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1.
Qin Yue Jianguo Sun Yijin Kang Yonghui Deng 《Angewandte Chemie (International ed. in English)》2020,59(37):15804-15817
Interfacing magnetic particles with ordered mesoporous materials is an effective direction for the development of functional porous composite materials with rationally designed core–shell structures. Owing to the combined properties of magnetic nanoparticles and mesoporous silica (high surface area, large pore volume, porosity, and biocompatibility), core–shell magnetic mesoporous silica materials have generated tremendous interest in various disciplines, including chemistry, materials, bioengineering, and biomedicine. Interfacial assembly strategies enable the rational construction of magnetic mesoporous silica materials with well‐defined core–shell structure, morphology, pore parameters, and surface wettability, which can decisively influence their physical and chemical properties and thus improve their application performance. This Minireview summarizes recent progress in the synthesis of core–shell magnetic mesoporous silica and the adjustment of key parameters, including pore size, morphology, and pore orientation. 相似文献
2.
《Comptes Rendus Chimie》2016,19(10):1247-1253
High surface area mesoporous silica based catalysts have been prepared by a simple hydrolysis/sol–gel process without using any organic template and hydrothermal treatment. A controlled hydrolysis of ethyl silicate-40, an industrial bulk chemical, as a silica precursor, resulted in the formation of very high surface area (719 m2/g) mesoporous (pore size 67 Å and pore volume 1.19 cc/g) silica. The formation of mesoporous silica has been correlated with the polymeric nature of the ethyl silicate-40 silica precursor which on hydrolysis and further condensation forms long chain silica species which hinders the formation of a close condensed structure thus creating larger pores resulting in the formation of high surface mesoporous silica. Ethyl silicate-40 was used further for preparing a solid acid catalyst by supporting molybdenum oxide nanoparticles on mesoporous silica by a simple hydrolysis sol–gel synthesis procedure. The catalysts showed very high acidity as determined by NH3-TPD with the presence of Lewis as well as Brønsted acidity. These catalysts showed very high catalytic activity for esterification; a typical acid catalyzed organic transformation of various mono- and di-carboxylic acids with a range of alcohols. The in situ formed silicomolybdic acid heteropoly-anion species during the catalytic reactions were found to be catalytically active species for these reactions. Ethyl silicate-40, an industrial bulk silica precursor, has shown a good potential for its use as a silica precursor for the preparation of mesoporous silica based heterogeneous catalysts on a larger scale at a lower cost. 相似文献
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Dr. Jeonghun Kim Dr. Byeonggwan Kim Dr. Chokkalingam Anand Dr. Ajayan Mano Dr. Javaid S. M. Zaidi Dr. Katsuhiko Ariga Dr. Jungmok You Prof. Dr. Ajayan Vinu Prof. Dr. Eunkyoung Kim 《Angewandte Chemie (International ed. in English)》2015,54(29):8407-8410
The single‐step preparation of highly ordered mesoporous silica hybrid nanocomposites with conjugated polymers was explored using a novel cationic 3,4‐propylenedioxythiophene (ProDOT) surfactant (PrS). The method does not require high‐temperature calcination or a washing procedure. The combination of self‐assembly of the silica surfactant and in situ polymerization of the ProDOT tail is responsible for creation of the mesoporosity with ultralarge pores, large pore volume, and electroactivity. As this novel material exhibits excellent textural parameters together with electrical conductivity, we believe that this could find potential applications in various fields. This novel concept of creating mesoporosity without a calcination process is a significant breakthrough in the field of mesoporous materials and the method can be further generalized as a rational preparation of various mesoporous hybrid materials having different structures and pore diameters. 相似文献
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Mesoporous silica nanoparticle based controlled release, drug delivery, and biosensor systems 总被引:3,自引:0,他引:3
Trewyn BG Giri S Slowing II Lin VS 《Chemical communications (Cambridge, England)》2007,(31):3236-3245
Recent advancements in controlling the surface properties and particle morphology of the structurally defined mesoporous silica materials with high surface area (>700 m(2) g(-1)) and pore volume (>1 cm(3) g(-1)) have significantly enhanced their biocompatibility. Various methods have been developed for the functionalization of both the internal pore and exterior particle surfaces of these silicates with a tunable pore diameter ranging from 2 to 30 nm and a narrow pore size distribution. Herein, we review the recent research progress on the design of functional mesoporous silica materials for stimuli-responsive controlled release delivery of pharmaceutical drugs, genes, and other chemicals. Furthermore, the recent breakthroughs in utilizing these nanoscale porous materials as sensors for selective detections of various neurotransmitters and biological molecules are summarized. 相似文献
6.
Carola Hofmann Axel Duerkop Antje J. Baeumner 《Angewandte Chemie (International ed. in English)》2019,58(37):12840-12860
Nanocontainers such as mesoporous silica particles and polymersomes are versatile structures containing holes or pores which are used for the entrapment of small molecules and the introduction of specific functionalities. They are widely applied in drug delivery, biomedicine, bioreactors, and analytical applications. In the last case, nanocontainers usually serve as amplification systems. They are hence synthesized to entrap signaling molecules and to bear functional moieties at the outer surface, which in turn enable specific analyte recognition and control of the nanocontainer pore permeability. This Review outlines the most important nanocontainer materials and discusses their synthesis, surface chemistry modifications, and strategies for molecule entrapment. Their advantages, challenges, and limitations are critically discussed in view of other common signal amplification strategies for different assay formats and various detection methods. 相似文献
7.
Ramesh P Okazaki T Taniguchi R Kimura J Sugai T Sato K Ozeki Y Shinohara H 《The journal of physical chemistry. B》2005,109(3):1141-1147
Double-wall carbon nanotubes (DWNTs) have been selectively synthesized over Fe/Co loaded mesoporous silica by catalytic chemical vapor deposition of alcohol. Several silica materials with desired pore diameter and morphology have been investigated for the DWNT growth. The diameter distribution and selectivity of the DWNT are found to depend on the reaction temperature, pore size, and thermal stability of the support material. A high-yield synthesis of DWNTs has been achieved at 900 degrees C over high-temperature stable mesoporous silica. The outer diameter of DWNTs is found to be in the range of 1.5-5.4 nm with a "d" spacing of 0.38 +/- 0.02 nm between inner and outer layers, which is much larger than those of multiwall carbon nanotubes. 相似文献
8.
We report a one‐step convenient chemical coating method of high alumina content onto mesoporous silicas. Aluminia‐coated mesoporous silica with high surface area (?900 m2/g), tuneable pore size (2.0–3.0 nm) and high hydrothermal stability (> 60 h) is obtained. The method may also be generalized for grafting other metal oxides onto mesoporous silica in future work. 相似文献
9.
Huh S Chen HT Wiench JW Pruski M Lin VS 《Journal of the American Chemical Society》2004,126(4):1010-1011
A series of bifunctionalized mesoporous silica nanosphere-based (MSN) heterogeneous catalysts for the nitroaldol (Henry) reaction have been synthesized. A common 3-[2-(2-aminoethylamino)ethylamino]propyl (AEP) primary group and three different secondary groups, ureidopropyl (UDP), mercaptopropyl (MP), and allyl (AL) functionalities, were incorporated to these mesoporous silica materials by introducing equal amounts of AEP-trimethoxysilane with UDP-, MP-, or AL-trialkoxysilane precursors to our previously reported co-condensation reaction. Structures and relative concentrations of the functional groups were detailed by solid-state NMR and other spectroscopic techniques. The AEP group served as a catalyst, and the other secondary groups provided different noncovalent interactions to reactants and thereby controlled the reaction selectivity. By varying the secondary group in these bifunctionalized MSN catalysts, we investigated the selectivity of a nitroaldol reaction of two competing benzaldehydes reacting with nitromethane by measuring the molar ratio of the nitroalkene products. The selectivity of the bifunctionalized MSN catalysts could be systematically tuned simply by varying the physicochemical properties of the pore surface-bound secondary groups, i.e., polarity and hydrophobicity. 相似文献
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Synthesis of highly ordered mesoporous crystalline WS(2) and MoS(2) via a high-temperature reductive sulfuration route 总被引:2,自引:0,他引:2
A high-temperature reductive sulfuration method is demonstrated to synthesize highly ordered mesoporous metal sulfide crystallites by using mesoporous silica as hard templates. H2S gas is utilized as a sulfuration agent to in situ convert phosphotungstic acid H3PW12O40.6H2O to hexagonal WS2 crystallites in the silica nanochannels at 600 degrees C. Upon etching silica, mesoporous, layered WS2 nanocrystal arrays are produced with a yield as high as 96 wt %. XRD, nitrogen sorption, SEM, and TEM results reveal that the WS2 products replicated from the mesoporous silica SBA-15 hard template possess highly ordered hexagonal mesostructure (space group, p6mm) and rodlike morphology, analogous to the mother template. The S-W-S trilayers of the WS2 nanocrystals are partially oriented, parallel to the mesochannels of the SBA-15 template. This orientation is related with the reduction of the high-energy layer edges in layered metal dichalcogenides and the confinement in anisotropic nanochannels. The mesostructure can be 3-D cubic bicontinuous if KIT-6 (Iad) is used as a hard template. Mesoporous WS2 replicas have large surface areas (105-120 m2/g), pore volumes ( approximately 0.20 cm3/g), and narrow pore size distributions ( approximately 4.8 nm). By one-step nanocasting with the H3PMo12O40.6H2O (PMA) precursor into the mesochannels of SBA-15 or KIT-6 hard template, highly ordered mesoporous MoS2 layered crystallites with the 2-D hexagonal (p6mm) and 3-D bicontinuous cubic (Iad) structures can also be prepared via this high-temperature reductive sulfuration route. When the loading amount of PMA precursor is low, multiwalled MoS2 nanotubes with 5-7 nm in diameter can be obtained. The high-temperature reductive sulfuration method is a general strategy and can be extended to synthesize mesoporous CdS crystals and other metal sulfides. 相似文献
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K Miyasaka H Hano Y Kubota Y Lin R Ryoo M Takata S Kitagawa AV Neimark O Terasaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(33):10300-10311
We present a modeling scheme to analyze cagelike silica mesoporous crystals based on in situ X-ray diffraction (XRD) data collected during gas adsorption-desorption (physisorption) processes. Nitrogen physisorption on a silica mesoporous crystal of SBA-16 was directly monitored by using synchrotron in situ powder XRD measurements conducted at SPring-8. SBA-16 is a well-ordered mesoporous silica in which three-dimensional interconnected cagelike primary mesopores are located at the body-centered cubic lattice points. In addition, the surrounding silica matrix contains random microporous and mesoporous intrawall porosities that are significantly influential to the diffusion properties, and thus important to be quantified for this media. The in situ XRD data exhibits seven Bragg reflections throughout the measurements, and the present method allows one to obtain the maximal and stand-alone information about the pore structure (for example, the mesopore size, the matrix density, the intrawall porosity, and pore surface roughness) together with the nitrogen film evolution in the primary mesopores and the intrawall pore-filling in the silica matrix. We furthermore observe a macroscopic amount of nitrogen adsorbed assuming the density of the fluid, and confirm that the XRD "isotherm" recalculated from the analysis result is consistent with the conventional nitrogen isotherm on a semi-quantitative level; however, these results suggest that the intrawall pores would have a greater contribution to the adsorption than considered based on the conventional isotherm analyses. The present method is readily extendable to any ordered mesopores wrapped by the wall matrix containing a certain intrawall porosity. 相似文献
13.
The unique properties of mesoporous silica materials (MPs) have attracted substantial interest for use as enzyme-immobilization
matrices. These features include high surface area, chemical, thermal, and mechanical stability, highly uniform pore distribution
and tunable pore size, high adsorption capacity, and an ordered porous network for free diffusion of substrates and reaction
products. Research demonstrated that enzymes encapsulated or entrapped in MPs retain their biocatalytic activity and are more
stable than enzymes in solution. This review discusses recent advances in the study and use of mesoporous silica for enzyme
immobilization and application in biosensor technology. Different types of MPs, their morphological and structural characteristics,
and strategies used for their functionalization with enzymes are discussed. Finally, prospective and potential benefits of
these materials for bioanalytical applications and biosensor technology are also presented.
Figure Enzyme-functionalized mesoporous silica fibers and their integration in a biosensor design. The immobilization process takes
place essentially in the silica micropores. 相似文献
14.
Zhen Li Bin Dong Fei Geng Ganzuo Li 《Journal of Dispersion Science and Technology》2013,34(8):1066-1071
This article reports a novel preparation of mesoporous silica with series of 1-alky-3-methylimidazolium bromide (CnMIM)Br (n = 12, 14, 16), a kind of amphiphilic room-temperature ionic liquids (RTILs), as a template via a sol-gel nanocasting technique. The pore morphology and structures of these mesoporous silica were characterized by Transmission electron microscopy (TEM). The results show that the RTIL bearing longer alkyl chain is preferred to form the mesoporous silica material with bigger pores. (C16MIM)Br has been chosen to study how the various influencing factors affect the synthesis and structure of the mesoporous silica material, such as the acid concentration, the solling time, the gelling time and the calcination time. N2 adsorption-desorption isotherms measurement was used to characterize the pore size distribution and BET surface area. The results indicate that all of the factors can make an influence on the preparation of the mesoporous silica, which is more sensitive to the concentration of the acid. 相似文献
15.
Eggenhuisen TM den Breejen JP Verdoes D de Jongh PE de Jong KP 《Journal of the American Chemical Society》2010,132(51):18318-18325
We explored melt infiltration of mesoporous silica supports to prepare supported metal catalysts with high loadings and controllable particle sizes. Melting of Co(NO(3))(2)·6H(2)O in the presence of silica supports was studied in situ with differential scanning calorimetry. The melting point depression of the intraporous phase was used to quantify the degree of pore loading after infiltration. Maximum pore-fillings corresponded to 70-80% of filled pore volume, if the intraporous phase was considered to be crystalline Co(NO(3))(2)·6H(2)O. However, diffraction was absent in XRD both from the ordered mesopores at low scattering angles and from crystalline cobalt nitrate phases at high angles. Hence, an amorphous, lower density, intraporous Co(NO(3))(2)·6H(2)O phase was proposed to fill the pores completely. Equilibration at 60 °C in a closed vessel was essential for successful melt infiltration. In an open crucible, dehydration of the precursor prior to infiltration inhibited homogeneous filling of support particles. The dispersion and distribution of Co(3)O(4) after calcination could be controlled using the same toolbox as for preparation via solution impregnation: confinement and the calcination gas atmosphere. Using ordered mesoporous silica supports as well as an industrial silica gel support, catalysts with Co metal loadings in the range of 10-22 wt % were prepared. The Co(3)O(4) crystallite sizes ranged from 4 to 10 nm and scaled with the support pore diameters. By calcination in N(2), pluglike nanoparticles were obtained that formed aggregates over several pore widths, while calcination in 1% NO/N(2) led to the formation of smaller individual nanoparticles. After reduction, the Co/SiO(2) catalysts showed high activity for the Fischer-Tropsch synthesis, illustrating the applicability of melt infiltration for supported catalyst preparation. 相似文献
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Pore and surface diffusion of carbon dioxide (CO(2)) and ethylene (C(2)H(4)) in the nanopores of ordered mesoporous silica fibers about 200 microm in length was measured by the transient gravimetric method. The experimentally determined pore diffusivity data, coupled with the porosity, pore size, and fiber length, are used to obtain the actual length of the nanopores in silica fibers. These measurements reveal a structure of the ordered nanopores whirling helically around the fiber axis with a spiral diameter of about 15 microm and a pitch value of 1.6 microm. At room temperature the surface diffusion contributes about 10% to the total diffusional flux for these two gases in the nanopores of the ordered mesoporous silica fibers. The surface diffusion coefficients for the ordered mesoporous silica fibers are about 1 order of magnitude larger than the non-ordered mesoporous alumina or silica with similar pore size. 相似文献
18.
A facile approach towards the scaled-up synthesis of a novel hierarchical sieve-like structure of mesoporous silica nanoparticle aggregates (hsMSNA) with high drug encapsulation efficiency and sustained release behaviors acting as a drug delivery system in the field of nanomedicine. 相似文献
19.
Magnetic mesoporous silica nanoparticles (M-MSNs) are emerging as one of the most appealing candidates for theranostic carriers. Herein, a simple synthesis method of M-MSNs with a single Fe(3)O(4) nanocrystal core and a mesoporous shell with radially aligned pores was elaborated using tetraethyl orthosilicate (TEOS) as silica source, cationic surfactant CTAB as template, and 1,3,5-triisopropylbenzene (TMB)/decane as pore swelling agents. Due to the special localization of TMB during the synthesis process, the pore size was increased with added TMB amount within a limited range, while further employment of TMB lead to severe particle coalescence and not well-developed pore structure. On the other hand, when a proper amount of decane was jointly incorporated with limited amounts of TMB, effective pore expansion of M-MSNs similar to that of analogous mesoporous silica nanoparticles was realized. The resultant M-MSN materials possessed smaller particle size (about 40-70 nm in diameter), tunable pore sizes (3.8-6.1 nm), high surface areas (700-1100 m(2)/g), and large pore volumes (0.44-1.54 cm(3)/g). We also demonstrate their high potential in conventional DNA loading. Maximum loading capacity of salmon sperm DNA (375 mg/g) was obtained by the use of the M-MSN sample with the largest pore size of 6.1 nm. 相似文献
20.
Highly ordered mesoporous SiC materials were prepared by infiltrating viscous liquid preceramic polymer, allylhydridopolycarbosilane, into two types of surface modified nanoporous silica templates: mesoporous silica SBA-15 and mesocellular siliceous foam. The silica templates were subsequently etched off after pyrolysis at 1000 degrees C under nitrogen atmosphere with the resultant formation of ordered mesoporous structures. The mesoporous SiC materials, synthesized from both types of templates possessed high Brunauer-Emmett-Teller (BET) surface areas in the range of 250-260 m(2)/g with pore sizes of 3.4-3.6 nm. The ordered structures of mesoporous SiC were exact inverse replicas of their respective silica templates, as characterized by small angle X-ray diffraction (XRD), transmission electron microscope (TEM) images, and the adsorption-desorption isotherm of nitrogen. 相似文献