solution, and the surface of nanoparticles could be encapsulated with single-stranded DNA. This nanomaterial has excellent bioactivity and its hydrolysate cannot cause damage to normal cell, thus the biocompatibility of the nanomaterial is improved. In addition, this nanomaterial showed an excellent drug release performance when loaded with drugs, which would be helpful to increase the treatment efficiency and decrease side effects of drugs.
Biocompatibility
Nanomaterials
Surface Modification
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Under alkaline condition,using cetyl trimethyl ammonium bromide as the template agent,and tetraethyl orthosilicate as silica sources,with the hydrothermal method and trimethylbenzene to expand the mesoporous silica's size,there modified a kind of mesoporous silica.Using BET,FT-IR and small angle XRD to analyze and characterize mesoporoue silica.In addition,the mesoporous silica's adsorption capacity of lead ion was tested,which shows that the capacity of expanded mesoporous silica is higher than the one haven't be expanded.The adsorption rate of Pb2+is 99.8%.
Ammonium bromide
Mesoporous organosilica
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A seeded watermelon‐like mesoporous nanostructure (mSiO 2 @CdTe@SiO 2 , mSQS) composed of a novel dendritic mesoporous silica core, fluorescent CdTe quantum dots (QDs), and a protective solid silica shell is successfully fabricated by loading QDs into dendritic mesoporous silica nanoparticles through electrostatic interaction, and then coating with a solid silica shell by the modified Stöber method. The shell thickness of mSQS can be tuned from 0 to 32 nm as desired by controlling the reaction parameters, including the amount of silica precursor, tetraethyl orthosilicate, that is introduced, the solvent ratio (H 2 O:ethanol), and the amount of catalyst (NH 3 ⋅H 2 O). These fluorescent mSiO 2 @QDs@SiO 2 nanoparticles possess excellent stability and thickness‐dependent cytotoxicity, and are successfully applied to bioimaging.
Cadmium telluride photovoltaics
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Highly ordered mesoporous silica, SBA-15 was synthesized using triblock copolymer (P123) as template and tetraethyl orthosilicate (TEOS) as silica source. Through the post-synthesis treatment, pore surface of the mesoporous silica was modified with aminosilane and then Eu3+ ions were incorporated in the modified mesoporous silica for the formation of Eu complex. Mesoporous silica with the hexagonal mesostructure was characterized by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The successful modification of the mesoporous silica was verified by FT-IR spectra and nitrogen adsorption/desorption isotherms. Eu incorporated mesoporous silicas showed different photoluminescent intensities depending on the pH of acidic and basic aqueous solutions.
Mesoporous organosilica
Europium
Small-angle X-ray scattering
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Mesoporous silica has been prepared using tetraethyl orthosilicate (TEOS) as the silica source and cetyltrimethylammonium bromide (CTAB) as the template, with Cl− and SO24− as the respective inorganic counterions. The as-made mesoporous silica samples were calcined at different temperatures, following which the adsorption isotherms of laccase onto the calcined mesoporous silica surface were obtained. The relationships between the adsorption isotherm type and the morphology, pore diameter, surface electrical potentials (ζ) as well as the values of the isoelectric point (IEP) of the mesoporous silica were discussed.
Mesoporous organosilica
MCM-41
Specific surface area
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This study emphasize on the modification of MSU-x molecular mesoporous sieve with tungstate ammonia and sulfate aluminum as W,Al source.In netural conditions,fatty alcohol polyoxyethylene ether is used as template,tetraethyl orthosilicate as silica source,the modified molecular mesoporous sieves W-MSU-x,Al-MSU-x were prepared.The characterizations of molecular mesoporous sieves modified by,W,Al are investigated by the technics of X Ray Diffraction,N2 adsorption-desorption isotherms,FT-IR spectra.The results show that,W,Al do not destroy the framework of molecular mesoporous sieves,rather,the order degree is improved by W loaded; Al atom change the pore performance of molecular mesoporous sieves,pore diameter is minimized,surface area is increased as well.
Mesoporous organosilica
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The synthesis of mesoporous silica with variable pore sizes was carried out for the purpose of controlled drug release study. Mesoporous silica containing three-dimensional cagelike structures was prepared by the simple hydrothermal method using triblock copolymer Pluronic F-127 as the template and tetraethyl orthosilicate (TEOS) as a silica source. The synthesized samples of plain and modified mesoporous silica were compared to measure the drug release ability of ibuprofen. The effect of cosurfactants, temperature, and different salts on the pore structure of the materials were also observed. The surface property enhancement of mesoporous silica was contributed by controlling its pore morphology. The materials were characterized by FT-IR, SEM, TGA, and UV-Visible spectroscopy and later used for the ibuprofen release study. The results indicated that the modified mesoporous silica with increased pore diameter showed increased storage capacity and high pH-responsive release behavior as compared to the plain mesoporous silica.
Mesoporous organosilica
Ibuprofen
Morphology
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Using Cetyltrimethyl ammonium bromide(CTAB) as the template,tetraethyl orthosilicate(TEOS) as the source of silicon,the hexagonal ordered mesoporous materials MCM-41 was prepared at room temperature.The MCM-41 was chemical modified by TMB and APTES,and then the modified MCM-41 was acquired.The structure of the samples were characterized by X-ray Diffraction,Infrared spectroscopy and Nitrogen adsorption-desorption methods.The results indi-cated that the modified MCM-41 remains the hexagonal ordered mesoporous structure.The product gets a larger pore diam-eter than the pure MCM-41 when expanded by TMB,reduced the surface silanols by the silane modification,and incre-ased the surface polarity of MCM-41,then it is advantageous for the assembly of the mesoporous material MCM-41.
MCM-41
Ammonium bromide
Mesoporous organosilica
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Hybrid polyurethane–silica composites were prepared using a sol-gel reaction between tetraethyl orthosilicate and triethoxysilyl groups grafted onto polyurethane. The TS series contained the same polyurethane composition but the tetraethyl orthosilicate content varied. Soft segment T m and T g values were not affected by the tetraethyl orthosilicate content, while ΔH for soft segment melting and crystallization increased with the tetraethyl orthosilicate content. The tensile strength sharply increased from the cross-linking of the grafted silica at low tetraethyl orthosilicate concentrations but decreased with the increase of tetraethyl orthosilicate content because excess silica inhibited cross-linking. The shape recovery of the TS series improved during cyclic tests, and shape retention slightly decreased as the test cycles repeated. Low temperature flexibility moderately improved with the formation of grafted silica. Therefore, the grafted sol-gel silica formation demonstrated a tensile strength improvement and reproducible shape recovery.
Orthosilicate
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