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Sample records for mesoporous silica catalytic

  1. Mesoporous silica nanoparticles for biomedical and catalytical applications

    SciTech Connect

    Sun, Xiaoxing

    2011-01-01

    Mesoporous silica materials, discovered in 1992 by the Mobile Oil Corporation, have received considerable attention in the chemical industry due to their superior textual properties such as high surface area, large pore volume, tunable pore diameter, and narrow pore size distribution. Among those materials, MCM-41, referred to Mobile Composition of Matter NO. 41, contains honeycomb liked porous structure that is the most common mesoporous molecular sieve studied. Applications of MCM-41 type mesoporous silica material in biomedical field as well as catalytical field have been developed and discussed in this thesis. The unique features of mesoporous silica nanoparticles were utilized for the design of delivery system for multiple biomolecules as described in chapter 2. We loaded luciferin into the hexagonal channels of MSN and capped the pore ends with gold nanoparticles to prevent premature release. Luciferase was adsorbed onto the outer surface of the MSN. Both the MSN and the gold nanoparticles were protected by poly-ethylene glycol to minimize nonspecific interaction of luciferase and keep it from denaturating. Controlled release of luciferin was triggered within the cells and the enzymatic reaction was detected by a luminometer. Further developments by varying enzyme/substrate pairs may provide opportunities to control cell behavior and manipulate intracellular reactions. MSN was also served as a noble metal catalyst support due to its large surface area and its stability with active metals. We prepared MSN with pore diameter of 10 nm (LP10-MSN) which can facilitate mass transfer. And we successfully synthesized an organo silane, 2,2'-Bipyridine-amide-triethoxylsilane (Bpy-amide-TES). Then we were able to functionalize LP10-MSN with bipyridinyl group by both post-grafting method and co-condensation method. Future research of this material would be platinum complexation. This Pt (II) complex catalyst has been reported for a C-H bond activation reaction as an

  2. Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica.

    PubMed

    Ji, Yazhou; Caskey, Christopher; Richards, Ryan M

    2015-01-01

    As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties of the materials were investigated. We used a one pot sol-gel approach to intercalate gold nano particles in the walls of mesoporous silica. To start with the synthesis, P123 was used as template to form micelles. Then TESPTS was used as a surface modification agent to intercalate gold nano particles. Following this process, TEOS was added in as a silica source which underwent a polymerization process in acid environment. After hydrothermal processing and calcination, the final product was acquired. Several techniques were utilized to characterize the porosity, morphology and structure of the gold intercalated mesoporous silica. The results showed a stable structure of mesoporous silica after gold intercalation. Through the oxidation of benzyl alcohol as a benchmark reaction, the GMS materials showed high selectivity and recyclability.

  3. Monodisperse metal nanoparticle catalysts on silica mesoporous supports: synthesis, characterizations, and catalytic reactions

    SciTech Connect

    Somorjai, G.A.

    2009-09-14

    The design of high performance catalyst achieving near 100% product selectivity at maximum activity is one of the most important goals in the modern catalytic science research. To this end, the preparation of model catalysts whose catalytic performances can be predicted in a systematic and rational manner is of significant importance, which thereby allows understanding of the molecular ingredients affecting the catalytic performances. We have designed novel 3-dimensional (3D) high surface area model catalysts by the integration of colloidal metal nanoparticles and mesoporous silica supports. Monodisperse colloidal metal NPs with controllable size and shape were synthesized using dendrimers, polymers, or surfactants as the surface stabilizers. The size of Pt, and Rh nanoparticles can be varied from sub 1 nm to 15 nm, while the shape of Pt can be controlled to cube, cuboctahedron, and octahedron. The 3D model catalysts were generated by the incorporation of metal nanoparticles into the pores of mesoporous silica supports via two methods: capillary inclusion (CI) and nanoparticle encapsulation (NE). The former method relies on the sonication-induced inclusion of metal nanoparticles into the pores of mesoporous silica, whereas the latter is performed by the encapsulation of metal nanoparticles during the hydrothermal synthesis of mesoporous silica. The 3D model catalysts were comprehensively characterized by a variety of physical and chemical methods. These catalysts were found to show structure sensitivity in hydrocarbon conversion reactions. The Pt NPs supported on mesoporous SBA-15 silica (Pt/SBA-15) displayed significant particle size sensitivity in ethane hydrogenolysis over the size range of 1-7 nm. The Pt/SBA-15 catalysts also exhibited particle size dependent product selectivity in cyclohexene hydrogenation, crotonaldehyde hydrogenation, and pyrrole hydrogenation. The Rh loaded SBA-15 silica catalyst showed structure sensitivity in CO oxidation reaction. In

  4. Gold Incorporated Mesoporous Silica Thin Film Model Surface as a Robust SERS and Catalytically Active Substrate.

    PubMed

    Sunil Sekhar, Anandakumari Chandrasekharan; Vinod, Chathakudath Prabhakaran

    2016-01-01

    Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement. The applicability of these thin films as catalysts as well as a robust SERS active substrate for model catalysis study is tested. Compared to bare silica film our gold incorporated silica, GSM-23F gave an enhancement factor of 10³ for RhB with a laser source 633 nm. The reduction reaction of p-nitrophenol with sodium borohydride from our thin films shows a decrease in peak intensity corresponding to -NO₂ group as time proceeds, confirming the catalytic activity. Such model surfaces can potentially bridge the material gap between a real catalytic system and surface science studies. PMID:27213321

  5. Multifunctional mesoporous silica catalyst

    DOEpatents

    Lin, Victor Shang-Yi; Tsai, Chih-Hsiang; Chen, Hung-Ting; Pruski, Marek; Kobayashi, Takeshi

    2015-03-31

    The present invention provides bifunctional silica mesoporous materials, including mesoporous silica nanoparticles ("MSN"), having pores modified with diarylammonium triflate and perfluoroaryl moieties, that are useful for the acid-catalyzed esterification of organic acids with organic alcohols.

  6. Facile Fabrication of Well-Dispersed Pt Nanoparticles in Mesoporous Silica with Large Open Spaces and Their Catalytic Applications.

    PubMed

    Liu, Xianchun; Chen, Dashu; Chen, Lin; Jin, Renxi; Xing, Shuangxi; Xing, Hongzhu; Xing, Yan; Su, Zhongmin

    2016-06-27

    In this paper, a facile strategy is reported for the preparation of well-dispersed Pt nanoparticles in ordered mesoporous silica (Pt@OMS) by using a hybrid mesoporous phenolic resin-silica nanocomposite as the parent material. The phenolic resin polymer is proposed herein to be the key in preventing the aggregation of Pt nanoparticles during their formation process and making contributions both to enhance the surface area and enlarge the pore size of the support. The Pt@OMS proves to be a highly active and stable catalyst for both gas-phase oxidation of CO and liquid-phase hydrogenation of 4-nitrophenol. This work might open new avenues for the preparation of noble metal nanoparticles in mesoporous silica with unique structures for catalytic applications. PMID:27245766

  7. Facile Fabrication of Well-Dispersed Pt Nanoparticles in Mesoporous Silica with Large Open Spaces and Their Catalytic Applications.

    PubMed

    Liu, Xianchun; Chen, Dashu; Chen, Lin; Jin, Renxi; Xing, Shuangxi; Xing, Hongzhu; Xing, Yan; Su, Zhongmin

    2016-06-27

    In this paper, a facile strategy is reported for the preparation of well-dispersed Pt nanoparticles in ordered mesoporous silica (Pt@OMS) by using a hybrid mesoporous phenolic resin-silica nanocomposite as the parent material. The phenolic resin polymer is proposed herein to be the key in preventing the aggregation of Pt nanoparticles during their formation process and making contributions both to enhance the surface area and enlarge the pore size of the support. The Pt@OMS proves to be a highly active and stable catalyst for both gas-phase oxidation of CO and liquid-phase hydrogenation of 4-nitrophenol. This work might open new avenues for the preparation of noble metal nanoparticles in mesoporous silica with unique structures for catalytic applications.

  8. Mesoporous Silica Supported Pd-MnOx Catalysts with Excellent Catalytic Activity in Room-Temperature Formic Acid Decomposition

    NASA Astrophysics Data System (ADS)

    Jin, Min-Ho; Oh, Duckkyu; Park, Ju-Hyoung; Lee, Chun-Boo; Lee, Sung-Wook; Park, Jong-Soo; Lee, Kwan-Young; Lee, Dong-Wook

    2016-09-01

    For the application of formic acid as a liquid organic hydrogen carrier, development of efficient catalysts for dehydrogenation of formic acid is a challenging topic, and most studies have so far focused on the composition of metals and supports, the size effect of metal nanoparticles, and surface chemistry of supports. Another influential factor is highly desired to overcome the current limitation of heterogeneous catalysis for formic acid decomposition. Here, we first investigated the effect of support pore structure on formic acid decomposition performance at room temperature by using mesoporous silica materials with different pore structures such as KIE-6, MCM-41, and SBA-15, and achieved the excellent catalytic activity (TOF: 593 h‑1) by only controlling the pore structure of mesoporous silica supports. In addition, we demonstrated that 3D interconnected pore structure of mesoporous silica supports is more favorable to the mass transfer than 2D cylindrical mesopore structure, and the better mass transfer provides higher catalytic activity in formic acid decomposition. If the pore morphology of catalytic supports such as 3D wormhole or 2D cylinder is identical, large pore size combined with high pore volume is a crucial factor to achieve high catalytic performance.

  9. Mesoporous Silica Supported Pd-MnOx Catalysts with Excellent Catalytic Activity in Room-Temperature Formic Acid Decomposition

    PubMed Central

    Jin, Min-Ho; Oh, Duckkyu; Park, Ju-Hyoung; Lee, Chun-Boo; Lee, Sung-Wook; Park, Jong-Soo; Lee, Kwan-Young; Lee, Dong-Wook

    2016-01-01

    For the application of formic acid as a liquid organic hydrogen carrier, development of efficient catalysts for dehydrogenation of formic acid is a challenging topic, and most studies have so far focused on the composition of metals and supports, the size effect of metal nanoparticles, and surface chemistry of supports. Another influential factor is highly desired to overcome the current limitation of heterogeneous catalysis for formic acid decomposition. Here, we first investigated the effect of support pore structure on formic acid decomposition performance at room temperature by using mesoporous silica materials with different pore structures such as KIE-6, MCM-41, and SBA-15, and achieved the excellent catalytic activity (TOF: 593 h−1) by only controlling the pore structure of mesoporous silica supports. In addition, we demonstrated that 3D interconnected pore structure of mesoporous silica supports is more favorable to the mass transfer than 2D cylindrical mesopore structure, and the better mass transfer provides higher catalytic activity in formic acid decomposition. If the pore morphology of catalytic supports such as 3D wormhole or 2D cylinder is identical, large pore size combined with high pore volume is a crucial factor to achieve high catalytic performance. PMID:27666280

  10. Bifunctionalized mesoporous silica-supported gold nanoparticles: intrinsic oxidase and peroxidase catalytic activities for antibacterial applications.

    PubMed

    Tao, Yu; Ju, Enguo; Ren, Jinsong; Qu, Xiaogang

    2015-02-11

    Bifunctionalized mesoporous silica-supported gold nanoparticles as oxidase and peroxidase mimics for antibacterial applications are demonstrated. For the first time, these mesoporous silica-supported gold nanoparticles are applied as oxidase and peroxidase mimics. Taking advantage of their prominent enzyme activities, the MSN-AuNPs show excellent antibacterial properties against both Gram-negative and Gram-positive bacteria. Furthermore, MSN-AuNPs also exhibit outstanding performance in biofilm elimination . PMID:25655182

  11. Synthesis of mesoporous iron-incorporated silica-pillared clay and catalytic performance for phenol hydroxylation

    NASA Astrophysics Data System (ADS)

    Yang, Shengjun; Liang, Guozheng; Gu, Aijuan; Mao, Huihui

    2013-11-01

    Fe-incorporated silica-pillared clays (Fe-SPCs) with ordered interlayer mesoporous structure have been synthesized through a new two-step procedure including the modification of the silica nano-pillars with potassium ferricyanide (K3Fe(CN)6) and successive calcination. X-ray diffraction, nitrogen adsorption-desorption, Fourier transform infrared spectra, X-ray fluorescence analyses, diffuse reflectance UV-vis spectra and X-ray absorption near-edge structure spectra were used to characterize the structures and the synthesizing mechanism of Fe-SPCs. Results show that all iron species were tetrahedrally coordinated with the interlayer silica nano-pillars, and the cationic surfactant molecule plays an important role in the intercalation of tetraethoxysilane and the introduction of iron into the intragallery silica framework. Moreover, the structural parameters of Fe-SPC can be adjusted by controlling the concentration of K3Fe(CN)6, as the concentration of K3Fe(CN)6 increases from 1 M to 2 M, the gallery height of Fe-SPC increases from 2.51 to 2.66 nm, while the Brunauer-Emmett-Teller (BET) surface area, pore volume and Barrett-Joyner-Halenda (BJH) pore size decrease from 856 to 794 m2/g, 0.75 to 0.69 cm3/g, and 2.2 to 2.0 nm, respectively. The Fe-SPCs show good catalytic activity in phenol hydroxylation using H2O2 as oxidant (phenol:H2O2 = 1:1, water), specifically, the phenol conversion is 46.2%, and the selectivity of dihydroxybenzenes is 70.6% at 343 K.

  12. Synthesis, Characterization, and Catalytic Function of Novel Highly Dispersed Tungsten Oxide Catalysts on Mesoporous Silica

    SciTech Connect

    Herrera, Jose E.; Kwak, Ja Hun; Hu, Jian Zhi; Wang, Yong; Peden, Charles HF; Macht, Josef; Iglesia, Enrique

    2006-04-01

    The physical and chemical properties of tungsten oxide supported on SBA-15 mesoporous silica prepared by a controlled grafting process through atomic layer deposition (ALD) were studied using complementary characterization methods. X-ray diffraction, optical absorption and transmission electron microscopy showed that tungsten oxide species are highly dispersed on SBA-15 surfaces, even at 30 wt.% WOx contents (surface density: 1.33 WOx/nm2). ALD methods led to samples with much better thermal stability than those prepared via impregnation. Dehydration reactions of 2-butanol and methanol dehydration were used as probe reactions. Differences in reaction rates between the samples prepared by ALD and conventional impregnation reflect the sintering resistance of catalysts prepared by ALD. Notably, temperature programmed oxidation of spent catalysts showed that carbon formation was not responsible for the different dehydration rates in samples prepared by ALD and impregnation..

  13. Effects of surface activation on the structural and catalytic properties of ruthenium nanoparticles supported on mesoporous silica

    NASA Astrophysics Data System (ADS)

    Ma, Xianfeng; Lin, Rui; Beuerle, Christopher; Jackson, James E.; Obare, Sherine O.; Ofoli, Robert Y.

    2014-01-01

    Using colloid-based methods to prepare supported catalytic metallic nanoparticles (NPs) often faces the challenge of removing the stabilizer used during synthesis and activating the catalyst without modifying the particles or the support. We explored three surface activation protocols (thermal oxidation at 150 ° C, thermal reduction at 350 ° C, and argon-protected calcination at 650 ° C) to activate ruthenium NPs supported on mesoporous silica (MSU-F), and assessed their effects on the structural and catalytic properties of the catalysts, and their activity by the aqueous phase hydrogenation of pyruvic acid. The NPs were synthesized by polyol reduction using poly-N-vinyl-2-pyrrolidone (PVP) as a stabilizer, and supported on MSU-F by sonication-assisted deposition. The NPs maintained their original morphology on the support during activation. Ar-protected calcination was the most efficient of the three for completely removing PVP from particle surfaces, and provided the highest degree of particle crystallinity and a metal dispersion comparable to commercial Ru/SiO2. Its catalytic performance was significantly higher than the other two protocols, although all three thermally activated catalysts achieved higher activity than the commercial catalyst at the same Ru loading. Post-reaction analysis also showed that the supported catalyst activated at 650 ° C retained its morphology during the reaction, which is an important requirement for recyclability.

  14. Carbon Nanotube Synthesis Using Mesoporous Silica Templates

    SciTech Connect

    Zheng, Feng; Liang, Liang; Gao, Yufei; Sukamto, Johanes H.; Aardahl, Chris L.

    2002-07-01

    Well-aligned carbon nanotubes (CNTs) were grown on mesoporous silica films by chemical vapor deposition (CVD). Ethylene was used as the carbon source and CVD was performed at 1023 K and atmospheric pressure. The films were doped with Fe during gelation, and three different structure directing agents were used for mesoporous silica synthesis: polyoxyethylene (10) cetyl ether (C16EO10), Pluronic tri-block copolymer (P123), and cetyltriethylammonium chloride (CTAC). A high degree of CNT alignment on C16EO10-mesoporous silica films was produced at Fe:Si molar ratio of 1.80. Similar alignment of CNTs was achieved on the other two types of films but on CTAC-mesoporous silica films, CNTs only grew parallel to the substrate surface from the cracks in the films because of the in-plane arrangement of the mesopores in such films. Considerable progress has been made in producing multi-walled carbon nanotubes (CNTs) by catalytic CVD techniques. If CNTs are to be integrated into certain useful devices, it is critical to be able to grow highly aligned arrays of CNTs with narrow size distribution and at specific locations on a substrate. Long-range alignment normal to the substrate results from steric crowding if the initial catalyst sites are sufficiently dense. Alignment may be improved with better control of the density of catalytic sites by means of a template of appropriate pore structure. The confinement of CNTs by the pores during the initial growth may also help align CNTs.

  15. A New Class of Highly Dispersed VOx Catalysts on Mesoporous Silica: Synthesis, Characterization, and Catalytic Activity in the Partial Oxidation of Ethanol

    SciTech Connect

    Kwak, Ja Hun; Herrera, Jose E.; Hu, Jian Zhi; Wang, Yong; Peden, Charles HF

    2006-01-26

    The morphology of vanadium oxide supported on a titania-modified mesoporous silica (MCM-41), obtained by means of a careful grafting process through atomic layer deposition, was studied using a variety of characterization techniques. The XRD together with TEM, 51V-NMR, Raman, FTIR and DRS-UV-Vis results showed that the vanadia species are extremely well dispersed onto the surface of the mesoporous support; the dispersion being stable upon thermal treatments up to 400 °C. Studies of the catalytic activity of these materials were performed using the partial oxidation of ethanol as a probe reaction. The results indicate an intrinsic relationship between dispersion, the presence of a TiO2-VOx phase, and catalytic activity for oxidation and dehydration.

  16. Mesoporous Silica: A Suitable Adsorbent for Amines

    PubMed Central

    2009-01-01

    Mesoporous silica with KIT-6 structure was investigated as a preconcentrating material in chromatographic systems for ammonia and trimethylamine. Its adsorption capacity was compared to that of existing commercial materials, showing its increased adsorption power. In addition, KIT-6 mesoporous silica efficiently adsorbs both gases, while none of the employed commercial adsorbents did. This means that KIT-6 Mesoporous silica may be a good choice for integrated chromatography/gas sensing micro-devices. PMID:20628459

  17. Cellular membrane trafficking of mesoporous silica nanoparticles

    SciTech Connect

    Fang, I-Ju

    2012-01-01

    This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulf some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine

  18. Utilization of a By-product Produced from Oxidative Desulfurization Process over Cs-Mesoporous Silica Catalysts

    SciTech Connect

    Kim, Hyeonjoo; Jeong, Kwang Eun; Jeong, Soon-Yong; Park, Young-Kwon; Kim, Do Heui; Jeon, Jong Ki

    2011-02-28

    We investigated the use of Cs-mesoporous silica catalysts to upgrade a by-product of oxidative desulfurization (ODS). Cs-mesoporous silica catalysts were chaeacterized through N2 adsorption, XRD, CO2-temperature-programmed desorption, and XRF. Cs-mesoporous silica prepared by the direct incorporation method showed higher catalytic performance than a Cs/MCM-41 catalyst by impregnation method for the catalytic decomposition of sulfone compounds produced from ODS process.

  19. Utilization of a by-product produced from oxidative desulfurization process over Cs-mesoporous silica catalysts.

    PubMed

    Kim, Hyeonjoo; Jeong, Kwang-Eun; Jeong, Soon-Yong; Park, Young-Kwon; Kim, Do Heui; Jeon, Jong-Ki

    2011-02-01

    We investigated the use of Cs-mesoporous silica catalysts to upgrade a by-product of oxidative desulfurization (ODS). Cs-mesoporous silica catalysts were characterized through N2 adsorption, XRD, CO2-temperature-programmed desorption, and XRF. Cs-mesoporous silica prepared by the direct incorporation method showed higher catalytic performance than a Cs/MCM-41 catalyst by impregnation method for the catalytic decomposition of sulfone compounds produced from ODS process. PMID:21456272

  20. Sample Desorption/Onization From Mesoporous Silica

    DOEpatents

    Iyer, Srinivas; Dattelbaum, Andrew M.

    2005-10-25

    Mesoporous silica is shown to be a sample holder for laser desorption/ionization of mass spectrometry. Supported mesoporous silica was prepared by coating an ethanolic silicate solution having a removable surfactant onto a substrate to produce a self-assembled, ordered, nanocomposite silica thin film. The surfactant was chosen to provide a desired pore size between about 1 nanometer diameter and 50 nanometers diameter. Removal of the surfactant resulted in a mesoporous silica thin film on the substrate. Samples having a molecular weight below 1000, such as C.sub.60 and tryptophan, were adsorbed onto and into the mesoporous silica thin film sample holder and analyzed using laser desorption/ionization mass spectrometry.

  1. Hollow mesoporous aluminosilica spheres with perpendicular pore channels as catalytic nanoreactors.

    PubMed

    Fang, Xiaoliang; Liu, Zhaohui; Hsieh, Ming-Feng; Chen, Mei; Liu, Pengxin; Chen, Cheng; Zheng, Nanfeng

    2012-05-22

    The design and synthesis of hollow/yolk-shell mesoporous structures with catalytically active ordered mesoporous shells can infuse new vitality into the applications of these attractive structures. In this study, we report that hollow/yolk-shell structures with catalytically active ordered mesoporous aluminosilica shells can be easily prepared by using silica spheres as the silica precursors. By simply treating with a hot alkaline solution in the presence of sodium aluminate (NaAlO(2)) and cetyltrimethylammonium bromide (CTAB), solid silica spheres can be directly converted into high-quality hollow mesoporous aluminosilica spheres with perpendicular pore channels. On the basis of the proposed formation mechanism of etching followed by co-assembly, the synthesis strategy developed in this work can be extended as a general strategy to prepare ordered mesoporous yolk-shell structures with diverse compositions and morphologies simply by replacing solid silica spheres with silica-coated nanocomposites. The reduction of 4-nitrophenol with yolk-shell structured Au@ordered mesoporous aluminosilica as the catalyst has clearly demonstrated that the highly permeable perpendicular pore channels of mesoporous aluminosilica can effectively prevent the catalytically active yolk from aggregating. Furthermore, with accessible acidity, the yolk-shell structured ordered mesoporous aluminosilica spheres containing Pd yolk exhibit high catalytic activity and recyclability in a one-pot two-step synthesis involving an acid catalysis and subsequent catalytic hydrogenation for desired benzimidazole derivative, which makes the proposed hollow ordered aluminosilica spheres a versatile and practicable scaffold for advanced catalytic nanoreactor systems.

  2. Bimodal mesoporous silica with bottleneck pores.

    PubMed

    Reber, M J; Brühwiler, D

    2015-11-01

    Bimodal mesoporous silica consisting of two sets of well-defined mesopores is synthesized by a partial pseudomorphic transformation of an ordered mesoporous starting material (SBA-15 type). The introduction of a second set of smaller mesopores (MCM-41 type) establishes a pore system with bottlenecks that restricts the access to the core of the bimodal mesoporous silica particles. The particle size and shape of the starting material are retained, but micropores present in the starting material disappear during the transformation, leading to a true bimodal mesoporous product. A varying degree of transformation allows the adjustment of the pore volume contribution of the two mesopore domains. Information on the accessibility of the mesopores is obtained by the adsorption of fluorescence-labeled poly(amidoamine) dendrimers and imaging by confocal laser scanning microscopy. This information is correlated with nitrogen sorption data to provide insights regarding the spatial distribution of the two mesopore domains. The bimodal mesoporous materials are excellent model systems for the investigation of cavitation effects in nitrogen desorption isotherms. PMID:26399172

  3. Ecodesign of ordered mesoporous silica materials.

    PubMed

    Gérardin, Corine; Reboul, Julien; Bonne, Magali; Lebeau, Bénédicte

    2013-05-01

    Characterized by a regular porosity in terms of pore size and pore network arrangement, ordered mesoporous solids have attracted increasing interest in the last two decades. These materials have been identified as potential candidates for several applications. However, more environmentally friendly and economical synthesis routes of mesoporous silica materials were found to be necessary in order to develop these applications on an industrial scale. Consequently, ecodesign of ordered mesoporous silica has been considerably developed with the objective of optimizing the chemistry and the processing aspects of the material synthesis. In this review, the main strategies developed with this aim are presented and discussed. PMID:23407854

  4. Preparation of periodic mesoporous silica-included divacant Keggin units for the catalytic oxidation of styrene to synthesize styrene oxide

    NASA Astrophysics Data System (ADS)

    Yu, Xiaodan; Xu, Leilei; Yang, Xia; Guo, Yingna; Li, Kexin; Hu, Jianglei; Li, Wei; Ma, Fengyan; Guo, Yihang

    2008-05-01

    Periodic mesoporous composite catalysts, [( n-C 4H 9) 4N] 4[γ-SiW 10O 34(H 2O) 2]/SBA-15 (TBA-1*/SBA-15, where TBA-1* = [( n-C 4H 9) 4N] 4[γ-SiW 10O 34(H 2O) 2]), with TBA-1* loadings of 4.3-14.8% were prepared by simultaneous hydrolysis and co-condensation of the tetraethoxysilane (TEOS) in the presence of divacant Keggin-type polyoxometalate and triblock copolymer surfactant (P123) followed by hydrothermal treatment process. Structure integrity of the Keggin unit in as-prepared composites was studied by Fourier transform infrared spectroscopy (FT-IR), Raman scattering spectra, and 29Si magic-angle spinning (MAS) NMR. Periodic mesoporous structure of the composites was evaluated by low-angle X-ray powder diffraction (LXRD) patterns, nitrogen porosimetry, and transmission electron microscope (TEM) measurements. As-prepared TBA-1*/SBA-15 was used as an heterogeneous oxidation catalyst for the styrene epoxidation reaction to synthesize styrene oxide in the presence of dilute H 2O 2 (30%), and influences of solvent, molar ratio of styrene to H 2O 2, TBA-1* loading on the styrene conversion, styrene oxide yield and selectivity were considered.

  5. Drug release from ordered mesoporous silicas.

    PubMed

    Doadrio, Antonio L; Salinas, Antonio J; Sánchez-Montero, José M; Vallet-Regí, M

    2015-01-01

    The state-of-the-art in the investigation of drugs release from Silica-based ordered Mesoporous Materials (SMMs) is reviewed. First, the SMM systems used like host matrixes are described. Then, the model drugs studied until now, including their pharmacological action, structure and the mesoporous matrix employed for each drug, are comprehensively listed. Next, the factors influencing the release of drugs from SMMs and the strategies used to control the drug delivery, specially the chemical functionalization of the silica surface, are discussed. In addition, how all these factors were gathered in a kinetic equation that describes the drug release from the mesoporous matrixes is explained. The new application of molecular modeling and docking in the investigation of the drug delivery mechanisms from SMMs is also presented. Finally, the new approaches under investigation in this field are mentioned including the design of smart stimuli-responsive materials and other recent proposals for a future investigation. PMID:26549760

  6. The formation of helical mesoporous silica nanotubes

    NASA Astrophysics Data System (ADS)

    Wan, Xiaobing; Pei, Xianfeng; Zhao, Huanyu; Chen, Yuanli; Guo, Yongmin; Li, Baozong; Hanabusa, Kenji; Yang, Yonggang

    2008-08-01

    Three chiral cationic gelators were synthesized. They can form translucent hydrogels in pure water. These hydrogels become highly viscous liquids under strong stirring. Mesoporous silica nanotubes with coiled pore channels in the walls were prepared using the self-assemblies of these gelators as templates. The mechanism of the formation of this hierarchical nanostructure was studied using transmission electron microscopy at different reaction times. The results indicated that there are some interactions between the silica source and the gelator. The morphologies of the self-assemblies of gelators changed gradually during the sol-gel transcription process. It seems that the silica source directed the organic self-assemblies into helical nanostructures.

  7. Self-Assembly and Compartmentalization of Nanozymes in Mesoporous Silica-Based Nanoreactors.

    PubMed

    Huang, Yanyan; Lin, Youhui; Ran, Xiang; Ren, Jinsong; Qu, Xiaogang

    2016-04-11

    Herein, to mimic complex natural system, polyelectrolyte multilayer (PEM)-coated mesoporous silica nanoreactors were used to compartmentalize two different artificial enzymes. PEMs coated on the surface of mesoporous silica could serve as a permeable membrane to control the flow of molecules. When assembling hemin on the surface of mesoporous silica, the hemin-based mesoporous silica system possessed remarkable peroxidase-like activity, especially at physiological pH, and could be recycled more easily than traditional graphene-hemin nanocompounds. The hope is that these new findings may pave the way for exploring novel nanoreactors to achieve compartmentalization of nanozymes and applying artificial cascade catalytic systems to mimic cell organelles or important biochemical transformations.

  8. Synthesis of manganese incorporated hierarchical mesoporous silica nanosphere with fibrous morphology by facile one-pot approach for efficient catalytic ozonation.

    PubMed

    Afzal, Shahzad; Quan, Xie; Chen, Shuo; Wang, Jing; Muhammad, Dost

    2016-11-15

    Manganese incorporated fibrous silica nanosphere (MnOx-0.013/KCC-1) was synthesized by one step hydrothermal method for the first time and its catalytic activity for ozonation of oxalic acid was studied. For comparison, manganese loaded MCM-41 (MnOx-0.013/MCM-41) was prepared by impregnation method. Various characterizations showed that the morphological, structural and textural properties of MnOx-0.013/KCC-1 were well preserved. Ozonation and catalytic ozonation by MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41 led to 4, 85 and 60% reduction in TOC respectively. Furthermore, 0.05 and 1.2mgL(-1) leaching of Mn was detected from MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41, which are approximately 2.0 and 42.0% of the total Mn present in MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41 respectively. The high catalytic activity was attributed to the generation of hydroxyl radical. Surface hydroxyl groups investigated by using phosphates and ATR-FTIR were believed to be the active sites. Our proposed method of synthesis can be generalized for the synthesis of other metal oxides incorporated fibrous silica for environmental catalysis and other catalytic reactions.

  9. Synthesis of manganese incorporated hierarchical mesoporous silica nanosphere with fibrous morphology by facile one-pot approach for efficient catalytic ozonation.

    PubMed

    Afzal, Shahzad; Quan, Xie; Chen, Shuo; Wang, Jing; Muhammad, Dost

    2016-11-15

    Manganese incorporated fibrous silica nanosphere (MnOx-0.013/KCC-1) was synthesized by one step hydrothermal method for the first time and its catalytic activity for ozonation of oxalic acid was studied. For comparison, manganese loaded MCM-41 (MnOx-0.013/MCM-41) was prepared by impregnation method. Various characterizations showed that the morphological, structural and textural properties of MnOx-0.013/KCC-1 were well preserved. Ozonation and catalytic ozonation by MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41 led to 4, 85 and 60% reduction in TOC respectively. Furthermore, 0.05 and 1.2mgL(-1) leaching of Mn was detected from MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41, which are approximately 2.0 and 42.0% of the total Mn present in MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41 respectively. The high catalytic activity was attributed to the generation of hydroxyl radical. Surface hydroxyl groups investigated by using phosphates and ATR-FTIR were believed to be the active sites. Our proposed method of synthesis can be generalized for the synthesis of other metal oxides incorporated fibrous silica for environmental catalysis and other catalytic reactions. PMID:27434734

  10. Mesoporous CLEAs-silica composite microparticles with high activity and enhanced stability

    PubMed Central

    Cui, Jiandong; Jia, Shiru; Liang, Longhao; Zhao, Yamin; Feng, Yuxiao

    2015-01-01

    A novel enzyme immobilization approach was used to generate mesoporous enzymes-silica composite microparticles by co-entrapping gelatinized starch and cross-linked phenylalanine ammonia lyase (PAL) aggregates (CLEAs) containing gelatinized starch into biomemitic silica and subsequently removing the starch by α-amylase treatment. During the preparation process, the gelatinzed starch served as a pore-forming agent to create pores in CLEAs and biomimetic silica. The resulting mesoporous CLEAs-silica composite microparticles exhibited higher activity and stability than native PAL, conventional CLEAs, and PAL encapsulated in biomimetic silica. Furthermore, the mesoporous CLEAs-silica composite microparticles displayed good reusability due to its suitable size and mechanical properties, and had excellent stability for storage. The superior catalytic performances were attributed to the combinational unique structure from the intra-cross-linking among enzyme aggregates and hard mesoporous silica shell, which not only decreased the enzyme-support negative interaction and mass-transfer limitations, but also improved the mechanical properties and monodispersity. This approach will be highly beneficial for preparing various bioactive mesoporous composites with excellent catalytic performance. PMID:26374188

  11. Dendrimer Templated Synthesis of One Nanometer Rh and Pt Particles Supported on Mesoporous Silica: Catalytic Activity for Ethylene and Pyrrole Hydrogenation.

    SciTech Connect

    Huang, Wenyu; Kuhn, John N.; Tsung, Chia-Kuang; Zhang, Yawen; Habas, Susan E.; Yang, Peidong; Somorjai, Gabor A.

    2008-05-09

    Monodisperse rhodium (Rh) and platinum (Pt) nanoparticles as small as {approx}1 nm were synthesized within a fourth generation polyaminoamide (PAMAM) dendrimer, a hyperbranched polymer, in aqueous solution and immobilized by depositing onto a high-surface-area SBA-15 mesoporous support. X-ray photoelectron spectroscopy indicated that the as-synthesized Rh and Pt nanoparticles were mostly oxidized. Catalytic activity of the SBA-15 supported Rh and Pt nanoparticles was studied with ethylene hydrogenation at 273 and 293 K in 10 torr of ethylene and 100 torr of H{sub 2} after reduction (76 torr of H{sub 2} mixed with 690 torr of He) at different temperatures. Catalysts were active without removing the dendrimer capping but reached their highest activity after hydrogen reduction at a moderate temperature (423 K). When treated at a higher temperature (473, 573, and 673 K) in hydrogen, catalytic activity decreased. By using the same treatment that led to maximum ethylene hydrogenation activity, catalytic activity was also evaluated for pyrrole hydrogenation.

  12. Morphological Control of Multifunctional Mesoporous Silica Nanomaterials for Catalysis Applications

    SciTech Connect

    Huh, Seong

    2004-12-19

    I found an efficient method to control the morphology of the organically monofunctionalized mesoporous silica materials by introducing different types of organoalkoxysilanes in a base-catalyzed co-condensation reaction. The monofunctionalized materials exhibit different particle morphologies relative to the pure MCM-41 material. The concentration dependence of the morphology is a critical factor to determine the final particle shape. A proposed mechanism of the shape evolution is also offered. After understanding the role of organoalkoxysilanes in producing various well-shaped nanomaterials, I also obtained a series of bifunctional mesoporous silica materials with certain particle morphology. A series of bifunctional mesoporous silica nanospheres (MSNs) whose physicochemical properties was investigated via solid state NMR techniques and Cu2+ adsorption capacity tests, The ratio of two different organic groups inside of mesopores of these MSNs could be fine-tuned. These MSNs serve as a useful model system to study substrate selectivity in catalytic reactions and sorption phenomena. For example, the Cu2+ adsorption capacity of these materials was dictated by the chemical nature of the mesopores generated by the different organic functional groups. An investigation of the substrate selectivity of the bifunctionalized MSNs in a competitive nitroaldol reaction using an equimolar amount of two competing 4-nitrobenzaldehyde derivatives was performed. Shape-controlled bifunctional MSNs were employed as the catalysts. The properties of the MSNs were investigated using various spectroscopic methods and electron microscopy. The more hydrophobic the surface organic groups are, the higher the ratio of hydrophobic final product. This is the first example to demonstrate the selection of substrate using physicochemical nature of the mesopore surface other than the conventional shape selection in zeolite systems. I also created a cooperative dual catalyst

  13. Catalytic Mesoporous Janus Nanomotors for Active Cargo Delivery

    PubMed Central

    2015-01-01

    We report on the synergy between catalytic propulsion and mesoporous silica nanoparticles (MSNPs) for the design of Janus nanomotors as active cargo delivery systems with sizes <100 nm (40, 65, and 90 nm). The Janus asymmetry of the nanomotors is given by electron beam (e-beam) deposition of a very thin platinum (2 nm) layer on MSNPs. The chemically powered Janus nanomotors present active diffusion at low H2O2 fuel concentration (i.e., <3 wt %). Their apparent diffusion coefficient is enhanced up to 100% compared to their Brownian motion. Due to their mesoporous architecture and small dimensions, they can load cargo molecules in large quantity and serve as active nanocarriers for directed cargo delivery on a chip. PMID:25844893

  14. Shape matters when engineering mesoporous silica-based nanomedicines.

    PubMed

    Hao, Nanjing; Li, Laifeng; Tang, Fangqiong

    2016-04-01

    Mesoporous silica nanomaterials have been successfully employed in the development of novel carriers for drug delivery. Numerous studies have been reported on engineering mesoporous silica-based carriers for drug loading, release, cellular uptake, and biocompatibility. A number of design parameters that govern the in vitro and in vivo performance of the carriers, including particle diameter, surface chemistry, and pore size, have been tuned to optimize nanomedicine efficacy. However, particle shape, which may generate a high impact on nanomedicine performance, has still not been thoroughly investigated. This is probably due to the limited availability of strategies and techniques to produce non-spherical mesoporous silica nanomaterials. Recent breakthroughs in controlling the particle shape of mesoporous silica nanomaterials have confirmed the important roles of shape on nanomedicine development. This review article introduces various fabrication methods for non-spherical mesoporous silica nanomaterials, including rod, ellipsoid, film, platelet/sheet, and cube, and the roles of particle shape in nanomedicine applications. PMID:26818852

  15. Intercalation of aggregation-free and well-dispersed gold nanoparticles into the walls of mesoporous silica as a robust "green" catalyst for n-alkane oxidation.

    PubMed

    Chen, Lifang; Hu, Juncheng; Richards, Ryan

    2009-01-28

    Aggregate-free and well-dispersed gold nanoparticles were intercalated into the walls of mesoporous silica forming a nanoreactor demonstrating high catalytic activity for "green" alkane oxidation. The material is robust and can be recycled. The method may be developed to intercalate other metal or alloy nanoparticles into the walls of mesoporous silica.

  16. Fluorescence properties of dye doped mesoporous silica

    SciTech Connect

    Carbonaro, Carlo M. Corpino, Riccardo Ricci, Pier Carlo Chiriu, Daniele; Cannas, Carla

    2014-10-21

    In this paper we present a review of the main results we obtained studying the emission properties of organic-inorganic hybrids obtained combining mesoporous silica and Xantene dyes, in particular the standard reference Rhodamine 6G. The purpose of the review is to show the possibility to efficiently 'dope' the transparent inorganic porous matrix to obtain promising systems for photonic and biomedical applications. The strategies to solve the concentration effect and the leaching phenomenon are discussed within the framework of the single exciton theory.

  17. Gated Silica Mesoporous Materials in Sensing Applications

    PubMed Central

    Sancenón, Félix; Pascual, Lluís; Oroval, Mar; Aznar, Elena; Martínez-Máñez, Ramón

    2015-01-01

    Silica mesoporous supports (SMSs) have a large specific surface area and volume and are particularly exciting vehicles for delivery applications. Such container-like structures can be loaded with numerous different chemical substances, such as drugs and reporters. Gated systems also contain addressable functions at openings of voids, and cargo delivery can be controlled on-command using chemical, biochemical or physical stimuli. Many of these gated SMSs have been applied for drug delivery. However, fewer examples of their use in sensing protocols have been reported. The approach of applying SMSs in sensing uses another concept—that of loading pores with a reporter and designing a capping mechanism that is selectively opened in the presence of a target analyte, which results in the delivery of the reporter. According to this concept, we provide herein a complete compilation of published examples of probes based on the use of capped SMSs for sensing. Examples for the detection of anions, cations, small molecules and biomolecules are provided. The diverse range of gated silica mesoporous materials presented here highlights their usefulness in recognition protocols. PMID:26491626

  18. Gated Silica Mesoporous Materials in Sensing Applications.

    PubMed

    Sancenón, Félix; Pascual, Lluís; Oroval, Mar; Aznar, Elena; Martínez-Máñez, Ramón

    2015-08-01

    Silica mesoporous supports (SMSs) have a large specific surface area and volume and are particularly exciting vehicles for delivery applications. Such container-like structures can be loaded with numerous different chemical substances, such as drugs and reporters. Gated systems also contain addressable functions at openings of voids, and cargo delivery can be controlled on-command using chemical, biochemical or physical stimuli. Many of these gated SMSs have been applied for drug delivery. However, fewer examples of their use in sensing protocols have been reported. The approach of applying SMSs in sensing uses another concept-that of loading pores with a reporter and designing a capping mechanism that is selectively opened in the presence of a target analyte, which results in the delivery of the reporter. According to this concept, we provide herein a complete compilation of published examples of probes based on the use of capped SMSs for sensing. Examples for the detection of anions, cations, small molecules and biomolecules are provided. The diverse range of gated silica mesoporous materials presented here highlights their usefulness in recognition protocols. PMID:26491626

  19. Preparation of bicontinuous mesoporous silica and organosilica materials containing gold nanoparticles by co-synthesis method

    SciTech Connect

    Lee, Byunghwan; Zhu, Haoguo; Zhang, Zongtao; Overbury, Steven {Steve} H; Dai, Sheng

    2004-01-01

    Catalytic activities of gold strongly depend on its particle size. It is necessary to have homogeneous distributions of small gold nanoparticles with diameters between 2 and 5 nm for excellent catalytic activities. In this study, gold-containing mesoporous silica materials were prepared by a co-synthesis method. The essence of this sol-gel co-synthesis method is to combine together neutral surfactant template synthesis of mesoporous silica materials with the introduction of metal ions via bifunctional silane ligands, so that the formation of mesostructures and metal-ion doping occur simultaneously. The formation of gold nanoparticles with size less than 5 nm inside mesoporous materials (HMS, MSU, and PMO) has been achieved by this co-synthesis sol-gel process. In addition, the effects of post-treatments, such as calcination and reduction, on pore structures and nanoparticle size distributions were also investigated.

  20. Crystallization of hollow mesoporous silica nanoparticles.

    PubMed

    Drisko, Glenna L; Carretero-Genevrier, Adrian; Perrot, Alexandre; Gich, Martí; Gàzquez, Jaume; Rodriguez-Carvajal, Juan; Favre, Luc; Grosso, David; Boissière, Cédric; Sanchez, Clément

    2015-03-11

    Complex 3D macrostructured nanoparticles are transformed from amorphous silica into pure polycrystalline α-quartz using catalytic quantities of alkaline earth metals as devitrifying agent. Walls as thin as 10 nm could be crystallized without losing the architecture of the particles. The roles of cation size and the mol% of the incorporated devitrifying agent in crystallization behavior are studied, with Mg(2+), Ca(2+), Sr(2+) and Ba(2+) all producing pure α-quartz under certain conditions.

  1. Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

    DOE PAGES

    Eedugurala, Naresh; Wang, Zhuoran; Chaudhary, Umesh; Nelson, Nicholas; Kandel, Kapil; Kobayashi, Takeshi; Slowing, Igor I.; Pruski, Marek; Sadow, Aaron D.

    2015-11-04

    The hydroboration of aldehydes and ketones using a silica-supported zirconium catalyst is reported. Reaction of Zr(NMe2)4 and mesoporous silica nanoparticles (MSN) provides the catalytic material Zr(NMe2)n@MSN. Exhaustive characterization of Zr(NMe2)n@MSN with solid-state (SS)NMR and infrared spectroscopy, as well as through reactivity studies, suggests its surface structure is primarily ≡SiOZr(NMe2)3. The presence of these nitrogen-containing zirconium sites is supported by 15N NMR spectroscopy, including natural abundance 15N NMR measurements using dynamic nuclear polarization (DNP) SSNMR. The Zr(NMe2)n@MSN material reacts with pinacolborane (HBpin) to provide Me2NBpin and the material ZrH/Bpin@MSN that is composed of interacting surface-bonded zirconium hydride and surface-bonded borane ≡SiOBpinmore » moieties in an approximately 1:1 ratio, as well as zirconium sites coordinated by dimethylamine. The ZrH/Bpin@MSN is characterized by 1H/2H and 11B SSNMR and infrared spectroscopy and through its reactivity with D2. The zirconium hydride material or the zirconium amide precursor Zr(NMe2)n@MSN catalyzes the selective hydroboration of aldehydes and ketones with HBpin in the presence of functional groups that are often reduced under hydroboration conditions or are sensitive to metal hydrides, including olefins, alkynes, nitro groups, halides, and ethers. Remarkably, this catalytic material may be recycled without loss of activity at least eight times, and air-exposed materials are catalytically active. These supported zirconium centers are robust catalytic sites for carbonyl reduction and that surface-supported, catalytically reactive zirconium hydride may be generated from zirconium-amide or zirconium alkoxide sites.« less

  2. Functionalized bimodal mesoporous silicas as carriers for controlled aspirin delivery

    NASA Astrophysics Data System (ADS)

    Gao, Lin; Sun, Jihong; Li, Yuzhen

    2011-08-01

    The bimodal mesoporous silica modified with 3-aminopropyltriethoxysilane was performed as the aspirin carrier. The samples' structure, drug loading and release profiles were characterized with X-ray diffraction, scanning electron microscopy, N 2 adsorption and desorption, Fourier transform infrared spectroscopy, TG analysis, elemental analysis and UV-spectrophotometer. For further exploring the effects of the bimodal mesopores on the drug delivery behavior, the unimodal mesoporous material MCM-41 was also modified as the aspirin carrier. Meantime, Korsmeyer-Peppas equation ft= ktn was employed to analyze the dissolution data in details. It is indicated that the bimodal mesopores are beneficial for unrestricted drug molecules diffusing and therefore lead to a higher loading and faster releasing than that of MCM-41. The results show that the aspirin delivery properties are influenced considerably by the mesoporous matrix, whereas the large pore of bimodal mesoporous silica is the key point for the improved controlled-release properties.

  3. Incorporation of anti-inflammatory agent into mesoporous silica

    NASA Astrophysics Data System (ADS)

    Rodrigues Braz, Wilson; Lamec Rocha, Natállia; de Faria, Emerson H.; Silva, Márcio L. A. e.; Ciuffi, Katia J.; Tavares, Denise C.; Furtado, Ricardo Andrade; Rocha, Lucas A.; Nassar, Eduardo J.

    2016-09-01

    The unique properties of macroporous, mesoporous, and microporous systems, including their ability to accommodate molecules of different sizes inside their pores and to act as drug delivery systems, have been the object of extensive studies. In this work, mesoporous silica with hexagonal structure was obtained by template synthesis via the sol-gel process. The resulting material was used as support to accommodate the anti-inflammatory agent indomethacin. The alkaline route was used to prepare the mesoporous silica; cetyltrimethylammonium bromide was employed as porogenic agent. The silica particles were functionalized with 3-aminopropyltriethoxysilane alkoxide (APTES) by the sol-gel post-synthesis method. Indomethacin was incorporated into the silica functionalized with APTES and into non-functionalized silica. The resulting systems were characterized by x-ray diffraction (XRD), specific area, infrared spectroscopy, and thermal analyses (TGA). XRD attested to formation of mesoporous silica with hexagonal structure. This structure remained after silica functionalization with APTES and incorporation of indomethacin. Typical infrared spectroscopy vibrations and organic material decomposition during TGA confirmed silica functionalization and drug incorporation. The specific surface area and pore volume of the functionalized material incorporated with indomethacin decreased as compared with the specific surface area and pore volume of the non-functionalized silica containing no drug, suggesting both the functionalizing agent and the drug were present in the silica. Cytotoxicity tests conducted on normal fibroblasts (GM0479A) cells attested that the silica matrix containing indomethacin was less toxic than the free drug.

  4. Incorporation of anti-inflammatory agent into mesoporous silica

    NASA Astrophysics Data System (ADS)

    Rodrigues Braz, Wilson; Lamec Rocha, Natállia; de Faria, Emerson H.; Silva, Márcio L. A. e.; Ciuffi, Katia J.; Tavares, Denise C.; Furtado, Ricardo Andrade; Rocha, Lucas A.; Nassar, Eduardo J.

    2016-09-01

    The unique properties of macroporous, mesoporous, and microporous systems, including their ability to accommodate molecules of different sizes inside their pores and to act as drug delivery systems, have been the object of extensive studies. In this work, mesoporous silica with hexagonal structure was obtained by template synthesis via the sol–gel process. The resulting material was used as support to accommodate the anti-inflammatory agent indomethacin. The alkaline route was used to prepare the mesoporous silica; cetyltrimethylammonium bromide was employed as porogenic agent. The silica particles were functionalized with 3-aminopropyltriethoxysilane alkoxide (APTES) by the sol–gel post-synthesis method. Indomethacin was incorporated into the silica functionalized with APTES and into non-functionalized silica. The resulting systems were characterized by x-ray diffraction (XRD), specific area, infrared spectroscopy, and thermal analyses (TGA). XRD attested to formation of mesoporous silica with hexagonal structure. This structure remained after silica functionalization with APTES and incorporation of indomethacin. Typical infrared spectroscopy vibrations and organic material decomposition during TGA confirmed silica functionalization and drug incorporation. The specific surface area and pore volume of the functionalized material incorporated with indomethacin decreased as compared with the specific surface area and pore volume of the non-functionalized silica containing no drug, suggesting both the functionalizing agent and the drug were present in the silica. Cytotoxicity tests conducted on normal fibroblasts (GM0479A) cells attested that the silica matrix containing indomethacin was less toxic than the free drug.

  5. Mesoporous silica nanoparticles inhibit cellular respiration.

    PubMed

    Tao, Zhimin; Morrow, Matthew P; Asefa, Tewodros; Sharma, Krishna K; Duncan, Cole; Anan, Abhishek; Penefsky, Harvey S; Goodisman, Jerry; Souid, Abdul-Kader

    2008-05-01

    We studied the effect of two types of mesoporous silica nanoparticles, MCM-41 and SBA-15, on mitochondrial O 2 consumption (respiration) in HL-60 (myeloid) cells, Jurkat (lymphoid) cells, and isolated mitochondria. SBA-15 inhibited cellular respiration at 25-500 microg/mL; the inhibition was concentration-dependent and time-dependent. The cellular ATP profile paralleled that of respiration. MCM-41 had no noticeable effect on respiration rate. In cells depleted of metabolic fuels, 50 microg/mL SBA-15 delayed the onset of glucose-supported respiration by 12 min and 200 microg/mL SBA-15 by 34 min; MCM-41 also delayed the onset of glucose-supported respiration. Neither SBA-15 nor MCM-41 affected cellular glutathione. Both nanoparticles inhibited respiration of isolated mitochondria and submitochondrial particles.

  6. Silica-based mesoporous nanoparticles for controlled drug delivery

    PubMed Central

    Kwon, Sooyeon; Singh, Rajendra K; Perez, Roman A; Abou Neel, Ensanya A

    2013-01-01

    Drug molecules with lack of specificity and solubility lead patients to take high doses of the drug to achieve sufficient therapeutic effects. This is a leading cause of adverse drug reactions, particularly for drugs with narrow therapeutic window or cytotoxic chemotherapeutics. To address these problems, there are various functional biocompatible drug carriers available in the market, which can deliver therapeutic agents to the target site in a controlled manner. Among the carriers developed thus far, mesoporous materials emerged as a promising candidate that can deliver a variety of drug molecules in a controllable and sustainable manner. In particular, mesoporous silica nanoparticles are widely used as a delivery reagent because silica possesses favourable chemical properties, thermal stability and biocompatibility. Currently, sol-gel-derived mesoporous silica nanoparticles in soft conditions are of main interest due to simplicity in production and modification and the capacity to maintain function of bioactive agents. The unique mesoporous structure of silica facilitates effective loading of drugs and their subsequent controlled release. The properties of mesopores, including pore size and porosity as well as the surface properties, can be altered depending on additives used to fabricate mesoporous silica nanoparticles. Active surface enables functionalisation to modify surface properties and link therapeutic molecules. The tuneable mesopore structure and modifiable surface of mesoporous silica nanoparticle allow incorporation of various classes of drug molecules and controlled delivery to the target sites. This review aims to present the state of knowledge of currently available drug delivery system and identify properties of an ideal drug carrier for specific application, focusing on mesoporous silica nanoparticles. PMID:24020012

  7. A highly ordered cubic mesoporous silica/graphene nanocomposite

    NASA Astrophysics Data System (ADS)

    Lee, Chang-Wook; Roh, Kwang Chul; Kim, Kwang-Bum

    2013-09-01

    A highly ordered cubic mesoporous silica (KIT-6)/graphene nanocomposite and 2D KIT-6 nanoflakes were synthesized using a novel synthesis methodology. The non-ionic triblock copolymer, P123, played a dual role as a structure-directing agent in the formation of the cubic mesoporous structure and as a cross-linking agent between mesoporous silica and graphene. The prepared (KIT-6)/graphene nanocomposite could act as a template for the preparation of mesoporous material/graphene nanocomposites.A highly ordered cubic mesoporous silica (KIT-6)/graphene nanocomposite and 2D KIT-6 nanoflakes were synthesized using a novel synthesis methodology. The non-ionic triblock copolymer, P123, played a dual role as a structure-directing agent in the formation of the cubic mesoporous structure and as a cross-linking agent between mesoporous silica and graphene. The prepared (KIT-6)/graphene nanocomposite could act as a template for the preparation of mesoporous material/graphene nanocomposites. Electronic supplementary information (ESI) available: S1: TEM images of disordered mesoporous silica/graphene nanocomposite; S2: TEM images of KIT-6/GO nanocomposite; S3: Thermogravimetric analysis of KIT-6/GO and KG-400-700; S4: SEM and TEM images of KIT-6; S5: Low angle XRD, Raman spectra, N2 adsorption isotherms, pore size distribution and photographic images of the prepared samples; S6: TEM image and N2 adsorption isotherms of mesoporous carbon/graphene nanocomposite; S7: XPS C1s spectra of the prepared samples. See DOI: 10.1039/c3nr03108j

  8. Nanoindentation studies of nickel zinc ferrite embedded mesoporous silica template

    NASA Astrophysics Data System (ADS)

    Banerjee, S.; Hajra, P.; Mada, M. R.; Bandopadhyay, S.; Chakravorty, D.

    2013-02-01

    Nickel zinc ferrite (NZF) embedded mesoporous silica KIT-6 nanocomposite (NZFMS) was synthesized via impregnation method. The microstructure of the samples was characterized by transmission electron microscopy (TEM). Nanoindentation (NI) studies were carried out on both mesoporous silica (MS) and the nanocomposite NZFMS. It was found that the young's modulus (E) and hardness (H) of the NZFMS were higher than that of the MS. From creep measurement it was observed that the creep-strain rate was greater for NZFMS compared to MS. This arose due to diffusion of Fe3+ ions from nickel zinc ferrite to the silica glass. The results indicate that the NZFMS material shows superplastic behaviour at room temperature.

  9. New insight into mesoporous silica for nano metal-organic framework.

    PubMed

    Kondo, Atsushi; Takanashi, Shinji; Maeda, Kazuyuki

    2012-10-15

    A micropore- and mesopore-integrated material was synthesized by using a mesoporous silica and a metal-organic framework (MOF). The composite was composed of nano MOF crystals and mesoporous silica showing high porosity based on the intrinsic micropores of MOF and mesopores of mesoporous silica and additional pore spaces that should be from the void between nano MOF crystals. The composite shows higher adsorption rate of ethanol at 303 K than that of the bulk MOF.

  10. Magnetic mesoporous silica nanoparticles: fabrication and their laccase immobilization performance.

    PubMed

    Wang, Feng; Guo, Chen; Yang, Liang-rong; Liu, Chun-Zhao

    2010-12-01

    Newly large-pore magnetic mesoporous silica nanoparticles (MMSNPs) with wormhole framework structures were synthesized for the first time by using tetraethyl orthosilicate as the silica source and amine-terminated Jeffamine surfactants as template. Iminodiacerate was attached on these MMSNPs through a silane-coupling agent and chelated with Cu(2+). The Cu(2+)-chelated MMSNPs (MMSNPs-CPTS-IDA-Cu(2+)) showed higher adsorption capacity of 98.1 mg g(-1)-particles and activity recovery of 92.5% for laccase via metal affinity adsorption in comparison with MMSNPs via physical adsorption. The Michaelis constant (K(m)) and catalytic constant (k(cat)) of laccase immobilized on the MMSNPs-CPTS-IDA-Cu(2+) were 3.28 mM and 155.4 min(-1), respectively. Storage stability and temperature endurance of the immobilized laccase on MMSNPs-CPTS-IDA-Cu(2+) increased significantly, and the immobilized laccase retained 86.6% of its initial activity after 10 successive batch reactions operated with magnetic separation.

  11. Functionalized bimodal mesoporous silicas as carriers for controlled aspirin delivery

    SciTech Connect

    Gao Lin; Sun Jihong; Li Yuzhen

    2011-08-15

    The bimodal mesoporous silica modified with 3-aminopropyltriethoxysilane was performed as the aspirin carrier. The samples' structure, drug loading and release profiles were characterized with X-ray diffraction, scanning electron microscopy, N{sub 2} adsorption and desorption, Fourier transform infrared spectroscopy, TG analysis, elemental analysis and UV-spectrophotometer. For further exploring the effects of the bimodal mesopores on the drug delivery behavior, the unimodal mesoporous material MCM-41 was also modified as the aspirin carrier. Meantime, Korsmeyer-Peppas equation f{sub t}=kt{sup n} was employed to analyze the dissolution data in details. It is indicated that the bimodal mesopores are beneficial for unrestricted drug molecules diffusing and therefore lead to a higher loading and faster releasing than that of MCM-41. The results show that the aspirin delivery properties are influenced considerably by the mesoporous matrix, whereas the large pore of bimodal mesoporous silica is the key point for the improved controlled-release properties. - Graphical abstract: Loading (A) and release profiles (B) of aspirin in N-BMMs and N-MCM-41 indicated that BMMs have more drug loading capacity and faster release rate than that MCM-41. Highlights: > Bimodal mesoporous silicas (BMMs) and MCM-41 modified with amino group via post-treatment procedure. > Loading and release profiles of aspirin in modified BMMs and MCM-41. > Modified BMMs have more drug loading capacity and faster release rate than that modified MCM-41.

  12. Photoluminescence of carbon dots from mesoporous silica

    NASA Astrophysics Data System (ADS)

    Nelson, D. K.; Razbirin, B. S.; Starukhin, A. N.; Eurov, D. A.; Kurdyukov, D. A.; Stovpiaga, E. Yu; Golubev, V. G.

    2016-09-01

    Photophysical properties of carbon dots were investigated under various excitation conditions and over a wide temperature region - from room to liquid helium temperatures. The carbon dots (CDs) were synthesized using mesoporous silica particles as a reactor and (3-aminopropyl)triethoxysilane (APTES) as a precursor. The photoluminescence spectra of CDs exhibit a strong dependence on the excitation wavelength and demonstrate a significant inhomogeneous broadening. Lowering sample temperature reveals the doublet structure of the spectra, which is associated with the vibronic structure of radiative transitions. The vibration energy ∼1200 cm-1 is close to the energy of Csbnd O stretching vibration. Long-lived phosphorescence of carbon dots with its decay time ∼0.2 s at T = 80 K was observed. The fluorescence and phosphorescence spectra are shown to be spectrally separated. The long-lived component of the emission was ascribed to optically forbidden triplet-singlet transitions. The value of the singlet-triplet splitting was found to be about 0.3 eV. Photo-induced polarization of the luminescence of carbon dots was revealed. The degree of the linear polarization is dependent on the wavelengths of both excitation and emitted light. The effect indicates a hidden anisotropy of optical dipole transitions in the dots and demonstrates the loss of the dipole orientation during the electron energy relaxation.

  13. Controlled drug release from bifunctionalized mesoporous silica

    SciTech Connect

    Xu Wujun; Gao Qiang; Xu Yao Wu Dong; Sun Yuhan; Shen Wanling; Deng Feng

    2008-10-15

    Serial of trimethylsilyl-carboxyl bifunctionalized SBA-15 (TMS/COOH/SBA-15) have been studied as carriers for controlled release of drug famotidine (Famo). To load Famo with large capacity, SBA-15 with high content of carboxyl groups was successfully synthesized by one-pot synthesis under the assistance of KCl. The mesostructure of carboxyl functionalized SBA-15 (COOH/SBA-15) could still be kept even though the content of carboxyl groups was up to 57.2%. Increasing carboxyl content could effectively enhance the loading capacity of Famo. Compared with pure SBA-15, into which Famo could be hardly adsorbed, the largest drug loading capacity of COOH/SBA-15 could achieve 396.9 mg/g. The release of Famo from mesoporous silica was studied in simulated intestine fluid (SIF, pH=7.4). For COOH/SBA-15, the release rate of Famo decreased with narrowing pore size. After grafting TMS groups on the surface of COOH/SBA-15 with hexamethyldisilazane, the release of Famo was greatly delayed with the increasing content of TMS groups. - Graphical abstract: Trimethylsilyl-carboxyl bifunctionalized SBA-15 has been studied as carrier for controlled release of drug famotidine. To load drug with large capacity, SBA-15 with high content of carboxyl groups was successfully synthesized. After grafting trimethylsilyl groups on the surface of carboxyl functionalized SBA-15, the release of Famo was greatly delayed with the increasing content of TMS groups.

  14. Ti containing mesoporous silica submicrometer-sphere, with tunable particle size for styrene oxidation

    NASA Astrophysics Data System (ADS)

    Wang, Jingjing; Lu, Jinming; Yang, Jianhua; Chen, Rui; Zhang, Yan; Yin, Dehong; Wang, Jinqu

    2013-10-01

    Ti-containing mesoporous silica materials with size-tunable mesopores and isolated tetrahedrally coordinated Ti species have widely applications in bulk molecular catalysis. Herein, mesoporous titanium silica submicrometer-spheres (Ti-MSSs) with tunable outer particle diameter were synthesized based on developed Stober method using nonionic surfactant P123 as particle dispersing agent at room temperature. P123 molecular assembled structures will interact with silica species through interface hydrogen bond leading to the formation of tunable sized particles. The particle size was controlled ranging from 400 to 80 nm by adjusting the P123 concentration. The influence of Ti-MSSs particle size on the oxidation of styrene with aqueous H2O2 as oxidant was investigated in detail. Ti-MSSs showed better catalytical performance compared to mesoporous titanium silica large particles. Moreover, the catalyst activity increased with decrease in particle size of Ti-MSSs. Nano-sized Ti-MSSs of about 80 nm demonstrated the optimized performance for styrene oxidation with styrene conversion 44.7%, benzaldehyde selectivity 82.2% and styrene oxide 17.7% while the reaction time was 6 h.

  15. Mesoporous silica nanoparticles in target drug delivery system: A review

    PubMed Central

    Bharti, Charu; Nagaich, Upendra; Pal, Ashok Kumar; Gulati, Neha

    2015-01-01

    Due to lack of specification and solubility of drug molecules, patients have to take high doses of the drug to achieve the desired therapeutic effects for the treatment of diseases. To solve these problems, there are various drug carriers present in the pharmaceuticals, which can used to deliver therapeutic agents to the target site in the body. Mesoporous silica materials become known as a promising candidate that can overcome above problems and produce effects in a controllable and sustainable manner. In particular, mesoporous silica nanoparticles (MSNs) are widely used as a delivery reagent because silica possesses favorable chemical properties, thermal stability, and biocompatibility. The unique mesoporous structure of silica facilitates effective loading of drugs and their subsequent controlled release of the target site. The properties of mesoporous, including pore size, high drug loading, and porosity as well as the surface properties, can be altered depending on additives used to prepare MSNs. Active surface enables functionalization to changed surface properties and link therapeutic molecules. They are used as widely in the field of diagnosis, target drug delivery, bio-sensing, cellular uptake, etc., in the bio-medical field. This review aims to present the state of knowledge of silica containing mesoporous nanoparticles and specific application in various biomedical fields. PMID:26258053

  16. Enzyme catalytic membrane based on a hybrid mesoporous membrane.

    PubMed

    Fu, Wensheng; Yamaguchi, Akira; Kaneda, Hideaki; Teramae, Norio

    2008-02-21

    Immobilization of glucose oxidase (GOD) within a hybrid mesoporous membrane with 12 nm pore diameter was successfully achieved, resulting in catalytically high efficiency during flow of a glucose solution across the membrane. PMID:18253526

  17. Preparation, characterization, and catalytic performance of Ta-HMS mesoporous molecular sieve

    NASA Astrophysics Data System (ADS)

    Li, Xuefeng; Zhang, Like; Gao, Huanxin; Chen, Qingling

    2016-08-01

    Various Ta-HMS (hexagonal mesoporous silica) samples with different Ta content were hydrothermally prepared and characterized by XRD, N2-adsorption, ICP-AES, FTIR, and UV-Vis spectroscopy. The catalytic performance of the samples was also evaluated in the epoxidation of cyclohexene with cumene hydroperoxide as oxidant. The regularity of mesoporous structure decreases while more extraframe Ta ions are formed with increasing the Ta content. Ta-HMS with Ta/Si ratio of 0.015 shows the highest conversion and selectivity in the studied epoxidation reaction. The catalyst can be used for three times without significant activity loss.

  18. Unusual reinforcement of silicone rubber compounds containing mesoporous silica particles as inorganic fillers.

    PubMed

    Suzuki, Norihiro; Kiba, Shosuke; Kamachi, Yuichiro; Miyamoto, Nobuyoshi; Yamauchi, Yusuke

    2012-03-14

    We fabricate mesoporous silica/silicone composites in a simple way and systematically examine their thermal stability, swelling characteristic, mechanical strength, and transparency. Simple calculations show that more than 90 vol% of mesopores are filled with silicone rubbers. Compared to non-porous silica/silicone composites, mesoporous silica/silicone composites showed a lower coefficient of linear thermal expansion (CTE). In addition, dramatic improvements of the tensile strength and Young's modulus are obtained with mesoporous silica/silicone composites. Furthermore, mesoporous silica/silicone composites show higher transparency than non-porous silica/silicone composites.

  19. Functionalized mesoporous silica materials for molsidomine adsorption: Thermodynamic study

    SciTech Connect

    Alyoshina, Nonna A.; Parfenyuk, Elena V.

    2013-09-15

    A series of unmodified and organically modified mesoporous silica materials was prepared. The unmodified mesoporous silica was synthesized via sol–gel synthesis in the presence of D-glucose as pore-forming agent. The functionalized by phenyl, aminopropyl and mercaptopropyl groups silica materials were prepared via grafting. The fabricated adsorbent materials were characterized by Fourier transform infrared spectroscopy (FTIR) analysis, N{sub 2} adsorption/desorption and elemental analysis methods. Then their adsorption properties for mesoionic dug molsidomine were investigated at 290–313 K and physiological pH value. Thermodynamic parameters of molsidomine adsorption on the synthesized materials have been calculated. The obtained results showed that the adsorption process of molsidomine on the phenyl modified silica is the most quantitatively and energetically favorable. The unmodified and mercaptopropyl modified silica materials exhibit significantly higher adsorption capacities and energies for molsidomine than the aminopropyl modified sample. The effects are discussed from the viewpoint of nature of specific interactions responsible for the adsorption. - Graphical abstract: Comparative analysis of the thermodynamic characteristics of molsidomine adsorption showed that the adsorption process on mesoporous silica materials is controlled by chemical nature of surface functional groups. Molsidomine adsorption on the phenyl modified silica is the most quantitatively and energetically favorable. Taking into account ambiguous nature of mesoionic compounds, it was found that molsidomine is rather aromatic than dipolar. Display Omitted - Highlights: • Unmodified and organically modified mesoporous silica materials were prepared. • Molsidomine adsorption on the silica materials was studied. • Phenyl modified silica shows the highest adsorption capacity and favorable energy. • Molsidomine exhibits the lowest affinity to aminopropyl modified silica.

  20. Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

    SciTech Connect

    Eedugurala, Naresh; Wang, Zhuoran; Chaudhary, Umesh; Nelson, Nicholas; Kandel, Kapil; Kobayashi, Takeshi; Slowing, Igor I.; Pruski, Marek; Sadow, Aaron D.

    2015-11-04

    The hydroboration of aldehydes and ketones using a silica-supported zirconium catalyst is reported. Reaction of Zr(NMe2)4 and mesoporous silica nanoparticles (MSN) provides the catalytic material Zr(NMe2)n@MSN. Exhaustive characterization of Zr(NMe2)n@MSN with solid-state (SS)NMR and infrared spectroscopy, as well as through reactivity studies, suggests its surface structure is primarily ≡SiOZr(NMe2)3. The presence of these nitrogen-containing zirconium sites is supported by 15N NMR spectroscopy, including natural abundance 15N NMR measurements using dynamic nuclear polarization (DNP) SSNMR. The Zr(NMe2)n@MSN material reacts with pinacolborane (HBpin) to provide Me2NBpin and the material ZrH/Bpin@MSN that is composed of interacting surface-bonded zirconium hydride and surface-bonded borane ≡SiOBpin moieties in an approximately 1:1 ratio, as well as zirconium sites coordinated by dimethylamine. The ZrH/Bpin@MSN is characterized by 1H/2H and 11B SSNMR and infrared spectroscopy and through its reactivity with D2. The zirconium hydride material or the zirconium amide precursor Zr(NMe2)n@MSN catalyzes the selective hydroboration of aldehydes and ketones with HBpin in the presence of functional groups that are often reduced under hydroboration conditions or are sensitive to metal hydrides, including olefins, alkynes, nitro groups, halides, and ethers. Remarkably, this catalytic material may be recycled without loss of activity at least eight times, and air-exposed materials are catalytically active. These supported zirconium centers are robust catalytic sites for carbonyl reduction and that surface-supported, catalytically reactive zirconium hydride may be generated from zirconium-amide or zirconium alkoxide sites.

  1. Mesoporous-silica films, fibers, and powders by evaporation

    DOEpatents

    Bruinsma, Paul J.; Baskaran, Suresh; Bontha, Jagannadha R.; Liu, Jun

    1999-01-01

    This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s).

  2. Mesoporous-silica films, fibers, and powders by evaporation

    DOEpatents

    Bruinsma, Paul J.; Baskaran, Suresh; Bontha, Jagannadha R.; Liu, Jun

    2008-05-06

    This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s).

  3. Mesoporous-silica films, fibers, and powders by evaporation

    DOEpatents

    Bruinsma, P.J.; Baskaran, S.; Bontha, J.R.; Liu, J.

    1999-07-13

    This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s). 24 figs.

  4. Thermally stable Pt/mesoporous silica core-shell nanocatalysts for high-temperature reactions.

    PubMed

    Joo, Sang Hoon; Park, Jeong Young; Tsung, Chia-Kuang; Yamada, Yusuke; Yang, Peidong; Somorjai, Gabor A

    2009-02-01

    Recent advances in colloidal synthesis enabled the precise control of the size, shape and composition of catalytic metal nanoparticles, enabling their use as model catalysts for systematic investigations of the atomic-scale properties affecting catalytic activity and selectivity. The organic capping agents stabilizing colloidal nanoparticles, however, often limit their application in high-temperature catalytic reactions. Here, we report the design of a high-temperature-stable model catalytic system that consists of a Pt metal core coated with a mesoporous silica shell (Pt@mSiO(2)). Inorganic silica shells encaged the Pt cores up to 750 degrees C in air and the mesopores providing direct access to the Pt core made the Pt@mSiO(2) nanoparticles as catalytically active as bare Pt metal for ethylene hydrogenation and CO oxidation. The high thermal stability of Pt@mSiO(2) nanoparticles enabled high-temperature CO oxidation studies, including ignition behaviour, which was not possible for bare Pt nanoparticles because of their deformation or aggregation. The results suggest that the Pt@mSiO(2) nanoparticles are excellent nanocatalytic systems for high-temperature catalytic reactions or surface chemical processes, and the design concept used in the Pt@mSiO(2) core-shell catalyst can be extended to other metal/metal oxide compositions. PMID:19029893

  5. Thermally Stable Nanocatalyst for High Temperature Reactions: Pt-Mesoporous Silica Core-Shell Nanoparticles

    SciTech Connect

    Joo, Sang Hoon; Park, J.Y.; Tsung, C.-K.; Yamada, Y.; Yang, P.; Somorjai, G.A.

    2008-10-25

    Recent advances in colloidal synthesis enabled the precise control of size, shape and composition of catalytic metal nanoparticles, allowing their use as model catalysts for systematic investigations of the atomic-scale properties affecting catalytic activity and selectivity. The organic capping agents stabilizing colloidal nanoparticles, however, often limit their application in high-temperature catalytic reactions. Here we report the design of a high-temperature stable model catalytic system that consists of Pt metal core coated with a mesoporous silica shell (Pt{at}mSiO{sub 2}). While inorganic silica shells encaged the Pt cores up to 750 C in air, the mesopores directly accessible to Pt cores made the Pt{at}mSiO{sub 2} nanoparticles as catalytically active as bare Pt metal for ethylene hydrogenation and CO oxidation. The high thermal stability of Pt{at}mSiO{sub 2} nanoparticles permitted high-temperature CO oxidation studies, including ignition behavior, which was not possible for bare Pt nanoparticles because of their deformation or aggregation. The results suggest that the Pt{at}mSiO{sub 2} nanoparticles are excellent nanocatalytic systems for high-temperature catalytic reactions or surface chemical processes, and the design concept employed in the Pt{at}mSiO{sub 2} core-shell catalyst can be extended to other metal-metal oxide compositions.

  6. Sulfonated mesoporous silica-carbon composites and their use as solid acid catalysts

    NASA Astrophysics Data System (ADS)

    Valle-Vigón, Patricia; Sevilla, Marta; Fuertes, Antonio B.

    2012-11-01

    The synthesis of highly functionalized porous silica-carbon composites made up of sulfonic groups attached to a carbon layer coating the pores of three types of mesostructured silica (i.e. SBA-15, KIT-6 and mesocellular silica) is presented. The synthesis procedure involves the following steps: (a) removal of the surfactant, (b) impregnation of the silica pores with a carbon precursor, (c) carbonization and (d) sulfonation. The resulting silica-carbon composites contain ˜30 wt % of carbonaceous matter with a high density of acidic groups attached to the deposited carbon (i.e.sbnd SO3H, sbnd COOH and sbnd OH). The structural characteristics of the parent silica are retained in the composite materials, which exhibit a high surface area, a large pore volume and a well-ordered porosity made up uniform mesopores. The high density of the sulfonic groups in combination with the mesoporous structure of the composites ensures that a large number of active sites are easily accessible to reactants. These sulfonated silica-carbon composites behave as eco-friendly, active, selective, water tolerant and recyclable solid acids. In this study we demonstrate the usefulness of these composites as solid acid catalysts for the esterification of maleic anhydride, succinic acid and oleic acid with ethanol. These composites exhibit a superior intrinsic catalytic activity to other commercial solid acids such as Amberlyst-15.

  7. Synthesis of mesoporous carbons using ordered and disordered mesoporous silica templates and polyacrylonitrile as carbon precursor.

    PubMed

    Kruk, Michal; Dufour, Bruno; Celer, Ewa B; Kowalewski, Tomasz; Jaroniec, Mietek; Matyjaszewski, Krzysztof

    2005-05-19

    Mesoporous carbons were synthesized from polyacrylonitrile (PAN) using ordered and disordered mesoporous silica templates and were characterized using transmission electron microscopy (TEM), powder X-ray diffraction, nitrogen adsorption, and thermogravimetry. The pores of the silica templates were infiltrated with carbon precursor (PAN) via polymerization of acrylonitrile from initiation sites chemically bonded to the silica surface. This polymerization method is expected to allow for a uniform filling of the template with PAN and to minimize the introduction of nontemplated PAN, thus mitigating the formation of nontemplated carbon. PAN was stabilized by heating to 573 K under air and carbonized under N2 at 1073 K. The resulting carbons exhibited high total pore volumes (1.5-1.8 cm3 g(-1)), with a primary contribution of the mesopore volume and with relatively low microporosity. The carbons synthesized using mesoporous templates with a 2-dimensional hexagonal structure (SBA-15 silica) and a face-centered cubic structure (FDU-1 silica) exhibited narrow pore size distributions (PSDs), whereas the carbon synthesized using disordered silica gel template had broader PSD. TEM showed that the SBA-15-templated carbon was composed of arrays of long, straight, or curved nanorods aligned in 2-D hexagonal arrays. The carbon replica of FDU-1 silica appeared to be composed of ordered arrays of spheres. XRD provided evidence of some degree of ordering of graphene sheets in the carbon frameworks. Elemental analysis showed that the carbons contain an appreciable amount of nitrogen. The use of our novel infiltration method and PAN as a carbon precursor allowed us to obtain ordered mesoporous carbons (OMCs) with (i) very high mesopore volume, (ii) low microporosity, (iii) low secondary mesoporosity, (iv) large pore diameter (8-12 nm), and (v) semi-graphitic framework, which represent a desirable combination of features that has not been realized before for OMCs. PMID:16852101

  8. Enhanced retention of aqueous transition metals in mesoporous silica

    NASA Astrophysics Data System (ADS)

    Nelson, J.; Bargar, J.; Brown, G. E.; Maher, K.

    2013-12-01

    Mesoporosity (2-50 nm diameter pores) is abundant within grain coatings and primary silicate minerals in natural environments. Mesopores often contribute significantly to total specific surface area and act as gateways for the transport of subsurface solutes, including nutrients and contaminants, between mineral surfaces and ambient fluids. However, the physiochemical mechanisms of sorption and transport within mesopores cannot be assumed to be the same as for macropores (>50 nm), because of confinement-induced changes in water properties, the structure of electrical double layers, solvation shells and dehydration rates of aquo ions, and the charge and reactive site densities of mineral surfaces. Despite the ubiquity of confined spaces in natural and industrial porous media, few studies have examined the molecular-scale mechanisms and geochemical reactions controlling meso-confinement phenomena in environmentally relevant materials. We conducted batch Zn sorption experiments using synthetic, controlled pore-size (i.e., 7.5-300 nm), metal-oxide beads as model geologic substrates. Comparison of Zn adsorbed onto macroporous and mesoporous silica beads indicates Zn adsorption capacity is increased in mesopores when normalized to surface area. In the presence of a background electrolyte (i.e., NaCl), Zn sorption capacity to macroporous silica is reduced; however, no significant difference in Zn sorption capacity on mesoporous silica was observed between the presence and absence of a background electrolyte. The effect of competing cations is indirect evidence that mesopores promote inner-sphere complexation and reduce outer-sphere complexation. EXAFS characterization of adsorbed zinc to macroporous silica matches that reported for low Zn coverages on silica (Roberts et al., JCIS, 2003), whereas a different spectrum is observed for the mesoporous case. Shell-by-shell fitting indicates that Zn is dominantly in octahedral coordination in macropores, as opposed to

  9. Incorporation of terbium(III) ion into mesoporous silica particles

    NASA Astrophysics Data System (ADS)

    Kataoka, Takuya; Wang, Liyin; Kobayashi, Kouhei; Nishikawa, Masami; Tagaya, Motohiro

    2016-10-01

    Terbium(III)-doped mesoporous silicas were synthesized, and the states of terbium ions in the silica frameworks were investigated. The mesopores were preserved upon doping at terbium ion molar concentrations relative to (Si+Tb) up to 15 mol %, indicating the interaction of terbium ions with Si-O bonds. Significant morphological changes of the particles were observed with increasing the doping concentration. The shapes of the photoluminescence spectra due to the transitions of 5D4 → 7F6 and 5D4 → 7F5 were indicative of the presence of terbium ions in the silica matrix, and the quantum efficiency (2.1-2.8%) and lifetime (1.6-1.9 ms) decreased with increasing the doping concentration up to 15 mol %. Therefore, the terbium ions are considered to be located inside the amorphous silica frameworks, where they electrostatically interact with the O atoms of silanol and siloxane groups.

  10. Microwave assisted N-alkylation of amine functionalized crystal-like mesoporous phenylene-silica.

    PubMed

    Lourenço, Mirtha A O; Siegel, Renée; Mafra, Luís; Ferreira, Paula

    2013-04-28

    N-alkylation reaction of amine functionalized phenylene moieties in crystal-like mesoporous silica is successfully achieved with about 87% of conversion in two reaction cycles. A potassium iodide catalyzed method commonly used for the selective N-monoalkylation of aniline is adapted and optimized to the N-monoalkylation reactions of the amine functionalized periodic mesoporous phenylene-silica (NH2-PMO) under microwave irradiation with preservation of the ordered mesostructure and of the crystal-like molecular scale periodicity of the material. This functionalization opens an avenue for the preparation of new materials with different amino-alkyl groups specially designed for a desired application, namely on the adsorption or catalytic fields.

  11. The synthesis and application of two mesoporous silica nanoparticles as drug delivery system with different shape

    NASA Astrophysics Data System (ADS)

    Wang, Jiayi; Wang, Zhuyuan; Chen, Hui; Zong, Shenfei; Cui, Yiping

    2015-05-01

    Mesoporous silica nanospheres(MSNSs) have been obtained utilizing the conventional reverse micelles synthesis method while the mesoporous silica nanorods(MSNRs) have been acquired by means of changing certain parameters. Afterwards, the prepared mesoporous silica nanospheres and nanorods were used as drug carriers to load and release the classical cancer therapeutic drug—DOX. According to the absorption spectra, the encapsulation efficiency of the mesoporous silica nanospheres is almost as high as that of the nanospheres. Different from the familiar encapsulation efficiency, the release characteristic curves of the mesoporous silica nanospheres and nanorods possessed certain differences during the release process. Finally incellular fluorescence imaging was achieved to observe the endocytosis of the mesoporous silica materials. Our results show that although both of the two kinds of nanoparticles possess favourable properties for loading and releasing drugs, the mesoporous silica nanospheres perform better in dispersity and controlled release than the nanorods, which probably endow them the potential as incellular drug delivery system.

  12. Plutonium complexation by phosphonate-functionalized mesoporous silica

    SciTech Connect

    Parsons-Moss, T; Schwaiger, L K; Hubaud, A; Hu, Y J; Tuysuz, H; Yang, P; Balasubramanian, K; Nitsche, H

    2010-10-27

    MCM-41-type mesoporous silica functionalized with the CMPO-based 'Ac-Phos' silane has been reported in the literature (1) to show good capacity as an acftinide sorbent material, with potential applications in environmental sequestration, aqueous waste separation and/or vitrification, and chemical sensing of actinides in solution. The study explores the complexation of Pu(IV and VI) and other selected actinides and lanthanides by SBA-15 type mesoporous silica functionalized with Ac-Phos. The Pu binding kinetics and binding capacity were determined for both the Ac-Phos functionalized and unmodified SBA-15. They analyzed the binding geometry and redox behavior of Pu(VI) by X-ray absorption spectroscopy (XAS). They discuss the synthesis and characterization of the functionalized mesoporous material, batch sorption experiments, and the detailed analyses of the actinide complexes that are formed. Structural measurements are paired with high-level quantum mechanical modeling to elucidate the binding mechanisms.

  13. Adsorption of mycotoxins in beverages onto functionalized mesoporous silicas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mycotoxins, natural toxins produced by fungi, are a global concern as contaminates of agricultural commodities. Exposure to these toxins can be reduced by the use of binding materials. Templated mesoporous silicas are promising materials with favorable adsorptive properties for dyes, ions, and toxin...

  14. Synthesis and catalytic applications of combined zeolitic/mesoporous materials

    PubMed Central

    Vernimmen, Jarian; Cool, Pegie

    2011-01-01

    Summary In the last decade, research concerning nanoporous siliceous materials has been focused on mesoporous materials with intrinsic zeolitic features. These materials are thought to be superior, because they are able to combine (i) the enhanced diffusion and accessibility for larger molecules and viscous fluids typical of mesoporous materials with (ii) the remarkable stability, catalytic activity and selectivity of zeolites. This review gives an overview of the state of the art concerning combined zeolitic/mesoporous materials. Focus is put on the synthesis and the applications of the combined zeolitic/mesoporous materials. The different synthesis approaches and formation mechanisms leading to these materials are comprehensively discussed and compared. Moreover, Ti-containing nanoporous materials as redox catalysts are discussed to illustrate a potential implementation of combined zeolitic/mesoporous materials. PMID:22259762

  15. Functionalized mesoporous silica nanoparticles for oral delivery of budesonide

    SciTech Connect

    Yoncheva, K.; Popova, M.; Szegedi, A.; Mihaly, J.; Tzankov, B.; Lambov, N.; Konstantinov, S.; Tzankova, V.; Pessina, F.; Valoti, M.

    2014-03-15

    Non-functionalized and amino-functionalized mesoporous silica nanoparticle were loaded with anti-inflammatory drug budesonide and additionally post-coated with bioadhesive polymer (carbopol). TEM images showed spherical shape of the nanoparticles and slightly higher polydispersity after coating with carbopol. Nitrogen physisorption and thermogravimetic analysis revealed that more efficient loading and incorporation into the pores of nanoparticles was achieved with the amino-functionalized silica carrier. Infrared spectra indicated that the post-coating of these nanoparticles with carbopol led to the formation of bond between amino groups of the functionalized carrier and carboxyl groups of carbopol. The combination of amino-functionalization of the carrier with the post-coating of the nanoparticles sustained budesonide release. Further, an in vitro model of inflammatory bowel disease showed that the cytoprotective effect of budesonide loaded in the post-coated silica nanoparticles on damaged HT-29 cells was more pronounced compared to the cytoprotection obtained with pure budesonide. -- Graphical abstract: Silica mesoporous MCM-41 particles were amino-functionalized, loaded with budesonide and post-coated with bioadhesive polymer (carbopol) in order to achieve prolonged residence of anti-inflammatory drug in GIT. Highlights: • Higher drug loading in amino-functionalized mesoporous silica. • Amino-functionalization and post-coating of the nanoparticles sustained drug release. • Achievement of higher cytoprotective effect with drug loaded into the nanoparticles.

  16. Surface properties of mesoporous carbon-silica gel adsorbents

    SciTech Connect

    Leboda, R.; Turov, V.V.; Charmas, B.; Skubiszewska-Zieba, J.; Gun'ko, V.M.

    2000-03-01

    Carbon/silica (carbosil) samples prepared utilizing mesoporous silica gel (Si-60) modified by methylene chloride pyrolysis were studied by nitrogen adsorption, quasi-isothermal thermogravimetry, p-nitrophenol adsorption from aqueous solution, and {sup 1}H NMR methods. The structural characteristics and other properties of carbosils depend markedly on the synthetic conditions and the amount of carbon deposited. The changes in the pore size distribution with increasing carbon concentration suggest grafting of carbon mainly in pores, leading to diminution of the mesopore radii. However, heating pure silica gel at the pyrolysis temperature of 550 C leads to an increase in the pore radii. The quasi-isothermal thermogravimetry and {sup 1}H NMR spectroscopy methods used to investigate the water layers on carbosils showed a significant capability of carbosils to adsorb water despite a relatively large content of the hydrophobic carbon deposit, which represents a nonuniform layer incompletely covering the oxide surface.

  17. Diamine Functionalized Cubic Mesoporous Silica for Ibuprofen Controlled Delivery.

    PubMed

    Sivaguru, J; Selvaraj, M; Ravi, S; Park, H; Song, C W; Chun, H H; Ha, C-S

    2015-07-01

    A diamine functionalized cubic mesostructured KIT-6 (N-KIT-6) has been prepared by post-synthetic method using calcined mesoporous KIT-6 with a diamine source, i.e., N-'[3-(tri methoxysilyl)- propyl]'ethylenediamine. The KIT-6 mesoporous silica used for N-KIT-6 was synthesized under weak acidic hydrothermal method using bitemplates, viz., Pluronic P123 and 1-butanol. The synthesized mesoporous materials, KIT-6 and N-KIT-6, have been characterized by the relevant instrumental techniques such as SAXS, N2 sorption isotherm, FT-IR, SEM, TEM and TGA to prove the standard mesoporous materials with the identification of diamine groups. The characterized mesoporous materials, KIT-6 and N-KIT-6, have been extensively used in the potential application of controlled drug delivery, where ibuprofen (IBU) employed as a model drug. The rate of IBU adsorption and release was monitored by UV vis-spectrometer. On the basis of the experimental results of controlled drug delivery system, the results of IBU adsorption and releasing rate in N-KIT-6 are higher than those of KIT-6 because of the higher hydrophobic nature as well as rich basic sites on the surface of inner pore wall silica.

  18. Rapid synthesis of ordered hexagonal mesoporous silica and their incorporation with Ag nanoparticles by solution plasma

    SciTech Connect

    Pootawang, Panuphong; Saito, Nagahiro; Takai, Osamu; Lee, Sang Yul

    2012-10-15

    Graphical abstract: Overall reactions of mesoporous silica and AgNPs-incorporated mesoporous silica syntheses by solution plasma process (SPP). Highlights: ► SPP for rapid synthesis of mesoporous silica. ► SPP for rapid synthesis of mesoporous silica and AgNPs incorporation. ► Higher surface area and larger pore diameter of mesoporous silica synthesized by SPP. -- Abstract: Rapid synthesis of silica with ordered hexagonal mesopore arrangement was obtained using solution plasma process (SPP) by discharging the mixture of P123 triblock copolymer/TEOS in acid solution. SPP, moreover, was utilized for Ag nanoparticles (AgNPs) incorporation in silica framework as one-batch process using silver nitrate (AgNO{sub 3}) solution as precursor. The turbid silicate gel was clearly observed after discharge for 1 min and the white precipitate formed at 3 min. The mesopore with hexagonal arrangement and AgNPs were observed in mesoporous silica. Two regions of X-ray diffraction patterns (2θ < 2° and 2θ = 35–90°) corresponded to the mesoporous silica and Ag nanocrystal characteristics. Comparing with mesoporous silica prepared by a conventional sol–gel route, surface area and pore diameter of mesoporous silica prepared by solution plasma were observed to be larger. In addition, the increase in Ag loading resulted in the decrease in surface area with insignificant variation in the pore diameter of mesoporous silica. SPP could be successfully utilized not only to enhance gelation time but also to increase surface area and pore diameter of mesoporous silica.

  19. Thin-Layer Polymer Wrapped Enzymes Encapsulated in Hierarchically Mesoporous Silica with High Activity and Enhanced Stability

    NASA Astrophysics Data System (ADS)

    Zhang, Fang; Wang, Meitao; Liang, Chao; Jiang, Huangyong; Shen, Jian; Li, Hexing

    2014-03-01

    A novel soft-hard cooperative approach was developed to synthesize bioactive mesoporous composite by pre-wrapping Penicillin G amidase with poly(acrylaimde) nanogel skin and subsequently incorporating such Penicillin G amidase nanocapsules into hierarchically mesoporous silica. The as-received bioactive mesoporous composite exhibited comparable activity and extraordinarily high stability in comparison with native Penicillin G amidase and could be used repetitively in the water-medium hydrolysis of penicillin G potassium salt. Furthermore, this strategy could be extended to the synthesis of multifunctional bioactive mesoporous composite by simultaneously introducing glucose oxidase nanocapsules and horseradish peroxidase nanocapsules into hierarchically mesoporous silica, which demonstrated a synergic effect in one-pot tandem oxidation reaction. Improvements in the catalytic performances were attributed to the combinational unique structure from soft polymer skin and hard inorganic mesoporous silica shell, which cooperatively helped enzyme molecules to retain their appropriate geometry and simultaneously decreased the enzyme-support negative interaction and mass transfer limitation under heterogeneous conditions.

  20. Thin-Layer Polymer Wrapped Enzymes Encapsulated in Hierarchically Mesoporous Silica with High Activity and Enhanced Stability

    PubMed Central

    Zhang, Fang; Wang, Meitao; Liang, Chao; Jiang, Huangyong; Shen, Jian; Li, Hexing

    2014-01-01

    A novel soft-hard cooperative approach was developed to synthesize bioactive mesoporous composite by pre-wrapping Penicillin G amidase with poly(acrylaimde) nanogel skin and subsequently incorporating such Penicillin G amidase nanocapsules into hierarchically mesoporous silica. The as-received bioactive mesoporous composite exhibited comparable activity and extraordinarily high stability in comparison with native Penicillin G amidase and could be used repetitively in the water-medium hydrolysis of penicillin G potassium salt. Furthermore, this strategy could be extended to the synthesis of multifunctional bioactive mesoporous composite by simultaneously introducing glucose oxidase nanocapsules and horseradish peroxidase nanocapsules into hierarchically mesoporous silica, which demonstrated a synergic effect in one-pot tandem oxidation reaction. Improvements in the catalytic performances were attributed to the combinational unique structure from soft polymer skin and hard inorganic mesoporous silica shell, which cooperatively helped enzyme molecules to retain their appropriate geometry and simultaneously decreased the enzyme-support negative interaction and mass transfer limitation under heterogeneous conditions. PMID:24651701

  1. Synthesis and Characterization of Bionanoparticle-Silica Composites and Mesoporous Silica with Large Pores

    SciTech Connect

    Niu, Z.; Yang, L.; Kabisatpathy, S.; He, J.; Lee, A.; Ron, J.; Sikha, G.; Popov, B.N.; Emrick, T.; Russell, T. P.; Wang. Q.

    2009-03-24

    A sol-gel process has been developed to incorporate bionanoparticles, such as turnip yellow mosaic virus, cowpea mosaic virus, tobacco mosaic virus, and ferritin into silica, while maintaining the integrity and morphology of the particles. The structures of the resulting materials were characterized by transmission electron microscopy, small angle X-ray scattering, and N{sub 2} adsorption-desorption analysis. The results show that the shape and surface morphology of the bionanoparticles are largely preserved after being embedded into silica. After removal of the bionanoparticles by calcination, mesoporous silica with monodisperse pores, having the shape and surface morphology of the bionanoparticles replicated inside the silica, was produced,. This study is expected to lead to both functional composite materials and mesoporous silica with structurally well-defined large pores.

  2. Mesoporous Silica Nanoparticles and Films for Cargo Delivery

    NASA Astrophysics Data System (ADS)

    Guardado Alvarez, Tania Maria

    Mesoporous silica materials are well known materials that can range from films to nanoparticles. Mesoporous silica nanoparticles (MSNs) and mesoporous silica films have been of increasing interest among the scientific community for its use in cargo delivery. Silica provides ease of functionalization, a robust support and biocompatibility. Several methods have been used in order to give the mesoporous silica nanomaterials different qualities that render them a useful material with different characteristics. Among these methods is surface modification by taking advantage of the OH groups on the surface. When a molecule attached to the surface can act as a molecular machine it transforms the nanomaterial to act as delivery system that can be activated upon command. The work covered in this thesis focuses on the development and synthesis of different mesoporous silica materials for the purpose of trapping and releasing cargo molecules. Chapter 2 focuses in the photoactivation of "snap-top" stoppers over the pore openings of mesoporous silica nanoparticles that releases intact cargo molecules from the pores. The on-command release can be stimulated by either one UV photon or two coherent near-IR photons. Two-photon activation is particularly desirable for use in biological systems because it enables good tissue penetration and precise spatial control. Chapter 3 focuses on the design and synthesis of a nano-container consisting of mesoporous silica nanoparticles with the pore openings covered by "snap-top" caps that are opened by near-IR light. A photo transducer molecule that is a reducing agent in an excited electronic state is covalently attached to the system. Near IR two-photon excitation causes intermolecular electron transfer that reduces a disulfide bond holding the cap in place, thus allowing the cargo molecules to escape. The operation of the "snap-top" release mechanism by both one- and two photon is described. This system presents a proof of concept of a near

  3. Surfactant-free synthesis of mesoporous and hollow silica nanoparticles with an inorganic template.

    PubMed

    Baù, Luca; Bártová, Barbora; Arduini, Maria; Mancin, Fabrizio

    2009-12-28

    A surfactant-free synthesis of mesoporous and hollow silica nanoparticles is reported in which boron acts as the templating agent. Using such a simple and mild procedure as a treatment with water, the boron-rich phase is selectively removed, affording mesoporous pure silica nanoparticles with wormhole-like pores or, depending on the synthetic conditions, silica nanoshells.

  4. Chemoradiotherapeutic wrinkled mesoporous silica nanoparticles for use in cancer therapy

    SciTech Connect

    Munaweera, Imalka; Balkus, Kenneth J. Jr. E-mail: Anthony.DiPasqua@unthsc.edu; Koneru, Bhuvaneswari; Shi, Yi; Di Pasqua, Anthony J. E-mail: Anthony.DiPasqua@unthsc.edu

    2014-11-01

    Over the last decade, the development and application of nanotechnology in cancer detection, diagnosis, and therapy have been widely reported. Engineering of vehicles for the simultaneous delivery of chemo- and radiotherapeutics increases the effectiveness of the therapy and reduces the dosage of each individual drug required to produce an observable therapeutic response. We here developed a novel chemoradiotherapeutic 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid coated/uncoated platinum drug loaded, holmium-containing, wrinkled mesoporous silica nanoparticle. The materials were characterized with TEM, FTIR, {sup 1}H NMR, energy dispersive x-ray, inductively coupled plasma-mass spectrometry, and zeta potential measurements. In vitro platinum drug release from both lipid coated and uncoated chemoradiotherapeutic wrinkled mesoporous silica are reported. Various kinetic models were used to analyze the release kinetics. The radioactivity of the chemoradiotherapeutic nanocarriers was measured after neutron-activation.

  5. Chemoradiotherapeutic wrinkled mesoporous silica nanoparticles for use in cancer therapy

    NASA Astrophysics Data System (ADS)

    Munaweera, Imalka; Koneru, Bhuvaneswari; Shi, Yi; Di Pasqua, Anthony J.; Balkus, Kenneth J., Jr.

    2014-11-01

    Over the last decade, the development and application of nanotechnology in cancer detection, diagnosis, and therapy have been widely reported. Engineering of vehicles for the simultaneous delivery of chemo- and radiotherapeutics increases the effectiveness of the therapy and reduces the dosage of each individual drug required to produce an observable therapeutic response. We here developed a novel chemoradiotherapeutic 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid coated/uncoated platinum drug loaded, holmium-containing, wrinkled mesoporous silica nanoparticle. The materials were characterized with TEM, FTIR, 1H NMR, energy dispersive x-ray, inductively coupled plasma-mass spectrometry, and zeta potential measurements. In vitro platinum drug release from both lipid coated and uncoated chemoradiotherapeutic wrinkled mesoporous silica are reported. Various kinetic models were used to analyze the release kinetics. The radioactivity of the chemoradiotherapeutic nanocarriers was measured after neutron-activation.

  6. Fluorescent Functionalized Mesoporous Silica for Radioactive Material Extraction

    SciTech Connect

    Li, Juan; Zhu, Kake; Shang, Jianying; Wang, Donghai; Nie, Zimin; Guo, Ruisong; Liu, Chongxuan; Wang, Zheming; Li, Xiaolin; Liu, Jun

    2012-08-01

    Mesoporous silica with covalently bound salicylic acid molecules incorporated in the structure was synthesized with a one-pot, co-condensation reaction at room temperature. The as-synthesized material has a large surface area, uniform particle size, and an ordered pore structure as determined by characterization with transmission electron microscopy, thermal gravimetric analysis, and infrared spectra, etc. Using the strong fluorescence and metal coordination capability of salicylic acid, functionalized mesoporous silica (FMS) was developed to track and extract radionuclide contaminants, such as uranyl [U(VI)] ions encountered in subsurface environments. Adsorption measurements showed a strong affinity of the FMS toward U(VI) with a Kd value of 105 mL/g, which is four orders of magnitude higher than the adsorption of U(VI) onto most of the sediments in natural environments. The new materials have a potential for synergistic environmental monitoring and remediation of the radionuclide U(VI) from contaminated subsurface environments.

  7. Contamination-resistant silica antireflective coating with closed ordered mesopores.

    PubMed

    Sun, Jinghua; Zhang, Qinghua; Ding, Ruimin; Lv, Haibing; Yan, Hongwei; Yuan, Xiaodong; Xu, Yao

    2014-08-21

    Porous silica optical antireflective (AR) coatings prepared by traditional sol-gel method have been extensively used for high power laser systems, but a serious drawback is that contamination existing in the high vacuum is easily absorbed by the disordered open pore structure, resulting in a fast decrease in transmittance. To improve the stability of transmittance in vacuum, a contamination-resistant silica AR coating with ordered mesopores completely closed by hydrophobic-oleophobic groups was successfully developed on a fused quartz substrate. The ordered mesopores in the coating were controlled under the direction of surfactant F127 via an evaporation-induced-self-assembling process and then were closed by post-grafting long chain fluoroalkylsilane. The grazing incidence small angle X-ray scattering (GISAXS) and the X-ray reflectivity (XRR) results indicated that the mesopores in the coating constructed a Fmmm orthorhombic symmetry structure with a (010) plane parallel to the substrate. Cage-like mesopores were confirmed by nitrogen adsorption-desorption analysis. The obtained coatings showed low surface roughness, excellent abrase-resistance and high transmittance of 100% on quartz substrate. Especially, the decrease of transmittance tested with polydimethylsiloxane pollution in vacuum within one-month was as small as 0.02%. The laser induced damage threshold was up to 59.8 J cm(-2) at a 12 ns laser pulse of 1053 nm wavelength. This work provides an alternative way to fabricate AR coatings with high stability. PMID:25000419

  8. Contamination-resistant silica antireflective coating with closed ordered mesopores.

    PubMed

    Sun, Jinghua; Zhang, Qinghua; Ding, Ruimin; Lv, Haibing; Yan, Hongwei; Yuan, Xiaodong; Xu, Yao

    2014-08-21

    Porous silica optical antireflective (AR) coatings prepared by traditional sol-gel method have been extensively used for high power laser systems, but a serious drawback is that contamination existing in the high vacuum is easily absorbed by the disordered open pore structure, resulting in a fast decrease in transmittance. To improve the stability of transmittance in vacuum, a contamination-resistant silica AR coating with ordered mesopores completely closed by hydrophobic-oleophobic groups was successfully developed on a fused quartz substrate. The ordered mesopores in the coating were controlled under the direction of surfactant F127 via an evaporation-induced-self-assembling process and then were closed by post-grafting long chain fluoroalkylsilane. The grazing incidence small angle X-ray scattering (GISAXS) and the X-ray reflectivity (XRR) results indicated that the mesopores in the coating constructed a Fmmm orthorhombic symmetry structure with a (010) plane parallel to the substrate. Cage-like mesopores were confirmed by nitrogen adsorption-desorption analysis. The obtained coatings showed low surface roughness, excellent abrase-resistance and high transmittance of 100% on quartz substrate. Especially, the decrease of transmittance tested with polydimethylsiloxane pollution in vacuum within one-month was as small as 0.02%. The laser induced damage threshold was up to 59.8 J cm(-2) at a 12 ns laser pulse of 1053 nm wavelength. This work provides an alternative way to fabricate AR coatings with high stability.

  9. Titanium-containing mesoporous molecular sieves for catalytic oxidation of aromatic compounds

    NASA Astrophysics Data System (ADS)

    Tanev, Peter T.; Chibwe, Malama; Pinnavaia, Thomas J.

    1994-03-01

    TITANIUM silicalite is an effective molecular-sieve catalyst for the selective oxidation of alkanes, the hydroxylation of phenol and the epoxidation of alkenes in the presence of H2O2 (refs 1-3). The range of organic compounds that can be oxidized is greatly limited, however, by the relatively small pore size (about 0.6 nm) of the host framework4. Large-pore (mesoporous) silica-based molecular sieves have been prepared recently by Kresge et all5-7 and Kuroda et al 8.; the former used a templating approach in which the formation of an inorganic mesoporous structure is assisted by self-organization of surfactants, and the latter involved topochemical rearrangement of a layered silica precursor. Here we describe the use of the templating approach to synthesize mesoporous silica-based molecular sieves partly substituted with titanium-large-pore analogues of titanium silicalite. We find that these materials show selective catalytic activity towards the oxidation of 2,6-ditert-butyl phenol to the corresponding quinone and the conversion of benzene to phenol.

  10. Adsorption behavior of natural anthocyanin dye on mesoporous silica

    NASA Astrophysics Data System (ADS)

    Kohno, Yoshiumi; Haga, Eriko; Yoda, Keiko; Shibata, Masashi; Fukuhara, Choji; Tomita, Yasumasa; Maeda, Yasuhisa; Kobayashi, Kenkichiro

    2014-01-01

    Because of its non-toxicity, naturally occurring anthocyanin is potentially suitable as a colorant for foods and cosmetics. To the wider use of the anthocyanin, the immobilization on the inorganic host for an easy handling as well as the improvement of the stability is required. This study is focused on the adsorption of significant amount of the natural anthocyanin dye onto mesoporous silica, and on the stability enhancement of the anthocyanin by the complexation. The anthocyanin has successfully been adsorbed on the HMS type mesoporous silica containing small amount of aluminum. The amount of the adsorbed anthocyanin has been increased by modifying the pore wall with n-propyl group to make the silica surface hydrophobic. The light fastness of the adsorbed anthocyanin has been improved by making the composite with the HMS samples containing aluminum, although the degree of the improvement is not so large. It has been proposed that incorporation of the anthocyanin molecule deep inside the mesopore is required for the further enhancement of the stability.

  11. Catalytic conversion of cellulose over mesoporous Y zeolite.

    PubMed

    Park, Young-Kwon; Jun, Bo Ram; Park, Sung Hoon; Jeon, Jong-Ki; Lee, See Hoon; Kim, Seong-Soo; Jeong, Kwang-Eun

    2014-07-01

    Mesoporous Y zeolite (Meso-Y) was applied, for the first time, to the catalytic pyrolysis of cellulose which is a major constituent of lignocellulosic biomass, to produce high-quality bio-oil. A representative mesoporous catalyst Al-MCM-41 was also used to compare its catalytic activity with that of Meso-Y. Pyrolysis-gas chromatography/mass spectrometry was used for the experiments. Meso-Y, with higher acidity, led to larger yields of aromatics and furans with high value-added than Al-MCM-41, resulting in the production of bio-oil with higher quality. The effect of temperature on the catalytic pyrolysis was not significant within the range of 400-500 degrees C. When the Meso-Y to cellulose ratio was increased from 1/1 via 2/1 to 3/1, the deoxygenation efficiency increased, leading to increased yield of aromatics. PMID:24757989

  12. Synthesis and structural evolution of mesoporous silica silver nanocomposites

    NASA Astrophysics Data System (ADS)

    Armelao, L.; Bottaro, G.; Campostrini, R.; Gialanella, S.; Ischia, M.; Poli, F.; Tondello, E.

    2007-04-01

    Mesoporous silica materials were prepared by a sol-gel procedure using Si(OCH2CH3)4 (TEOS) as the silica source and the non-ionic alkyl-poly(ethyleneoxide) oligomer Brij76 as the structure-directing agent. Pure inorganic hexagonal-like mesostructured SiO2 powders were obtained after annealing, performed in air between 400 and 600 °C. Upon calcination, the organic template was removed and silica networks with a different amount of Si-OH groups as well as porous features were prepared. Ag-SiO2 nanocomposites were obtained by metallation of the mesoporous silica powders with aqueous solutions of silver acetate. Ag+ ions were chemically grafted on the silica pores by taking advantage of the basic character of acetate anions and the acidic properties of Si-OH groups. Different silver concentrations were achieved on the mesostructured silica powders, depending on their former annealing treatment. For all samples the formation of silver nanoclusters occurred spontaneously at room temperature. Monodispersed, spherical Ag crystallites, with an average diameter of a few nanometres, were obtained starting from the 400 °C-treated silica, whereas clusters with different sizes (3-20 nm) and irregular shapes were grown for metallation of the 600 °C-heated SiO2 matrix. The sample's chemical composition was studied by x-ray photoelectron spectroscopy (XPS) and x-ray excited Auger electron spectroscopy (XE-AES), whereas the porous features were investigated by N2 BET adsorption. Information concerning structure and microstructure was obtained by x-ray diffraction (XRD) and transmission electron microscopy (TEM).

  13. Thermally stable polymer composites with improved transparency by using colloidal mesoporous silica nanoparticles as inorganic fillers.

    PubMed

    Suzuki, Norihiro; Zakaria, Mohamed B; Chiang, Ya-Dong; Wu, Kevin C-W; Yamauchi, Yusuke

    2012-05-28

    The colloidal mesoporous silica nanoparticles with small particle sizes (namely, CMS) are used as inorganic fillers of polymers (i.e. epoxy and silicone). From simple calculation, almost all polymers are estimated to be confined in the mesopores. To clarify the superiority of CMS over nonporous silica particles and mesoporous silica particles with much larger size (TMPS-4) as inorganic fillers, a systematic study on mechanical strength and transparency of polymer-silica nanocomposites was conducted. Compared with nonporous silica particles, similar to TMPS-4, CMS shows a greater effect on lowering the CTE. In addition, obtained polymer-CMS nanocomposites show improved transparency than polymer-TMPS-4 nanocomposites.

  14. A High Temperature Capacitive Humidity Sensor Based on Mesoporous Silica

    PubMed Central

    Wagner, Thorsten; Krotzky, Sören; Weiß, Alexander; Sauerwald, Tilman; Kohl, Claus-Dieter; Roggenbuck, Jan; Tiemann, Michael

    2011-01-01

    Capacitive sensors are the most commonly used devices for the detection of humidity because they are inexpensive and the detection mechanism is very specific for humidity. However, especially for industrial processes, there is a lack of dielectrics that are stable at high temperature (>200 °C) and under harsh conditions. We present a capacitive sensor based on mesoporous silica as the dielectric in a simple sensor design based on pressed silica pellets. Investigation of the structural stability of the porous silica under simulated operating conditions as well as the influence of the pellet production will be shown. Impedance measurements demonstrate the utility of the sensor at both low (90 °C) and high (up to 210 °C) operating temperatures. PMID:22163790

  15. Amine-functionalized magnetic mesoporous silica nanoparticles for DNA separation

    NASA Astrophysics Data System (ADS)

    Sheng, Wei; Wei, Wei; Li, Junjian; Qi, Xiaoliang; Zuo, Gancheng; Chen, Qi; Pan, Xihao; Dong, Wei

    2016-11-01

    We report a modified approach for the functionalized magnetic mesoporous silica nanoparticles (MMSN) using polymer microspheres incorporated with magnetic nanoparticles in the presence of cetyltrimethylammonium bromide (CTAB) and the core-shell magnetic silica nanoparticles (MSN). These particles were functionalized with amino groups via the addition of aminosilane directly to the particle sol. We then evaluate their DNA separation abilities and find the capacity of DNA binding significantly increased (210.22 μg/mg) compared with normal magnetic silica spheres (138.44 μg/mg) by using an ultraviolet and visible spectrophotometer (UV). The morphologies, magnetic properties, particle size, pore size, core-shell structure and Zeta potential are characterized by Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), Transmission electron microscopy (TEM), Powder X-ray diffraction (XRD), and dynamic light scattering (DLS). This work demonstrates that our MMSN own an excellent potential application in bioseparation and drug delivery.

  16. Polyoxomolybdate-stabilized Ru(0) nanoparticles deposited on mesoporous silica as catalysts for aromatic hydrogenation.

    PubMed

    Boujday, Souhir; Blanchard, Juliette; Villanneau, Richard; Krafft, Jean-Marc; Geantet, Christophe; Louis, Catherine; Breysse, Michèle; Proust, Anna

    2007-12-21

    We use polyoxometalates as precursors for the preparation of heterogeneous catalysts. In the starting molecular precursor [{Ru(C6Me6)}(2)Mo5O18{Ru(C6Me6)(H2O)}], three ruthenium arene fragments are supported on a formally lacunary Lindqvist-type polyoxomolybdate. This species was introduced by incipient wetness impregnation into the porosity of a SBA-15-type mesoporous silica. The evolution of the system under reducing atmosphere is followed by several methods, such as temperature-programmed reduction (TPR), Raman, and X-ray absorption spectroscopy (XAS). The results indicate that the polyoxometalate structure is retained after grafting on silica and allows the stabilization of Ru(0) nanoparticles after reduction. The resulting system exhibits interesting catalytic activity in benzene hydrogenation. PMID:18058778

  17. Controlled epitaxial growth of mesoporous silica/gold nanorod nanolollipops and nanodumb-bells

    SciTech Connect

    Huang, Ching-Mao; Chung, Ming-Fang; Lo, Leu-Wei; Souris, Jeffrey S.

    2014-11-01

    In this work, we describe the controlled synthesis of novel heterogeneous nanostructures comprised of mesoporous silica-coated gold nanorods (MSGNRs) in the form of core–shell nanolollipops and nanodumb-bells, using a seed-mediated sol–gel method. Although MSGNR core–shell (θ-MSGNR) structures have been reported previously by us and others, we herein discuss the first ever fabrication of MSGNR nanolollipops (φ-MSGNR) and nanodumb-bells (β-MSGNR), achieved by simply controlling the aging time of gold nanorods (GNRs), the residual cetyltrimethylammonium bromide (CTAB) coating of GNRs, and the addition of dimethyl formamide during incubation, centrifugation, and sonication, respectively. Transmission electron microscopy revealed two bare GNR isoforms, with aspect ratios of approximately 4 and 6, while scanning electron microscopy was used to further elucidate the morphology of φ-MSGNR and β-MSGNR heterostructures. In agreement with the smaller dielectric constants afforded by incomplete silica encasement, spectroscopic studies of φ-MSGNR and β-MSGNR, surface plasmon resonance (SPR) bands revealed 20-40 nm blue shifts relative to the SPR of θ-MSGNR. On the basis of the attributes and applications of more conventional θ-MSGNRs, φ-MSGNRs and β-MSGNRs are anticipated to provide most of the utility of θ-MSGNRs, but with the additional functionalities that accompany their incorporation of both bare gold and mesoporous silica encased tips; with significant/unique implications for biomedical and catalytic applications.

  18. Controlled epitaxial growth of mesoporous silica/gold nanorod nanolollipops and nanodumb-bells

    NASA Astrophysics Data System (ADS)

    Huang, Ching-Mao; Chung, Ming-Fang; Souris, Jeffrey S.; Lo, Leu-Wei

    2014-11-01

    In this work, we describe the controlled synthesis of novel heterogeneous nanostructures comprised of mesoporous silica-coated gold nanorods (MSGNRs) in the form of core-shell nanolollipops and nanodumb-bells, using a seed-mediated sol-gel method. Although MSGNR core-shell (θ-MSGNR) structures have been reported previously by us and others, we herein discuss the first ever fabrication of MSGNR nanolollipops (φ-MSGNR) and nanodumb-bells (β-MSGNR), achieved by simply controlling the aging time of gold nanorods (GNRs), the residual cetyltrimethylammonium bromide (CTAB) coating of GNRs, and the addition of dimethyl formamide during incubation, centrifugation, and sonication, respectively. Transmission electron microscopy revealed two bare GNR isoforms, with aspect ratios of approximately 4 and 6, while scanning electron microscopy was used to further elucidate the morphology of φ-MSGNR and β-MSGNR heterostructures. In agreement with the smaller dielectric constants afforded by incomplete silica encasement, spectroscopic studies of φ-MSGNR and β-MSGNR, surface plasmon resonance (SPR) bands revealed 20-40 nm blue shifts relative to the SPR of θ-MSGNR. On the basis of the attributes and applications of more conventional θ-MSGNRs, φ-MSGNRs and β-MSGNRs are anticipated to provide most of the utility of θ-MSGNRs, but with the additional functionalities that accompany their incorporation of both bare gold and mesoporous silica encased tips; with significant/unique implications for biomedical and catalytic applications.

  19. Is there any microporosity in ordered mesoporous silicas?

    PubMed

    Silvestre-Alberto, A; Jardim, E O; Bruijn, E; Meynen, V; Cool, P; Sepulveda-Escribano, A; Silvestre-Alberto, J; Rodriguez-Reinoso, F

    2009-01-20

    The porous structure of nanostructured silicas MCM-41 and SBA-15 has been characterized using N2 adsorption at 77 K, before and after n-nonane preadsorption, together with immersion calorimetry into liquids of different molecular dimensions. Selective blocking of the microporosity with n-nonane proves experimentally that MCM-41 is exclusively mesoporous while SBA-15 exhibits both micro- and mesopores. Additionally, N2 adsorption experiments on the preadsorbed samples show that the microporosity on SBA-15 is located in intrawall positions, the micropore volume accounting for only approximately 7-8 % of the total pore volume. Calorimetric measurements into n-hexane (0.43 nm), 2-methylpentane (0.49 nm), and 2,2-dimethylbutane (0.56 nm) estimate the size of these micropores to be < or = 0.56 nm.

  20. Mesoporous Silica Nanomaterials for Applications in Catalysis, Sensing, Drug Delivery and Gene Transfection

    SciTech Connect

    Radu, Daniela Rodica

    2004-01-01

    The central theme of this dissertation is represented by the versatility of mesoporous silica nanomaterials in various applications such as catalysis and bio-applications, with main focus on biological applications of Mesoporous Silica Nanospheres (MSN). The metamorphosis that we impose to these materials from catalysis to sensing and to drug and gene delivery is detailed in this dissertation. First, we developed a synthetic method that can fine tune the amount of chemically accessible organic functional groups on the pores surface of MSN by exploiting electrostatic and size matching between the cationic alkylammonium head group of the cetyltrimethylammonium bromide (CTAB) surfactant and various anionic organoalkoxysilane precursors at the micelle-water interface in a base-catalyzed condensation reaction of silicate. Aiming nature imitation, we demonstrated the catalytic abilities of the MSNs, We utilized an ethylenediamine functional group for chelating Cu2+ as a catalytic functional group anchored inside the mesopores. Thus, a polyalkynylene-based conducting polymer (molecular wire) was synthesized within the Cu-functionalized MSNs silica catalyst. For sensing applications, we have synthesized a poly(lactic acid) coated mesoporous silica nanosphere (PLA-MSN) material that serves as a fluorescence sensor system for detection of amino-containing neurotransmitters in neutral aqueous buffer. We exploited the mesoporosity of MSNs for encapsulating pharmaceutical drugs. We examined bio-friendly capping molecules such as polyamidoamine dendrimers of generations G2 to G4, to prevent the drug leaching. Next, the drug delivery system employed MSNs loaded with Doxorubicin, an anticancer drug. The results demonstrated that these nano-Trojan horses have ability to deliver Doxorubicin to cancer cells and induce their death. Finally, to demonstrate the potential of MSN as an universal cellular transmembrane nanovehicle, we anchored positively charged dendrimers on

  1. Silver nanoparticles incorporated onto ordered mesoporous silica from Tollen's reagent

    NASA Astrophysics Data System (ADS)

    Zienkiewicz-Strzałka, M.; Pasieczna-Patkowska, S.; Kozak, M.; Pikus, S.

    2013-02-01

    Noble metal nanostructures supported on mesoporous silica are bridge between traditional silica adsorbents and modern catalysts. In this work the Ag/SBA-15 mesoporous materials were synthesized and characterized. Various forms of nanosilver supported on ordered mesoporous template have been successfully obtained via proposed procedures. In all synthesized materials, Tollen's reagent (diammine silver complex [Ag(NH3)2]+) was used as a silver source. Silver nanoparticles were prepared by reduction of ammoniacal silver complex by formaldehyde in the solution of stabilizer. After reduction, Ag nanoparticles could be deposited on SBA-15, or added during traditional synthesis of SBA-15 giving silver or silver chloride nanoparticles in the combination with porous silica. Silver nanostructures as nanoparticles or nanowires were also embedded onto the SBA-15 by incipient wetness impregnation of silver ions. Absorbed silver ions were next reduced under hydrogen at high temperature. There are many advantages of utilized ammoniacal silver complex as a silver source. Proposed method is capable to synthesis of various metal nanostructures with controlled composition and morphology. The silver ammonia complex is composed of two ions surrounding and protecting the central silver ion, so it is possible to obtain very small nanoparticles using simple approach without any functionalization of external and internal surface of SBA-15. This approach allows obtaining greatly small silver nanoparticles on SBA-15 (4 nm) or nanowires depending on the metal loading amount. Moreover, the colloidal silver solution prepared from Tollen's reagent, in the presence of triblock copolymer, remains stable for a long time. Reduction of Tollen's reagent to silver colloidal solution seems to be efficient, fast and interesting approach for the preparation of supported silver nanostructures Obtained samples were characterized by powder X-ray diffraction, small angle X-ray scattering (SAXS), UV

  2. A mesoporous silica biomaterial for dental biomimetic crystallization.

    PubMed

    Chiang, Yu-Chih; Lin, Hong-Ping; Chang, Hao-Hueng; Cheng, Ya-Wen; Tang, Hsin-Yen; Yen, Wei-Ching; Lin, Po-Yen; Chang, Kei-Wen; Lin, Chun-Pin

    2014-12-23

    The loss of overlying enamel or cementum exposes dentinal tubules and increases the risk of several dental diseases, such as dentin hypersensitivity (causing sharp pain and anxiety), caries, and pulp inflammation. This paper presents a fast-reacting, more reliable and biocompatible biomaterial that effectively occludes exposed dentinal tubules by forming a biomimetic crystalline dentin barrier. To generate this biomaterial, a gelatin-templated mesoporous silica biomaterial (CaCO3@mesoporous silica, CCMS) containing nanosized calcium carbonate particles is mixed with 30% H3PO4 at a 1/1 molar ratio of Ca/P (denoted as CCMS-HP), which enables Ca2+ and PO4(3-)/HPO4(2-) ions to permeate the dentinal tubules and form dicalcium phosphate dihydrate (DCPD), tricalcium phosphate (TCP) or hydroxyapatite (HAp) crystals at a depth of approximately 40 μm (sub-μ-CT and nano-SEM/EDS examinations). In vitro biocompatibility tests (WST-1 and lactate dehydrogenase) and ALP assays show high cell viability and mineralization ability in a transwell dentin disc model treated with CCMS-HP (p<0.05). The in vivo efficacy and biocompatibility analyses of the biomaterial in an animal model reveal significant crystal growth (DCPD, TCP or HAp-like) and no pulp irritation after 70 days (p<0.05). The developed CCMS-HP holds great promise for treating exposed dentin by growing biomimetic crystals within dentinal tubules. These findings demonstrate that the mesoporous silica biomaterials presented here have great potential for serving as both a catalyst and carrier in the repair or regeneration of dental hard tissue.

  3. Sponge mesoporous silica formation using disordered phospholipid bilayers as template.

    PubMed

    Galarneau, Anne; Sartori, Federica; Cangiotti, Michela; Mineva, Tzonka; Di Renzo, Francesco; Ottaviani, M Francesca

    2010-02-18

    Lecithin/dodecylamine/lactose mixtures in ethanol/aqueous media led to the formation of sponge mesoporous silica (SMS) materials by means of tetraethoxysilane (TEOS) as silica source. SMS materials show a "sponge-mesoporous" porosity with a pore diameter of about 5-6 nm, in accordance to the length of a lecithin bilayer. SMS synthesis was developed to create a new class of powerful biocatalysts able to efficiently encapsulate enzymes by adding a porosity control to the classical sol-gel synthesis and by using phospholipids and lactose as protecting agents for the enzymes. In the present study, the formation of SMS was investigated by using electron paramagnetic resonance (EPR) probes inserted inside phospholipid bilayers. The influence of progressive addition of each component (ethanol, dodecylamine, lactose, TEOS) on phospholipid bilayers was first examined; then, the time evolution of EPR spectra during SMS synthesis was studied. Parameters informative of mobility, structure, order, and polarity around the probes were extracted by computer analysis of the EPR line shape. The results were discussed on the basis of solids characterization by X-ray diffraction, nitrogen isotherm, transmission electron microscopy, and scanning electron microscopy. The results, together with the well-known ability of ethanol to promote membrane hemifusion, suggested that the templating structure is a bicontinuous phospholipid bilayer phase, shaped as a gyroid, resulting of multiple membrane hemifusions induced by the high alcohol content used in SMS synthesis. SMS synthesis was compared to hexagonal mesoporous silica (HMS) synthesis accomplished by adding TEOS to a dodecylamine/EtOH/water mixture. EPR evidenced the difference between HMS and SMS synthesis; the latter uses an already organized but slowly growing mesophase of phospholipids, never observed before, whereas the former shows a progressive elongation of micelles into wormlike structures. SMS-type materials represent a new

  4. Multiplexed immunoassay using the stabilized enzymes in mesoporous silica.

    PubMed

    Piao, Yunxian; Lee, Dohoon; Lee, Jinwoo; Hyeon, Taeghwan; Kim, Jungbae; Kim, Hak-Sung

    2009-12-15

    Multiplexed immunoassay system was developed using the enzyme-immobilized mesoporous silica in a form of nanoscale enzyme reactors (NERs), which improve the enzyme loading, activity, and stability. Glucose oxidase (GO) and trypsin (TR) were adsorbed into mesoporous silica and further crosslinked for the construction of NERs, and antibody-conjugated NERs were employed for the analysis of target antigens in a sandwich-type magnetic bead-based immunoassay. This approach, called as NER-LISA (NER-linked immunosorbent assay), generated signals out of enzyme reactions that correlated well with the concentration of target antigens. The detection limit of NER-LISA using NER-GO and anti-human IgG was 67pM human IgG, and the sensitivity was 20 times higher than that of the conventional ELISA using anti-human IgG conjugated GO. Antibody-conjugated NER-GO and NER-TR were successfully employed for the simultaneous detection of two target antigens (human IgG and chicken IgG) in a solution by taking advantage of signals at different wavelengths (absorbances at 570nm and 410nm, respectively) from the assays of GO and TR activities, demonstrating the potential of NER-LISA in multiplexed immunoassay. The NER-LISA approach also enabled the successful use of a protease (trypsin), because the NER approach can effectively retain the protease molecules within the mesoporous silica and prevent the digestion of antibodies and enzymes during the whole process of NER-LISA.

  5. Functioning of nanovalves on polymer coated mesoporous silica Nanoparticles

    NASA Astrophysics Data System (ADS)

    Dong, Juyao; Xue, Min; Zink, Jeffrey I.

    2013-10-01

    Nanomachines activated by a pH change can be combined with polymer coatings on mesoporous silica nanoparticles to produce a new generation of nanoparticles for drug delivery that exhibits properties of both components. The nanovalves can trap cargos inside the mesoporous silica nanoparticles without premature release and only respond to specific stimuli, resulting in a high local concentration of drugs at the site of release. The polymer surface coatings can increase the cellular uptake, avoid the reticuloendothelial uptake, provide protected space for storing siRNA, and enhance the biodistribution of nanoparticles. Two nanovalve-polymer systems are designed and their successful assembly is confirmed by solid state NMR and thermogravimetric analysis. The fluorescence spectroscopy results demonstrate that the controlled release functions of the nanomachines in both of the systems are not hindered by the polymer surface coatings. These new multifunctional nanoparticles combining stimulated molecule release together with the functionality provided by the polymers produce enhanced biological properties and multi-task drug delivery applications.Nanomachines activated by a pH change can be combined with polymer coatings on mesoporous silica nanoparticles to produce a new generation of nanoparticles for drug delivery that exhibits properties of both components. The nanovalves can trap cargos inside the mesoporous silica nanoparticles without premature release and only respond to specific stimuli, resulting in a high local concentration of drugs at the site of release. The polymer surface coatings can increase the cellular uptake, avoid the reticuloendothelial uptake, provide protected space for storing siRNA, and enhance the biodistribution of nanoparticles. Two nanovalve-polymer systems are designed and their successful assembly is confirmed by solid state NMR and thermogravimetric analysis. The fluorescence spectroscopy results demonstrate that the controlled release

  6. Synthesis of palladium nanoparticles supported on mesoporous N-doped carbon and their catalytic ability for biofuel upgrade.

    PubMed

    Xu, Xuan; Li, Yi; Gong, Yutong; Zhang, Pengfei; Li, Haoran; Wang, Yong

    2012-10-17

    We report a catalyst made of Pd nanoparticles (NPs) supported on mesoporous N-doped carbon, Pd@CN(0132), which was shown to be highly active in promoting biomass refining. The use of a task-specific ionic liquid (3-methyl-1-butylpyridine dicyanamide) as a precursor and silica NPs as a hard template afforded a high-nitrogen-content (12 wt %) mesoporous carbon material that showed high activity in stabilizing Pd NPs. The resulting Pd@CN(0.132) catalyst showed very high catalytic activity in hydrodeoxygenation of vanillin (a typical model compound of lignin) at low H(2) pressure under mild conditions in aqueous media. Excellent catalytic results (100% conversion of vanillin and 100% selectivity for 2-methoxy-4-methylphenol) were achieved, and no loss of catalytic activity was observed after six recycles. PMID:23030399

  7. Monodisperse Mesoporous Carbon Nanoparticles from Polymer/Silica Self-Aggregates and Their Electrocatalytic Activities.

    PubMed

    Huang, Xiaoxi; Zhou, Li-Jing; Voiry, Damien; Chhowalla, Manish; Zou, Xiaoxin; Asefa, Tewodros

    2016-07-27

    In our quest to make various chemical processes sustainable, the development of facile synthetic routes and inexpensive catalysts can play a central role. Herein we report the synthesis of monodisperse, polyaniline (PANI)-derived mesoporous carbon nanoparticles (PAMCs) that can serve as efficient metal-free electrocatalysts for the hydrogen peroxide reduction reaction (HPRR) as well as the oxygen reduction reaction (ORR) in fuel cells. The materials are synthesized by polymerization of aniline with the aid of (NH4)2S2O8 as oxidant and colloidal silica nanoparticles as templates, then carbonization of the resulting PANI/silica composite material at different high temperatures, and finally removal of the silica templates from the carbonized products. The PAMC materials that are synthesized under optimized synthetic conditions possess monodisperse mesoporous carbon nanoparticles with an average size of 128 ± 12 nm and an average pore size of ca. 12 nm. Compared with Co3O4, a commonly used electrocatalyst for HPRR, these materials show much better catalytic activity for this reaction. In addition, unlike Co3O4, the PAMCs remain relatively stable during the reaction, under both basic and acidic conditions. The nanoparticles also show good electrocatalytic activity toward ORR. Based on the experimental results, PAMCs' excellent electrocatalytic activity is attributed partly to their heteroatom dopants and/or intrinsic defect sites created by vacancies in their structures and partly to their high porosity and surface area. The reported synthetic method is equally applicable to other polymeric precursors (e.g., polypyrrole (PPY)), which also produces monodisperse, mesoporous carbon nanoparticles in the same way. The resulting materials are potentially useful not only for electrocatalysis of HPRR and ORR in fuel cells but also for other applications where high surface area, small sized, nanostructured carbon materials are generally useful for (e.g., adsorption

  8. Monodisperse Mesoporous Carbon Nanoparticles from Polymer/Silica Self-Aggregates and Their Electrocatalytic Activities.

    PubMed

    Huang, Xiaoxi; Zhou, Li-Jing; Voiry, Damien; Chhowalla, Manish; Zou, Xiaoxin; Asefa, Tewodros

    2016-07-27

    In our quest to make various chemical processes sustainable, the development of facile synthetic routes and inexpensive catalysts can play a central role. Herein we report the synthesis of monodisperse, polyaniline (PANI)-derived mesoporous carbon nanoparticles (PAMCs) that can serve as efficient metal-free electrocatalysts for the hydrogen peroxide reduction reaction (HPRR) as well as the oxygen reduction reaction (ORR) in fuel cells. The materials are synthesized by polymerization of aniline with the aid of (NH4)2S2O8 as oxidant and colloidal silica nanoparticles as templates, then carbonization of the resulting PANI/silica composite material at different high temperatures, and finally removal of the silica templates from the carbonized products. The PAMC materials that are synthesized under optimized synthetic conditions possess monodisperse mesoporous carbon nanoparticles with an average size of 128 ± 12 nm and an average pore size of ca. 12 nm. Compared with Co3O4, a commonly used electrocatalyst for HPRR, these materials show much better catalytic activity for this reaction. In addition, unlike Co3O4, the PAMCs remain relatively stable during the reaction, under both basic and acidic conditions. The nanoparticles also show good electrocatalytic activity toward ORR. Based on the experimental results, PAMCs' excellent electrocatalytic activity is attributed partly to their heteroatom dopants and/or intrinsic defect sites created by vacancies in their structures and partly to their high porosity and surface area. The reported synthetic method is equally applicable to other polymeric precursors (e.g., polypyrrole (PPY)), which also produces monodisperse, mesoporous carbon nanoparticles in the same way. The resulting materials are potentially useful not only for electrocatalysis of HPRR and ORR in fuel cells but also for other applications where high surface area, small sized, nanostructured carbon materials are generally useful for (e.g., adsorption

  9. Thrombin-Responsive Gated Silica Mesoporous Nanoparticles As Coagulation Regulators.

    PubMed

    Bhat, Ravishankar; Ribes, Àngela; Mas, Núria; Aznar, Elena; Sancenón, Félix; Marcos, M Dolores; Murguía, Jose R; Venkataraman, Abbaraju; Martínez-Máñez, Ramón

    2016-02-01

    The possibility of achieving sophisticated actions in complex biological environments using gated nanoparticles is an exciting prospect with much potential. We herein describe new gated mesoporous silica nanoparticles (MSN) loaded with an anticoagulant drug and capped with a peptide containing a thrombin-specific cleavage site. When the coagulation cascade was triggered, active thrombin degraded the capping peptidic sequence and induced the release of anticoagulant drugs to delay the clotting process. The thrombin-dependent response was assessed and a significant increase in coagulation time in plasma from 2.6 min to 5 min was found. This work broadens the application of gated silica nanoparticles and demonstrates their ability to act as controllers in a complex scenario such as hemostasis. PMID:26794474

  10. The Role of Non-Bonded Interactions in the Conformational Dynamics of Organophosphorous Hydrolase Adsorbed onto Functionalized Mesoporous Silica Surfaces

    SciTech Connect

    Gomes, Diego Enry B.; Lins, Roberto D.; Pascutti, Pedro G.; Lei, Chenghong; Soares, Thereza A.

    2010-01-14

    The enzyme organophosphorous hydrolase (OPH) catalyzes the hydrolysis of a wide variety of organophosphorous compounds with high catalytic efficiency and broad substrate specificity. The immobilization of OPH in functionalized mesoporous silica surfaces increases significantly its catalytic specific activity compared to the enzyme in solution with important applications for the detection and decontamination of insecticides and chemical warfare agents. Experimental measurements of immobilization efficiency as function of the charge and coverage percentage of different functional groups have been interpreted as electrostatic forces being the predominant interactions underlying the adsorption of OPH onto functionalized mesoporous silica surfaces. Explicit solvent molecular dynamics simulations have been performed for OPH in bulk solution and adsorbed onto two distinct interaction potential models of the mesoporous silica functional groups in order to investigate the relative contributions of non-bonded interactions to the conformational dynamics and adsorption of the protein. Our results support the conclusion that while electrostatic interactions are responsible for the specific binding of OPH to the FMS surface, van der Waals forces are detrimental for enhanced interfacial adhesion. Key-words: molecular dynamics simulations; bacterial phosphotriesterase; conformational changes; confined environments; coarse-grain and atomistic models; silanol molecular model.

  11. Post-treatment and characterization of novel luminescent hybrid bimodal mesoporous silicas

    NASA Astrophysics Data System (ADS)

    Li, Yuzhen; Sun, Jihong; Wu, Xia; Lin, Li; Gao, Lin

    2010-08-01

    A novel luminescent hybrid bimodal mesoporous silicas (LHBMS) were synthesized via grafting 1,8-Naphthalic anhydride into the pore channels of bimodal mesoporous silicas (BMMs) for the first time. The resulting samples were characterized by powder X-ray diffraction (XRD), N 2 adsorption/desorption measurement, Fourier transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM), UV-vis absorption spectroscopy, and Photoluminescence spectroscopy (PL). The results show that 1,8-Naphthalic anhydride organic groups have been successfully introduced into the mesopores of the BMMs and the hybrid silicas are of bimodal mesoporous structure with the ordered small mesopores of around 3 nm and the large mesopores of uniform intra-nanoparticle. The excellent photoluminescent performance of LHBMS has a blue shift compared to that of 2-[3-(triethoxysilyl) propyl-1 H-Benz [de]isoquinoline-1, 3(2 H)-dione, suggesting the existence of the quantum confinement effectiveness.

  12. Mesoporous silica as carrier of antioxidant for food packaging materials

    NASA Astrophysics Data System (ADS)

    Buonocore, Giovanna Giuliana; Gargiulo, Nicola; Verdolotti, Letizia; Liguori, Barbara; Lavorgna, Marino; Caputo, Domenico

    2014-05-01

    Mesoporous silicas have been long recognized as very promising materials for the preparation of drug delivery systems. In this work SBA-15 mesoporous silica has been functionalized with amino-silane to be used as carrier of antioxidant compound in the preparation of active food packaging materials exhibiting tailored release properties. Active films have been prepared by loading the antioxidant tocopherol, the purely siliceous SBA-15 and the aminofunctionalized SBA-15 loaded with tocopherol into LDPE matrix trough a two-step process (mixing+extrusion). The aim of the present work is the study of the effect of the pore size and of the chemical functionality of the internal walls of the mesophase on the migration of tocopherol from active LDPE polymer films. Moreover, it has been proved that the addition of the active compound do not worsen the properties of the film such as optical characteristic and water vapor permeability, thus leading to the development of a material which could be favorably used mainly, but not exclusively, in the sector of food packaging.

  13. Facile preparation of mesoporous carbon-silica-coated graphene for the selective enrichment of endogenous peptides.

    PubMed

    Zhang, Quanqing; Zhang, Qinghe; Xiong, Zhichao; Wan, Hao; Chen, Xiaoting; Li, Hongmei; Zou, Hanfa

    2016-01-01

    A sandwich-like composite composed of ordered mesoporous carbon-silica shell-coated graphene (denoted as graphene@mSiO2-C) was prepared by an in-situ carbonation strategy. A mesoporous silica shell was synthesized by a sol-gel method, and cetyltrimethyl ammonium bromide inside the mesopores were in-situ carbonized as a carbon source to obtain a carbon-silica shell. The resulting mesoporous carbon-silica material with a sandwich structure possesses a high surface area (600 m(2) g(-1)), large pore volume (0.587 cm(3) g(-1)), highly ordered mesoporous pore (3 nm), and high carbon content (30%). This material shows not only high hydrophobicity of graphene and mesoporous carbon but also a hydrophilic silica framework that ensures excellent dispersibility in aqueous solution. The material can capture many more peptides from bovine serum albumin tryptic digests than mesoporous silica shell-coated graphene, demonstrating great enrichment efficiency for peptides. Furthermore, the prepared composite was applied to the enrichment of low-abundance endogenous peptides in human serum. Based on Matrix-Assisted Laser Desorption/ Ionization Time of Flight Mass Spectrometry identification, the graphene@mSiO2-C could efficiently size-exclude proteins and enriches the low-abundant peptides on the graphene and mesoporous carbon. And based on the LC-MS/MS results, 892 endogenous peptides were obtained by graphene@mSiO2-C, hinting at its great potential in peptides analysis. PMID:26695263

  14. Facile preparation of mesoporous carbon-silica-coated graphene for the selective enrichment of endogenous peptides.

    PubMed

    Zhang, Quanqing; Zhang, Qinghe; Xiong, Zhichao; Wan, Hao; Chen, Xiaoting; Li, Hongmei; Zou, Hanfa

    2016-01-01

    A sandwich-like composite composed of ordered mesoporous carbon-silica shell-coated graphene (denoted as graphene@mSiO2-C) was prepared by an in-situ carbonation strategy. A mesoporous silica shell was synthesized by a sol-gel method, and cetyltrimethyl ammonium bromide inside the mesopores were in-situ carbonized as a carbon source to obtain a carbon-silica shell. The resulting mesoporous carbon-silica material with a sandwich structure possesses a high surface area (600 m(2) g(-1)), large pore volume (0.587 cm(3) g(-1)), highly ordered mesoporous pore (3 nm), and high carbon content (30%). This material shows not only high hydrophobicity of graphene and mesoporous carbon but also a hydrophilic silica framework that ensures excellent dispersibility in aqueous solution. The material can capture many more peptides from bovine serum albumin tryptic digests than mesoporous silica shell-coated graphene, demonstrating great enrichment efficiency for peptides. Furthermore, the prepared composite was applied to the enrichment of low-abundance endogenous peptides in human serum. Based on Matrix-Assisted Laser Desorption/ Ionization Time of Flight Mass Spectrometry identification, the graphene@mSiO2-C could efficiently size-exclude proteins and enriches the low-abundant peptides on the graphene and mesoporous carbon. And based on the LC-MS/MS results, 892 endogenous peptides were obtained by graphene@mSiO2-C, hinting at its great potential in peptides analysis.

  15. Silica Nanospheres: Hollow Structure Improved Anti-Cancer Immunity of Mesoporous Silica Nanospheres In Vivo (Small 26/2016).

    PubMed

    Wang, Xiupeng; Li, Xia; Ito, Atsuo; Yoshiyuki, Kazuko; Sogo, Yu; Watanabe, Yohei; Yamazaki, Atsushi; Ohno, Tadao; Tsuji, Noriko M

    2016-07-01

    Hollow and non-hollow mesoporous silica nanospheres are synthesized and used for cancer vaccine adjuvants by X. Wang, A. Ito, N. M. Tsuji, and co-workers on page 3510. The hollow structure of mesoporous silica nanospheres significantly promotes cellular uptake of a model cancer antigen by macrophage-like cells in vitro, improves anti-cancer immunity, and increases CD4+ and CD8+ T cell populations in splenocytes of mice in vivo. PMID:27383037

  16. Synthesis of Nanodispersed Oxides of Vanadium, Titanium, Molybdenum, and Tungsten on Mesoporous Silica using Atomic Layer Deposition

    SciTech Connect

    Herrera, Jose E.; Kwak, Ja Hun; Hu, Jian Zhi; Wang, Yong; Peden, Charles HF

    2006-10-01

    The advantages of the atomic layer deposition (ALD) method for preparation of tungsten, vanadium, titanium and molybdenum oxide catalyst supported on mesoporous silica are discussed, with emphasis on the importance of synthesis conditions on dispersion, structure and activity of the resulting materials. A suite of complementary techniques such as DRS-UV/Vis, BET, 1H-NMR, XRD, and TEM were used to study the structural properties of the supported metal oxides, and probe reactions such as 2-butanol dehydration and ethanol partial oxidation were used to demonstrate the potential advantages of the ALD prepared catalysts. Specifically, highly dispersed oxides of titanium, molybdenum, and tungsten oxide on mesoporous silica were synthesized using the ALD method. It is also demonstrated that attainment of high dispersions of vanadium oxide on mesoporous silica requires the presence of at least a single layer of titanium oxide due to the well-known poor interaction between vanadia and silica. The highly dispersed catalysts prepared here by ALD methods exhibited superior catalytic performance relative to those prepared using conventional incipient wetness impregnation.

  17. Colorimetric detection of hydrogen peroxide and glucose using the magnetic mesoporous silica nanoparticles.

    PubMed

    Wang, Yonghong; Zhou, Bo; Wu, Shun; Wang, Kemin; He, Xiaoxiao

    2015-03-01

    In this work, we synthesized a type of magnetic mesoporous silica nanoparticle (denoted as Fe3O4@MSN) with Fe3O4 as the core and mesoporous silica the shell. The superparamagnetic Fe3O4-core provides high peroxidase-mimic activity and makes the artificial enzymatic system easily recyclable. Furthermore, Fe3O4 nanoparticles are encapsulated in MSN shells to hinder the aggregation and keep them stable even under harsh conditions. Meanwhile, small active molecules are allowed to diffuse in and out of the MSN shells. Based on these functional units, the Fe3O4@MSN as robust nanoreactors can catalyze a self-organized cascade reaction, which includes oxidation of glucose by oxygen to yield gluconic acid and H2O2, and the latter further oxidizes 3,3,5,5-tetramethylbenzidine (TMB) to produce a color change. The Fe3O4@MSN, whose catalytic efficiency was not strongly dependent on pH and temperature, was successfully used for the detection of glucose and showed excellent sensitivity with a detection limit of 0.4×10(-5) mol/L. Nevertheless, the assay is also highly selective toward the glucose detection. PMID:25618726

  18. Gold nanoparticles supported on mesoporous silica: origin of high activity and role of Au NPs in selective oxidation of cyclohexane

    PubMed Central

    Wu, Pingping; Bai, Peng; Yan, Zifeng; Zhao, George X. S.

    2016-01-01

    Homogeneous immobilization of gold nanoparticles (Au NPs) on mesoporous silica has been achieved by using a one-pot synthesis method in the presence of organosilane mercapto-propyl-trimethoxysilane (MPTMS). The resultant Au NPs exhibited an excellent catalytic activity in the solvent-free selective oxidation of cyclohexane using molecular oxygen. By establishing the structure-performance relationship, the origin of the high activity of mesoporous supported Au catalyst was identified to be due to the presence of low-coordinated Au (0) sites with high dispersion. Au NPs were confirmed to play a critical role in the catalytic oxidation of cyclohexane by promoting the activation of O2 molecules and accelerating the formation of surface-active oxygen species. PMID:26729288

  19. Gold nanoparticles supported on mesoporous silica: origin of high activity and role of Au NPs in selective oxidation of cyclohexane

    NASA Astrophysics Data System (ADS)

    Wu, Pingping; Bai, Peng; Yan, Zifeng; Zhao, George X. S.

    2016-01-01

    Homogeneous immobilization of gold nanoparticles (Au NPs) on mesoporous silica has been achieved by using a one-pot synthesis method in the presence of organosilane mercapto-propyl-trimethoxysilane (MPTMS). The resultant Au NPs exhibited an excellent catalytic activity in the solvent-free selective oxidation of cyclohexane using molecular oxygen. By establishing the structure-performance relationship, the origin of the high activity of mesoporous supported Au catalyst was identified to be due to the presence of low-coordinated Au (0) sites with high dispersion. Au NPs were confirmed to play a critical role in the catalytic oxidation of cyclohexane by promoting the activation of O2 molecules and accelerating the formation of surface-active oxygen species.

  20. Complete magnesiothermic reduction reaction of vertically aligned mesoporous silica channels to form pure silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Kim, Kyoung Hwan; Lee, Dong Jin; Cho, Kyeong Min; Kim, Seon Joon; Park, Jung-Ki; Jung, Hee-Tae

    2015-03-01

    Owing to its simplicity and low temperature conditions, magnesiothermic reduction of silica is one of the most powerful methods for producing silicon nanostructures. However, incomplete reduction takes place in this process leaving unconverted silica under the silicon layer. This phenomenon limits the use of this method for the rational design of silicon structures. In this effort, a technique that enables complete magnesiothermic reduction of silica to form silicon has been developed. The procedure involves magnesium promoted reduction of vertically oriented mesoporous silica channels on reduced graphene oxides (rGO) sheets. The mesopores play a significant role in effectively enabling magnesium gas to interact with silica through a large number of reaction sites. Utilizing this approach, highly uniform, ca. 10 nm sized silicon nanoparticles are generated without contamination by unreacted silica. The new method for complete magnesiothermic reduction of mesoporous silica approach provides a foundation for the rational design of silicon structures.

  1. Complete magnesiothermic reduction reaction of vertically aligned mesoporous silica channels to form pure silicon nanoparticles

    PubMed Central

    Kim, Kyoung Hwan; Lee, Dong Jin; Cho, Kyeong Min; Kim, Seon Joon; Park, Jung-Ki; Jung, Hee-Tae

    2015-01-01

    Owing to its simplicity and low temperature conditions, magnesiothermic reduction of silica is one of the most powerful methods for producing silicon nanostructures. However, incomplete reduction takes place in this process leaving unconverted silica under the silicon layer. This phenomenon limits the use of this method for the rational design of silicon structures. In this effort, a technique that enables complete magnesiothermic reduction of silica to form silicon has been developed. The procedure involves magnesium promoted reduction of vertically oriented mesoporous silica channels on reduced graphene oxides (rGO) sheets. The mesopores play a significant role in effectively enabling magnesium gas to interact with silica through a large number of reaction sites. Utilizing this approach, highly uniform, ca. 10 nm sized silicon nanoparticles are generated without contamination by unreacted silica. The new method for complete magnesiothermic reduction of mesoporous silica approach provides a foundation for the rational design of silicon structures. PMID:25757800

  2. Influence of spatial configurations on electromagnetic interference shielding of ordered mesoporous carbon/ordered mesoporous silica/silica composites

    PubMed Central

    Wang, Jiacheng; Zhou, Hu; Zhuang, Jiandong; Liu, Qian

    2013-01-01

    Ordered mesoporous carbons (OMCs), obtained by nanocasting using ordered mesoporous silicas (OMSs) as hard templates, exhibit unique arrangements of ordered regular nanopore/nanowire mesostructures. Here, we used nanocasting combined with hot-pressing to prepare 10 wt% OMC/OMS/SiO2 ternary composites possessing various carbon mesostructure configurations of different dimensionalities (1D isolated CS41 carbon nanowires, 2D hexagonal CMK-3 carbon, and 3D cubic CMK-1 carbon). The electric/dielectric properties and electromagnetic interference (EMI) shielding efficiency (SE) of the composites were influenced by spatial configurations of carbon networks. The complex permittivity and the EMI SE of the composites in the X-band frequency range decreased for the carbon mesostructures in the following order: CMK-3-filled > CMK-1-filled > CS41-filled. Our study provides technical directions for designing and preparing high-performance EMI shielding materials. Our OMC-based silica composites can be used for EMI shielding, especially in high-temperature or corrosive environments, owing to the high stability of the OMC/OMS fillers and the SiO2 matrix. Related shielding mechanisms are also discussed. PMID:24248277

  3. Rapid pathogen detection with bacterial-assembled magnetic mesoporous silica.

    PubMed

    Lee, Soo Youn; Lee, Jiho; Lee, Hye Sun; Chang, Jeong Ho

    2014-03-15

    We report rapid and accurate pathogen detection by coupling with high efficiency magnetic separation of pathogen by Ni(2+)-heterogeneous magnetic mesoporous silica (Ni-HMMS) and real time-polymerase chain reaction (RT-PCR) technique. Ni-HMMS was developed with a significant incorporation of Fe particles within the silica mesopores by programmed thermal hydrogen reaction and functionalized with Ni(2+) ion on the surface by the wet impregnation process. High abundant Ni(2+) ions on the Ni-HMMS surface were able to assemble with cell wall component protein NikA (nickel-binding membrane protein), which contains several pathogenic bacteria including Escherichia coli O157:H7. NikA protein expression experiment showed the outstanding separation rate of the nikA gene-overexpressed E. coli (pSY-Nik) when comparing with wild-type E. coli (44.5 ± 13%) or not over-expressed E. coli (pSY-Nik) (53.2 ± 2.7%). Moreover, Ni-HMMS showed lower obstacle effect by large reaction volume (10 mL) than spherical core/shell-type silica magnetic nanoparticles functionalized with Ni(2+) (ca. 40 nm-diameters). Finally, the Ni-HMMS was successfully assessed to separate pathogenic E. coli O157:H7 and applied to direct and rapid RT-PCR to quantitative detection at ultralow concentration (1 Log10 cfu mL(-1)) in the real samples (milk and Staphylococcus aureus culture broth) without bacterial amplification and DNA extraction step.

  4. PEG-templated mesoporous silica nanoparticles exclusively target cancer cells

    NASA Astrophysics Data System (ADS)

    Morelli, Catia; Maris, Pamela; Sisci, Diego; Perrotta, Enrico; Brunelli, Elvira; Perrotta, Ida; Panno, Maria Luisa; Tagarelli, Antonio; Versace, Carlo; Casula, Maria Francesca; Testa, Flaviano; Andò, Sebastiano; Nagy, Janos B.; Pasqua, Luigi

    2011-08-01

    Mesoporous silica nanoparticles (MSNs) have been proposed as DNA and drug delivery carriers, as well as efficient tools for fluorescent cell tracking. The major limitation is that MSNs enter cells regardless of a target-specific functionalization. Here we show that non functionalized MSNs, synthesized using a PEG surfactant-based interfacial synthesis procedure, do not enter cells, while a highly specific, receptor mediated, cellular internalization of folic acid (FOL) grafted MSNs (MSN-FOL), occurs exclusively in folate receptor (FR) expressing cells. Neither the classical clathrin pathway nor macropinocytosis is involved in the MSN endocytic process, while fluorescent MSNs (MSN-FITC) enter cells through aspecific, caveolae-mediated, endocytosis. Moreover, internalized particles seem to be mostly exocytosed from cells within 96 h. Finally, cisplatin (Cp) loaded MSN-FOL were tested on cancerous FR-positive (HeLa) or normal FR-negative (HEK293) cells. A strong growth arrest was observed only in HeLa cells treated with MSN-FOL-Cp. The results presented here show that our mesoporous nanoparticles do not enter cells unless opportunely functionalized, suggesting that they could represent a promising vehicle for drug targeting applications.Mesoporous silica nanoparticles (MSNs) have been proposed as DNA and drug delivery carriers, as well as efficient tools for fluorescent cell tracking. The major limitation is that MSNs enter cells regardless of a target-specific functionalization. Here we show that non functionalized MSNs, synthesized using a PEG surfactant-based interfacial synthesis procedure, do not enter cells, while a highly specific, receptor mediated, cellular internalization of folic acid (FOL) grafted MSNs (MSN-FOL), occurs exclusively in folate receptor (FR) expressing cells. Neither the classical clathrin pathway nor macropinocytosis is involved in the MSN endocytic process, while fluorescent MSNs (MSN-FITC) enter cells through aspecific, caveolae

  5. Reaction mechanisms in irradiated, precipitated, and mesoporous silica.

    PubMed

    Dondi, D; Buttafava, A; Zeffiro, A; Bracco, S; Sozzani, P; Faucitano, A

    2013-04-25

    A matrix EPR spectroscopy study of the low temperature γ radiolysis of precipitated (Zeosil) and mesoporous high surface silica has afforded evidence of the formation of trapped H-atoms, H-atom centers, siloxy radicals ≡Si-O(•), anomalous silyl peroxy radicals ≡Si-OO(•) with reduced g tensor anisotropy, siloxy radical-cations (≡Si-O-Si≡)(+•), E' centers, and two species from Ge impurity. Coordination of peroxyl radicals with diamagnetic ≡Si(+) centers is proposed and tested by DFT computations in order to justify the observed g tensor. Coordination of H-atoms to ≡Si(+) centers is also proposed for the structure of the H-atom centers as an alternative model not requiring the intervention of Ge, Sn, or CO impurities. The DFT method has been employed to assess the electronic structure of siloxy radical-cations and its similarity with that of the carbon radical-cation analogues; the results have prompted a revision of the structures proposed in the literature for ST1 and ST2 centers. The comparison between the two types of silica has afforded evidence of different radiolysis mechanisms leading to a greater yield of trapped H-atoms and H-atom centers in zeosil silica, which is reckoned with the 4-fold greater concentration of silanol groups. Parallel radiolysis experiments carried out by using both types of silica with polybutadiene oligomers as adsorbate have afforded evidence of free valence and energy migration phenomena leading to irreversible linking of polybutadiene chains onto silica. Reaction mechanisms are proposed based on the detection of SiO2-bonded free radicals whose structure has been defined by EPR. PMID:23521082

  6. Impregnation of Fenofibrate on mesoporous silica using supercritical carbon dioxide.

    PubMed

    Bouledjouidja, Abir; Masmoudi, Yasmine; Van Speybroeck, Michiel; Schueller, Laurent; Badens, Elisabeth

    2016-02-29

    Low oral bioavailability can be circumvented by the formulation of the poorly water soluble drug in ordered mesoporous silica (OMS-L-7). Fenofibrate is an orally administered, poorly water-soluble active pharmaceutical ingredient (API), used clinically to lower lipid levels. Fenofibrate was loaded into silica using two methods: incipient wetness and supercritical impregnation. This study investigates the impact of loading and the impact of varying supercritical carbon dioxide (scCO2) processing conditions. The objective is to enhance Fenofibrate loading into silica while reducing degree of the drug crystallinity, so as to increase the drug's dissolution rate and its bioavailability. The comparison of both impregnation processes was made in terms of impregnation yields and duration as well as physical characterization of the drug. While incipient wetness method led to a Fenofibrate loading up to 300 mgdrug/gsilica in 48 h of impregnation, the supercritical impregnation method yielded loading up to 485 mgdrug/gsilica in 120 min of impregnation duration, at 16 MPa and 308 K, with a low degree of crystallinity (about 1%) comparable to the crystallinity observed via the solvent method. In addition to the enhancement of impregnation efficiency, the supercritical route provides a solvent-free alternative for impregnation.

  7. Impregnation of Fenofibrate on mesoporous silica using supercritical carbon dioxide.

    PubMed

    Bouledjouidja, Abir; Masmoudi, Yasmine; Van Speybroeck, Michiel; Schueller, Laurent; Badens, Elisabeth

    2016-02-29

    Low oral bioavailability can be circumvented by the formulation of the poorly water soluble drug in ordered mesoporous silica (OMS-L-7). Fenofibrate is an orally administered, poorly water-soluble active pharmaceutical ingredient (API), used clinically to lower lipid levels. Fenofibrate was loaded into silica using two methods: incipient wetness and supercritical impregnation. This study investigates the impact of loading and the impact of varying supercritical carbon dioxide (scCO2) processing conditions. The objective is to enhance Fenofibrate loading into silica while reducing degree of the drug crystallinity, so as to increase the drug's dissolution rate and its bioavailability. The comparison of both impregnation processes was made in terms of impregnation yields and duration as well as physical characterization of the drug. While incipient wetness method led to a Fenofibrate loading up to 300 mgdrug/gsilica in 48 h of impregnation, the supercritical impregnation method yielded loading up to 485 mgdrug/gsilica in 120 min of impregnation duration, at 16 MPa and 308 K, with a low degree of crystallinity (about 1%) comparable to the crystallinity observed via the solvent method. In addition to the enhancement of impregnation efficiency, the supercritical route provides a solvent-free alternative for impregnation. PMID:26732521

  8. High-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles for phenol hydrogenation

    NASA Astrophysics Data System (ADS)

    Huang, Chao; Yang, Xu; Yang, Hui; Huang, Peiyan; Song, Huiyu; Liao, Shijun

    2014-10-01

    A high-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles (MSN), PdRu/MSN, was prepared by a facile impregnation-hydrogen reduction method. It was found that PdRu/MSN showed 5 times higher activity than that of Pd/MSN towards the liquid-phase hydrogenation of phenol. The catalysts were characterized comprehensively by multiple techniques, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature program reduction (TPR). It was revealed that adding Ru could effectively improve the Pd dispersion and promote the electronic interaction between the Pd and Ru, both of which contribute to enhancing the catalytic activity.

  9. Synthesis of mesoporous silica materials from municipal solid waste incinerator bottom ash.

    PubMed

    Liu, Zhen-Shu; Li, Wen-Kai; Huang, Chun-Yi

    2014-05-01

    Incinerator bottom ash contains a large amount of silica and can hence be used as a silica source for the synthesis of mesoporous silica materials. In this study, the conditions for alkaline fusion to extract silica from incinerator bottom ash were investigated, and the resulting supernatant solution was used as the silica source for synthesizing mesoporous silica materials. The physical and chemical characteristics of the mesoporous silica materials were analyzed using BET, XRD, FTIR, SEM, and solid-state NMR. The results indicated that the BET surface area and pore size distribution of the synthesized silica materials were 992 m2/g and 2-3.8 nm, respectively. The XRD patterns showed that the synthesized materials exhibited a hexagonal pore structure with a smaller order. The NMR spectra of the synthesized materials exhibited three peaks, corresponding to Q(2) [Si(OSi)2(OH)2], Q(3) [Si(OSi)3(OH)], and Q(4) [Si(OSi)4]. The FTIR spectra confirmed the existence of a surface hydroxyl group and the occurrence of symmetric Si-O stretching. Thus, mesoporous silica was successfully synthesized from incinerator bottom ash. Finally, the effectiveness of the synthesized silica in removing heavy metals (Pb2+, Cu2+, Cd2+, and Cr2+) from aqueous solutions was also determined. The results showed that the silica materials synthesized from incinerator bottom ash have potential for use as an adsorbent for the removal of heavy metals from aqueous solutions. PMID:24656468

  10. Towards understanding of shape formation mechanism of mesoporous silica particles.

    PubMed

    Volkov, Dmytro O; Benson, James; Kievsky, Yaroslav Y; Sokolov, Igor

    2010-01-14

    Growth of even simple crystals is a rather hard problem to describe because of the non-equilibrium nature of the process. Meso(nano)porous silica particles, which are self-assembled in a sol-gel template synthesis, demonstrate an example of shapes of high complexity, similar to those observed in the biological world. Despite such complexity, here we present the evidence that at least a part of the formation of these shapes is an equilibrium process. We demonstrate it for an example of mesoporous fibers, one of the abundant shapes. We present a quantitative proof that the fiber free energy is described by the Boltzmann distribution, which is predicted by the equilibrium thermodynamics. This finding may open up new ground for a quantitative description of the morphogenesis of complex self-assembled shapes, including biological hierarchy.

  11. Breakable mesoporous silica nanoparticles for targeted drug delivery.

    PubMed

    Maggini, Laura; Cabrera, Ingrid; Ruiz-Carretero, Amparo; Prasetyanto, Eko A; Robinet, Eric; De Cola, Luisa

    2016-04-01

    "Pop goes the particle". Here we report on the preparation of redox responsive mesoporous organo-silica nanoparticles containing disulfide (S-S) bridges (ss-NPs) that, even upon the exohedral grafting of targeting ligands, retained their ability to undergo structural degradation, and increase their local release activity when exposed to a reducing agent. This degradation could be observed also inside glioma C6 cancer cells. Moreover, when anticancer drug-loaded pristine and derivatized ss-NPs were fed to glioma C6 cells, the responsive hybrids were more effective in their cytotoxic action compared to non-breakable particles. The possibility of tailoring the surface functionalization of this hybrid, yet preserving its self-destructive behavior and enhanced drug delivery properties, paves the way for the development of effective biodegradable materials for in vivo targeted drug delivery.

  12. Breakable mesoporous silica nanoparticles for targeted drug delivery.

    PubMed

    Maggini, Laura; Cabrera, Ingrid; Ruiz-Carretero, Amparo; Prasetyanto, Eko A; Robinet, Eric; De Cola, Luisa

    2016-04-01

    "Pop goes the particle". Here we report on the preparation of redox responsive mesoporous organo-silica nanoparticles containing disulfide (S-S) bridges (ss-NPs) that, even upon the exohedral grafting of targeting ligands, retained their ability to undergo structural degradation, and increase their local release activity when exposed to a reducing agent. This degradation could be observed also inside glioma C6 cancer cells. Moreover, when anticancer drug-loaded pristine and derivatized ss-NPs were fed to glioma C6 cells, the responsive hybrids were more effective in their cytotoxic action compared to non-breakable particles. The possibility of tailoring the surface functionalization of this hybrid, yet preserving its self-destructive behavior and enhanced drug delivery properties, paves the way for the development of effective biodegradable materials for in vivo targeted drug delivery. PMID:26974603

  13. Externally Controlled Nanomachines on Mesoporous Silica Nanoparticles for Biomedical Applications.

    PubMed

    Rühle, Bastian; Saint-Cricq, Philippe; Zink, Jeffrey I

    2016-06-17

    Many machines (including nanomachines) consist of a solid support with moving parts that can undergo large amplitude motion to carry out specific tasks. In this Minireview, we will describe nanomachines that are supported on mesoporous silica nanoparticles that are typically 50-100 nanometers in diameter and have an array of open, readily accessible pores with an average width of a few nanometers. For triggering a large amplitude motion of the moving parts, we will focus primarily on external stimuli such as heat or light. As for the specific task the machines are carrying out, this Minireview will focus on the controlled release of pharmaceutically active agents in biomedical applications. We will discuss examples of how nanomachines can be used for remotely controlled cargo release and how existing machines that were originally designed to respond to internal physiological stimuli could be reconfigured to respond to external stimuli instead.

  14. Porous thin films of functionalized mesoporous silica nanoparticles.

    PubMed

    Kobler, Johannes; Bein, Thomas

    2008-11-25

    The synthesis of extremely small mesoporous silica nanoparticles via a specific co-condensation process with phenyl groups is demonstrated. The suspensions are ideally suited for the production of nanoscale thin films by spin-coating. Thanks to the small particle size and the resulting low surface roughness, the films show excellent optical qualities and exhibit good diffusion properties and a highly accessible pore system. The availability of such homogeneous porous thin films made it possible to use ellipsometric porosimetry (EP) as a convenient method to determine the effective porosity of the films on their original support without destroying it. It was possible to record sorption isotherms of the thin films with ellipsometry and to correlate the data with nitrogen sorption data of dried powders of the same material. The thin films showed very low refractive indices of around 1.2. PMID:19206399

  15. Gated proton transport in aligned mesoporous silica films

    NASA Astrophysics Data System (ADS)

    Fan, Rong; Huh, Seong; Yan, Ruoxue; Arnold, John; Yang, Peidong

    2008-04-01

    Modulated proton transport plays significant roles in biological processes such as ATP synthesis as well as in technologically important applications including, for example, hydrogen fuel cells. The state-of-the-art proton-exchange membrane is the sulphonated tetrafluoroethylene copolymer Nafion developed by DuPont in the late 1960s, with a high proton conductivity. However, actively switchable proton conduction, a functional mimic of the ion transport within a cell membrane, has yet to be realized. Herein, we report the electrostatic gating of proton transport within aligned mesoporous silica thin film. It is observed that surface-charge-mediated transport is dominant at low proton concentrations. We have further demonstrated that the proton conduction can be actively modulated by two-fourfold with a gate voltage as low as 1V. Such artificial gatable ion transport media could have potential applications in nanofluidic chemical processors, biomolecular separation and electrochemical energy conversion.

  16. Synthesis of hydrothermally stable, hierarchically mesoporous aluminosilicate Al-SBA-1 and their catalytic properties

    NASA Astrophysics Data System (ADS)

    Li, Na; Wang, Jin-Gui; Xu, Jian-Xiong; Liu, Jin-Yu; Zhou, Hui-Jing; Sun, Ping-Chuan; Chen, Tie-Hong

    2012-03-01

    Hydrothermally stable mesoporous aluminosilicates Al-SBA-1 with hierarchical pore structure have been successfully synthesized under alkaline condition at 120 °C by employing organic mesomorphous complexes of polyelectrolyte (poly(acrylic acid) (PAA)) and cationic surfactant (hexadecyl pyridinium chloride (CPC)) as template. The Si/Al ratio could be as high as 5 and the incorporation of Al into the silica framework did not disturb the well-ordered cubic Pm3&cmb.macr;n mesostructure. Meanwhile, the incorporation of Al could greatly increase the specific surface area and pore volume of the samples. The Al-SBA-1 materials exhibited a high hydrothermal stability and remained stable even after being treated in boiling water for 10 days. The catalytic activity of the Al-SBA-1 materials was investigated by employing the Friedel-Crafts alkylation of toluene with benzyl alcohol as a model reaction and they exhibited excellent catalytic property due to the incorporated acid sites and the hierarchically mesoporous structure.

  17. Breakable mesoporous silica nanoparticles for targeted drug delivery

    NASA Astrophysics Data System (ADS)

    Maggini, Laura; Cabrera, Ingrid; Ruiz-Carretero, Amparo; Prasetyanto, Eko A.; Robinet, Eric; de Cola, Luisa

    2016-03-01

    ``Pop goes the particle''. Here we report on the preparation of redox responsive mesoporous organo-silica nanoparticles containing disulfide (S-S) bridges (ss-NPs) that, even upon the exohedral grafting of targeting ligands, retained their ability to undergo structural degradation, and increase their local release activity when exposed to a reducing agent. This degradation could be observed also inside glioma C6 cancer cells. Moreover, when anticancer drug-loaded pristine and derivatized ss-NPs were fed to glioma C6 cells, the responsive hybrids were more effective in their cytotoxic action compared to non-breakable particles. The possibility of tailoring the surface functionalization of this hybrid, yet preserving its self-destructive behavior and enhanced drug delivery properties, paves the way for the development of effective biodegradable materials for in vivo targeted drug delivery.``Pop goes the particle''. Here we report on the preparation of redox responsive mesoporous organo-silica nanoparticles containing disulfide (S-S) bridges (ss-NPs) that, even upon the exohedral grafting of targeting ligands, retained their ability to undergo structural degradation, and increase their local release activity when exposed to a reducing agent. This degradation could be observed also inside glioma C6 cancer cells. Moreover, when anticancer drug-loaded pristine and derivatized ss-NPs were fed to glioma C6 cells, the responsive hybrids were more effective in their cytotoxic action compared to non-breakable particles. The possibility of tailoring the surface functionalization of this hybrid, yet preserving its self-destructive behavior and enhanced drug delivery properties, paves the way for the development of effective biodegradable materials for in vivo targeted drug delivery. Electronic supplementary information (ESI) available: Full experimental procedures, additional SEM and TEM images of particles, complete UV-Vis and PL-monitored characterization of the breakdown of

  18. Nucleic acid-mesoporous silica nanoparticle conjugates for keypad lock security operation.

    PubMed

    Pu, Fang; Liu, Zhen; Ren, Jinsong; Qu, Xiaogang

    2013-03-21

    We fabricated a keypad lock system based on mesoporous silica nanoparticle (MSN)-nucleic acid conjugates. DNA strand displacement triggered the release of guest molecules entrapped within the pores of MSNs through logic-based control.

  19. A cationic surfactant assisted selective etching strategy to hollow mesoporous silica spheres.

    PubMed

    Fang, Xiaoliang; Chen, Cheng; Liu, Zhaohui; Liu, Pengxin; Zheng, Nanfeng

    2011-04-01

    Hollow mesoporous silica spheres have recently attracted increasing attention. However, effective synthesis of uniform hollow mesoporous spheres with controllable well-defined pore structures for fundamental research and practical applications has remained a significant challenge. In this work, a straightforward and effective "cationic surfactant assisted selective etching" synthetic strategy was developed for the preparation of high-quality hollow mesoporous silica spheres with either wormhole-like or oriented mesoporous shell. The as-prepared hollow mesoporous silica spheres have large surface area, high pore volume, and controllable structure parameters. Our experiments demonstrated that cationic surfactant plays critical roles in forming the hollow mesoporous structure. A formation mechanism involving the etching of solid SiO(2) accelerated by cationic surfactant followed by the redeposition of dissolved silica species directed by cationic surfactant is proposed. Furthermore, the strategy can be extended as a general strategy to transform silica-coated composite materials into yolk-shell structures with either wormhole-like or oriented mesoporous shell.

  20. Membrane interactions of mesoporous silica nanoparticles as carriers of antimicrobial peptides.

    PubMed

    Braun, Katharina; Pochert, Alexander; Lindén, Mika; Davoudi, Mina; Schmidtchen, Artur; Nordström, Randi; Malmsten, Martin

    2016-08-01

    Membrane interactions are critical for the successful use of mesoporous silica nanoparticles as delivery systems for antimicrobial peptides (AMPs). In order to elucidate these, we here investigate effects of nanoparticle charge and porosity on AMP loading and release, as well as consequences of this for membrane interactions and antimicrobial effects. Anionic mesoporous silica particles were found to incorporate considerable amounts of the cationic AMP LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES (LL-37), whereas loading is much lower for non-porous or positively charged silica nanoparticles. Due to preferential pore localization, anionic mesoporous particles, but not the other particles, protect LL-37 from degradation by infection-related proteases. For anionic mesoporous nanoparticles, membrane disruption is mediated almost exclusively by peptide release. In contrast, non-porous silica particles build up a resilient LL-37 surface coating due to their higher negative surface charge, and display largely particle-mediated membrane interactions and antimicrobial effects. For positively charged mesoporous silica nanoparticles, LL-37 incorporation promotes the membrane binding and disruption displayed by the particles in the absence of peptide, but also causes toxicity against human erythrocytes. Thus, the use of mesoporous silica nanoparticles as AMP delivery systems requires consideration of membrane interactions and selectivity of both free peptide and the peptide-loaded nanoparticles, the latter critically dependent on nanoparticle properties. PMID:27174622

  1. One-step synthesis of hydrophobic mesoporous silica and its application in nonylphenol adsorption

    NASA Astrophysics Data System (ADS)

    Zhao, Yanling; Song, Jinliang; Wu, Dong; Tang, Tao; Sun, Yuhan

    2015-11-01

    Highly CH3-functionalized mesoporous silica with nearly spherical morphology was synthesized under acidic conditions by co-condensation of two different silica precursors polymethylhydrosiloxane (PMHS) and tetraethoxysilane (TEOS) in the presence of triblock copolymer P123 as template. XRD, N2 adsorption-desorption, HRTEM, SEM and 29Si MAS NMR were used to identify its highly-ordered mesopore array structure, nearly spherical particle morphology and CH3 functionalization of the as-synthesized material. The resulting hydrophobic mesoporous silica possessed regular mesochannel arrays, indicating that the introduction of PMHS had little impact on the formation of an ordered mesostructure. Also, PMHS played an important role in morphology control and organic functionalization, ensuring nearly spherical particle morphology and high CH3 functionalization degree of the obtained mesoporous silica material. As compared with pristine mesoporous silica SBA-15, the hydrophobic mesoporous silica showed the higher adsorption performance when they were used as adsorbents to remove organic pollutant nonylphenol at a very low concentration from aqueous solution.

  2. High performance of phosphonate-functionalized mesoporous silica for U(VI) sorption from aqueous solution.

    PubMed

    Yuan, Li-Yong; Liu, Ya-Lan; Shi, Wei-Qun; Lv, Yu-Long; Lan, Jian-Hui; Zhao, Yu-Liang; Chai, Zhi-Fang

    2011-07-28

    The renaissance of nuclear energy promotes increasing basic research on the separation and enrichment of nuclear fuel associated radionuclides. Herein, we report the first study for developing mesoporous silica functionalized with phosphonate (NP10) as a sorbent for U(VI) sorption from aqueous solution. The mesoporous silica was synthesized by co-condensation of diethylphosphatoethyltriethoxysilane (DPTS) and tetraethoxysilane (TEOS), using cationic surfactant cetyltrimethylammonium bromide (CTAB) as the template. The synthesized silica nanoparticles were observed to possess a mesoporous structure with a uniform pore diameter of 2.7 nm, and to have good stability and high efficiency for U(VI) sorption from aqueous solution. A maximum sorption capacity of 303 mg g(-1) and fast equilibrium time of 30 min were achieved under near neutral conditions at room temperature. The adsorbed U(VI) can be easily desorbed by using 0.1 mol L(-1) HNO(3), and the reclaimed mesoporous silica can be reused with no decrease of sorption capacity. In addition, the preconcentration of U(VI) from a 100 mL aqueous solution using the functionalized mesoporous silica was also studied. The preconcentration factor was found to be as high as 100, suggesting the vast opportunities of this kind of mesoporous silica for the solid-phase extraction and enrichment of U(VI). PMID:21681327

  3. Membrane interactions of mesoporous silica nanoparticles as carriers of antimicrobial peptides.

    PubMed

    Braun, Katharina; Pochert, Alexander; Lindén, Mika; Davoudi, Mina; Schmidtchen, Artur; Nordström, Randi; Malmsten, Martin

    2016-08-01

    Membrane interactions are critical for the successful use of mesoporous silica nanoparticles as delivery systems for antimicrobial peptides (AMPs). In order to elucidate these, we here investigate effects of nanoparticle charge and porosity on AMP loading and release, as well as consequences of this for membrane interactions and antimicrobial effects. Anionic mesoporous silica particles were found to incorporate considerable amounts of the cationic AMP LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES (LL-37), whereas loading is much lower for non-porous or positively charged silica nanoparticles. Due to preferential pore localization, anionic mesoporous particles, but not the other particles, protect LL-37 from degradation by infection-related proteases. For anionic mesoporous nanoparticles, membrane disruption is mediated almost exclusively by peptide release. In contrast, non-porous silica particles build up a resilient LL-37 surface coating due to their higher negative surface charge, and display largely particle-mediated membrane interactions and antimicrobial effects. For positively charged mesoporous silica nanoparticles, LL-37 incorporation promotes the membrane binding and disruption displayed by the particles in the absence of peptide, but also causes toxicity against human erythrocytes. Thus, the use of mesoporous silica nanoparticles as AMP delivery systems requires consideration of membrane interactions and selectivity of both free peptide and the peptide-loaded nanoparticles, the latter critically dependent on nanoparticle properties.

  4. Carbon functionalized mesoporous silica-based gas sensors for indoor volatile organic compounds.

    PubMed

    Liu, Yupu; Chen, Junchen; Li, Wei; Shen, Dengke; Zhao, Yujuan; Pal, Manas; Yu, Haijun; Tu, Bo; Zhao, Dongyuan

    2016-09-01

    Indoor organic gaseous pollution is a global health problem, which seriously threats the health and life of human all over the world. Hence, it is important to fabricate new sensing materials with high sensitivity and efficiency for indoor volatile organic compounds. In this study, a series of ordered mesoporous silica-based nanocomposites with uniform carbon coatings on the internal surface of silica mesopore channels were synthesized through a simple template-carbonization strategy. The obtained mesoporous silica-carbon nanocomposites not only possess ordered mesostructures, high surface areas (up to ∼759m(2)g(-1)), large and tunable pore sizes (2.6-10.2nm), but also have the improved hydrophobicity and anti-interference capability to environmental humidity. The sensing performances of the mesoporous silica-carbon nanocomposites to volatile organic compounds, such as ethylbenzene, methylbenzene, benzene, methanol, acetone, formaldehyde, dichloromethane and tetrahydrofuran, were systematically investigated. The relationships between the sensing performances and their properties, including mesostructures, surface areas, pore sizes, carbon contents and surface hydrophilic/hydrophobic interactions, have been achieved. The mesoporous silica-carbon nanocomposites with hexagonal mesostructure exhibit outstanding performance at room temperature to benzene and acetone with high responses, short response (2-3s) and recovery (16-19s) time, strong anti-interference to environmental humidity, and long-term stability (less than ∼5% loss of the frequency shifts after 42days). Therefore, the obtained mesoporous silica-carbon nanocomposites have a hopeful prospect in the field of environmental air quality monitoring.

  5. Mechanical Stability of Templated Mesoporous Silica Thin Films

    SciTech Connect

    Williford, Rick E.; Li, Xiaohong S.; Addleman, Raymond S.; Fryxell, Glen E.; Baskaran, Suresh; Birnbaum, Jerome C.; Coyle, Christopher A.; Zemanian, Thomas S.; Wang, Chong M.; Courtney, Andrea R.

    2005-11-07

    Mesoporous silica thin films about 1 micron thick were prepared by spin casting using several organic templates that provide a range of pore structures from disordered (sponge-like) to more ordered (honeycomb-like) 2D hexagonal arrays. Nanoindentation measurements indicate that the elastic modulus (E), and thus the density, of the pore wall material are substantially lower than for fused silica. The corresponding lower dielectric constant for pore walls was used to calculate film porosities (P) with recent correlations from the literature. Curve fits to the standard modulus vs. porosity correlation, E/Eporewall=(1-P)n, for the films gave lower n=2.2 for the honeycomb-like film with higher E, but higher n=2.5 for the sponge-like film with lower E, in contrast to theoretical expectations (n=2 for sponge-like and n=3 for honeycomb-like). Although the dielectric constant depends primarily on first-order structural information (P), the elastic modulus of these structurally imperfect films required second-order (pore wall thickness/diameter ratio) and third-order (pore connectivity) parameters to resolve the data. The power law exponent n can vary continuously, depending on the details of the mesostructure, and should not be assumed a' priori unless justified by detailed structural information

  6. Synthesis of cubic Ia-3d mesoporous silica in anionic surfactant templating system with the aid of acetate.

    PubMed

    Deng, Shao-Xin; Xu, Xue-Yan; He, Wen-Chao; Wang, Jin-Gui; Chen, Tie-Hong

    2014-08-01

    Mesoporous silica with three-dimensional (3D) bicontinuous cubic Ia-3d structure and fascinating caterpillar-like morphology was synthesized by using anionic surfactant N-lauroylsarcosine sodium (Sar-Na) as the template and 3-amionpropyltrimethoxysilane (APS) as the co-structure-directing agent (CSDA) with the aid of acetate. A phase transformation from high interfacial curvature 2D hexagonal to low interfacial curvature 3D cubic Ia-3d occurred in the presence of a proper amount of acetate. Other species of salts (excluding acetate) had the ability to induce the caterpillar-like morphology, but failed to induce the cubic Ia-3d mesostructure. Furthermore, [3-(2-aminoethyl)-aminopropyl]trimethoxysilane (DAPS) was also used as the CSDA to synthesize Ia-3d mesostructured silica under the aid of sodium acetate. After extraction of the anionic surfactants, amino and di-amine functionalized 3D bicontinuous cubic Ia-3d mesoporous silicas were obtained and used as supports to immobilize Pd nanoparticles for supported catalysts. The catalytic activity of the catalysts was tested by catalytic hydrogenation of allyl alcohol.

  7. Development of nanoaptamers using a mesoporous silica model labeled with (99m)tc for cancer targeting.

    PubMed

    Sá, Lucas Torres Miranda; Pessoa, Claudia; Meira, Assuero Silva; da Silva, Maria Isabel Pais; Missailidis, Sotiris; Santos-Oliveira, Ralph

    2012-01-01

    The use of mesoporous silica in targeted cancer therapy is increasing daily. The combination of a rigid model of nanoparticles like mesoporous silica and biological compounds with an affinity for oncological diseases is the most promising drug-targeting system nowadays. In this study, we used the mesoporous silica SBA-15 combined with aptamer (functionalized for tumor with MUC1). The results obtained were of interest and showed the formation of the silica mesoporous structure. The impregnation methodology of mesoporous silica with the aptamer was also confirmed. Cytotoxicity results demonstrated that the particle associated with the aptamer has no cytotoxicity. We conclude that although further studies are required, the mesoporous silica nanoparticle model loaded with aptamer is very functional and can be used for other applications, especially in nuclear medicine. PMID:22508189

  8. Synthesis, characterization and catalytic activity of carbon-silica hybrid catalyst from rice straw

    NASA Astrophysics Data System (ADS)

    Janaun, J.; Safie, N. N.; Siambun, N. J.

    2016-07-01

    The hybrid-carbon catalyst has been studied because of its promising potential to have high porosity and surface area to be used in biodiesel production. Silica has been used as the support to produce hybrid carbon catalyst due to its mesoporous structure and high surface area properties. The chemical synthesis of silica-carbon hybrid is expensive and involves more complicated preparation steps. The presence of natural silica in rice plants especially rice husk has received much attention in research because of the potential as a source for solid acid catalyst synthesis. But study on rice straw, which is available abundantly as agricultural waste is limited. In this study, rice straw undergone pyrolysis and functionalized using fuming sulphuric acid to anchor -SO3H groups. The presence of silica and the physiochemical properties of the catalyst produced were studied before and after sulphonation. The catalytic activity of hybrid carbon silica acid catalyst, (H-CSAC) in esterification of oleic acid with methanol was also studied. The results showed the presence of silica-carbon which had amorphous structure and highly porous. The carbon surface consisted of higher silica composition, had lower S element detected as compared to the surface that had high carbon content but lower silica composition. This was likely due to the fact that Si element which was bonded to oxygen was highly stable and unlikely to break the bond and react with -SO3H ions. H-CSAC conversions were 23.04 %, 35.52 % and 34.2 7% at 333.15 K, 343.15 K and 353.15 K, respectively. From this research, rice straw can be used as carbon precursor to produce hybrid carbon-silica catalyst and has shown catalytic activity in biodiesel production. Rate equation obtained is also presented.

  9. Fabrication of mesoporous silica for ultra-low-k interlayer dielectrics

    NASA Astrophysics Data System (ADS)

    Fujii, Nobutoshi; Kohmura, Kazuo; Nakayama, Takahiro; Tanaka, Hirofumi; Hata, Nobuhiro; Seino, Yutaka; Kikkawa, Takamaro

    2005-11-01

    We have developed sol-gel self-assembly techniques to control the pore structure and diameter of ultra-low-k interlayer dielectric (ILD) films. Porous silica films have been fabricated using cationic and nonionic surfactants as templates, resulting in 2D-hexagonal and disordered pore structures, respectively. The disordered mesoporous silica film has a worm-hole like network of pore channels having a uniform diameter. Precursors of the mesoporous silica films were synthesized by use of tetraethyl-orthosilicate (TEOS), inorganic acid, water, ethanol and various surfactants. The surfactants used were cationic alkyltrimethyl-ammonium (ATMA) chloride surfactants for 2D-hexagonal pores and nonionic tri-block copolymer for disordered structures. Dimethyldiethoxysilane (DMDEOS) was added for forming the disordered mesoporous silica. The disordered cylindrical pore structure with a uniform pore size was fabricated by controlling the static electrical interaction between the surfactant and the silica oligomer with methyl group of DMDEOS. Tetramethylcycrotetrasiloxane (TMCTS) vapor treatment was developed, which improved the mechanical strength of mesoporous silica films. The TMCTS polymer covered the pore wall surface and cross-linked to passivate the mechanical defects in the silica wall. Significant enhancement of mechanical strength was demonstrated by TMCTS vapor treatment. The porous silica film modified with a catalyst and a plasma treatment achieved higher mechanical strength and lower dielectric constant than conventional porous silica films because the TMCTS vapor treatment was more effective for mechanical reinforcement and hydrophobicity.

  10. Preparation of Mesoporous Silica Templated Metal Nanowire Films on Foamed Nickel Substrates

    SciTech Connect

    Campbell, Roger; Kenik, Edward A; Bakker, Martin; Havrilla, George; Montoya, Velma; Shamsuzzoha, Mohammed

    2006-01-01

    A method has been developed for the formation of high surface area nanowire films on planar and three-dimensional metal electrodes. These nanowire films are formed via electrodeposition into a mesoporous silica film. The mesoporous silica films are formed by a sol-gel process using Pluronic tri-block copolymers to template mesopore formation on both planar and three-dimensional metal electrodes. Surface area increases of up to 120-fold have been observed in electrodes containing a templated film when compared to the same types of electrodes without the templated film.

  11. Carboxylic acid-grafted mesoporous material and its high catalytic activity in one-pot three-component coupling reaction

    NASA Astrophysics Data System (ADS)

    Gomes, Ruth; Dutta, Saikat; Bhaumik, Asim

    2014-11-01

    A new carboxylic acid functionalized mesoporous organic polymer has been synthesized via in situ radical polymerization of divinylbenzene and acrylic acid using a mesoporous silica as a seed during the polymerization process under solvothermal conditions. The mesoporous material MPDVAA-1 has been thoroughly characterized employing powder XRD, solid state 13C cross polarization magic angle spinning-nuclear magnetic resonance, FT-IR spectroscopy, N2 sorption, HR-TEM, and NH3 temperature programmed desorption-thermal conductivity detector (TPD-TCD) analysis to understand its porosity, chemical environment, bonding, and surface properties. The mesoporous polymer was used as a catalyst for a three comp onent Biginelli condensation between various aldehydes, β-keto esters, and urea/thioureas to give 3,4-dihydropyrimidine-2(1H)-ones. The reactions were carried out under conventional heating as well as solvent-free microwave irradiation of solid components, and in both the cases, the mesoporous polymer MPDVAA-1 proved to be a powerful, robust, and reusable catalyst with high catalytic efficiency.

  12. Carboxylic acid-grafted mesoporous material and its high catalytic activity in one-pot three-component coupling reaction

    SciTech Connect

    Gomes, Ruth; Bhaumik, Asim; Dutta, Saikat

    2014-11-01

    A new carboxylic acid functionalized mesoporous organic polymer has been synthesized via in situ radical polymerization of divinylbenzene and acrylic acid using a mesoporous silica as a seed during the polymerization process under solvothermal conditions. The mesoporous material MPDVAA-1 has been thoroughly characterized employing powder XRD, solid state {sup 13}C cross polarization magic angle spinning-nuclear magnetic resonance, FT-IR spectroscopy, N{sub 2} sorption, HR-TEM, and NH{sub 3} temperature programmed desorption-thermal conductivity detector (TPD-TCD) analysis to understand its porosity, chemical environment, bonding, and surface properties. The mesoporous polymer was used as a catalyst for a three comp onent Biginelli condensation between various aldehydes, β-keto esters, and urea/thioureas to give 3,4-dihydropyrimidine-2(1H)-ones. The reactions were carried out under conventional heating as well as solvent-free microwave irradiation of solid components, and in both the cases, the mesoporous polymer MPDVAA-1 proved to be a powerful, robust, and reusable catalyst with high catalytic efficiency.

  13. N-doped mesoporous carbons supported palladium catalysts prepared from chitosan/silica/palladium gel beads.

    PubMed

    Zeng, Minfeng; Wang, Yudong; Liu, Qi; Yuan, Xia; Feng, Ruokun; Yang, Zhen; Qi, Chenze

    2016-08-01

    In this study, a heterogeneous catalyst including palladium nanoparticles supported on nitrogen-doped mesoporous carbon (Pd@N-C) is synthesized from palladium salts as palladium precursor, colloidal silica as template, and chitosan as carbon source. N2 sorption isotherm results show that the prepared Pd@N-C had a high BET surface area (640m(2)g(-1)) with large porosity. The prepared Pd@N-C is high nitrogen-rich as characterized with element analysis. X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy characterization of the catalyst shows that the palladium species with different chemical states are well dispersed on the nitrogen-containing mesoporous carbon. The Pd@N-C is high active and shows excellent stability as applied in Heck coupling reactions. This work supplies a successful method to prepare Pd heterogeneous catalysts with high performance from bulk biopolymer/Pd to high porous nitrogen-doped carbon supported palladium catalytic materials. PMID:27155234

  14. Preparation of mesoporous silica thin films by photocalcination method and their adsorption abilities for various proteins.

    PubMed

    Kato, Katsuya; Nakamura, Hitomi; Yamauchi, Yoshihiro; Nakanishi, Kazuma; Tomita, Masahiro

    2014-07-01

    Mesoporous silica (MPS) thin film biosensor platforms were established. MPS thin films were prepared from tetraethoxysilane (TEOS) via using sol-gel and spin-coating methods using a poly-(ethylene oxide)-block-poly-(propylene oxide)-block-poly-(ethylene oxide) triblock polymer, such as P123 ((EO)20(PO)70(EO)20) or F127 ((EO)106(PO)70(EO)106), as the structure-directing agent. The MPS thin film prepared using P123 as the mesoporous template and treated via vacuum ultraviolet (VUV) irradiation to remove the triblock copolymer had a more uniform pore array than that of the corresponding film prepared via thermal treatment. Protein adsorption and enzyme-linked immunosorbent assay (ELISA) on the synthesized MPS thin films were also investigated. VUV-irradiated MPS thin films adsorbed a smaller quantity of protein A than the thermally treated films; however, the human immunoglobulin G (IgG) binding efficiency was higher on the former. In addition, protein A-IgG specific binding on MPS thin films was achieved without using a blocking reagent; i.e., nonspecific adsorption was inhibited by the uniform pore arrays of the films. Furthermore, VUV-irradiated MPS thin films exhibited high sensitivity for ELISA testing, and cytochrome c adsorbed on the MPS thin films exhibited high catalytic activity and recyclability. These results suggest that MPS thin films are attractive platforms for the development of novel biosensors. PMID:24857463

  15. Post-treatment and characterization of novel luminescent hybrid bimodal mesoporous silicas

    SciTech Connect

    Li Yuzhen; Sun Jihong; Wu Xia; Lin Li; Gao Lin

    2010-08-15

    A novel luminescent hybrid bimodal mesoporous silicas (LHBMS) were synthesized via grafting 1,8-Naphthalic anhydride into the pore channels of bimodal mesoporous silicas (BMMs) for the first time. The resulting samples were characterized by powder X-ray diffraction (XRD), N{sub 2} adsorption/desorption measurement, Fourier transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM), UV-vis absorption spectroscopy, and Photoluminescence spectroscopy (PL). The results show that 1,8-Naphthalic anhydride organic groups have been successfully introduced into the mesopores of the BMMs and the hybrid silicas are of bimodal mesoporous structure with the ordered small mesopores of around 3 nm and the large mesopores of uniform intra-nanoparticle. The excellent photoluminescent performance of LHBMS has a blue shift compared to that of 2-[3-(triethoxysilyl) propyl-1 H-Benz [de]isoquinoline-1, 3(2 H)-dione, suggesting the existence of the quantum confinement effectiveness. - Graphical abstract: A novel luminescent hybrid bimodal mesoporous silicas was synthesized via modification and then grafting with 1, 8-Naphthalic anhydride, which would be strong potential application in the photoluminescent fields.

  16. Surface functionalized mesoporous silica nanoparticles for intracellular drug delivery

    NASA Astrophysics Data System (ADS)

    Vivero-Escoto, Juan Luis

    Mesoporous silica nanoparticles (MSNs) are a highly promising platform for intracellular controlled release of drugs and biomolecules. Despite that the application of MSNs in the field of intracellular drug delivery is still at its infancy very exciting breakthroughs have been achieved in the last years. A general review of the most recent progress in this area of research is presented, including a description of the latest findings on the pathways of entry into live mammalian cells together with the intracellular trafficking, a summary on the contribution of MSNs to the development of site-specific drug delivery systems, a report on the biocompatibility of this material in vitro andin vivo, and a discussion on the most recent breakthroughs in the synthesis and application of stimuli-responsive mesoporous silica-based delivery vehicles. A gold nanoparticles (AuNPs)-capped MSNs-based intracellular photoinduced drug delivery system (PR-AuNPs-MSNs) for the controlled release of anticancer drug inside of human fibroblast and liver cells was synthesized and characterized. We found that the mesoporous channels of MSNs could be efficiently capped by the photoresponsive AuNPs without leaking the toxic drug, paclitaxel, inside of human cells. Furthermore, we demonstrated that the cargo-release property of this PR-AuNPs-MSNs system could be easily photo-controlled under mild and biocompatible conditions in vitro. In collaboration with Renato Mortera (a visiting student from Italy), a MSNs based intracellular delivery system for controlled release of cell membrane impermeable cysteine was developed. A large amount of cysteine molecules were covalently attached to the silica surface of MSNs through cleavable disulfide linkers. These cysteine-containing nanoparticles were efficiently endocytosed by human cervical cancer cells HeLa. These materials exhibit 450 times higher cell growth inhibition capability than that of the conventional N-acetylcysteine prodrug. The ability to

  17. A reversible light-operated nanovalve on mesoporous silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Tarn, Derrick; Ferris, Daniel P.; Barnes, Jonathan C.; Ambrogio, Michael W.; Stoddart, J. Fraser; Zink, Jeffrey I.

    2014-02-01

    Two azobenzene α-cyclodextrin based nanovalves are designed, synthesized and assembled on mesoporous silica nanoparticles. Under aqueous conditions, the cyclodextrin cap is tightly bound to the azobenzene moiety and capable of holding back loaded cargo molecules. Upon irradiation with a near-UV light laser, trans to cis-photoisomerization of azobenzene initiates a dethreading process, which causes the cyclodextrin cap to unbind followed by the release of cargo. The addition of a bulky stopper to the end of the stalk allows this design to be reversible; complete dethreading of cyclodextrin as a result of unbinding with azobenzene is prevented as a consequence of steric interference. As a result, thermal relaxation of cis- to trans-azobenzene allows for the rebinding of cyclodextrin and resealing of the nanopores, a process which entraps the remaining cargo. Two stalks were designed with different lengths and tested with alizarin red S and propidium iodide. No cargo release was observed prior to light irradiation, and the system was capable of multiuse. On/off control was also demonstrated by monitoring the release of cargo when the light stimulus was applied and removed, respectively.Two azobenzene α-cyclodextrin based nanovalves are designed, synthesized and assembled on mesoporous silica nanoparticles. Under aqueous conditions, the cyclodextrin cap is tightly bound to the azobenzene moiety and capable of holding back loaded cargo molecules. Upon irradiation with a near-UV light laser, trans to cis-photoisomerization of azobenzene initiates a dethreading process, which causes the cyclodextrin cap to unbind followed by the release of cargo. The addition of a bulky stopper to the end of the stalk allows this design to be reversible; complete dethreading of cyclodextrin as a result of unbinding with azobenzene is prevented as a consequence of steric interference. As a result, thermal relaxation of cis- to trans-azobenzene allows for the rebinding of cyclodextrin and

  18. Bio-templated synthesis of highly ordered macro-mesoporous silica material for sustained drug delivery

    NASA Astrophysics Data System (ADS)

    Qu, Fengyu; Lin, Huiming; Wu, Xiang; Li, Xiaofeng; Qiu, Shilun; Zhu, Guangshan

    2010-05-01

    The bimodal porous structured silica materials consisting of macropores with the diameter of 5-20 μm and framework-like mesopores with the diameter of 4.7-6.0 nm were prepared using natural Manchurian ash and mango linin as macropored hard templates and P123 as mesopore soft templates, respectively. The macroporous structures of Manchurian ash and mango linin were replicated with the walls containing highly ordered mesoporous silica as well. As-synthesized dual porous silica was characterized by scanning electron microscope (SEM), powder X-ray diffraction (XRD), transmission electron microscope (TEM) and nitrogen adsorption/desorption, fourier transform IR (FTIR) spectroscopy, and thermo-gravimetric analyzer (TGA). Ibuprofen (Ibu) was employed as a model drug and the release profiles showed that the dual porous material had a sustained drug delivery capability. And such highly ordered dual pore silica materials may have potential applications for bimolecular adsorption/separation and tissue repairing.

  19. Well-Dispersed ZIF-Derived Co,N-Co-doped Carbon Nanoframes through Mesoporous-Silica-Protected Calcination as Efficient Oxygen Reduction Electrocatalysts.

    PubMed

    Shang, Lu; Yu, Huijun; Huang, Xing; Bian, Tong; Shi, Run; Zhao, Yufei; Waterhouse, Geoffrey I N; Wu, Li-Zhu; Tung, Chen-Ho; Zhang, Tierui

    2016-02-24

    A well-dispersed Co,N co-doped carbon nanoframework (Co,N-CNF) with hierarchically porous structure is successfully synthesized from zeolitic imidazolate framework (ZIF) precursors via a mesoporous-silica-protected calcination strategy. By preventing the irreversible fusion and aggregation during the high-temperature pyrolysis step with this protection strategy, the Co,N-CNF exhibits comparable oxygen reduction reaction (ORR) catalytic activity to that of commercial Pt catalysts with the same loading.

  20. Hollow mesoporous ceria nanoreactors with enhanced activity and stability for catalytic application.

    PubMed

    Liu, Baocang; Yu, Shengli; Wang, Qin; Hu, Wenting; Jing, Peng; Liu, Yang; Jia, Wenjing; Liu, Yongxin; Liu, Lixia; Zhang, Jun

    2013-05-01

    Novel hollow mesoporous @M/CeO(2) (M = Au, Pd, and Au-Pd) nanospheres are created. The nanospheres can be used as effective nanoreactors with superior catalytic activity and stability for reduction of 4-nitrophenol due to their hollow mesoporous structural features.

  1. Protective effect of mesoporous silica particles on encapsulated folates.

    PubMed

    Ruiz-Rico, María; Daubenschüz, Hanna; Pérez-Esteve, Édgar; Marcos, María D; Amorós, Pedro; Martínez-Máñez, Ramón; Barat, José M

    2016-08-01

    Mesoporous silica particles (MSPs) are considered suitable supports to design gated materials for the encapsulation of bioactive molecules. Folates are essential micronutrients which are sensitive to external agents that provoke nutritional deficiencies. Folates encapsulation in MSPs to prevent degradation and to allow their controlled delivery is a promising strategy. Nevertheless, no information exists about the protective effect of MSPs encapsulation to prevent their degradation. In this work, 5-formyltetrahydrofolate (FO) and folic acid (FA) were entrapped in MSPs functionalized with polyamines, which acted as pH-dependent molecular gates. The stability of free and entrapped vitamins after acidic pH, high temperature and light exposure was studied. The results showed the degradation of FO after high temperature and acidic pH, whereas entrapped FO displayed enhanced stability. Free FA was degraded by light, but MSPs stabilized the vitamin. The obtained results point toward the potential use of MSPs as candidates to enhance stability and to improve the bioavailability of functional biomolecules. PMID:27235728

  2. Protective effect of mesoporous silica particles on encapsulated folates.

    PubMed

    Ruiz-Rico, María; Daubenschüz, Hanna; Pérez-Esteve, Édgar; Marcos, María D; Amorós, Pedro; Martínez-Máñez, Ramón; Barat, José M

    2016-08-01

    Mesoporous silica particles (MSPs) are considered suitable supports to design gated materials for the encapsulation of bioactive molecules. Folates are essential micronutrients which are sensitive to external agents that provoke nutritional deficiencies. Folates encapsulation in MSPs to prevent degradation and to allow their controlled delivery is a promising strategy. Nevertheless, no information exists about the protective effect of MSPs encapsulation to prevent their degradation. In this work, 5-formyltetrahydrofolate (FO) and folic acid (FA) were entrapped in MSPs functionalized with polyamines, which acted as pH-dependent molecular gates. The stability of free and entrapped vitamins after acidic pH, high temperature and light exposure was studied. The results showed the degradation of FO after high temperature and acidic pH, whereas entrapped FO displayed enhanced stability. Free FA was degraded by light, but MSPs stabilized the vitamin. The obtained results point toward the potential use of MSPs as candidates to enhance stability and to improve the bioavailability of functional biomolecules.

  3. Mixed surfactants-directed the mesoporous silica materials with various morphologies and structures

    SciTech Connect

    Lin Huiming; Qu Fengyu; Wu Xiang; Xue Ming; Zhu Guangshan; Qiu Shilun

    2011-06-15

    A new mixed surfactants system using alkyl carboxylic acids and quaternized poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl] urea] (PEPU) as the co-template was used to synthesize mesoporous silica materials with various morphologies and structures, including flakes, regular spheres, nanoparticles, and tube-spheres. The cationic polymer connected the anionic surfactant micelle to the anionic polysilicate species to induce the synthesis of the mesoporous silica materials. The structure and property of the surfactant and the cationic polymer determined the formation of mesoporous silica, and also had a signification influence on the morphology and structure of the final materials. To further explore the possible formation mechanism of these mesoporous materials, zeta potential was utilized to evaluate the interaction between the anionic surfactant and the cationic co-template. In addition, the structure, morphology, and porosity of these materials were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N{sub 2} adsorption-desorption measurements. - Graphical abstract: A new mixed surfactants system using alkyl carboxylic acids and PEPU as the co-template was used to synthesize mesoporous silica materials with various morphologies and structures. Highlights: {yields}A new mixed surfactants system induced the mesoporous silica materials with various morphologies and structure. > It is a development of the type S{sup -}N{sup +}I{sup -} route of the mesoporous formation. > Zeta potential was utilized to evaluate the interaction between the anionic surfactant and the cationic co-template. > The property and amount of surfactant and polymer determined the formation of the mesoporous materials.

  4. Mesoporous graphitic carbon nanodisks fabricated via catalytic carbonization of coordination polymers.

    PubMed

    Su, Panpan; Jiang, Liang; Zhao, Jiao; Yan, Jingwang; Li, Can; Yang, Qihua

    2012-09-11

    Mesoporous graphitic carbon nanodisks with hierarchical porous structure, facilely fabricated by catalytic carbonization of iron-based coordination polymer nanodisks, exhibit high capacitance even at high scan rates as electrode materials for electrochemical double layer capacitors.

  5. Comprehensive Mechanism Analysis of Mesoporous-Silica-Nanoparticle-Induced Cancer Immunotherapy.

    PubMed

    Wang, Xiupeng; Li, Xia; Yoshiyuki, Kazuko; Watanabe, Yohei; Sogo, Yu; Ohno, Tadao; Tsuji, Noriko M; Ito, Atsuo

    2016-05-01

    A plain mesoporous silica nanoparticle without any immunomodulatory molecules significantly enhances anticancer immunity in vivo. Comprehensive mechanism of mesoporous-silica-nanoparticle-induced cancer immunotherapy is analyzed in this paper. The mesoporous silica nanoparticle promotes both Th1 and Th2 immune responses, as it accelerates lymphocytes proliferation, stimulates IFN-γ, IL-2, IL-4, and IL-10 cytokine secretion by lymphocytes ex vivo, and increases IgG, IgG1, IgG2a, IgM, and IgA antibody titers in mice serum compared with those of alum and adjuvant-free groups. Moreover, the mesoporous silica nanoparticle enhances effector memory CD4(+) and CD8(+) T cell populations in three most important immune organs (bone marrow, lymph node, and spleen) of mice compared with those of alum and adjuvant-free groups three months after adjuvant injection. The present study paves the way for the application of mesoporous silica nanoparticle as immunoadjuvant for cancer immunotherapy. PMID:26987867

  6. Chemical Insight into the Adsorption of Chromium(III) on Iron Oxide/Mesoporous Silica Nanocomposites.

    PubMed

    Egodawatte, Shani; Datt, Ashish; Burns, Eric A; Larsen, Sarah C

    2015-07-14

    Magnetic iron oxide/mesoporous silica nanocomposites consisting of iron oxide nanoparticles embedded within mesoporous silica (MCM-41) and modified with aminopropyl functional groups were prepared for application to Cr(III) adsorption followed by magnetic recovery of the nanocomposite materials from aqueous solution. The composite materials were extensively characterized using physicochemical techniques, such as powder X-ray diffraction, thermogravimetric and elemental analysis, nitrogen adsorption, and zeta potential measurements. For aqueous Cr(III) at pH 5.4, the iron oxide/mesoporous silica nanocomposite exhibited a superior equilibrium adsorption capacity of 0.71 mmol/g, relative to 0.17 mmol/g for unmodified mesoporous silica. The aminopropyl-functionalized iron oxide/mesoporous silica nanocomposites displayed an equilibrium adsorption capacity of 2.08 mmol/g, the highest adsorption capacity for Cr(III) of all the materials evaluated in this study. Energy-dispersive spectroscopy (EDS) with transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) experiments provided insight into the chemical nature of the adsorbed chromium species.

  7. Comprehensive Mechanism Analysis of Mesoporous-Silica-Nanoparticle-Induced Cancer Immunotherapy.

    PubMed

    Wang, Xiupeng; Li, Xia; Yoshiyuki, Kazuko; Watanabe, Yohei; Sogo, Yu; Ohno, Tadao; Tsuji, Noriko M; Ito, Atsuo

    2016-05-01

    A plain mesoporous silica nanoparticle without any immunomodulatory molecules significantly enhances anticancer immunity in vivo. Comprehensive mechanism of mesoporous-silica-nanoparticle-induced cancer immunotherapy is analyzed in this paper. The mesoporous silica nanoparticle promotes both Th1 and Th2 immune responses, as it accelerates lymphocytes proliferation, stimulates IFN-γ, IL-2, IL-4, and IL-10 cytokine secretion by lymphocytes ex vivo, and increases IgG, IgG1, IgG2a, IgM, and IgA antibody titers in mice serum compared with those of alum and adjuvant-free groups. Moreover, the mesoporous silica nanoparticle enhances effector memory CD4(+) and CD8(+) T cell populations in three most important immune organs (bone marrow, lymph node, and spleen) of mice compared with those of alum and adjuvant-free groups three months after adjuvant injection. The present study paves the way for the application of mesoporous silica nanoparticle as immunoadjuvant for cancer immunotherapy.

  8. Avidin-biotin capped mesoporous silica nanoparticles as an ion-responsive release system to determine lead(II).

    PubMed

    Song, Weiling; Li, Jingyu; Li, Qing; Ding, Wenyao; Yang, Xiaoyan

    2015-02-15

    We have developed DNAzyme-functionalized silica nanoparticles for the rapid, sensitive, and selective detection of lead ion (Pb(2+)). The specific binding between avidin and biotinylated DNAzymes was used to cap the pore of dye-trapped silica nanoparticles. In the presence of Pb(2+), DNAzymes were catalytically cleaved to uncap the pore, releasing the dye cargo with detectable enhancements of fluorescence signal. This method enables rapid (15 min) and sensitive (limit of detection=8.0 nM) detection. Moreover, the Pb(2+)-responsive behavior shows high selectivity with other metal ions. The superior properties of the as-designed DNAzyme-functionalized silica nanoparticles can be attributed to the large loading capacity and highly ordered pore structure of mesoporous silica nanoparticles as well as the catalytical cleaving of DNAzymes with Pb(2+). The recoveries obtained by standard Pb(II) addition to real samples-tap water, commercial mineral water, and lake water-were all from 98 to 101%. Our design serves as a new prototype for metal-ion sensing systems, and it also has promising potential for detection of various targets in stimulus-release systems. PMID:25447495

  9. Direct imaging Au nanoparticle migration inside mesoporous silica channels.

    PubMed

    Liu, Zhengwang; Che, Renchao; Elzatahry, Ahmed A; Zhao, Dongyuan

    2014-10-28

    Supported metal nanoparticle (NP) catalysts have been widely used in many industry processes and catalytic reactions. Catalyst deactivation is mainly caused by the sintering of supported metal NPs. Hence, understanding the metal NPs' sintering behaviors has great significance in preventing catalyst deactivation. Here we report the metal particle migration inside/between mesochannels by scanning transmission electron microscopy and electron energy loss spectroscopy via an in situ TEM heating technique. A sintering process is proposed that particle migration predominates, driven by the difference of gravitational potential from the height of the uneven internal surface of the mesopores; when the distance of the gold nanoparticles with a size of about 3 and 5 nm becomes short after migration, the coalescence process is completed, which is driven by an "octopus-claw-like" expansion of a conduction electron cloud outside the Au NPs. The supports containing an abundance of micropores help to suppress particle migration and coalescence. Our findings provide the understanding toward the rational design of supported industrial catalysts and other nanocomposites with enhanced activity and stability for applications such as batteries, catalysis, drug delivery, gas sensors, and solar cells.

  10. Mesoporous silica film from a solution containing a surfactant and methods of making same

    DOEpatents

    Liu, Jun [West Richland, WA; Domansky, Karel [Cambridge, MA; Li, Xiaohong [Richland, WA; Fryxell, Glen E [Kennewick, WA; Baskaran, Suresh [Kennewick, WA; Kohler, Nathan J [Richland, WA; Thevuthasan, Suntharampillai [Kennewick, WA; Coyle, Christopher A [Richland, WA; Birnbaum, Jerome C [Richland, WA

    2001-12-11

    The present invention is a mesoporous silica film having a low dielectric constant and method of making having the steps of combining a surfactant in a silica precursor solution, spin-coating a film from this solution mixture, forming a partially hydroxylated mesoporous film, and dehydroxylating the hydroxylated film to obtain the mesoporous film. It is advantageous that the small polyoxyethylene ether surfactants used in spin-coated films as described in the present invention will result in fine pores smaller on average than about 20 nm. The resulting mesoporous film has a dielectric constant less than 3, which is stable in moist air with a specific humidity. The present invention provides a method for superior control of film thickness and thickness uniformity over a coated wafer, and films with low dielectric constant.

  11. Bimetallic Nanocatalysts in Mesoporous Silica for Hydrogen Production from Coal-Derived Fuels

    SciTech Connect

    Kuila, Debasish; Ilias, Shamsuddin

    2013-02-13

    In steam reforming reactions (SRRs) of alkanes and alcohols to produce H2, noble metals such as platinum (Pt) and palladium (Pd) are extensively used as catalyst. These metals are expensive; so, to reduce noble-metal loading, bi-metallic nanocatalysts containing non-noble metals in MCM-41 (Mobil Composition of Material No. 41, a mesoporous material) as a support material with high-surface area were synthesized using one-pot hydrothermal procedure with a surfactant such as cetyltrimethylammonium bromide (CTAB) as a template. Bi-metallic nanocatalysts of Pd-Ni and Pd-Co with varying metal loadings in MCM-41 were characterized by x-ray diffraction (XRD), N2 adsorption, and Transmission electron microscopy (TEM) techniques. The BET surface area of MCM-41 (~1000 m2/g) containing metal nanoparticles decreases with the increase in metal loading. The FTIR studies confirm strong interaction between Si-O-M (M = Pd, Ni, Co) units and successful inclusion of metal into the mesoporous silica matrix. The catalyst activities were examined in steam reforming of methanol (SRM) reactions to produce hydrogen. Reference tests using catalysts containing individual metals (Pd, Ni and Co) were also performed to investigate the effect of the bimetallic system on the catalytic behavior in the SRM reactions. The bimetallic system remarkably improves the hydrogen selectivity, methanol conversion and stability of the catalyst. The results are consistent with a synergistic behavior for the Pd-Ni-bimetallic system. The performance, durability and thermal stability of the Pd-Ni/MCM-41 and Pd-Co/MCM-41 suggest that these materials may be promising catalysts for hydrogen production from biofuels. A part of this work for synthesis and characterization of Pd-Ni-MCM-41 and its activity for SRM reactions has been published (“Development of Mesoporous Silica Encapsulated Pd-Ni Nanocatalyst for Hydrogen Production” in “Production and Purification of Ultraclean

  12. Reversible control of pore size and surface chemistry of mesoporous silica through dynamic covalent chemistry: philicity mediated catalysis

    NASA Astrophysics Data System (ADS)

    Singh, Dheeraj Kumar; Pavan Kumar, B. V. V. S.; Eswaramoorthy, M.

    2015-08-01

    Here, we report the synthesis of adaptive hybrid mesoporous silica having the ability to reconfigure its pore properties such as pore size and philicity in response to the external environment. Decyl chains were reversibly appended to the pore walls of silica through imine motifs as dynamic covalent modules to switch the pore size and philicity in response to pH. This switching of pore properties was used to gate the access of reactants to the gold nanoparticles immobilized inside the nanopores, thus enabling us to turn-on/turn-off the catalytic reaction. The use of such dynamic covalent modules to govern pore properties would enable the realization of intelligent hybrids capable of controlling many such chemical processes in response to stimuli.Here, we report the synthesis of adaptive hybrid mesoporous silica having the ability to reconfigure its pore properties such as pore size and philicity in response to the external environment. Decyl chains were reversibly appended to the pore walls of silica through imine motifs as dynamic covalent modules to switch the pore size and philicity in response to pH. This switching of pore properties was used to gate the access of reactants to the gold nanoparticles immobilized inside the nanopores, thus enabling us to turn-on/turn-off the catalytic reaction. The use of such dynamic covalent modules to govern pore properties would enable the realization of intelligent hybrids capable of controlling many such chemical processes in response to stimuli. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02959g

  13. Modulation of microporous/mesoporous structures in self-templated cobalt-silica

    NASA Astrophysics Data System (ADS)

    Martens, Dana L.; Wang, David K.; Motuzas, Julius; Smart, Simon; da Costa, João C. Diniz

    2015-01-01

    Finite control of pore size distributions is a highly desired attribute when producing porous materials. While many methodologies strive to produce such materials through one-pot strategies, oftentimes the pore structure requires post-treatment modification. In this study, modulation of pore size in cobalt-silica systems was investigated by a novel, non-destructive, self-templated method. These systems were produced from two cobalt-containing silica starting materials which differed by extent of condensation. These starting materials, sol (SG') and xerogel (XG'), were mixed with pure silica sol to produce materials containing 5-40 mol% Co. The resultant SG-series materials exhibited typical attributes for cobalt-silica systems: mesoporous characteristics developed at high cobalt concentrations, coinciding with Co3O4 formation; whereas, in the XG-series materials, these mesoporous characteristics were extensively suppressed. Based on an examination of the resultant materials a mechanism describing the pore size formation and modulation of the two systems was proposed. Pore size modulation in the XG-series was caused, in part, by the cobalt source acting as an autogenous template for the condensation of the silica network. These domains could be modified when wetted, allowing for the infiltration and subsequent condensation of silica oligomers into the pre-formed, mesoporous cages, leading to a reduction in the mesoporous content of the final product.

  14. Dual latex/surfactant templating of hollow spherical silica particles with ordered mesoporous shells.

    PubMed

    Tan, Bing; Rankin, Stephen E

    2005-08-30

    Hollow spherical silica particles with hexagonally ordered mesoporous shells are synthesized with the dual use of cetyltrimethylammonium bromide (CTAB) and unmodified polystyrene latex microspheres as templates in concentrated aqueous ammonia. In most of the hollow mesoporous particles, cylindrical pores run parallel to the hollow core due to interactions of CTAB/silica aggregates with the latices. Effects on the product structure of the CTAB:latex ratio, the amount of aqueous ammonia, and the latex size are studied. Hollow particles with hexagonally patterned mesoporous shells are obtained at moderate CTAB:latex ratios. Too little CTAB causes silica shell growth without surfactant templating, and too much induces nucleation of new mesoporous silica particles without latex cores. The concentration of ammonia must be large to induce co-assembly of CTAB, silica, and latex into dispersed particles. The results are consistent with the formation of particles by addition of CTAB/silica aggregates to the surface of latex microspheres. When the size and number density of the latex microspheres are changed, the size of the hollow core and the shell thickness can be controlled. However, if the microspheres are too small (50 nm in this case), agglomerated particles with many hollow voids are obtained, most likely due to colloidal instability.

  15. Synthesis and Characterization of Mesoporous Silica Functionalized with Calix[4]arene Derivatives

    PubMed Central

    Alahmadi, Sana M.; Mohamad, Sharifah; Maah, Mohd Jamil

    2012-01-01

    This work reports a new method to covalently attach calix[4]arene derivatives onto MCM-41, using a diisocyanate as a linker. The modified mesoporous silicates were characterized by fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA) and elemental analysis. The FTIR spectra and TGA analysis verified that the calix[4]arene derivates are covalently attached to the mesoporous silica. The preservation of the MCM-41 channel system was checked by X-ray diffraction and nitrogen adsorption analysis. PMID:23202977

  16. Synthesis of silica-pillared clay (SPC) with ordered mesoporous structure by one-step method without preswelling process

    NASA Astrophysics Data System (ADS)

    Mao, Huihui; Li, Baoshan; Li, Xiao; Liu, Zhengxing; Ma, Wei

    2009-02-01

    The simultaneous intercalation of surfactants and TEOS into clay interlayers and subsequent intragallery ammonia-catalyzed hydrolysis of TEOS resulted in mesoporous silica-pillared clay (SPC). These SPC materials exhibited refractions corresponding to a basal spacing of 3.7-4.3 nm, a uniform pore size of 2.5-3.16 nm and large surface areas of 567-576 m 2/g. Our results indicate that surfactants play a decisive role in pore formation, because they act as micelle-like template during the hydrolysis of TOES. Moreover, the pore size of SPC derivatives is controllable by the molecular length of surfactant. All of the SPC materials reported here exhibit high catalytic activity and selectivity for coker gas oil (CGO) cracking reaction in comparison to parent MCM-41 and Al-MCM-41. The excellent acid catalytic activity, together with their sable, well-organized porous structure, opens up new opportunities for applications in catalysis.

  17. A photostable bi-luminophore pressure-sensitive paint measurement system developed with mesoporous silica nanoparticles.

    PubMed

    Mochizuki, Dai; Tamura, Shinichi; Yasutake, Hiroaki; Kataoka, Tomoharu; Mitsuo, Kazunori; Wada, Yuji

    2013-04-01

    The accurate and high-resolution measurement of surface pressure is achieved by a pressure/ temperature-sensitive composite paint (bi-PSP), whereas the pressure-sensitive dye photodegraded the temperature sensitive dye in close arrangement of both dyes. In the present study, an attempt was made to synthesize a homogeneous bi-PSP membrane without light-induced degradation of the dye using mesoporous silica. Mesoporous silica as a molecular sieve was the separation of pressure- and temperature-sensitive dyes. Both achievement of control of photodegradation in temperature-sensitive paints with molecule-screening capacity and macroscopically uniform placement of insoluble pigments in the respective solvent, was accomplished using the mesoporous silica nanoparticles in a compound PSP.

  18. Fabrication and testing of engineered forms of self-assembled monolayers on mesoporous silica (SAMMS) material

    SciTech Connect

    Mattigod, S.V.; Liu, J.; Fryxell, G.E.; Baskaran, S.; Gong, M.; Nie, Z.; Feng, X.; Klasson, K.T.

    1998-09-01

    A number of engineered forms such as flexible extrudates, beads, and rods were fabricated using thiol-SAMMS (Self-Assembled Monolayers on Mesoporous Silica) and tested for their mercury adsorption capacities. The flexible extrudate form had a mercury adsorption capacity of 340 mg/g but was found to be structurally unstable. A structurally sound bead form of thiol-SAMMS was fabricated with 5, 10, 25, and 40% by weight clay binder (attapulgite) and successfully functionalized. A structurally stable but non-optimized rod form of thiol-SAMMS was also fabricated. Bench-scale processes were developed to silanize and functionalize mesoporous silica beads made with attapulgite clay binder. Contact angle measurements were conducted to assess the degree of surface coverage by functional groups on mesoporous silica materials.

  19. Cellulose conjugated FITC-labelled mesoporous silica nanoparticles: intracellular accumulation and stimuli responsive doxorubicin release.

    PubMed

    Hakeem, Abdul; Zahid, Fouzia; Duan, Ruixue; Asif, Muhammad; Zhang, Tianchi; Zhang, Zhenyu; Cheng, Yong; Lou, Xiaoding; Xia, Fan

    2016-03-01

    Herein, we design novel cellulose conjugated mesoporous silica nanoparticle (CLS-MSP) based nanotherapeutics for stimuli responsive intracellular doxorubicin (DOX) delivery. DOX molecules are entrapped in pores of the fabricated mesoporous silica nanoparticles (MSPs) while cellulose is used as an encapsulating material through esterification on the outlet of the pores of the MSPs to avoid premature DOX release under physiological conditions. In in vitro studies, stimuli responsive DOX release is successfully achieved from DOX loaded cellulose conjugated mesoporous silica nanoparticles (DOX/CLS-MSPs) by pH and cellulase triggers. Intracellular accumulation of DOX/CLS-MSPs in human liver cancer cells (HepG2 cells) is investigated through confocal microscope magnification. Cell viability of HepG2 cells is determined as the percentage of the cells incubated with DOX/CLS-MSPs compared with that of non-incubated cells through an MTT assay.

  20. Bone tissue engineering using silica-based mesoporous nanobiomaterials:Recent progress.

    PubMed

    Shadjou, Nasrin; Hasanzadeh, Mohammad

    2015-10-01

    Bone disorders are of significant concern due to increase in the median age of our population. It is in this context that tissue engineering has been emerging as a valid approach to the current therapies for bone regeneration/substitution. Tissue-engineered bone constructs have the potential to alleviate the demand arising from the shortage of suitable autograft and allograft materials for augmenting bone healing. Silica based mesostructured nanomaterials possessing pore sizes in the range 2-50 nm and surface reactive functionalities have elicited immense interest due to their exciting prospects in bone tissue engineering. In this review we describe application of silica-based mesoporous nanomaterials for bone tissue engineering. We summarize the preparation methods, the effect of mesopore templates and composition on the mesopore-structure characteristics, and different forms of these materials, including particles, fibers, spheres, scaffolds and composites. Also, the effect of structural and textural properties of mesoporous materials on development of new biomaterials for production of bone implants and bone cements was discussed. Also, application of different mesoporous materials on construction of manufacture 3-dimensional scaffolds for bone tissue engineering was discussed. It begins by giving the reader a brief background on tissue engineering, followed by a comprehensive description of all the relevant components of silica-based mesoporous biomaterials on bone tissue engineering, going from materials to scaffolds and from cells to tissue engineering strategies that will lead to "engineered" bone.

  1. Cellulose conjugated FITC-labelled mesoporous silica nanoparticles: intracellular accumulation and stimuli responsive doxorubicin release

    NASA Astrophysics Data System (ADS)

    Hakeem, Abdul; Zahid, Fouzia; Duan, Ruixue; Asif, Muhammad; Zhang, Tianchi; Zhang, Zhenyu; Cheng, Yong; Lou, Xiaoding; Xia, Fan

    2016-02-01

    Herein, we design novel cellulose conjugated mesoporous silica nanoparticle (CLS-MSP) based nanotherapeutics for stimuli responsive intracellular doxorubicin (DOX) delivery. DOX molecules are entrapped in pores of the fabricated mesoporous silica nanoparticles (MSPs) while cellulose is used as an encapsulating material through esterification on the outlet of the pores of the MSPs to avoid premature DOX release under physiological conditions. In in vitro studies, stimuli responsive DOX release is successfully achieved from DOX loaded cellulose conjugated mesoporous silica nanoparticles (DOX/CLS-MSPs) by pH and cellulase triggers. Intracellular accumulation of DOX/CLS-MSPs in human liver cancer cells (HepG2 cells) is investigated through confocal microscope magnification. Cell viability of HepG2 cells is determined as the percentage of the cells incubated with DOX/CLS-MSPs compared with that of non-incubated cells through an MTT assay.Herein, we design novel cellulose conjugated mesoporous silica nanoparticle (CLS-MSP) based nanotherapeutics for stimuli responsive intracellular doxorubicin (DOX) delivery. DOX molecules are entrapped in pores of the fabricated mesoporous silica nanoparticles (MSPs) while cellulose is used as an encapsulating material through esterification on the outlet of the pores of the MSPs to avoid premature DOX release under physiological conditions. In in vitro studies, stimuli responsive DOX release is successfully achieved from DOX loaded cellulose conjugated mesoporous silica nanoparticles (DOX/CLS-MSPs) by pH and cellulase triggers. Intracellular accumulation of DOX/CLS-MSPs in human liver cancer cells (HepG2 cells) is investigated through confocal microscope magnification. Cell viability of HepG2 cells is determined as the percentage of the cells incubated with DOX/CLS-MSPs compared with that of non-incubated cells through an MTT assay. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08753h

  2. Antibacterial dental composites with chlorhexidine and mesoporous silica.

    PubMed

    Zhang, J F; Wu, R; Fan, Y; Liao, S; Wang, Y; Wen, Z T; Xu, X

    2014-12-01

    One of the leading causes for the failure of dental composite restorations is secondary caries. Effectively inhibiting cariogenic biofilms and reducing secondary caries could extend the service life of composite restorations. Dental composites releasing antibacterial agents such as chlorhexidine (CHX) have shown biofilm-inhibitory efficacy, but they usually have poor physical and mechanical properties. Herein, we present a study of a new method to encapsulate and release CHX from dental composite using mesoporous silica nanoparticles (MSNs). SBA-15 MSNs were synthesized according to a reported procedure. CHX (62.9 wt%) was encapsulated into dried MSN from 0.3 M CHX ethanol solution. The dental composites containing 0% (control), 3%, 5%, and 6.3% CHX or the same amounts of CHX entrapped in MSN (denoted as CHX@MSN) were fabricated with methacrylate monomers and silanized glass fillers (CHX or CHX@MSN + glass filler particle = 70 wt%). The monomer mixture consisted of bisphenol A glycidyl methacrylate (BisGMA), hexanediol dimethacrylate (HDDMA), ethoxylated bisphenol A dimethacrylate (EBPADMA), and urethane dimethacrylates (UEDMA) at a weight ratio of 40:30:20:10. The composites were tested for CHX release and recharge, flexural strength and modulus (at 24 hr and 1 mo), surface roughness, in vitro wear, and antibacterial activity against Streptococcus mutans and Lactobacillus casei (in both planktonic growth and biofilm formation). The results showed that the composites with CHX@MSN largely retained mechanical properties and smooth surfaces and showed controlled release of CHX over a long time. In contrast, the composites with directly mixed CHX showed reduced mechanical properties, rough surfaces, and burst release of CHX in a short time. The composites with CHX either directly mixed or in MSN showed strong inhibition to S. mutans and L. casei. This research has demonstrated the successful application of MSNs as a novel nanotechnology in dental materials to inhibit

  3. Antibacterial Dental Composites with Chlorhexidine and Mesoporous Silica

    PubMed Central

    Zhang, J.F.; Wu, R.; Fan, Y.; Liao, S.; Wang, Y.; Wen, Z.T.; Xu, X.

    2014-01-01

    One of the leading causes for the failure of dental composite restorations is secondary caries. Effectively inhibiting cariogenic biofilms and reducing secondary caries could extend the service life of composite restorations. Dental composites releasing antibacterial agents such as chlorhexidine (CHX) have shown biofilm-inhibitory efficacy, but they usually have poor physical and mechanical properties. Herein, we present a study of a new method to encapsulate and release CHX from dental composite using mesoporous silica nanoparticles (MSNs). SBA-15 MSNs were synthesized according to a reported procedure. CHX (62.9 wt%) was encapsulated into dried MSN from 0.3 M CHX ethanol solution. The dental composites containing 0% (control), 3%, 5%, and 6.3% CHX or the same amounts of CHX entrapped in MSN (denoted as CHX@MSN) were fabricated with methacrylate monomers and silanized glass fillers (CHX or CHX@MSN + glass filler particle = 70 wt%). The monomer mixture consisted of bisphenol A glycidyl methacrylate (BisGMA), hexanediol dimethacrylate (HDDMA), ethoxylated bisphenol A dimethacrylate (EBPADMA), and urethane dimethacrylates (UEDMA) at a weight ratio of 40:30:20:10. The composites were tested for CHX release and recharge, flexural strength and modulus (at 24 hr and 1 mo), surface roughness, in vitro wear, and antibacterial activity against Streptococcus mutans and Lactobacillus casei (in both planktonic growth and biofilm formation). The results showed that the composites with CHX@MSN largely retained mechanical properties and smooth surfaces and showed controlled release of CHX over a long time. In contrast, the composites with directly mixed CHX showed reduced mechanical properties, rough surfaces, and burst release of CHX in a short time. The composites with CHX either directly mixed or in MSN showed strong inhibition to S. mutans and L. casei. This research has demonstrated the successful application of MSNs as a novel nanotechnology in dental materials to inhibit

  4. Antibacterial dental composites with chlorhexidine and mesoporous silica.

    PubMed

    Zhang, J F; Wu, R; Fan, Y; Liao, S; Wang, Y; Wen, Z T; Xu, X

    2014-12-01

    One of the leading causes for the failure of dental composite restorations is secondary caries. Effectively inhibiting cariogenic biofilms and reducing secondary caries could extend the service life of composite restorations. Dental composites releasing antibacterial agents such as chlorhexidine (CHX) have shown biofilm-inhibitory efficacy, but they usually have poor physical and mechanical properties. Herein, we present a study of a new method to encapsulate and release CHX from dental composite using mesoporous silica nanoparticles (MSNs). SBA-15 MSNs were synthesized according to a reported procedure. CHX (62.9 wt%) was encapsulated into dried MSN from 0.3 M CHX ethanol solution. The dental composites containing 0% (control), 3%, 5%, and 6.3% CHX or the same amounts of CHX entrapped in MSN (denoted as CHX@MSN) were fabricated with methacrylate monomers and silanized glass fillers (CHX or CHX@MSN + glass filler particle = 70 wt%). The monomer mixture consisted of bisphenol A glycidyl methacrylate (BisGMA), hexanediol dimethacrylate (HDDMA), ethoxylated bisphenol A dimethacrylate (EBPADMA), and urethane dimethacrylates (UEDMA) at a weight ratio of 40:30:20:10. The composites were tested for CHX release and recharge, flexural strength and modulus (at 24 hr and 1 mo), surface roughness, in vitro wear, and antibacterial activity against Streptococcus mutans and Lactobacillus casei (in both planktonic growth and biofilm formation). The results showed that the composites with CHX@MSN largely retained mechanical properties and smooth surfaces and showed controlled release of CHX over a long time. In contrast, the composites with directly mixed CHX showed reduced mechanical properties, rough surfaces, and burst release of CHX in a short time. The composites with CHX either directly mixed or in MSN showed strong inhibition to S. mutans and L. casei. This research has demonstrated the successful application of MSNs as a novel nanotechnology in dental materials to inhibit

  5. N2O decomposition by mesoporous silica supported Rh catalysts.

    PubMed

    Hussain, Murid; Fino, Debora; Russo, Nunzio

    2012-04-15

    Nitrous oxide (N(2)O), a greenhouse gas produced by nitric acid and adipic acid plants, damages the ozone layer and causes many environmental problems. The potential of MCM-41, SBA-15-Conventional (SBA-15-C), SBA-15-Spherical (SBA-15-S) and KIT-6 supported Rh catalysts has been explored at specific conditions for N(2)O decomposition in order to investigate the characteristics of new catalyst supports (SBA-15-S, KIT-6) for this application. A Rh metal loading of 1 wt% was impregnated to synthesize mesoporous silica supported Rh catalysts. The catalysts were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), N(2) adsorption/desorption, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and CO-chemisorption techniques. Of all the catalysts, Rh/SBA-15-S not only showed the highest activity, but also the best strength against ageing impact, O(2) inhibiting effect and long-term stability. The higher metal dispersion due to the smaller Rh particle size and a greater formation of Rh(+1) than Rh(0) or Rh(+3) on SBA-15-S compared to the other supports, favoured a higher N(2)O decomposition. The larger pore size of SBA-15-S in Rh/SBA-15-S might favour a better Rh access, diffusion and dispersion and lead to higher activity. The higher long-term stability of Rh/SBA-15-S, with preserved support characteristics, than the other supports indicates its significance.

  6. Targeted anticancer prodrug with mesoporous silica nanoparticles as vehicles

    NASA Astrophysics Data System (ADS)

    Fan, Jianquan; Fang, Gang; Wang, Xiaodan; Zeng, Fang; Xiang, Yufei; Wu, Shuizhu

    2011-11-01

    A targeted anticancer prodrug system was fabricated with 180 nm mesoporous silica nanoparticles (MSNs) as carriers. The anticancer drug doxorubicin (DOX) was conjugated to the particles through an acid-sensitive carboxylic hydrazone linker which is cleavable under acidic conditions. Moreover, folic acid (FA) was covalently conjugated to the particle surface as the targeting ligand for folate receptors (FRs) overexpressed in some cancer cells. The in vitro release profiles of DOX from the MSN-based prodrug systems showed a strong dependence on the environmental pH values. The fluorescent dye FITC was incorporated in the MSNs so as to trace the cellular uptake on a fluorescence microscope. Cellular uptakes by HeLa, A549 and L929 cell lines were tested for FA-conjugated MSNs and plain MSNs respectively, and a much more efficient uptake by FR-positive cancer cells (HeLa) can be achieved by conjugation of folic acid onto the particles because of the folate-receptor-mediated endocytosis. The cytotoxicities for the FA-conjugated MSN prodrug, the plain MSN prodrug and free DOX against three cell lines were determined, and the result indicates that the FA-conjugated MSN prodrug exhibits higher cytotoxicity to FR-positive cells, and reduced cytotoxicity to FR-negative cells. Thus, with 180 nm MSNs as the carriers for the prodrug system, good drug loading, selective targeting and sustained release of drug molecules within targeted cancer cells can be realized. This study may provide useful insights for designing and improving the applicability of MSNs in targeted anticancer prodrug systems.

  7. Removal of mercury from aqueous solution using mesoporous silica nanoparticles modified with polyamide receptor.

    PubMed

    He, Chunsheng; Ren, Long; Zhu, Weiping; Xu, Yufang; Qian, Xuhong

    2015-11-15

    Based on the principle of supramolecular recognition and fluorescent chemical sensors, a novel kind of material for the separation of toxic heavy metal ions was designed and synthesized. Mesoporous silica nanoparticles MCM-41 with high surface areas and large ordered pores were used as the supporting matrix. Poly-amide derivative, was grafted to the mesoporous silica nanoparticles for extracting and separating trace Hg(2+) from aqueous solution, with a short adsorption time (t=3min) and a wide range of pH application (pH 3-11). The separation material could also extract trace mercury from Traditional Chinese Medicine, and has no influence on their effective components. PMID:26232282

  8. Ionic liquid-templated preparation of mesoporous silica embedded with nanocrystalline sulfated zirconia

    NASA Astrophysics Data System (ADS)

    Ward, Antony J.; Pujari, Ajit A.; Costanzo, Lorenzo; Masters, Anthony F.; Maschmeyer, Thomas

    2011-12-01

    A series of mesoporous silicas impregnated with nanocrystalline sulphated zirconia was prepared by a sol-gel process using an ionic liquid-templated route. The physicochemical properties of the mesoporous sulphated zirconia materials were studied using characterisation techniques such as inductively coupled optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray microanalysis, elemental analysis and X-ray photoelectron spectroscopy. Analysis of the new silicas indicates isomorphous substitution of silicon with zirconium and reveals the presence of extremely small (< 10 nm) polydispersed zirconia nanoparticles in the materials with zirconium loadings from 27.77 to 41.4 wt.%.

  9. Ionic liquid-templated preparation of mesoporous silica embedded with nanocrystalline sulfated zirconia

    PubMed Central

    2011-01-01

    A series of mesoporous silicas impregnated with nanocrystalline sulphated zirconia was prepared by a sol-gel process using an ionic liquid-templated route. The physicochemical properties of the mesoporous sulphated zirconia materials were studied using characterisation techniques such as inductively coupled optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray microanalysis, elemental analysis and X-ray photoelectron spectroscopy. Analysis of the new silicas indicates isomorphous substitution of silicon with zirconium and reveals the presence of extremely small (< 10 nm) polydispersed zirconia nanoparticles in the materials with zirconium loadings from 27.77 to 41.4 wt.%. PMID:21711725

  10. Ordered mesoporous silica prepared by quiescent interfacial growth method - effects of reaction chemistry

    PubMed Central

    2013-01-01

    Acidic interfacial growth can provide a number of industrially important mesoporous silica morphologies including fibers, spheres, and other rich shapes. Studying the reaction chemistry under quiescent (no mixing) conditions is important for understanding and for the production of the desired shapes. The focus of this work is to understand the effect of a number of previously untested conditions: acid type (HCl, HNO3, and H2SO4), acid content, silica precursor type (TBOS and TEOS), and surfactant type (CTAB, Tween 20, and Tween 80) on the shape and structure of products formed under quiescent two-phase interfacial configuration. Results show that the quiescent growth is typically slow due to the absence of mixing. The whole process of product formation and pore structuring becomes limited by the slow interfacial diffusion of silica source. TBOS-CTAB-HCl was the typical combination to produce fibers with high order in the interfacial region. The use of other acids (HNO3 and H2SO4), a less hydrophobic silica source (TEOS), and/or a neutral surfactant (Tweens) facilitate diffusion and homogenous supply of silica source into the bulk phase and give spheres and gyroids with low mesoporous order. The results suggest two distinct regions for silica growth (interfacial region and bulk region) in which the rate of solvent evaporation and local concentration affect the speed and dimension of growth. A combined mechanism for the interfacial bulk growth of mesoporous silica under quiescent conditions is proposed. PMID:24237719

  11. Self-cleaning antireflective coatings assembled from peculiar mesoporous silica nanoparticles.

    PubMed

    Li, Xiaoyu; Du, Xin; He, Junhui

    2010-08-17

    Novel mesoporous silica nanoparticles of peculiar shapes were synthesized, from which hierarchically porous silica coatings were fabricated on glass substrates via layer-by-layer (LbL) assembly, followed by calcination. These porous silica coatings were highly transparent and superhydrophilic. The maximum transmittance reached as high as 94%, whereas that of the glass substrate is 91%. The time for a droplet to spread lower than 5 degrees decreased to as short as 0.25 s. After the coating surface was treated with a low surface energy material, the surface became superhydrophobic (water contract angle >150 degrees) with a very low sliding angle of <1 degree. Compared with MCM-41-type mesoporous silica nanoparticles, the coatings fabricated using the novel mesoporous silica nanoparticles possess much better self-cleaning property. We used scanning (SEM) and transmission (TEM) electron microscopy to observe the morphology and structure of nanoparticles and surfaces. Transmission spectra and their change with time were characterized by UV-vis spectrophotometer. We studied the surface wettability by a contact angle/interface system. The influence of mesopores on the transmittance and wetting properties of coatings was discussed on the basis of experimental observations.

  12. Preparation and CO{sub 2} adsorption properties of aminopropyl-functionalized mesoporous silica microspheres

    SciTech Connect

    Araki, S.; Doi, H.; Sano, Y.; Tanaka, S.; Miyake, Y.

    2009-11-15

    Aminopropyl-functionalized mesoporous silica microspheres (AF-MSM) were synthesized by a simple one-step modified Stober method. Dodecylamine (DDA) was used as the catalyst for the hydrolysis and condensation of the silica source and as the molecular template to prepare the ordered mesopores. The mesoporous silica surfaces were modified to aminopropyl groups by the co-condensation of tetraethoxysilane (TEOS) with 3-aminopropyltriethoxysilane (APTES), up to a maximum of 20 mol.% APTES content in the silica source. The particle size, Brunauer-Emmet-Teller (BET) specific surface area, and mesoporous regularity decreased with increasing APTES content. It is believed that this result is caused by a decreasing amount of DDA incorporated into AF-MSM with increasing APTES content. It was also confirmed that the spherical shape and the mesostructure were maintained even if 20 mol.% of APTES was added to the silica source. Moreover, AF-MSM was applied to the CO{sub 2} adsorbent. The breakthrough time of the CO{sub 2} and CO{sub 2} adsorption capacities increased with increasing APTES content. The adsorption capacity of CO{sub 2} for AF-MSM, prepared at 20 mol.% APTES, was 0.54 mmol g{sup -1}. Carbon dioxide adsorbed onto AF-MSM was completely desorbed by heating in a N{sub 2} purge at 423 K for 30 min.

  13. Synthesis of mesoporous silica materials from municipal solid waste incinerator bottom ash

    SciTech Connect

    Liu, Zhen-Shu Li, Wen-Kai; Huang, Chun-Yi

    2014-05-01

    Highlights: • The optimal alkaline agent for the extraction of silica from bottom ash was Na{sub 2}CO{sub 3}. • The pore sizes for the mesoporous silica synthesized from bottom ash were 2–3.8 nm. • The synthesized materials exhibited a hexagonal pore structure with a smaller order. • The materials have potential for the removal of heavy metals from aqueous solutions. - Abstract: Incinerator bottom ash contains a large amount of silica and can hence be used as a silica source for the synthesis of mesoporous silica materials. In this study, the conditions for alkaline fusion to extract silica from incinerator bottom ash were investigated, and the resulting supernatant solution was used as the silica source for synthesizing mesoporous silica materials. The physical and chemical characteristics of the mesoporous silica materials were analyzed using BET, XRD, FTIR, SEM, and solid-state NMR. The results indicated that the BET surface area and pore size distribution of the synthesized silica materials were 992 m{sup 2}/g and 2–3.8 nm, respectively. The XRD patterns showed that the synthesized materials exhibited a hexagonal pore structure with a smaller order. The NMR spectra of the synthesized materials exhibited three peaks, corresponding to Q{sup 2} [Si(OSi){sub 2}(OH){sub 2}], Q{sup 3} [Si(OSi){sub 3}(OH)], and Q{sup 4} [Si(OSi){sub 4}]. The FTIR spectra confirmed the existence of a surface hydroxyl group and the occurrence of symmetric Si–O stretching. Thus, mesoporous silica was successfully synthesized from incinerator bottom ash. Finally, the effectiveness of the synthesized silica in removing heavy metals (Pb{sup 2+}, Cu{sup 2+}, Cd{sup 2+}, and Cr{sup 2+}) from aqueous solutions was also determined. The results showed that the silica materials synthesized from incinerator bottom ash have potential for use as an adsorbent for the removal of heavy metals from aqueous solutions.

  14. TiO2 nanoparticles doped SiO2 films with ordered mesopore channels: a catalytic nanoreactor.

    PubMed

    Saha, Jony; Mitra, Anuradha; Dandapat, Anirban; De, Goutam

    2014-04-01

    Titanium dioxide (TiO2) incorporated ordered 2D hexagonal mesoporous silica (SiO2) films on a glass substrate were fabricated for use as a catalytic nanoreactor. Films were prepared using a tetraethyl orthosilicate (TEOS) derived SiO2 sol and a commercially available dispersion of TiO2 nanoparticles (NPs) in the presence of pluronic P123 as the structure directing agent. The effect of TiO2 doping (4-10 mol% with respect to the equivalent SiO2) into the ordered mesoporous SiO2 matrix was thoroughly investigated. The undoped SiO2 film showed a mesostructural transformation after heat-treatment at 350 °C whereas incorporation of TiO2 restricted such a transformation. Among all the TiO2 incorporated films, TEM showed that the 7 equivalent mol% TiO2 doped SiO2 film (ST-7) had an optimal composition which could retain the more organized 2D hexagonal (space group p6mm)-like mesostructures after heat-treatment. The catalytic activities of the TiO2 doped (4-10 mol%) films were investigated for the reduction of toxic KMnO4 in an aqueous medium. ST-7 film showed the maximum catalytic activity, as well as reusability. A TEM study on the resultant solution after KMnO4 reduction revealed the formation of MnO2 nanowires. It was understood that the embedded TiO2 NPs bonded SiO2 matrix increased the surface hydroxyl groups of the composite films resulting in the generation of acidic sites. The catalytic process can be explained by this enhanced surface acidity. The mesoporous channel of the ST-7 films with TiO2 doping can be used as a nanoreactor to form extremely thin MnO2 nanowires.

  15. Effect of polyvinylpyrrolidone on mesoporous silica morphology and esterification of lauric acid with 1-butanol catalyzed by immobilized enzyme

    SciTech Connect

    Zhang, Jinyu; Zhou, Guowei Jiang, Bin; Zhao, Minnan; Zhang, Yan

    2014-05-01

    Mesoporous silica materials with a range of morphology evolution, i.e., from curved rod-shaped mesoporous silica to straight rod-shaped mesoporous silica, were successfully prepared using polyvinylpyrrolidone (PVP) and triblock copolymer as dual template. The effects of PVP molecular weight and concentration on mesoporous silica structure parameters were studied. Results showed that surface area and pore volume continuously decreased with increased PVP molecular weight. Mesoporous silica prepared with PVP K30 also possessed larger pore diameter, interplanar spacing (d{sub 100}), and cell parameter (a{sub 0}) than that prepared with PVP K15 and PVP K90. In addition, with increased PVP concentration, d{sub 100} and a{sub 0} continuously decreased. The mechanism of morphology evolution caused by the change in PVP concentration was investigated. The conversion rate of lauric acid with 1-butanol catalyzed by immobilized Porcine pancreatic lipase (PPL) was also evaluated. Results showed that PPL immobilized on amino-functionalized straight rod-shaped mesoporous silica maintained 50% of its esterification conversion rate even after five cycles of use with a maximum conversion rate was about 90.15%. - Graphical abstract: Curved rod-shaped mesoporous silica can be obtained at low and the highest PVP concentration, while straight rod-shaped mesoporous silica can be obtained at higher PVP concentration. - Highlights: • Mesoporous silica with morphology evolution from CRMS to SRMS were prepared. • Effects of PVP molecular weight and concentration on silica morphology were studied. • A possible mechanism for the formation of morphology evolution SiO{sub 2} was proposed. • Esterification of lauric acid with 1-butanol catalyzed by immobilized PPL.

  16. SBA-15 Mesoporous Silica Modified with Gallic Acid and Evaluation of Its Cytotoxic Activity

    PubMed Central

    Lewandowski, Dawid

    2015-01-01

    Gallic acid has been covalently conjugated to SBA-15 mesoporous silica surface through different linkers. Cytotoxic activity of the hybrid organic-inorganic systems against HeLa and KB cell lines has been analyzed. Up to 67% of HeLa or KB tumor cells growth inhibition has been achieved at low silica concentration used (10 μg mL-1). PMID:26151908

  17. Monodisperse spherical mesoporous silica particles: fast synthesis procedure and fabrication of photonic-crystal films

    NASA Astrophysics Data System (ADS)

    Trofimova, E. Yu; Kurdyukov, D. A.; Yakovlev, S. A.; Kirilenko, D. A.; Kukushkina, Yu A.; Nashchekin, A. V.; Sitnikova, A. A.; Yagovkina, M. A.; Golubev, V. G.

    2013-04-01

    A procedure for the synthesis of monodisperse spherical mesoporous silica particles (MSMSPs) via the controlled coagulation of silica/surfactant clusters into spherical aggregates with mean diameters of 250-1500 nm has been developed. The synthesis is fast (taking less than 1 h) because identical clusters are simultaneously formed in the reaction mixture. The results of microscopic, x-ray diffraction, adsorption and optical measurements allowed us to conclude that the clusters are ˜15 nm in size and have hexagonally packed cylindrical pore channels. The channel diameters in MSMSPs obtained with cethyltrimethylammonium bromide and decyltrimethylammonium bromide as structure-directing agents were 3.1 ± 0.15 and 2.3 ± 0.12 nm, respectively. The specific surface area and the pore volume of MSMSP were, depending on synthesis conditions, 480-1095 m2 g-1 and 0.50-0.65 cm3 g-1. The MSMSP were used to grow opal-like photonic-crystal films possessing a hierarchical macro-mesoporous structure, with pores within and between the particles. A selective filling of mesopore channels with glycerol, based on the difference between the capillary pressures in macro- and mesopores, was demonstrated. It is shown that this approach makes it possible to control the photonic bandgap position in mesoporous opal films by varying the degree of mesopore filling with glycerol.

  18. Integrated, cascading enzyme-/chemocatalytic cellulose conversion using catalysts based on mesoporous silica nanoparticles.

    PubMed

    Lee, Yi-Chun; Dutta, Saikat; Wu, Kevin C-W

    2014-12-01

    This article reports a novel approach to deconstructing cellulose into 5-hydroxymethylfurfural (HMF) with a high yield (46.1%) by integrating a sequential enzyme cascade technique in an aqueous system with solid acid catalysis in an organic-solvent system. We executed the rational design and synthesis of mesoporous silica nanoparticles (MSNs) with various pore sizes and surface functionalities, which proved to be useful for the immobilization of various enzymes (i.e., cellulase and isomerase) and nanoparticles (i.e., magnetic Fe3 O4 ) and for functionalization of various acid groups (i.e., H2 PO3 , COOH, and SO3 H). We separately applied the synthesized biocatalysts (i.e., cellulase-Fe3 O4 @MSN and isomerase-Fe3 O4 @MSN) and chemical catalysts (i.e., HSO3 -MSN) in a sequential cellulose-to-glucose, glucose-to-fructose, and fructose-to-HMF conversion, respectively, across both aqueous- and organic-solvent systems after the optimization of reaction conditions (e.g., reaction temperature, water ratio, catalyst amount). The integrated enzymatic and chemocatalytic concept in this study could be an effective and economically friendly process for various catalytic applications. PMID:25257168

  19. Textural and structural properties and surface acidity characterization of mesoporous silica-zirconia molecular sieves

    NASA Astrophysics Data System (ADS)

    Rodríguez-Castellón, E.; Jiménez-López, A.; Maireles-Torres, P.; Jones, D. J.; Rozière, J.; Trombetta, M.; Busca, G.; Lenarda, M.; Storaro, L.

    2003-11-01

    Homogeneous mesoporous zirconium-containing MCM-41 type silica were prepared by supramolecular templating and their textural and structural properties were studied using powder X-ray diffraction, N 2 porosimetry, atomic force microscopy, EXAFS, XPS, and UV-VIS-NIR diffuse reflectance spectroscopy. Their acid properties were also studied by using IR spectroscopy and by the use of catalytic tests such as the decomposition of isopropanol and the isomerization of 1-butene. The materials prepared show a good degree of crystallinity with a regular ordering of the pores into a hexagonal arrangement and high thermal stability. The specific surface area of the prepared materials decreases as the zirconium content rises. Zirconium atoms are in coordination 7 to 8 and located at the surface of the pores such that a high proportion of the oxygen atoms bonded to zirconium corresponds to surface non-condensed oxygen atoms. Both facts are responsible for the acid properties of the solids that show weak Brønsted and medium strong Lewis acidity.

  20. Controllable synthesis of hollow mesoporous silica spheres and application as support of nano-gold

    SciTech Connect

    Wang, Tao; Ma, Weihua Shangguan, Junnan; Jiang, Wei; Zhong, Qin

    2014-07-01

    Hollow silica spheres with mesoporous structure were synthesized by sol–gel/emulsion method. In the process, the surfactant, cetyltrimethylammonium bromide (CTAB) was used to stabilize the oil droplet and also used as structure direct agent. The diameter of the hollow silica spheres, ranging from 895 nm to 157 nm, can be controlled by changing the ratio of ethanol to water and the concentration of the surfactant as well. The shell thickness of the spheres decreased when the ratio of ethanol to water decreased. The proposed mechanism of the formation of silica spheres could elucidate the experimental results well. Furthermore, the resultant hollow mesoporous silica spheres were then employed as support of nano-gold which was used to catalyze the isomerization reaction of propylene oxide to produce allyl alcohol. - Graphical abstract: It is the schematic mechanism for the formation of hollow mesoporous silica spheres. - Highlights: • The formation mechanism of the hollow spheres is proposed. • The isomerization of propylene oxide can be catalyzed by the nano-gold/SiO{sub 2}. • The hollow silica spheres can be prepared controllably.

  1. Facile large-scale synthesis of brain-like mesoporous silica nanocomposites via a selective etching process

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Wang, Qihua; Wang, Tingmei

    2015-10-01

    The core-shell structured mesoporous silica nanomaterials (MSNs) are experiencing rapid development in many applications such as heterogeneous catalysis, bio-imaging and drug delivery wherein a large pore volume is desirable. We develop a one-pot method for large-scale synthesis of brain-like mesoporous silica nanocomposites based on the reasonable change of the intrinsic nature of the -Si-O-Si- framework of silica nanoparticles together with a selective etching strategy. The as-synthesized products show good monodispersion and a large pore volume of 1.0 cm3 g-1. The novelty of this approach lies in the use of an inorganic-organic hybrid layer to assist the creation of large-pore morphology on the outermost shell thereby promoting efficient mass transfer or storage. Importantly, the method is reliable and grams of products can be easily prepared. The morphology on the outermost silica shell can be controlled by simply adjusting the VTES-to-TEOS molar ratio (VTES: triethoxyvinylsilane, TEOS: tetraethyl orthosilicate) as well as the etching time. The as-synthesized products exhibit fluorescence performance by incorporating rhodamine B isothiocyanate (RITC) covalently into the inner silica walls, which provide potential application in bioimaging. We also demonstrate the applications of as-synthesized large-pore structured nanocomposites in drug delivery systems and stimuli-responsive nanoreactors for heterogeneous catalysis.The core-shell structured mesoporous silica nanomaterials (MSNs) are experiencing rapid development in many applications such as heterogeneous catalysis, bio-imaging and drug delivery wherein a large pore volume is desirable. We develop a one-pot method for large-scale synthesis of brain-like mesoporous silica nanocomposites based on the reasonable change of the intrinsic nature of the -Si-O-Si- framework of silica nanoparticles together with a selective etching strategy. The as-synthesized products show good monodispersion and a large pore volume

  2. Biological Applications and Transmission Electron Microscopy Investigations of Mesoporous Silica Nanoparticles

    SciTech Connect

    Trewyn, Brian G.

    2006-01-01

    The research presented and discussed within involves the development of novel biological applications of mesoporous silica nanoparticles (MSN) and an investigation of mesoporous material by transmission electron microscopy (TEM). Mesoporous silica nanoparticles organically functionalized shown to undergo endocytosis in cancer cells and drug release from the pores was controlled intracellularly and intercellularly. Transmission electron microscopy investigations demonstrated the variety of morphologies produced in this field of mesoporous silica nanomaterial synthesis. A series of room-temperature ionic liquid (RTIL) containing mesoporous silica nanoparticle (MSN) materials with various particle morphologies, including spheres, ellipsoids, rods, and tubes, were synthesized. By changing the RTIL template, the pore morphology was tuned from the MCM-41 type of hexagonal mesopores to rotational moire type of helical channels, and to wormhole-like porous structures. These materials were used as controlled release delivery nanodevices to deliver antibacterial ionic liquids against Escherichia coli K12. The involvement of a specific organosiloxane function group, covalently attached to the exterior of fluorescein doped mesoporous silica nanoparticles (FITC-MSN), on the degree and kinetics of endocytosis in cancer and plant cells was investigated. The kinetics of endocystosis of TEG coated FITC-MSN is significantly quicker than FITC-MSN as determined by flow cytometry experiments. The fluorescence confocal microscopy investigation showed the endocytosis of TEG coated-FITC MSN triethylene glycol grafted fluorescein doped MSN (TEG coated-FITC MSN) into both KeLa cells and Tobacco root protoplasts. Once the synthesis of a controlled-release delivery system based on MCM-41-type mesoporous silica nanorods capped by disulfide bonds with superparamagnetic iron oxide nanoparticles was completed. The material was characterized by general methods and the dosage and kinetics of the

  3. Mesoporous carbon-supported Pd nanoparticles with high specific surface area for cyclohexene hydrogenation: Outstanding catalytic activity of NaOH-treated catalysts

    NASA Astrophysics Data System (ADS)

    Puskás, R.; Varga, T.; Grósz, A.; Sápi, A.; Oszkó, A.; Kukovecz, Á.; Kónya, Z.

    2016-06-01

    Extremely high specific surface area mesoporous carbon-supported Pd nanoparticle catalysts were prepared with both impregnation and polyol-based sol methods. The silica template used for the synthesis of mesoporous carbon was removed by both NaOH and HF etching. Pd/mesoporous carbon catalysts synthesized with the impregnation method has as high specific surface area as 2250 m2/g. In case of NaOH-etched impregnated samples, the turnover frequency of cyclohexene hydrogenation to cyclohexane at 313 K was obtained ~ 14 molecules • site- 1 • s- 1. The specific surface area of HF-etched samples was higher compared to NaOH-etched samples. However, catalytic activity was ~ 3-6 times higher on NaOH-etched samples compared to HF-etched samples, which can be attributed to the presence of sodium and surface hydroxylgroups of the catalysts etched with NaOH solution.

  4. A generalized method toward high dispersion of transition metals in large pore mesoporous metal oxide/silica hybrids.

    PubMed

    Bérubé, François; Khadraoui, Abdelkarim; Florek, Justyna; Kaliaguine, Serge; Kleitz, Freddy

    2015-07-01

    A series of transition metal acetylacetonates and acetates were used as precursors to generate high loadings of metal sites finely dispersed on SBA-15 silica. To achieve this, grafting of chelated transition metal precursors was performed directly to the surface of the as-synthesized SBA-15/P123 composite material. The thus-obtained metal/SBA-15 materials were studied by a variety of methods, e.g., elemental analysis, Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance UV-visible spectroscopy (DR-UV-vis), X-ray photoelectron spectroscopy (XPS) and N2 physisorption measurements at -196 °C. From the results, the proposed functionalization method was found to be a highly tunable and reproducible strategy to disperse transition metal oxides in mesoporous silica materials. The results from elemental analysis of the modified materials confirmed that the amount of grafted species is a function of the initial concentration of precursor in the solution used for grafting. The chelated complexes were found to strongly interact with the silanol groups of the silica material, resulting in a ligand-exchange process, as corroborated by FTIR. However, different metal precursors showed distinct reactivity towards the surface of mesoporous silica, owing to differences in the stability of the complexes under the conditions used for grafting. DR-UV-vis and XPS analyses suggest that when the stability of a given precursor decreases, the grafting procedure can lead to the formation of small clusters of the metal oxide on the silica surface. XRD and SEM also show that grafting of lower stability complexes, such as Mn(acac)3, Cu(acetate)2 and VO(acac)2, on the silica surface can result in the formation of large crystals on the external surface of the SBA-15 particles. Nevertheless, it was established by XPS analysis that only a small percentage of the grafted species leads to the formation of bulk

  5. Shape control of mesoporous silica nanomaterials templated with dual cationic surfactants and their antibacterial activities.

    PubMed

    Hao, Nanjing; Chen, Xuan; Jayawardana, Kalana W; Wu, Bin; Sundhoro, Madanodaya; Yan, Mingdi

    2016-01-01

    Mesoporous silica nanomaterials of different shapes (film, platelet, sphere, rod) were synthesized simply by tuning the mole ratio of dual cationic surfactant templates, cetyltrimethylammonium bromide (CTAB) and tetrabutylammonium iodine (TBAI). The film showed the most potent antibacterial activity against mycobacteria. PMID:26364920

  6. Shape Control of Mesoporous Silica Nanomaterials Templated with Dual Cationic Surfactants and Their Antibacterial Activities

    PubMed Central

    Hao, Nanjing; Chen, Xuan; Jayawardana, Kalana W.; Wu, Bin; Sundhoro, Madanodaya; Yan, Mingdi

    2015-01-01

    Mesoporous silica nanomaterials of different shapes (film, platelet, sphere, rod) were synthesized simply by tuning the mole ratio of dual cationic surfactant templates, cetyltrimethylammonium bromide (CTAB) and tetrabutylammonium iodine (TBAI). The film showed the most potent antibacterial activities against mycobacteria. PMID:26364920

  7. Functionalization of SBA-15 mesoporous silica by Cu-phosphonate units: Probing of synthesis route

    SciTech Connect

    Laskowski, Lukasz; Laskowska, Magdalena

    2014-12-15

    Mesoporous silica SBA-15 containing propyl-copper phosphonate units was investigated. The structure of mesoporous samples was tested by N{sub 2} isothermal sorption (BET and BHJ analysis), TEM microscopy and X-Ray scattering. Quantitative analysis EDX has given information about proportions between component atoms in the sample. Quantitative elemental analysis has been carried out to support EDX. To examine bounding between copper atoms and phosphonic units the Raman spectroscopy was carried out. As a support of Raman scattering, the theoretical calculations were made based on density functional theory, with the B3LYP method. By comparison of the calculated vibrational spectra of the molecule with experimental results, distribution of the active units inside silica matrix has been determined. - Graphical abstract: The present study is devoted to mesoporous silica SBA-15 containing propyl-copper phosphonate units. The species were investigated to confirm of synthesis procedure correctness by the micro-Raman technique combined with DFT numerical simulations. Complementary research was carried out to test the structure of mesoporous samples. - Highlights: • SBA-15 silica functionalized with propyl-copper phosphonate units was synthesized. • Synthesis efficiency probed by Raman study supported with DFT simulations. • Homogenous distribution of active units was proved. • Synthesis route enables precise control of distance between copper ions.

  8. CD44-engineered mesoporous silica nanoparticles for overcoming multidrug resistance in breast cancer

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Liu, Ying; Wang, Shouju; Shi, Donghong; Zhou, Xianguang; Wang, Chunyan; Wu, Jiang; Zeng, Zhiyong; Li, Yanjun; Sun, Jing; Wang, Jiandong; Zhang, Longjiang; Teng, Zhaogang; Lu, Guangming

    2015-03-01

    Multidrug resistance is a major impediment for the successful chemotherapy in breast cancer. CD44 is over-expressed in multidrug resistant human breast cancer cells. CD44 monoclonal antibody exhibits anticancer potential by inhibiting proliferation and regulating P-glycoprotein-mediated drug efflux activity in multidrug resistant cells. Thereby, CD44 monoclonal antibody in combination with chemotherapeutic drug might be result in enhancing chemosensitivity and overcoming multidrug resistance. The purpose of this study is to investigate the effects of the CD44 monoclonal antibody functionalized mesoporous silica nanoparticles containing doxorubicin on human breast resistant cancer MCF-7 cells. The data showed that CD44-modified mesoporous silica nanoparticles increased cytotoxicity and enhanced the downregulation of P-glycoprotein in comparison to CD44 antibody. Moreover, CD44-engineered mesoporous silica nanoparticles provided active target, which promoted more cellular uptake of DOX in the resistant cells and more retention of DOX in tumor tissues than unengineered counterpart. Animal studies of the resistant breast cancer xenografts demonstrated that CD44-engineered drug delivery system remarkably induced apoptosis and inhibited the tumor growth. Our results indicated that the CD44-engineered mesoporous silica nanoparticle-based drug delivery system offers an effective approach to overcome multidrug resistance in human breast cancer.

  9. Rod-shaped silica particles derivatized with elongated silver nanoparticles immobilized within mesopores

    NASA Astrophysics Data System (ADS)

    Mnasri, Najib; Charnay, Clarence; de Ménorval, Louis-Charles; Elaloui, Elimame; Zajac, Jerzy

    2016-11-01

    Silver-derivatized silica particles possessing a non-spherical morphology and surface plasmon resonance properties have been achieved. Nanometer-sized silica rods with uniformly sized mesopore channels were prepared first making use of alkyltrimethyl ammonium surfactants as porogens and the 1:0.10 tetraethyl orthosilicate (TEOS) : 3-aminopropyltriethoxysilane (APTES) mixture as a silicon source. Silica rods were subsequently functionalized by introducing elongated silver nanoparticles within the intra-particle mesopores thanks to the AgNO3 reduction procedure based on the action of hemiaminal groups previously located on the mesopore walls. The textural and structural features of the samples were inferred from the combined characterization studies including SEM and TEM microscopy, nitrogen adsorption-desorption at 77 K, powder XRD in the small- and wide-angle region, as well as UV-visible spectroscopy. 129Xe NMR spectroscopy appeared particularly useful to obtain a correct information about the porous structure of rod-shaped silica particles and the silver incorporation within their intra-particle mesopores.

  10. Hydrophobic core/hydrophilic shell structured mesoporous silica nanospheres: enhanced adsorption of organic compounds from water.

    PubMed

    Li, Shuru; Jiao, Xuan; Yang, Hengquan

    2013-01-29

    Inspired by the structure features of micelle, we attempt to synthesize a novel functionalized mesoporous silica nanosphere consisting of a hydrophobic core and a hydrophilic shell. The obtained solid materials were structurally confirmed by N(2) sorption, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Their compositions were characterized by Fourier transfer infrared spectroscopy (FT-IR), solid state NMR, X-ray photoelectron spectroscopy (XPS), and elemental analysis. Its fundamental properties such as dispersibility in water or organic phase, wettability, and adsorption ability toward hydrophobic organics in water were investigated. It was revealed that these important properties could be facilely adjusted through varying structure and composition. In particular, these materials showed much better adsorption ability toward hydrophobic organic molecules in water than conventional monofunctionalized mesoporous materials, owing to possessing the hydrophobic/hydrophilic domain-segregated and hierarchically functionalized mesoporous structures. The intriguing properties would make mesoporous materials more accessible to many important applications, especially in aqueous systems.

  11. Micro-mesoporous materials obtained by zeolite recrystallization: synthesis, characterization and catalytic applications.

    PubMed

    Ivanova, Irina I; Knyazeva, Elena E

    2013-05-01

    The review covers the recent developments in the field of novel micro-mesoporous materials obtained by zeolite recrystallization. The materials are classified into three distinctly different groups depending on the degree of recrystallization: (i) coated mesoporous zeolites (RZEO-1); (ii) micro-mesoporous nanocomposites (RZEO-2); and (iii) mesoporous materials with zeolitic fragments in the walls (RZEO-3). The first part of the review is focused on the analysis of the synthetic strategies leading to different types of recrystallized materials. In the second part, a comprehensive view on their structure, texture and porosity in connection with acidic and diffusion properties is given. The last part is devoted to the catalytic applications of recrystallized materials. The advantages and disadvantages with respect to pure micro- and mesoporous molecular sieves and other hierarchical zeolites are critically analyzed and the future opportunities and perspectives are discussed.

  12. Mesoporous MgO: Synthesis, physico-chemical, and catalytic properties

    NASA Astrophysics Data System (ADS)

    Maerle, A. A.; Kasyanov, I. A.; Moskovskaya, I. F.; Romanovsky, B. V.

    2016-06-01

    Mesoporous MgO was obtained via the hydrothermal synthesis using both ionogenic and non-ionogenic surfactants as structure-directing templates. The materials prepared were characterized by SEM, BET-N2, XRD, and TG-DTA techniques. MgO particles are spherical 20-μm aggregates of primary oxide particles well shaped as rectangular parallelepipeds. Magnesium oxide samples have the specific surface area of 290-400 m2/g and pore sizes of 3.3-4.1 nm. Their mesoporous structure remained unchanged after calcination up to 350°C. Catalytic activity of mesoporous MgO was studied in acetone condensation reaction.

  13. Synthesis of mesoporous silica helical fibers using a catanionic-neutral ternary surfactant in a highly dilute silica solution: biomimetic silicification.

    PubMed

    Lin, Giung-Ling; Tsai, Yi-Hua; Lin, Hong-Ping; Tang, Chih-Yuan; Lin, Ching-Yen

    2007-04-10

    Mesoporous silica helical fibers in many different shapes have been synthesized in a highly dilute silicate solution at pH approximately 2.0 by using CnTMAB-SDS-P123 (n = 14-18) ternary surfactant as a template. The mesoporous silica helical fibers possess a well-ordered hexagonal mesostructure, high surface area, and large pore volume. Thus, the microtome sections of the helical fibers demonstrate a concentric mesotructure or two hemiconcentric mesostructures. In addition to triblock copolymer, adding the proper amount of 1-butanol or pentanol can promote the yield of the helical fibers as well. The yield of the surfactant-templated helical fibers is also dependent on the water content, reaction temperature, and pH value of the solution. The mesoporous silica helical fiber can be used as a solid template to prepare mesoporous carbon helical fibers via impregnation of phenol-formaldehyde, pyrolysis, and silica removal.

  14. Wet powder processing of sol-gel derived mesoporous silica-hydroxyapatite hybrid powders.

    PubMed

    Andersson, Jenny; Johannessen, Espen; Areva, Sami; Järn, Mikael; Lindén, Mika

    2006-08-01

    This paper describes a method by which a porous silica coating layer can be obtained on different apatite particles through a simple sol-gel synthesis route. Sol-gel derived powders of hydroxyapatite (HAP) and beta tricalciumphosphate (beta-TCP) were coated with a mesoporous silica using C16TAB (hexadecyltrimethylammonium bromide) as a template in order to induce mesophase formation. Further calcination of the material removes the template from the mesophase and leaves a highly ordered hexagonal arranged mesoporous silica structure with a core of HAP/beta-TCP. The phase purity of the SiO2/apatite composites has been thoroughly investigated by the means of FT-IR, XRD, and solid state 31P MAS NMR. The phase purity of these materials is shown to be dependent on the solubility properties of the used apatites. The hybrid materials are suitable as a multifunctional biomaterial where osteoconductive properties can be combined with drug delivery.

  15. Fe-TAML encapsulated inside mesoporous silica nanoparticles as peroxidase mimic: femtomolar protein detection.

    PubMed

    Kumari, Sushma; Dhar, Basab B; Panda, Chakadola; Meena, Abhishek; Sen Gupta, Sayam

    2014-08-27

    Peroxidase, such as horseradish peroxidase (HRP), conjugated to antibodies are routinely used for the detection of proteins via an ELISA type assay in which a critical step is the catalytic signal amplification by the enzyme to generate a detectable signal. Synthesis of functional mimics of peroxidase enzyme that display catalytic activity which far exceeds the native enzyme is extremely important for the precise and accurate determination of very low quantities of proteins (fM and lower) that is necessary for early clinical diagnosis. Despite great advancements, analyzing proteins of very low abundance colorimetrically, a method that is most sought after since it requires no equipment for the analysis, still faces great challenges. Most reported HRP mimics that show catalytic activity greater than native enzyme (∼10-fold) are based on metal/metal-oxide nanoparticles such as Fe3O4. In this paper, we describe a second generation hybrid material developed by us in which approximately 25,000 alkyne tagged biuret modified Fe-tetraamido macrocyclic ligand (Fe-TAML), a very powerful small molecule synthetic HRP mimic, was covalently attached inside a 40 nm mesoporous silica nanoparticle (MSN). Biuret-modified Fe-TAMLs represent one of the best small molecule functional mimics of the enzyme HRP with reaction rates in water close to the native enzyme and operational stability (pH, ionic strength) far exceeding the natural enzyme. The catalytic activity of this hybrid material is around 1000-fold higher than that of natural HRP and 100-fold higher than that of most metal/metal oxide nanoparticle based HRP mimics reported to date. We also show that using antibody conjugates of this hybrid material it is possible to detect and, most importantly, quantify femtomolar quantities of proteins colorimetrically in an ELISA type assay. This represents at least 10-fold higher sensitivity than other colorimetric protein assays that have been reported using metal/metal oxide

  16. Ordered mesoporous silica modified with lanthanum for ibuprofen loading and release behaviour.

    PubMed

    Goscianska, Joanna; Olejnik, Anna; Nowak, Izabela; Marciniak, Michal; Pietrzak, Robert

    2015-08-01

    The ordered mesoporous silicas SBA-15 and KIT-6, modified with lanthanum, have been for the first time applied in investigation of ibuprofen adsorption and release. The materials of hexagonal and regular structure were obtained by the hydrothermal method using a triblock copolymer Pluronic P123 as a template. The mesoporous silicas were impregnated with an aqueous solution of lanthanum(III) chloride in the amount necessary to obtain 1, 3 and 5wt.% La loading. The physicochemical properties of the modified silicas were characterised by X-ray diffraction, transmission electron microscopy, UV-Vis spectrophotometry and low-temperature nitrogen sorption. The results showed that lanthanum strongly determined structural as well as textural properties of the silicas. The samples of modified silica were checked for the ability to adsorb and release of ibuprofen. The storage capacity of the modified silicas obtained increased with increasing their average pore diameter and percentage content of lanthanum. The amount of ibuprofen adsorbed onto KIT-6 silica modified with La was higher than that adsorbed onto SBA-15 materials. The high coverage of lanthanum on the surface of KIT-6 and SBA-15 solids was found to increase the amount of ibuprofen and the rate of its release.

  17. Adsorption of Methyl Blue on Mesoporous Materials Using Rice Husk Ash as Silica Source.

    PubMed

    Nguyen, Nhat Thien; Chen, Shiao-shing; Nguyen, Nguyen Cong; Nguyen, Hau Thi; Tsai, Hsiao Hsin; Chang, Chang Tang

    2016-04-01

    It is recognized that recycling and reuse of waste can result in significant savings in materials and energy. In this research, the adsorption of methyl blue (MB) using waste rice husk ash (Rha) and mesoporous silica materials made from Rha (R-MCM) were analyzed. Mesoporous silica materials were synthesized using cetyltrimethyl ammonium bromide (CTAB) as a cationic surfactant and Rha as the silica source. The prepared samples were characterized by Brunnaur-Emmet-Teller (BET) adsorption isotherm analyzer and transmission electron microscope (TEM) analysis. The results showed the surface area of R-MCM materials was 1347 m2g-1 and the pore volume was 0.906 cm3g-1. TEM analysis showed that the mesoporous materials generally exhibited ordered hexagonal arrays of mesopores with a uniform pore size. The effects on adsorption performance under different initial dye concentrations, different pH values and different dosages of adsorbent were also studied. Both Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. The results show that the maximum removal efficiency of MB more than 99%. PMID:27451772

  18. Nanocomposite hydrogels for cartilage tissue engineering: mesoporous silica nanofibers interlinked with siloxane derived polysaccharide.

    PubMed

    Buchtová, Nela; Réthoré, Gildas; Boyer, Cécile; Guicheux, Jérôme; Rambaud, Frédéric; Vallé, Karine; Belleville, Philippe; Sanchez, Clément; Chauvet, Olivier; Weiss, Pierre; Le Bideau, Jean

    2013-08-01

    Injectable materials for mini-invasive surgery of cartilage are synthesized and thoroughly studied. The concept of these hybrid materials is based on providing high enough mechanical performances along with a good medium for chondrocytes proliferation. The unusual nanocomposite hydrogels presented herein are based on siloxane derived hydroxypropylmethylcellulose (Si-HPMC) interlinked with mesoporous silica nanofibers. The mandatory homogeneity of the nanocomposites is checked by fluorescent methods, which show that the silica nanofibres dispersion is realized down to nanometric scale, suggesting an efficient immobilization of the silica nanofibres onto the Si-HPMC scaffold. Such dispersion and immobilization are reached thanks to the chemical affinity between the hydrophilic silica nanofibers and the pendant silanolate groups of the Si-HPMC chains. Tuning the amount of nanocharges allows tuning the resulting mechanical features of these injectable biocompatible hybrid hydrogels. hASC stem cells and SW1353 chondrocytic cells viability is checked within the nanocomposite hydrogels up to 3 wt% of silica nanofibers.

  19. Simple Synthesis of Hierarchically Ordered Mesocellular Mesoporous Silica Materials Hosting Crosslinked Enzyme Aggregates

    SciTech Connect

    Lee, Jinwoo; Kim, Jungbae; Kim, Jaeyun; Jia, Hongfei; Kim, Moon Il; Kwak, Ja Hun; Jin, Sunmi; Dohnalkova, Alice; Park, Hyun-Gyu; Chang, Ho Nam; Wang, Ping; Grate, Jay W.; Hyeon, Taeghwan

    2005-07-01

    : Hierarchically ordered mesocellular mesoporous silica materials (MMS) were synthesized using a single structure directing agent under neutral conditions for the first time. The mesocellular pores are synthesized without adding any pore expander, and the walls of cellular pores in MMS are composed of SBA-15 type mesopores. The small-angle X-ray scattering (SAXS) pattern of MMS revealed the presence of ordered pore structures with two different length scales. The current MMS possesses four different pore systems; complementary micro/mesopores, main 13 nm mesopores, 40 nm mesocellular spherical pores, and textural inter-particle macropores. Nanometer-scale enzyme reactors (NER) were developed in mesocellular mesoporous silica (MMS) via a ship-in-a-bottle approach, which employs adsorption of enzymes followed by cross-linking using glutaraldehyde (GA) treatment. The resulting NER show an impressive stability and activity with an extremely high loading of enzymes. For example, NER containing α-chymotrypsin (NER-CT) could hold 0.5 g CT in 1 g of silica, but the specific activity of NER-CT was 10.4 times higher than that of the adsorbed CT with a lower loading (0.07 g CT per 1 g of silica), which was further decreased by a continuous leaching of adsorbed CT. NER-CT showed excellent stability without any leaching, i.e. no activity decrease at all in a rigorously-shaking condition for two weeks (a half-life with 3.8 years), while the conventional adsorption method resulted in a half-life of 3.6 days in the same condition.

  20. Silica mesoporous thin films as containers for benzotriazole for corrosion protection of 2024 aluminium alloys

    NASA Astrophysics Data System (ADS)

    Recloux, Isaline; Mouanga, Maixent; Druart, Marie-Eve; Paint, Yoann; Olivier, Marie-Georges

    2015-08-01

    This work contributes to the development of a new environmentally friendly alternative pretreatment for 2024 aluminium alloys to replace hexavalent chromium based conversion layers in the aeronautical field. A silica mesoporous thin film, synthesized through the evaporation induced self-assembly process, was doped with benzotriazole to obtain active corrosion protection. Inhibitor loading contents were correlated with pore characteristics. The release kinetics was studied as function of pH. The application of the doped mesoporous film on 2024 aluminium alloy revealed a slowing down of corrosion processes, demonstrating its potential as an active inhibitor storage layer.

  1. Selective functionalization of mesoporous silica nanoparticles with ibuprofen and Gd(III) chelates: a new probe for potential theranostic applications.

    PubMed

    Carniato, Fabio; Muñoz-Úbeda, Mónica; Tei, Lorenzo; Botta, Mauro

    2015-11-01

    Organo-modified mesoporous silica nanoparticles, loaded with ibuprofen into the pores and functionalized on the external surface with a stable Gd(iii)-DOTA-monoamide chelate, were prepared and explored as potential theranostic probes.

  2. Facile growth of well-dispersed and ultra-small MoS2 nanodots in ordered mesoporous silica nanoparticles.

    PubMed

    Wang, Yi; Wang, Shanshan; Li, Chengyi; Qian, Min; Bu, Juan; Wang, Jianxin; Huang, Rongqin

    2016-08-11

    A facile one-step solvothermal method was developed for the homogeneously confined growth of ultra-small (∼1.5 nm) and monodispersed 2H phase MoS2 nanodots into mesoporous silica nanoparticles (MSNs). PMID:27387440

  3. Controllable synthesis of hollow mesoporous silica particles by a facile one-pot sol-gel method.

    PubMed

    Song, Jing-Chuan; Xue, Fei-Fei; Lu, Zhong-Yuan; Sun, Zhao-Yan

    2015-07-01

    A simple and facile one-pot sol-gel method is proposed for the fabrication of hollow mesoporous silica particles. Both the particle size and the shell thickness can be well controlled by moderately tuning some experimental parameters.

  4. Facile growth of well-dispersed and ultra-small MoS2 nanodots in ordered mesoporous silica nanoparticles.

    PubMed

    Wang, Yi; Wang, Shanshan; Li, Chengyi; Qian, Min; Bu, Juan; Wang, Jianxin; Huang, Rongqin

    2016-08-11

    A facile one-step solvothermal method was developed for the homogeneously confined growth of ultra-small (∼1.5 nm) and monodispersed 2H phase MoS2 nanodots into mesoporous silica nanoparticles (MSNs).

  5. Self-assembly of supramolecular triarylamine nanowires in mesoporous silica and biocompatible electrodes thereof

    NASA Astrophysics Data System (ADS)

    Licsandru, Erol-Dan; Schneider, Susanne; Tingry, Sophie; Ellis, Thomas; Moulin, Emilie; Maaloum, Mounir; Lehn, Jean-Marie; Barboiu, Mihail; Giuseppone, Nicolas

    2016-03-01

    Biocompatible silica-based mesoporous materials, which present high surface areas combined with uniform distribution of nanopores, can be organized in functional nanopatterns for a number of applications. However, silica is by essence an electrically insulating material which precludes applications for electro-chemical devices. The formation of hybrid electroactive silica nanostructures is thus expected to be of great interest for the design of biocompatible conducting materials such as bioelectrodes. Here we show that we can grow supramolecular stacks of triarylamine molecules in the confined space of oriented mesopores of a silica nanolayer covering a gold electrode. This addressable bottom-up construction is triggered from solution simply by light irradiation. The resulting self-assembled nanowires act as highly conducting electronic pathways crossing the silica layer. They allow very efficient charge transfer from the redox species in solution to the gold surface. We demonstrate the potential of these hybrid constitutional materials by implementing them as biocathodes and by measuring laccase activity that reduces dioxygen to produce water.Biocompatible silica-based mesoporous materials, which present high surface areas combined with uniform distribution of nanopores, can be organized in functional nanopatterns for a number of applications. However, silica is by essence an electrically insulating material which precludes applications for electro-chemical devices. The formation of hybrid electroactive silica nanostructures is thus expected to be of great interest for the design of biocompatible conducting materials such as bioelectrodes. Here we show that we can grow supramolecular stacks of triarylamine molecules in the confined space of oriented mesopores of a silica nanolayer covering a gold electrode. This addressable bottom-up construction is triggered from solution simply by light irradiation. The resulting self-assembled nanowires act as highly conducting

  6. Highly ordered poly(thiophene)s prepared in mesoporous silica nanoparticles.

    PubMed

    Seo, Seogjae; Kim, Jeonghun; Kim, Byeonggwan; Vinu, Ajayan; Kim, Eunkyoung

    2011-05-01

    Nanostructured PEDOT was synthesized using mesoporous silica as a nano-template. The polymerization of thiophene monomers was performed with an oxidant and mesoporous silica nanoparticles. The silica particles took essential role in absorbing monomers and oxidant molecules, and growth of polymers inside their pores. As prepared polymer/silica composite was treated with HF solution to remove silica template to result in 1D wire structure and mesh type porous 3D structures from SBA-15 and KIT-6 template, respectively. The average size of the poly(thiophene) wires was 10 15 nm, which was matched well to the pores size of the silica templates, as determined from an electron microscopy. At optimized condition, the room temperature electrical conductivities of the PEDOT grown from SBA-15 and KIT-6 template were similar as 1.1 and 1.0 S/cm, respectively. However, the evolution of the PEDOT conductivity versus temperature was different depending on the templates. These results gave a unique chance to tailor made 3 dimensional structure as well as properties of conductive polymer. PMID:21780498

  7. Spark Plasma Sintering and Multi-scale Characterization of Mesoporous Silica Disks

    NASA Astrophysics Data System (ADS)

    Maheshwari, Harsh

    Oil from shale and tight formations has helped the United States produce close to 10 million barrels of oil per day, a 40-year high. Well characterized sintered nano materials will serve as calibration materials for understanding important thermodynamic and flow properties of fluids in similar formations. To this effect, sintered mesoporous silica monoliths containing micro- and nano-porosity are characterized across multiple length scales at various processing temperatures using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Vickers hardness tests, and Brunauer-Emmett-Teller (BET) gas adsorption measurements. Results show that the mesoporosity in raw SBA-15 silica powders can be retained during spark-plasma sintering (SPS) up to 850 ºC which is lower than those achieved by conventional sintering techniques (>1050 ºC). Details of micro- and meso-porosity were revealed by studying the internal structure through SEM and in-situ TEM tomography of the sintered specimens in comparison to the pristine silica powder. The microporosity is retained up to 950°C under the same pressure, and the degree of microporosity increases when the mesopores collapse due to individual nanoparticle shrinkage. In situ TEM characterization of mesoporosity in the absence of applied pressure reveal pore collapse above 1050°C, which is considerably above the temperatures observed under applied pressures during SPS processing. The degree of microporosity, obtained under different processing conditions, is correlated to the mechanical properties, available surface area and pore morphology. In spite of the unique synthesis process, sintered mesoporous silica satisfies the Ryshkewitch relationship -- the correlation of mechanical properties to porosity. Subsequently, in-situ TEM nanoindentation was conducted to investigate the mechanical properties of individual mesoporous silica nanoparticles. The ability to control the micro- and meso-porosity of these

  8. Effect of polyvinylpyrrolidone on mesoporous silica morphology and esterification of lauric acid with 1-butanol catalyzed by immobilized enzyme

    NASA Astrophysics Data System (ADS)

    Zhang, Jinyu; Zhou, Guowei; Jiang, Bin; Zhao, Minnan; Zhang, Yan

    2014-05-01

    Mesoporous silica materials with a range of morphology evolution, i.e., from curved rod-shaped mesoporous silica to straight rod-shaped mesoporous silica, were successfully prepared using polyvinylpyrrolidone (PVP) and triblock copolymer as dual template. The effects of PVP molecular weight and concentration on mesoporous silica structure parameters were studied. Results showed that surface area and pore volume continuously decreased with increased PVP molecular weight. Mesoporous silica prepared with PVP K30 also possessed larger pore diameter, interplanar spacing (d100), and cell parameter (a0) than that prepared with PVP K15 and PVP K90. In addition, with increased PVP concentration, d100 and a0 continuously decreased. The mechanism of morphology evolution caused by the change in PVP concentration was investigated. The conversion rate of lauric acid with 1-butanol catalyzed by immobilized Porcine pancreatic lipase (PPL) was also evaluated. Results showed that PPL immobilized on amino-functionalized straight rod-shaped mesoporous silica maintained 50% of its esterification conversion rate even after five cycles of use with a maximum conversion rate was about 90.15%.

  9. Surface texture and physicochemical characterization of mesoporous carbon--wrapped Pd-Fe catalysts for low-temperature CO catalytic oxidation.

    PubMed

    Han, Weiliang; Zhang, Guodong; Zhao, Kun; Lu, Gongxuan; Tang, Zhicheng

    2015-11-21

    In this paper, mesoporous carbon (meso-C) with three-dimensional mesoporous channels was synthesized through a nanocasting route using three-dimensional mesoporous silica KIT-6 as the template. Mesoporous carbon wrapped Pd-Fe nanocomposite catalysts were synthesized by the co-precipitation method. The effects of the experimental conditions, such as pH value, Fe loading content and calcination temperature, on CO oxidation were studied in detail. The prepared Pd-Fe/meso-C catalysts showed excellent catalytic activity after optimizing the experimental conditions. The surface tetravalent Pd content, existing forms of Fe species, surface chemical adsorbed oxygen concentration, and pore channels of mesoporous carbon played vital roles in achieving the highest performance for the Pd-Fe/meso-C catalyst. The reaction pathway was conjectured according to the XPS analysis of the Pd-Fe/meso-C catalysts for CO oxidation, which maybe adhered to the Langmuir-Hinshelwood + redox mechanism. The effect of moisture on CO conversion was investigated, and the superior Pd-Fe/meso-C catalyst could maintain its activity beyond 12 h. This catalyst also showed excellent activity compared to the reported values in the existing literature.

  10. Rare-earth metal oxide doped transparent mesoporous silica plates under non-aqueous condition as a potential UV sensor.

    PubMed

    Lee, Sang-Joon; Park, Sung Soo; Lee, Sang Hyun; Hong, Sang-Hyun; Ha, Chang-Sik

    2013-11-01

    Transparent mesoporous silica plates doped with rare-earth metal oxide were prepared using solvent-evaporation method based on the self-organization between structure-directing agent and silicate in a non-aqueous solvent. A triblock copolymer, Pluronic (F127 or P123), was used as the structure-directing agent, while tetraethyl orthosilicate (TEOS) was used as a silica source. The pore diameter and the surface area of the mesoporous silica plate prepared with the optimized conditions were ca 40 A and 600 m2 g(-1), respectively, for both structure-directing agent. Rare-earth metal oxides (Eu, Tb, Tm oxide) in mesochannel were formed via one-step synthetic route based on the preparation method of a silica plate. Optical properties of rare-earth metal oxide-doped mesoporous silica plates were investigated by UV irradiation and photoluminescence (PL) spectroscopy. Under the exitation wavelength of 254 nm, the doped mesoporous silica plates emitted red, green and blue for Eu, Tb and Tm oxides, respectively. Rare-earth metal oxide-doped mesoporous silica plates showed enhanced PL intensity compared to that of the bulk rare-earth metal oxide.

  11. Nanorods of Various Oxides and Hierarchically Structured Mesoporous Silica by Sol-Gel Electrophoresis

    SciTech Connect

    Limmer, Steven J.; Hubler, Timothy L.; Cao, Guozhong

    2003-01-02

    In this paper, we report the template-based growth of nanorods of oxides and hierarchically structured mesoporous silica, formed by means of a combination of sol-gel processing and elecrophoretic deposition. Both single metal oxides (TiO2) and complex oxides (Pb(Zr0.52Ti0.48)O3) have been grown by this method. This method has also been applied to the growth of nanorods of mesoporous silica having an ordered pore structure, where the pores are aligned parallel to the long axis of the nanorod. Uniformly sized nanorods of about 125-200 nm in diameter and 10 um in length were grown over large areas with near unidirectional alignment. Appropriate sol preparation yielded the desired stoichiometric chemical composition and crystal structure of the oxide nanorods, with a heat treatment (500-700 C for 15-30 min) for crystallization, densification and any necessary pyrolysis.

  12. Magnetic mesoporous silica nanoparticles for potential delivery of chemotherapeutic drugs and hyperthermia.

    PubMed

    Tao, Cuilian; Zhu, Yufang

    2014-11-01

    Magnetic mesoporous silica (MMS) nanoparticles with controllable magnetization have been synthesized by encapsulating Fe3O4 nanoparticles in a mesoporous silica matrix. The structure, magnetic heating capacity and drug delivery ability of MMS nanoparticles were evaluated. The results showed that MMS nanoparticles had an average particle size of 150 nm and showed low cytotoxicity and efficient cell uptake ability. MMS nanoparticles exhibited a sustained drug release in the medium of pH 5.0, but a very slow release in the medium of pH 7.4. On the other hand, MMS nanoparticles could controllably generate heat to reach the hyperthermia temperature within a short time upon exposure to an alternating magnetic field due to the superparamagnetic behavior and controllable magnetization. Therefore, MMS nanoparticles could provide a promising multifunctional platform for the combination of chemotherapy and hyperthermia for cancer therapy. PMID:25190592

  13. Potential of ordered mesoporous silica for oral delivery of poorly soluble drugs.

    PubMed

    Vialpando, Monica; Martens, Johan A; Van den Mooter, Guy

    2011-08-01

    The use of ordered mesoporous silica is one of the more recent and rapidly developing formulation techniques for enhancing the solubility of poorly water-soluble drugs. Their large surface area and pore volume make ordered mesoporous silica materials excellent candidates for efficient drug loading and rapid release. While this new approach offers many promising advantages, further research is still necessary to elucidate the molecular mechanisms and to improve our scientific insight into the behavior of this system. In this review, the significant developments to date are presented and research challenges highlighted. Aspects of downstream processability are discussed in view of their special bulk powder properties and unique pore architecture. Lastly, perspectives for successful oral dosage form development are presented. PMID:22833866

  14. Codelivery of anticancer drugs and siRNA by mesoporous silica nanoparticles.

    PubMed

    Hanafi-Bojd, Mohammad Yahya; Ansari, Legha; Malaekeh-Nikouei, Bizhan

    2016-09-01

    The most common method for cancer treatment is chemotherapy. Multidrug resistance (MDR) is one of the major obstacles in chemotherapeutic treatment of many human cancers. One strategy to overcome this challenge is the delivery of anticancer drugs and siRNA simultaneously using nanoparticles. Mesoporous silica nanoparticles are one of the most popular nanoparticles for cargo delivery because of their intrinsic porosity. This paper highlights recent advances in codelivery of chemotherapeutic and siRNA with mesoporous silica nanoparticles for cancer therapy. In addition, synthesis and functionalization approaches of these nanoparticles are summarized. This review presents insight into the utilization of nanoparticles and combination therapy to achieve more promising results in chemotherapy. PMID:27582236

  15. Utilization of rice husk ash as silica source for the synthesis of mesoporous silicas and their application to CO2 adsorption through TREN/TEPA grafting.

    PubMed

    Bhagiyalakshmi, Margandan; Yun, Lee Ji; Anuradha, Ramani; Jang, Hyun Tae

    2010-03-15

    Mesoporous MCM-41, MCM-48 and SBA-15 were synthesized using Rice husk ash (RHA) as the silica source and their defective Si-OH sites were functionalized by 3-chloropropyltrimethoxysilane (CPTMS) which was subsequently grafted with amine compounds, Tris(2-aminoethyl)amine (TREN) and Tetraethylenepentamine (TEPA). X-ray powder diffraction (XRD) and BET results of the parent mesoporous silica suggested their closeness of structural properties to those obtained from conventional silica sources. CO(2) adsorption of branched amine TREN and straight chain amine TEPA at 25, 50 and 75 degrees C was obtained by Thermogravimetric Analyser (TGA) at atmospheric pressure. TREN grafted mesoporous silica showed 7% of CO(2) adsorption while TEPA grafted mesoporous silicas showed less CO(2) adsorption, which is due to the presence of isolated amine groups in TREN. TREN grafted mesoporous silicas were also observed to be selective towards CO(2), thermally stable and recyclable. The order of CO(2) adsorption with respect to amount of amine grafting was observed to be MCM-48/TREN>MCM-41/TREN>SBA-15/TREN.

  16. Mesoporous silica nanotubes hybrid membranes for functional nanofiltration

    NASA Astrophysics Data System (ADS)

    El-Safty, Sherif A.; Shahat, Ahmed; Mekawy, Moataz; Nguyen, Hoa; Warkocki, Wojciech; Ohnuma, Masato

    2010-09-01

    The development of nanofiltration systems would greatly assist in the production of well-defined particles and biomolecules with unique properties. We report a direct, simple synthesis of hexagonal silica nanotubes (NTs), which vertically aligned inside anodic alumina membranes (AAM) by means of a direct templating method of microemulsion phases with cationic surfactants. The direct approach was used as soft templates for predicting ordered assemblies of surfactant/silica composites through strong interactions within AAM pockets. Thus, densely packed NTs were successfully formed in the entirety of the AAM channels. These silica NTs were coated with layers of organic moieties to create a powerful technique for the ultrafine filtration. The resulting modified-silica NTs were chemically robust and showed affinity toward the transport of small molecular particles. The rigid silica NTs inside AAM channels had a pore diameter of <= 4 nm and were used as ultrafine filtration systems for noble metal nanoparticles (NM NPs) and semiconductor nanocrystals (SC NCs) fabricated with a wide range of sizes (1.0-50 nm) and spherical/pyramidal morphologies. Moreover, the silica NTs hybrid membranes were also found to be suitable for separation of biomolecules such as cytochrome c (CytC). Importantly, this nanofilter design retains high nanofiltration efficiency of NM NPs, SC NCs and biomolecules after a number of reuse cycles. Such retention is crucial in industrial applications.

  17. Large pore mesoporous silica nanomaterials for application in delivery of biomolecules

    NASA Astrophysics Data System (ADS)

    Knežević, Nikola Ž.; Durand, Jean-Olivier

    2015-01-01

    Various approaches for the synthesis of mesoporous silicate nanoparticles (MSN) with large pore (LP) diameters (in the range of 3-50 nm) are reviewed in this article. The work also covers the construction of magnetic analogues of large pore-mesoporous silica nanoparticles (LPMMSN) and their biomedical applications. The constructed materials exhibit vast potential for application in the loading and delivery of large drug molecules and biomolecules. Literature reports on the application of LPMSN and LPMMSN materials for the adsorption and delivery of proteins, enzymes, antibodies, and nucleic acids are covered in depth, which exemplify their highly potent characteristics for use in drug and biomolecule delivery to diseased tissues.Various approaches for the synthesis of mesoporous silicate nanoparticles (MSN) with large pore (LP) diameters (in the range of 3-50 nm) are reviewed in this article. The work also covers the construction of magnetic analogues of large pore-mesoporous silica nanoparticles (LPMMSN) and their biomedical applications. The constructed materials exhibit vast potential for application in the loading and delivery of large drug molecules and biomolecules. Literature reports on the application of LPMSN and LPMMSN materials for the adsorption and delivery of proteins, enzymes, antibodies, and nucleic acids are covered in depth, which exemplify their highly potent characteristics for use in drug and biomolecule delivery to diseased tissues. Dedicated to Professor Jeffrey I. Zink on the occasion of his 70th birthday.

  18. Phosphate adsorption on aluminum-coordinated functionalized macroporous–mesoporous silica: Surface structure and adsorption behavior

    SciTech Connect

    Huang, Weiya; Li, Dan; Zhu, Yi; Xu, Kai; Li, Jianqiang; Han, Boping; Zhang, Yuanming

    2013-12-15

    Graphical abstract: - Highlights: • Al-coordinated functionalized macroporous–mesoporous silica for phosphate removal. • It had the maximum adsorption capacity of 23.59 mg P/g. • Over 95% of the final adsorption capacity reached in the first 1 min. - Abstract: In this study, Al(III)-coordinated diamino-functionalized macroporous–mesoporous silica was synthesized and characterized by X-ray diffraction, N{sub 2} adsorption–desorption, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy. Because of well-defined and interconnecting macroporous–mesoporous networks, the resulting adsorbent (MM-SBA) exhibited a significantly better phosphate adsorption performance and faster removal rate, as compared with the mesoporous adsorbent (M-SBA). Based on the Freundlich and Langmuir models, the phosphate adsorption capacity and the maximum adsorption capacity of MM-SBA were 7.99 mg P/g and 23.59 mg P/g, respectively. In the kinetic study of MM-SBA, over 95% of its final adsorption capacity reached in the first 1 min; whereas that of M-SBA was less than 79%.

  19. Mesoporous and biocompatible surface active silica aerogel synthesis using choline formate ionic liquid.

    PubMed

    Meera, Kamal Mohamed Seeni; Sankar, Rajavelu Murali; Jaisankar, Sellamuthu N; Mandal, Asit Baran

    2011-09-01

    In this paper, we report the preparation and characterization of mesoporous and biocompatible transparent silica aerogel by the sol-gel polymerization of tetraethyl orthosilicate using ionic liquid. Choline cation based ionic liquid allows the silica framework to form in a non collapsing environment and controls the pore size of the gel. FT-IR spectra reveal the interaction of ionic liquid with surface -OH of the gel. DSC thermogram giving the evidence of confinement of ionic liquid within the silica matrix, which helps to avoid the shrinkage of the gel during the aging process. Nitrogen sorption measurements of gel prepared with ionic liquid exhibit a low surface area of 100.53 m2/g and high average pore size of 3.74 nm. MTT assay proves the biocompatibility and cell viability of the prepared gels. This new nanoporous silica material can be applied to immobilize biological molecules, which may retain their stability over a longer period.

  20. Exchange bias effect in nickel zinc ferrite-mesoporous silica nanocomposites

    NASA Astrophysics Data System (ADS)

    Banerjee, Shilpi; Hajra, Partha; Mada, Mykanth Reddy; Bhaumik, Asim; Bandyopadhyay, Sri; Chakravorty, Dipankar

    2013-04-01

    Nickel zinc ferrite-mesoporous silica nanocomposite (NZF-MS) was synthesized using impregnation method. The microstructure was investigated by transmission electron microscopy. A magnetic exchange bias effect was exhibited by the nanocomposites. This was ascribed to the presence of a ferromagnetic core and antiferromagnetic shell structure. Electron microscopic studies confirmed the presence of a core-shell structure with NZF forming the core. The zero-field cooled magnetization data as a function of temperature indicated the presence of an antiferromagnetic phase which is believed to be formed by the diffusion of Fe3+ or Ni2+ ions into the silica glass.

  1. Core-Cone Structured Monodispersed Mesoporous Silica Nanoparticles with Ultra-large Cavity for Protein Delivery.

    PubMed

    Xu, Chun; Yu, Meihua; Noonan, Owen; Zhang, Jun; Song, Hao; Zhang, Hongwei; Lei, Chang; Niu, Yuting; Huang, Xiaodan; Yang, Yannan; Yu, Chengzhong

    2015-11-25

    A new type of monodispersed mesoporous silica nanoparticles with a core-cone structure (MSN-CC) has been synthesized. The large cone-shaped pores are formed by silica lamellae closely packed encircling a spherical core, showing a structure similar to the flower dahlia. MSN-CC has a large pore size of 45 nm and a high pore volume of 2.59 cm(3) g(-1). MSN-CC demonstrates a high loading capacity of large proteins and successfully delivers active β-galactosidase into cells, showing their potential as efficient nanocarriers for the cellular delivery of proteins with large molecular weights. PMID:26426420

  2. Self-Immolative Linkers as Caps for the Design of Gated Silica Mesoporous Supports.

    PubMed

    Juárez, L Alberto; Añón, Elena; Giménez, Cristina; Sancenón, Félix; Martínez-Máñez, Ramón; Costero, Ana M; Gaviña, Pablo; Parra, Margarita; Bernardos, Andrea

    2016-09-26

    A new hybrid material based on sulforhodamine B dye-loaded silica mesoporous nanoparticles capped with a self-immolative gate has been synthesized and characterized. The gated material's controlled release behavior is monitored under different pH conditions. Under acidic and neutral conditions, a low level of dye release is detected. However, at slightly basic pH, significant dye release occurs owing to deprotonation of the phenol moiety in the capping molecule, which results in its disassembly. PMID:27304830

  3. Application of mesoporous silica materials for the immobilization of polyphenol oxidase.

    PubMed

    Corell Escuin, Paula; García-Bennett, Alfonso; Ros-Lis, Jose Vicente; Argüelles Foix, Angel; Andrés, Ana

    2017-02-15

    The ability of a number of mesoporous silica materials (SBA-15, SBA-3, and MCM-48) to immobilize polyphenol oxidase (PPO) at different pH has been tested. Pore size and volume are the structural characteristics with higher influence on the PPO immobilization. Mesoropous material SBA-15 adsorbs a larger quantity of PPO at pH 4.00 and offers an inhibition of enzymatic activity close the 50% in apple extracts. PMID:27664646

  4. Neoglycoenzyme-Gated Mesoporous Silica Nanoparticles: Toward the Design of Nanodevices for Pulsatile Programmed Sequential Delivery.

    PubMed

    Díez, Paula; Sánchez, Alfredo; de la Torre, Cristina; Gamella, María; Martínez-Ruíz, Paloma; Aznar, Elena; Martínez-Máñez, Ramón; Pingarrón, José M; Villalonga, Reynaldo

    2016-03-01

    We report herein the design of a stimulus-programmed pulsatile delivery system for sequential cargo release based on the use of a lactose-modified esterase as a capping agent in phenylboronic acid functionalized mesoporous silica nanoparticles. The dual-release mechanism was based on the distinct stability of the cyclic boronic acid esters formed with lactose residues and the long naturally occurring glycosylation chains in the modified neoglycoenzyme. Cargo delivery in succession was achieved using glucose and ethyl butyrate as triggers.

  5. Self-Immolative Linkers as Caps for the Design of Gated Silica Mesoporous Supports.

    PubMed

    Juárez, L Alberto; Añón, Elena; Giménez, Cristina; Sancenón, Félix; Martínez-Máñez, Ramón; Costero, Ana M; Gaviña, Pablo; Parra, Margarita; Bernardos, Andrea

    2016-09-26

    A new hybrid material based on sulforhodamine B dye-loaded silica mesoporous nanoparticles capped with a self-immolative gate has been synthesized and characterized. The gated material's controlled release behavior is monitored under different pH conditions. Under acidic and neutral conditions, a low level of dye release is detected. However, at slightly basic pH, significant dye release occurs owing to deprotonation of the phenol moiety in the capping molecule, which results in its disassembly.

  6. Application of mesoporous silica materials for the immobilization of polyphenol oxidase.

    PubMed

    Corell Escuin, Paula; García-Bennett, Alfonso; Ros-Lis, Jose Vicente; Argüelles Foix, Angel; Andrés, Ana

    2017-02-15

    The ability of a number of mesoporous silica materials (SBA-15, SBA-3, and MCM-48) to immobilize polyphenol oxidase (PPO) at different pH has been tested. Pore size and volume are the structural characteristics with higher influence on the PPO immobilization. Mesoropous material SBA-15 adsorbs a larger quantity of PPO at pH 4.00 and offers an inhibition of enzymatic activity close the 50% in apple extracts.

  7. Cancer therapy improvement with mesoporous silica nanoparticles combining photodynamic and photothermal therapy

    NASA Astrophysics Data System (ADS)

    Zhao, Z. X.; Huang, Y. Z.; Shi, S. G.; Tang, S. H.; Li, D. H.; Chen, X. L.

    2014-07-01

    In this work, we develop novel mesoporous silica composite nanoparticles (hm-SiO2(AlC4Pc)@Pd) for the co-delivery of photosensitizer (PS) tetra-substituted carboxyl aluminum phthalocyanine (AlC4Pc) and small Pd nanosheets as a potential dual carrier system to combine photodynamic therapy (PDT) with photothermal therapy (PTT). In the nanocomposite, PS AlC4Pc was covalently conjugated to a mesoporous silica network, and small Pd nanosheets were coated onto the surface of mesoporous silica by both coordination and electrostatic interaction. Since small Pd nanosheets and AlC4Pc display matched maximum absorptions in the 600-800 nm near-infrared (NIR) region, the fabricated hm-SiO2(AlC4Pc)@Pd nanocomposites can generate both singlet oxygen and heat upon 660 nm single continuous wavelength (CW) laser irradiation. In vitro results indicated that the cell-killing efficacy by simultaneous PDT/PTT treatment using hm-SiO2(AlC4Pc)@Pd was higher than PDT or PTT treatment alone after exposure to a 660 nm CW-NIR laser.

  8. Large-Pore Mesoporous Silica with Three-Dimensional Wormhole Framework Structures

    PubMed Central

    Park, In; Pinnavaia, Thomas J.

    2009-01-01

    Large-pore mesoporous silica with 3D wormhole framework structures (denoted MSU-J) are prepared through a supramolecular hydrogen-bonding assembly pathway from low-cost sodium silicate as the silica source and commercially available mono- and triamine Jeffamine and Surfonamine surfactants as structure-directing porogens. The calcined mesostructures exhibit large pore sizes (up to 8.2 nm), surface areas (632–1030 m2/g) and pore volumes (0.5–2.0 cm3/g), depending on the surfactant chain length and synthesis temperature (25–65 °C). The textural properties of these new wormhole mesostructures are comparable to those of hexagonal SBA-15 derivatives and large pore MCM-48. However, unlike the SBA-15 structure type, wherein the 3D pore network is formed by connecting 1D cylindrical mesopores through micropores, MSU-J mesophases have wormhole framework structures containing fully interconnected 3D mesopores that can minimize the diffusion limitations often encountered in adsorption and chemical catalysis. Also, unlike large pore MCM-48, which requires cost-intensive tetraethylorthosilicate as a silica source and the use of a co-surfactant as a pore expander under strong acid conditions, MSU-J mesostructures are assembled from low cost sodium silicate in the presence of a single Jeffamine or Surfonamine porogen at near-neutral pH. PMID:20126285

  9. On-chip evaluation of platelet adhesion and aggregation upon exposure to mesoporous silica nanoparticles.

    PubMed

    Kim, Donghyuk; Finkenstaedt-Quinn, Solaire; Hurley, Katie R; Buchman, Joseph T; Haynes, Christy L

    2014-03-01

    Mesoporous silica nanoparticles are promising drug delivery agents; however, their interaction with various in vivo biological components is still under investigation. In this work, the impact of sub-50 nm diameter mesoporous silica nanoparticles on platelet function is investigated using a microfluidic platform to model blood vessel characteristics. Platelet adhesion and aggregation in the presence of mesoporous silica nanoparticles is investigated, controlling whether or not platelets are activated ahead of nanoparticle exposure. The results indicate that nanoparticles slightly compromise platelet adhesion to endothelial cells at low nanoparticle doses, but that high nanoparticle doses significantly increase the number of platelet adhesion events, leading to higher probability for uncontrolled platelet actions (e.g. clot formation in vivo). High nanoparticle doses also induced platelet aggregation. While platelet activation and aggregation occurred, in no case did nanoparticle exposure result in significant loss of platelet viability; as such, this work clearly demonstrates that aspects besides viability, such as cellular adhesion and interaction with other cell types, have to be considered in the context of nanotoxicology. This simple and highly adaptable analytical platform will be useful for further nanotoxicity studies involving other nanoparticle and cell types.

  10. Large-Pore Mesoporous Silica with Three-Dimensional Wormhole Framework Structures.

    PubMed

    Park, In; Pinnavaia, Thomas J

    2009-02-01

    Large-pore mesoporous silica with 3D wormhole framework structures (denoted MSU-J) are prepared through a supramolecular hydrogen-bonding assembly pathway from low-cost sodium silicate as the silica source and commercially available mono- and triamine Jeffamine and Surfonamine surfactants as structure-directing porogens. The calcined mesostructures exhibit large pore sizes (up to 8.2 nm), surface areas (632-1030 m(2)/g) and pore volumes (0.5-2.0 cm(3)/g), depending on the surfactant chain length and synthesis temperature (25-65 °C). The textural properties of these new wormhole mesostructures are comparable to those of hexagonal SBA-15 derivatives and large pore MCM-48. However, unlike the SBA-15 structure type, wherein the 3D pore network is formed by connecting 1D cylindrical mesopores through micropores, MSU-J mesophases have wormhole framework structures containing fully interconnected 3D mesopores that can minimize the diffusion limitations often encountered in adsorption and chemical catalysis. Also, unlike large pore MCM-48, which requires cost-intensive tetraethylorthosilicate as a silica source and the use of a co-surfactant as a pore expander under strong acid conditions, MSU-J mesostructures are assembled from low cost sodium silicate in the presence of a single Jeffamine or Surfonamine porogen at near-neutral pH.

  11. Alendronate decorated nano hydroxyapatite in mesoporous silica: Cytotoxicity and osteogenic properties

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Liu, Weiqiang; She, Zhending; Wu, Hongkai; Shi, Xuetao

    2011-09-01

    Mesoporous silica is a promising drug delivery vehicle due to its large surface area and order porous structure. Hydroxyapatite-modified mesoporous silica materials (MSH) have been developed, and the cytotoxicity of MSH and unmodified mesoporous silica (HMS) has also been studied in this work. The results indicated that MSH exhibited lower cytotoxicity than HMS. The drug release property of MSH was also investigated in this paper. Alendronate (AL) was laden into MSH and HMS, respectively. MSH exhibited long release period lasting over 30 days with a weak burst release in the first 5 days; however, the AL release period of HMS was just 5 days with a remarkable burst release. In addition, the osteogenic commitment induced in human marrow mesenchymal stem cells (MSCs) by MSH-alendronate (MSH-AL) was also investigated, and the osteogenesis of MSCs was evaluated by alkaline phosphatase (ALP) assay. The osteogenesis of MSCs induced by MSH-AL is comparable to that induced by the osteogenic medium. Taken together, MSH can be severed as potential bone repair materials with lower cytotoxicity.

  12. Fabrication of high specificity hollow mesoporous silica nanoparticles assisted by Eudragit for targeted drug delivery.

    PubMed

    She, Xiaodong; Chen, Lijue; Velleman, Leonora; Li, Chengpeng; Zhu, Haijin; He, Canzhong; Wang, Tao; Shigdar, Sarah; Duan, Wei; Kong, Lingxue

    2015-05-01

    Hollow mesoporous silica nanoparticles (HMSNs) are one of the most promising carriers for effective drug delivery due to their large surface area, high volume for drug loading and excellent biocompatibility. However, the non-ionic surfactant templated HMSNs often have a broad size distribution and a defective mesoporous structure because of the difficulties involved in controlling the formation and organization of micelles for the growth of silica framework. In this paper, a novel "Eudragit assisted" strategy has been developed to fabricate HMSNs by utilising the Eudragit nanoparticles as cores and to assist in the self-assembly of micelle organisation. Highly dispersed mesoporous silica spheres with intact hollow interiors and through pores on the shell were fabricated. The HMSNs have a high surface area (670 m(2)/g), small diameter (120 nm) and uniform pore size (2.5 nm) that facilitated the effective encapsulation of 5-fluorouracil within HMSNs, achieving a high loading capacity of 194.5 mg(5-FU)/g(HMSNs). The HMSNs were non-cytotoxic to colorectal cancer cells SW480 and can be bioconjugated with Epidermal Growth Factor (EGF) for efficient and specific cell internalization. The high specificity and excellent targeting performance of EGF grafted HMSNs have demonstrated that they can become potential intracellular drug delivery vehicles for colorectal cancers via EGF-EGFR interaction. PMID:25617610

  13. Protocells: Modular Mesoporous Silica Nanoparticle-Supported Lipid Bilayers for Drug Delivery.

    PubMed

    Butler, Kimberly S; Durfee, Paul N; Theron, Christophe; Ashley, Carlee E; Carnes, Eric C; Brinker, C Jeffrey

    2016-04-27

    Mesoporous silica nanoparticle-supported lipid bilayers, termed 'protocells,' represent a potentially transformative class of therapeutic and theranostic delivery vehicle. The field of targeted drug delivery poses considerable challenges that cannot be addressed with a single 'magic bullet'. Consequently, the protocell has been designed as a modular platform composed of interchangeable biocompatible components. The mesoporous silica core has variable size and shape to direct biodistribution and a controlled pore size and surface chemistry to accommodate diverse cargo. The encapsulating supported lipid bilayer can be modified with targeting and trafficking ligands as well as polyethylene glycol (PEG) to effect selective binding, endosomal escape of cargo, drug efflux prevention, and potent therapeutic delivery, while maintaining in vivo colloidal stability. This review describes the individual components of the platform, including the mesoporous silica nanoparticle core and supported lipid bilayer, their assembly (by multiple techniques) into a protocell, and the combined, often synergistic, performance of the protocell based on in vitro and in vivo studies, including the assessment of biocompatibility and toxicity. In closing, the many emerging variations of the protocell theme and the future directions for protocell research are commented on. PMID:26780591

  14. Predictable Heating and Positive MRI Contrast from a Mesoporous Silica-Coated Iron Oxide Nanoparticle.

    PubMed

    Hurley, Katie R; Ring, Hattie L; Etheridge, Michael; Zhang, Jinjin; Gao, Zhe; Shao, Qi; Klein, Nathan D; Szlag, Victoria M; Chung, Connie; Reineke, Theresa M; Garwood, Michael; Bischof, John C; Haynes, Christy L

    2016-07-01

    Iron oxide nanoparticles have great potential as diagnostic and therapeutic agents in cancer and other diseases; however, biological aggregation severely limits their function in vivo. Aggregates can cause poor biodistribution, reduced heating capability, and can confound their visualization and quantification by magnetic resonance imaging (MRI). Herein, we demonstrate that the incorporation of a functionalized mesoporous silica shell can prevent aggregation and enable the practical use of high-heating, high-contrast iron oxide nanoparticles in vitro and in vivo. Unmodified and mesoporous silica-coated iron oxide nanoparticles were characterized in biologically relevant environments including phosphate buffered saline, simulated body fluid, whole mouse blood, lymph node carcinoma of prostate (LNCaP) cells, and after direct injection into LNCaP prostate cancer tumors in nude mice. Once coated, iron oxide nanoparticles maintained colloidal stability along with high heating and relaxivity behaviors (SARFe = 204 W/g Fe at 190 kHz and 20 kA/m and r1 = 6.9 mM(-1) s(-1) at 1.4 T). Colloidal stability and minimal nonspecific cell uptake allowed for effective heating in salt and agarose suspensions and strong signal enhancement in MR imaging in vivo. These results show that (1) aggregation can lower the heating and imaging performance of magnetic nanoparticles and (2) a coating of functionalized mesoporous silica can mitigate this issue, potentially improving clinical planning and practical use. PMID:26991550

  15. Protocells: Modular Mesoporous Silica Nanoparticle-Supported Lipid Bilayers for Drug Delivery.

    PubMed

    Butler, Kimberly S; Durfee, Paul N; Theron, Christophe; Ashley, Carlee E; Carnes, Eric C; Brinker, C Jeffrey

    2016-04-27

    Mesoporous silica nanoparticle-supported lipid bilayers, termed 'protocells,' represent a potentially transformative class of therapeutic and theranostic delivery vehicle. The field of targeted drug delivery poses considerable challenges that cannot be addressed with a single 'magic bullet'. Consequently, the protocell has been designed as a modular platform composed of interchangeable biocompatible components. The mesoporous silica core has variable size and shape to direct biodistribution and a controlled pore size and surface chemistry to accommodate diverse cargo. The encapsulating supported lipid bilayer can be modified with targeting and trafficking ligands as well as polyethylene glycol (PEG) to effect selective binding, endosomal escape of cargo, drug efflux prevention, and potent therapeutic delivery, while maintaining in vivo colloidal stability. This review describes the individual components of the platform, including the mesoporous silica nanoparticle core and supported lipid bilayer, their assembly (by multiple techniques) into a protocell, and the combined, often synergistic, performance of the protocell based on in vitro and in vivo studies, including the assessment of biocompatibility and toxicity. In closing, the many emerging variations of the protocell theme and the future directions for protocell research are commented on.

  16. Mesoporous silica as a membrane for ultra-thin implantable direct glucose fuel cells.

    PubMed

    Sharma, Tushar; Hu, Ye; Stoller, Meryl; Feldman, Marc; Ruoff, Rodney S; Ferrari, Mauro; Zhang, Xiaojing

    2011-07-21

    The design, fabrication and characterization of an inorganic catalyst based direct glucose fuel cell using mesoporous silica coating as a functional membrane is reported. The desired use of mesoporous silica based direct glucose fuel cell is for a blood vessel implantable device. Blood vessel implantable direct glucose fuel cells have access to higher continuous glucose concentrations. However, reduction in the implant thickness is required for application in the venous system as part of a stent. We report development of an implantable device with a platinum thin-film (thickness: 25 nm) deposited on silicon substrate (500 μm) to serve as the anode, and graphene pressed on a stainless steel mesh (175 μm) to serve as the cathode. Control experiments involved the use of a surfactant-coated polypropylene membrane (50 μm) with activated carbon (198 μm) electrodes. We demonstrate that a mesoporous silica thin film (270 nm) is capable of replacing the conventional polymer based membranes with an improvement in the power generated over conventional direct glucose fuel cells. PMID:21637881

  17. Doxorubicin-loaded mesoporous silica nanoparticle composite nanofibers for long-term adjustments of tumor apoptosis

    NASA Astrophysics Data System (ADS)

    Yuan, Ziming; Pan, Yue; Cheng, Ruoyu; Sheng, Lulu; Wu, Wei; Pan, Guoqing; Feng, Qiming; Cui, Wenguo

    2016-06-01

    There is a high local recurrence (LR) rate in breast-conserving therapy (BCT) and enhancement of the local treatment is promising as a way to improve this. Thus we propose a drug delivery system using doxorubicin (DOX)-loaded mesoporous silica nanoparticle composite nanofibers which can release anti-tumor drugs in two phases—burst release in the early stage and sustained release at a later stage—to reduce the LR of BCT. In the present study, we designed a novel composite nanofibrous scaffold to realize the efficient release of drugs by loading both DOX and DOX-loaded mesoporous silica nanoparticles into an electrospun PLLA nanofibrous scaffold. In vitro results demonstrated that this kind of nanomaterial can release DOX in two phases, and the results of in vivo experiments showed that this hybrid nanomaterial significantly inhibited the tumor growth in a solid tumor model. Histopathological examination demonstrated that the apoptosis of tumor cells in the treated group over a 10 week period was significant. The anti-cancer effects were also accompanied with decreased expression of Bcl-2 and TNF-α, along with up-regulation of Bax, Fas and the activation of caspase-3 levels. The present study illustrates that the mesoporous silica nanoparticle composite nanofibrous scaffold could have anti-tumor properties and could be further developed as adjuvant therapeutic protocols for the treatment of cancer.

  18. Direct electrochemistry of glucose oxidase immobilized on a hexagonal mesoporous silica-MCM-41 matrix.

    PubMed

    Dai, Z H; Ni, J; Huang, X H; Lu, G F; Bao, J C

    2007-05-01

    The direct electrochemistry of glucose oxidase (GOD) immobilized on a hexagonal mesoporous silica modified glassy carbon electrode was investigated. The adsorbed GOD displayed a pair of redox peaks with a formal potential of -417 mV in 0.1 M pH 6.1 phosphate buffer solution (PBS). The response showed a diffusion-controlled electrode process with a two-electron transfer coupled with a two-proton transfer reaction process. GOD immobilized on a hexagonal mesoporous silica retained its bioactivity and stability. In addition, the immobilized GOD could electrocatalyze the oxidation of glucose to gluconlactone by taking ferrocene monocarboxylic acid (FMCA) as a mediator in N(2) saturated solutions, indicating that the electrode may have the potential application in biosensors to analyze glucose. The sensor could exclude the interference of commonly coexisted uric acid, p-acetaminophenol and ascorbic acid and diagnose diabetes very fast and sensitively. This work demonstrated that the mesoporous silica provided a novel matrix for protein immobilization and the construction of biosensors.

  19. Synthesis and characterization of full interpenetrating structure mesoporous polycarbonate-silica spheres and p-phenylenediamine adsorption.

    PubMed

    Zu, Lei; Li, Ruirui; Shi, Yue; Lian, Huiqin; Liu, Yang; Cui, Xiuguo; Bai, Zongwu

    2014-04-01

    As a common used and hardly emulsified amorphous thermoplastic, the bisphenol-A polycarbonates were used as the polymer candidate to form a novel monodispersed sub-micrometer mesoporous polymer-silica spheres with full interpenetrating structure. The synthesis procedure was based on a modified sol-gel approach in which the polycarbonate was plasticized in advanced by the surfactant of polymer emulsion. The mesoporous spheres possess a perfect uniform particle size and the polymer-silica spheres are held together by permanent entanglement in three dimensions. The defined crystallization of the polycarbonate was occurred when it was entrapped in the silica laminated matrix due to the plasticizing effect of the surfactant, and directly affected the thermal stability of the mesoporous spheres. The specific surface areas and pore diameters of mesoporous sphere were affected by the mass content and crystallization behavior of the polycarbonate. The p-phenylenediamine was used as adsorbate to investigate the cationic organics adsorption ability of the mesoporous spheres. The results shown that the polycarbonate-silica possess a well adsorption capacity for p-phenylenediamine by virtue of two kinds of hydrogen bond, and the maximum adsorption capacity was nearly 7.5 times larger than that of the hollow mesoporous silica.

  20. Surface engineering on mesoporous silica chips for enriching low molecular weight phosphorylated proteins

    NASA Astrophysics Data System (ADS)

    Hu, Ye; Peng, Yang; Lin, Kevin; Shen, Haifa; Brousseau, Louis C., III; Sakamoto, Jason; Sun, Tong; Ferrari, Mauro

    2011-02-01

    Phosphorylated peptides and proteins play an important role in normal cellular activities, e.g., gene expression, mitosis, differentiation, proliferation, and apoptosis, as well as tumor initiation, progression and metastasis. However, technical hurdles hinder the use of common fractionation methods to capture phosphopeptides from complex biological fluids such as human sera. Herein, we present the development of a dual strategy material that offers enhanced capture of low molecular weight phosphoproteins: mesoporous silica thin films with precisely engineered pore sizes that sterically select for molecular size combined with chemically selective surface modifications (i.e. Ga3+, Ti4+ and Zr4+) that target phosphoroproteins. These materials provide high reproducibility (CV = 18%) and increase the stability of the captured proteins by excluding degrading enzymes, such as trypsin. The chemical and physical properties of the composite mesoporous thin films were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and ellipsometry. Using mass spectroscopy and biostatistics analysis, the enrichment efficiency of different metal ions immobilized on mesoporous silica chips was investigated. The novel technology reported provides a platform capable of efficiently profiling the serum proteome for biomarker discovery, forensic sampling, and routine diagnostic applications.Phosphorylated peptides and proteins play an important role in normal cellular activities, e.g., gene expression, mitosis, differentiation, proliferation, and apoptosis, as well as tumor initiation, progression and metastasis. However, technical hurdles hinder the use of common fractionation methods to capture phosphopeptides from complex biological fluids such as human sera. Herein, we present the development of a dual strategy material that offers enhanced capture of low molecular weight phosphoproteins: mesoporous

  1. Biological applications and transmission electron microscopy investigation of mesoporous silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Trewyn, Brian G.

    The research presented and discussed within involves the development of novel biological applications of mesoporous silica nanoparticles (MSN) and an investigation of mesoporous material by transmission electron microscopy (TEM). A series of room-temperature ionic liquid (RTIL) containing mesoporous silica nanoparticle (MSN) materials with various particle morphologies, including spheres, ellipsoids, rods, and tubes, were synthesized. By changing the RTIL template, the pore morphology was tuned from the MCM-41 type of hexagonal mesopores to rotational moire type of helical channels, and to wormhole-like porous structures. These materials were used as controlled release delivery nanodevices to deliver antibacterial ionic liquids against Escherichia coli K12. The involvement of a specific organosiloxane function group, covalently attached to the exterior of fluorescein doped mesoporous silica nanoparticles (FITC-MSN), on the degree and kinetics of endocytosis in cancer and plant cells was investigated. The kinetics of endocystosis of TEG coated FITC-MSN is significantly quicker than FITC-MSN as determined by flow cytometry experiments. The fluorescence confocal microscopy investigation showed the endocytosis of TEG coated-FITC MSN triethylene glycol grafted fluorescein doped MSN (TEG coated-FITC MSN) into both HeLa cells and Tobacco root protoplasts. Once the synthesis of a controlled-release delivery system based on MCM-41-type mesoporous silica nanorods capped by disulfide bonds with superparamagnetic iron oxide nanoparticles was completed. The material was characterized by general methods and the dosage and kinetics of the antioxidant dependent release was measured. Finally, the biological interaction of the material was determined along with TEM measurements. An electron microscopy investigation proved that the pore openings of the MSN were indeed blocked by the Fe 3O4 nanoparticles. The biological interaction investigation demonstrated Fe3O4-capped MSN

  2. Electrografting of 3-Aminopropyltriethoxysilane on a Glassy Carbon Electrode for the Improved Adhesion of Vertically Oriented Mesoporous Silica Thin Films.

    PubMed

    Nasir, Tauqir; Zhang, Lin; Vilà, Neus; Herzog, Grégoire; Walcarius, Alain

    2016-05-01

    Vertically oriented mesoporous silica has proven to be of interest for applications in a variety of fields (e.g., electroanalysis, energy, and nanotechnology). Although glassy carbon is widely used as an electrode material, the adherence of silica deposits is rather poor, causing mechanical instability. A solution to improve the adhesion of mesoporous silica films onto glassy carbon electrodes without compromising the vertical orientation and the order of the mesopores will greatly contribute to the use of this kind of modified carbon electrode. We propose here the electrografting of 3-aminopropyltriethoxysilane on glassy carbon as a molecular glue to improve the mechanical stability of the silica film on the electrode surface without disturbing the vertical orientation and the order of the mesoporous silica obtained by electrochemically assisted self-assembly. These findings are supported by a series of surface chemistry techniques such as X-ray photoelectron spectroscopy, scanning and transmission electron microscopy, and cyclic voltammetry. Finally, methylviologen was used as a model redox probe to investigate the cathodic potential region of both glassy carbon and indium tin oxide electrodes modified with mesoporous silica in order to demonstrate further the interest in the approach developed here. PMID:27065214

  3. Probing hydrodesulfurization over bimetallic phosphides using monodisperse Ni2-xMxP nanoparticles encapsulated in mesoporous silica

    NASA Astrophysics Data System (ADS)

    Danforth, Samuel J.; Liyanage, D. Ruchira; Hitihami-Mudiyanselage, Asha; Ilic, Boris; Brock, Stephanie L.; Bussell, Mark E.

    2016-06-01

    Metal phosphide nanoparticles encapsulated in mesoporous silica provide a well-defined system for probing the fundamental chemistry of the hydrodesulfurization (HDS) reaction over this new class of hydrotreating catalysts. To investigate composition effects in bimetallic phosphides, the HDS of dibenzothiophene (DBT) was carried out over a series of Ni-rich Ni2-xMxP@mSiO2 (M = Co, Fe) nanocatalysts (x ≤ 0.50). The Ni2-xMxP nanoparticles (average diameters: 11-13 nm) were prepared by solution-phase arrested precipitation and encapsulated in mesoporous silica, characterized by a range of techniques (XRD, TEM, IR spectroscopy, BET surface area, CO chemisorption) and tested for DBT HDS activity and selectivity. The highest activity was observed for a Ni1.92Co0.08P@mSiO2 nanocatalyst, but the overall trend was a decrease in HDS activity with increasing Co or Fe content. In contrast, the highest turnover frequency (TOF) was observed for the most Co- and Fe-rich compositions based on sites titrated by CO chemisorption. IR spectral studies of adsorbed CO on the Ni2-xMxP@mSiO2 catalysts indicate that an increase in electron density occurs on Ni sites as the Co or Fe content is increased, which may be responsible for the increased TOFs of the catalytic sites. The Ni2-xMxP@mSiO2 nanocatalysts exhibit a strong preference for the direct desulfurization pathway (DDS) for DBT HDS that changes only slightly with increasing Co or Fe content.

  4. Enzymes immobilized in mesoporous silica: a physical-chemical perspective.

    PubMed

    Carlsson, Nils; Gustafsson, Hanna; Thörn, Christian; Olsson, Lisbeth; Holmberg, Krister; Åkerman, Björn

    2014-03-01

    Mesoporous materials as support for immobilized enzymes have been explored extensively during the last two decades, primarily not only for biocatalysis applications, but also for biosensing, biofuels and enzyme-controlled drug delivery. The activity of the immobilized enzymes inside the pores is often different compared to that of the free enzymes, and an important challenge is to understand how the immobilization affects the enzymes in order to design immobilization conditions that lead to optimal enzyme activity. This review summarizes methods that can be used to understand how material properties can be linked to changes in enzyme activity. Real-time monitoring of the immobilization process and techniques that demonstrate that the enzymes are located inside the pores is discussed by contrasting them to the common practice of indirectly measuring the depletion of the protein concentration or enzyme activity in the surrounding bulk phase. We propose that pore filling (pore volume fraction occupied by proteins) is the best standard for comparing the amount of immobilized enzymes at the molecular level, and present equations to calculate pore filling from the more commonly reported immobilized mass. Methods to detect changes in enzyme structure upon immobilization and to study the microenvironment inside the pores are discussed in detail. Combining the knowledge generated from these methodologies should aid in rationally designing biocatalyst based on enzymes immobilized in mesoporous materials.

  5. Hierarchical mesoporous silica nanoparticles as superb light scattering materials.

    PubMed

    Ryu, Jaehoon; Yun, Juyoung; Lee, Jungsup; Lee, Kisu; Jang, Jyongsik

    2016-02-01

    A novel approach to enhance the light scattering effect was explored by applying hierarchical silica nanoparticles in DSSCs as scattering layers. The WSN-incorporated cells showed a PCE value of 9.53% and a PCE enhancement of 30.19% compared with those of the reference cells. PMID:26699659

  6. Heterogeneous copper-silica catalyst from agricultural biomass and its catalytic activity

    NASA Astrophysics Data System (ADS)

    Andas, Jeyashelly; Adam, Farook; Rahman, Ismail Ab.

    2013-11-01

    A series of highly mesoporous copper catalysts (5-20 wt.%) supported on silica rice husk were synthesized via sol-gel route at room temperature. The FT-IR and 29Si MAS NMR spectroscopic studies revealed the successful substitution of copper into the silica matrix. Copper in the +2 oxidation state was evidenced from the DR/UV-vis and XPS analyses. Introduction of copper up to 10 wt.% (RH-10Cu) results in a progressive enhancement in the BET surface area. The activity of the copper catalysts was studied in the liquid-phase oxidation of phenol with H2O2 yielding catechol (CAT) and hydroquinone (HQ). Phenol conversion was influenced by various experimental conditions such as temperature, catalyst dosage, molar ratio of reactants, nature of solvent and percentage metal loading. Excellent activity was achieved when 10 wt.% copper was used and decreased with further increase in the copper loading. RH-10Cu could be regenerated several times without significant loss in the catalytic activity.

  7. Stabilizing Surfactant Templated Cylindrical Mesopores in Polymer and Carbon Films through Composite Formation with Silica Reinforcement

    SciTech Connect

    Song, Lingyan; Feng, Dan; Lee, Hae-Jeong; Wang, Chengqing; Wu, Quanyan; Zhao, Dongyuan; Vogt, Bryan D.

    2010-10-22

    A facile approach to maintain the periodic mesostructure of cylindrical pores in polymer-resin and carbon films after thermal template removal is explored through the reactive coassembly of resol (carbon precursor) and tetraethylorthosilicate (silica precursor) with triblock copolymer Pluronic F127. Without silica, a low porosity, disordered film is formed after pyrolysis despite the presence of an ordered mesostructure prior to template removal. However for silica concentration greater than 25 wt %, pyrolysis at 350 C yields a mesoporous silica-polymer film with well-defined pore mesostructure. These films remain well ordered upon carbonization at 800 C. In addition to the mesostructural stability, the addition of silica to the matrix impacts other morphological characteristics. For example, the average pore size and porosity of the films increase from 3.2 to 7.5 nm and 12 to 45%, respectively, as the concentration of silica in the wall matrix increases from 0 to 32 wt %. The improved thermal stability of the ordered mesostructure with the addition of silica to the matrix is attributed to the reinforcement of the mechanical properties leading to resistance to stress induced collapse of the mesostructure during template removal.

  8. Preparation of fluorescent mesoporous hollow silica-fullerene nanoparticles via selective etching for combined chemotherapy and photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Yang, Yannan; Yu, Meihua; Song, Hao; Wang, Yue; Yu, Chengzhong

    2015-07-01

    Well-dispersed mesoporous hollow silica-fullerene nanoparticles with particle sizes of ~50 nm have been successfully prepared by incorporating fullerene molecules into the silica framework followed by a selective etching method. The fabricated fluorescent silica-fullerene composite with high porosity demonstrates excellent performance in combined chemo/photodynamic therapy.Well-dispersed mesoporous hollow silica-fullerene nanoparticles with particle sizes of ~50 nm have been successfully prepared by incorporating fullerene molecules into the silica framework followed by a selective etching method. The fabricated fluorescent silica-fullerene composite with high porosity demonstrates excellent performance in combined chemo/photodynamic therapy. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02769a

  9. Waste-Glycerol-Directed Synthesis of Mesoporous Silica and Carbon with Superior Performance in Room-Temperature Hydrogen Production from Formic Acid

    PubMed Central

    Lee, Dong-Wook; Jin, Min-Ho; Park, Ji Chan; Lee, Chun-Boo; Oh, Duckkyu; Lee, Sung-Wook; Park, Jin-Woo; Park, Jong-Soo

    2015-01-01

    The development of easier, cheaper, and more ecofriendly synthetic methods for mesoporous materials remains a challenging topic to commercialize them, and the transformation of waste glycerol, as a biodiesel byproduct, into something useful and salable is one of the pending issues to be resolved. Here we first report that mesoporous silica (KIE-6) and carbon (KIE-7) can be simultaneously synthesized by using cheap and ecofriendly crude-waste-glycerol of biodiesel with or without glycerol purification, and we demonstrated the excellent performance of the mesoporous material as a catalyst support for formic acid decomposition. As a result, Pd-MnOx catalysts supported on NH2-functionalized KIE-6 showed the highest catalytic activity (TOF: 540.6 h−1) ever reported for room-temperature formic acid decomposition without additives. Moreover, we conducted life-cycle assessment (LCA) from biomass cultivation through biodiesel production to KIE-6 and KIE-7 preparation, and it was confirmed that CO2 emission during synthesis of KIE-6 and KIE-7 could be reduced by 87.1% and 85.7%, respectively. We believe that our study suggested more ecofriendly and industry-friendly approaches for preparation of mesoporous materials, and utilization of waste glycerol. PMID:26515193

  10. Waste-Glycerol-Directed Synthesis of Mesoporous Silica and Carbon with Superior Performance in Room-Temperature Hydrogen Production from Formic Acid

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Wook; Jin, Min-Ho; Park, Ji Chan; Lee, Chun-Boo; Oh, Duckkyu; Lee, Sung-Wook; Park, Jin-Woo; Park, Jong-Soo

    2015-10-01

    The development of easier, cheaper, and more ecofriendly synthetic methods for mesoporous materials remains a challenging topic to commercialize them, and the transformation of waste glycerol, as a biodiesel byproduct, into something useful and salable is one of the pending issues to be resolved. Here we first report that mesoporous silica (KIE-6) and carbon (KIE-7) can be simultaneously synthesized by using cheap and ecofriendly crude-waste-glycerol of biodiesel with or without glycerol purification, and we demonstrated the excellent performance of the mesoporous material as a catalyst support for formic acid decomposition. As a result, Pd-MnOx catalysts supported on NH2-functionalized KIE-6 showed the highest catalytic activity (TOF: 540.6 h-1) ever reported for room-temperature formic acid decomposition without additives. Moreover, we conducted life-cycle assessment (LCA) from biomass cultivation through biodiesel production to KIE-6 and KIE-7 preparation, and it was confirmed that CO2 emission during synthesis of KIE-6 and KIE-7 could be reduced by 87.1% and 85.7%, respectively. We believe that our study suggested more ecofriendly and industry-friendly approaches for preparation of mesoporous materials, and utilization of waste glycerol.

  11. Waste-Glycerol-Directed Synthesis of Mesoporous Silica and Carbon with Superior Performance in Room-Temperature Hydrogen Production from Formic Acid.

    PubMed

    Lee, Dong-Wook; Jin, Min-Ho; Park, Ji Chan; Lee, Chun-Boo; Oh, Duckkyu; Lee, Sung-Wook; Park, Jin-Woo; Park, Jong-Soo

    2015-01-01

    The development of easier, cheaper, and more ecofriendly synthetic methods for mesoporous materials remains a challenging topic to commercialize them, and the transformation of waste glycerol, as a biodiesel byproduct, into something useful and salable is one of the pending issues to be resolved. Here we first report that mesoporous silica (KIE-6) and carbon (KIE-7) can be simultaneously synthesized by using cheap and ecofriendly crude-waste-glycerol of biodiesel with or without glycerol purification, and we demonstrated the excellent performance of the mesoporous material as a catalyst support for formic acid decomposition. As a result, Pd-MnOx catalysts supported on NH2-functionalized KIE-6 showed the highest catalytic activity (TOF: 540.6 h(-1)) ever reported for room-temperature formic acid decomposition without additives. Moreover, we conducted life-cycle assessment (LCA) from biomass cultivation through biodiesel production to KIE-6 and KIE-7 preparation, and it was confirmed that CO2 emission during synthesis of KIE-6 and KIE-7 could be reduced by 87.1% and 85.7%, respectively. We believe that our study suggested more ecofriendly and industry-friendly approaches for preparation of mesoporous materials, and utilization of waste glycerol. PMID:26515193

  12. Semiconducting polymer encapsulated mesoporous silica particles with conjugated Europium complexes: toward enhanced luminescence under aqueous conditions.

    PubMed

    Zhang, Jixi; Prabhakar, Neeraj; Näreoja, Tuomas; Rosenholm, Jessica M

    2014-01-01

    Immobilization of lanthanide organic complexes in meso-organized hybrid materials for luminescence applications have attracted immense interest due to the possibility of controlled segregation at the nanoscopic level for novel optical properties. Aimed at enhancing the luminescence intensity and stability of the hybrid materials in aqueous media, we developed polyvinylpyrrolidone (PVP) stabilized, semiconducting polymer (poly(9-vinylcarbazole), PVK) encapsulated mesoporous silica hybrid particles grafted with Europium(III) complexes. Monosilylated β-diketonate ligands (1-(2-naphthoyl)-3,3,3-trifluoroacetonate, NTA) were first co-condensed in the mesoporous silica particles as pendent groups for bridging and anchoring the lanthanide complexes, resulting in particles with an mean diameter of ∼ 450 nm and a bimodal pore size distribution centered at 3.5 and 5.3 nm. PVK was encapsulated on the resulted particles by a solvent-induced surface precipitation process, in order to seal the mesopores and protect Europium ions from luminescence quenching by producing a hydrophobic environment. The obtained polymer encapsulated MSN-EuLC@PVK-PVP particles exhibit significantly higher intrinsic quantum yield (Φ(Ln) = 39%) and longer lifetime (τ(obs) = 0.51 ms), as compared with those without polymer encapsulation. Most importantly, a high luminescence stability was realized when MSN-EuLC@PVK-PVP particles were dispersed in various aqueous media, showing no noticeable quenching effect. The beneficial features and positive attributes of both mesoporous silica and semiconducting polymers as lanthanide-complex host were merged in a single hybrid carrier, opening up the possibility of using these hybrid luminescent materials under complex aqueous conditions such as biological/physiological environments.

  13. Adsorption of n-pentane on mesoporous silica and adsorbent deformation.

    PubMed

    Gor, Gennady Yu; Paris, Oskar; Prass, Johannes; Russo, Patrícia A; Ribeiro Carrott, M Manuela L; Neimark, Alexander V

    2013-07-01

    Development of quantitative theory of adsorption-induced deformation is important, e.g., for enhanced coalbed methane recovery by CO2 injection. It is also promising for the interpretation of experimental measurements of elastic properties of porous solids. We study deformation of mesoporous silica by n-pentane adsorption. The shape of experimental strain isotherms for this system differs from the shape predicted by thermodynamic theory of adsorption-induced deformation. We show that this difference can be attributed to the difference of disjoining pressure isotherm, responsible for the solid-fluid interactions. We suggest the disjoining pressure isotherm suitable for n-pentane adsorption on silica and derive the parameters for this isotherm from experimental data of n-pentane adsorption on nonporous silica. We use this isotherm in the formalism of macroscopic theory of adsorption-induced deformation of mesoporous materials, thus extending this theory for the case of weak solid-fluid interactions. We employ the extended theory to calculate solvation pressure and strain isotherms for SBA-15 and MCM-41 silica and compare it with experimental data obtained from small-angle X-ray scattering. Theoretical predictions for MCM-41 are in good agreement with the experiment, but for SBA-15 they are only qualitative. This deviation suggests that the elastic modulus of SBA-15 may change during pore filling.

  14. In vitro and in vivo evaluation of ordered mesoporous silica as a novel adsorbent in liquisolid formulation

    PubMed Central

    Chen, Bao; Wang, Zhouhua; Quan, Guilan; Peng, Xinsheng; Pan, Xin; Wang, Rongchang; Xu, Yuehong; Li, Ge; Wu, Chuanbin

    2012-01-01

    Background A liquisolid technique has been reported to be a new approach to improve the release of poorly water-soluble drugs for oral administration. However, an apparent limitation of this technique is the formulation of a high dose because a large amount of liquid vehicle is needed, which finally results in a low-dose liquisolid formulation. Silica as an absorbent has been used extensively in liquisolid formulations. Although nanoparticle silica can be prepared and used to improve liquid adsorption capacity, loading a high dose of drug into a liquisolid is still a challenge. With the aim of improving adsorption capacity and accordingly achieving high drug loading, ordered mesoporous silica with a high surface area and narrow pore size distribution was synthesized and used in a liquisolid formulation. Methods Ordered mesoporous silica was synthesized and its particle size and morphology were tailored by controlling the concentration of cetyltrimethyl ammonium bromide. The ordered mesoporous silica synthesized was characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, small-angle x-ray diffraction, wide angle x-ray diffraction, and nitrogen adsorption-desorption measurements. The liquid adsorption capacity of ordered mesoporous silica was subsequently compared with that of conventional silica materials using PEG400 as the model liquid. Carbamazepine was chosen as a model drug to prepare the liquisolid formulation, with ordered mesoporous silica as the adsorbent material. The preparation was evaluated and compared with commercially available fast-release carbamazepine tablets in vitro and in vivo. Results Characterization of the ordered mesoporous silica synthesized in this study indicated a huge Brunauer–Emmett–Teller surface area (1030 m2/g), an ordered mesoporous structure with a pore size of 2.8 nm, and high adsorption capacity for liquid compared with conventional silica. Compared with fast

  15. Two-dimensional crystals of mesoporous silica SBA-15 nanosheets with perpendicular and open channels

    NASA Astrophysics Data System (ADS)

    Yeh, Yi-Qi; Tang, Chih-Yuan; Mou, Chung-Yuan

    2014-11-01

    A preparation of mesoporous silica SBA-15 thin sheets with perpendicular nanochannels (SBA(⊥)) and open ends is reported here. At a synthesis condition of pH = 2 where the silica condensation is extremely slow, micron-sized single-crystal-like hexagonally faceted nanosheets (SBA(⊥)-pH2) with aspect ratio of 10-50 were formed. The nanosheets can attach to each other in sideway to extend the thin sheet. At pH = 5, multi-domain SBA(⊥)-pH5 nanosheets are formed, and stacking attachment of sheets is preferred. Vivid Moiré patterns are observed in large areas of stacked silica sheets, indicating excellent structure order.

  16. Synthesis of metal ion-histidine complex functionalized mesoporous silica nanocatalysts for enhanced light-free tooth bleaching.

    PubMed

    Lee, Bor-Shiunn; Huang, Li-Chun; Hong, Chen-Yu; Wang, Shy-Guey; Hsu, Wei-Hang; Yamauchi, Yusuke; Hsieh, Chia-Jung; Lai, Juin-Yih; Wu, Kevin C-W

    2011-05-01

    Several metal ion-histidine complex functionalized mesoporous silica nanoparticles (MSN) were synthesized and utilized as efficient catalysts for enhanced and light-free tooth bleaching. Fe(II), Mn(II), and Cu(II) ions were successfully immobilized in histidine-functionalized MSN and their catalytic abilities against discoloration of a dye (Orange II) in both test tubes and extracted tooth models were compared and discussed. Through direct observation of test tubes and calculation of mean color changes of extracted teeth we concluded that Fe(II)-his-MSN exhibited better catalytic competence than Mn(II)-his-MSN and Cu(II)-his-MSN because of its intrinsic redox ability. In test tubes Orange II was completely degraded within 6 h when Fe(II)-his-MSN was used as the catalyst. For the extracted tooth model the presence of Fe(II)- or Mn(II)-his-MSN significantly enhanced the efficacy of tooth bleaching for three regions, the enamel, outer dentin, and inner dentin, of stained teeth compared with H(2)O(2) alone. Furthermore, unlike current tooth bleaching techniques that need an LED or laser to catalyze H(2)O(2) bleaching, we demonstrated a light-free tooth bleaching system using Fe(II)-his-MSN as an efficient and reliable catalyst.

  17. Functionalized magnetic mesoporous silica nanoparticles for U removal from low and high pH groundwater.

    PubMed

    Li, Dien; Egodawatte, Shani; Kaplan, Daniel I; Larsen, Sarah C; Serkiz, Steven M; Seaman, John C

    2016-11-01

    U(VI) species display limited adsorption onto sediment minerals and synthetic sorbents in pH <4 or pH >8 groundwater. In this work, magnetic mesoporous silica nanoparticles (MMSNs) with magnetite nanoparticle cores were functionalized with various organic molecules using post-synthetic methods. The functionalized MMSNs were characterized using N2 adsorption-desorption isotherms, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), (13)C cross polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy, and powder X-ray diffraction (XRD), which indicated that mesoporous silica (MCM-41) particles of 100-200nm formed around a core of magnetic iron oxide, and the functional groups were primarily grafted into the mesopores of ∼3.0nm in size. The functionalized MMSNs were effective for U removal from pH 3.5 and 9.6 artificial groundwater (AGW). Functionalized MMSNs removed U from the pH 3.5 AGW by as much as 6 orders of magnitude more than unfunctionalized nanoparticles or silica and had adsorption capacities as high as 38mg/g. They removed U from the pH 9.6 AGW as much as 4 orders of magnitude greater than silica and 2 orders of magnitude greater than the unfunctionalized nanoparticles with adsorption capacities as high as 133mg/g. These results provide an applied solution for treating U contamination that occurs at extreme pH environments and a scientific foundation for solving critical industrial issues related to environmental stewardship and nuclear power production.

  18. Functionalized magnetic mesoporous silica nanoparticles for U removal from low and high pH groundwater.

    PubMed

    Li, Dien; Egodawatte, Shani; Kaplan, Daniel I; Larsen, Sarah C; Serkiz, Steven M; Seaman, John C

    2016-11-01

    U(VI) species display limited adsorption onto sediment minerals and synthetic sorbents in pH <4 or pH >8 groundwater. In this work, magnetic mesoporous silica nanoparticles (MMSNs) with magnetite nanoparticle cores were functionalized with various organic molecules using post-synthetic methods. The functionalized MMSNs were characterized using N2 adsorption-desorption isotherms, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), (13)C cross polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy, and powder X-ray diffraction (XRD), which indicated that mesoporous silica (MCM-41) particles of 100-200nm formed around a core of magnetic iron oxide, and the functional groups were primarily grafted into the mesopores of ∼3.0nm in size. The functionalized MMSNs were effective for U removal from pH 3.5 and 9.6 artificial groundwater (AGW). Functionalized MMSNs removed U from the pH 3.5 AGW by as much as 6 orders of magnitude more than unfunctionalized nanoparticles or silica and had adsorption capacities as high as 38mg/g. They removed U from the pH 9.6 AGW as much as 4 orders of magnitude greater than silica and 2 orders of magnitude greater than the unfunctionalized nanoparticles with adsorption capacities as high as 133mg/g. These results provide an applied solution for treating U contamination that occurs at extreme pH environments and a scientific foundation for solving critical industrial issues related to environmental stewardship and nuclear power production. PMID:27341378

  19. Tailoring of the nanotexture of mesoporous silica films and their functionalized derivatives for selectively harvesting low molecular weight protein.

    PubMed

    Hu, Ye; Bouamrani, Ali; Tasciotti, Ennio; Li, Li; Liu, Xuewu; Ferrari, Mauro

    2010-01-26

    We present a fast, efficient, and reliable system based on mesoporous silica chips to specifically fractionate and enrich the low molecular weight proteome. Mesoporous silica thin films with tunable features at the nanoscale were fabricated using the triblock copolymer template pathway. Using different templates and concentrations in the precursor solution, various pore size distributions, pore structures, and connectivity were obtained and applied for selective recovery of low mass proteins. In combination with mass spectrometry and statistic analysis, we demonstrated the correlation between the nanophase characteristics of the mesoporous silica thin films and the specificity and efficacy of low mass proteome harvesting. In addition, to overcome the limitations of the prefunctionalization method in polymer selection, plasma ashing was used for the first time for the treatment of the mesoporous silica surface prior to chemical modification. Surface charge modifications by different functional groups resulted in a selective capture of the low molecular weight proteins from serum sample. In conclusion, our study demonstrates that the ability to tune the physicochemical properties of mesoporous silica surfaces, for a selective enrichment of the low molecular weight proteome from complex biological fluids, has the potential to promote proteomic biomarker discovery.

  20. [Preparation and anti-cancer activity in vitro of curcumin loaded mesoporous silica nanoparticle].

    PubMed

    He, Li-li; Gu, Jian

    2015-11-01

    This paper is to prepare curcumin (Cur) loaded mesoporous silica nanoparticle (Cur-MSN), evaluate its release behavior and anti-cancer activity in vitro. Mesoporous silica nanoparticle (MSN) was prepared by polymerization method and Cur-MSN was obtained using solvent evaporation method and impregnation centrifugation method. The preparation method was optimized using entrapment efficiency (EE) and loading efficiency (LE) as indexes. Cur-MSN was characterized with scanning electron microscope and its particle size and zeta potential were determined. Finally, in vitro release behavior in 0.2% SDS solution and its cell-killing effect on HeLa cells were also evaluated. The Cur-MSN prepared with process optimization method was round and uniform and exhibited typical mesoporous characterization. The mean particle size and Zeta potential of Cur-MSN were 75.8 nm and -30.1 mV, respectively. EE and LE of three batches of Cur-MSN were (72.55 ± 2.01)% and (16.21 ± 1.12)%, respectively. In vitro release behavior of Cur-MSN showed a sustained release profile with 83.5% cumulative release within 96 h. The killing effect of Cur-MSN on HeLa cells was dose-dependent with IC50 of 19.40 mg x L(-1), which was similar to that of Cur. PMID:27071254

  1. Structural investigation of nonionic fluorinated micelles by SANS in relation to mesoporous silica materials.

    PubMed

    Michaux, Florentin; Blin, Jean-Luc; Teixeira, José; Stébé, Marie José

    2012-01-12

    In an attempt to answer the question if there is dependence between the pore ordering of the mesoporous silica, obtained through the cooperative template mechanism, and the shape of the micellar aggregates of the surfactant solutions, the micellar structures of two nonionic fluorinated surfactant based-systems are studied by SANS. By fitting the experimental spectra with theoretical models, the structural evolution of the molecular aggregates can be described, and some important parameters can be obtained, such as the water and eventually oil penetration into the surfactant film, the aggregation number, the area per polar head of the surfactant, and the surfactant chain conformations. We have shown that for the C(8)F(17)C(2)H(4)(OC(2)H(4))(9)OH system, the micelles are prolate spheroids. The increase of the surfactant concentration in water does not change the characteristics of the interfacial film, but the aggregation number raises and the particles become more elongated. By contrast, the experimental curves of C(7)F(15)C(2)H(4)(OC(2)H(4))(8)OH cannot be fitted considering a small particle model. However, progressive incorporation of fluorocarbon induces a change of size and shape of the globules, which become smaller and more and more spherical. Regarding the material mesopore ordering, it appears that the micelles that lead to hexagonal mesoporous silica materials are described with a model of quasi-spherical globules. On the contrary, when large micelles are found, only wormhole-like structures are obtained.

  2. Capillary Condensation Pathways of CO2 under Templated Mesoporous Silica Confinement

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Sokol, Paul

    2014-03-01

    Adsorption of CO2 in porous medium has been of great current interest due to its potential for mitigating the global warming caused by greenhouse gases. In particular, the behavior of confined CO2 in mesoporous media near room temperature is particularly relevant to sequestration efforts. Realistic mesoporous systems, such as shales and coals, represent a complex fractal pore structure that complicates the interpretation of adsorption studies. We present the results of a study focused on the adsorption of CO2 in model mesoporous media with well-defined pore structures. Templated porous glasses, such as MCM-41 which has a regular network of 1D pores, provide an ideal system for fundamental studies of the adsorption process. In this study, we focus on the structure of adsorbed CO2 films which evolves in a mixture of phases and the development of nucleation occurs during the formation of high density liquid CO2 inside the confining matrix. We have used Small Angle Neutron Scattering to study the spatial distribution of material radially and transversely within the pores. The 30m SANS NG7 at NIST was used to map out the details of CO2 condensation pathway under mesoporous silica confinement.

  3. Template-free fabrication of mesoporous carbons from carbon quantum dots and their catalytic application to the selective oxidation of hydrocarbons

    NASA Astrophysics Data System (ADS)

    Zhou, Lei; Liu, Juan; Zhang, Xing; Liu, Ruihua; Huang, Hui; Liu, Yang; Kang, Zhenhui

    2014-05-01

    Mesoporous carbons (pore size 5 nm) were successfully synthesized without templates from carbon quantum dots. As catalysts, both mesoporous carbons and Cu nanoparticles on mesoporous carbons show superior catalytic activity and stability for the selective oxidation of cyclooctene.Mesoporous carbons (pore size 5 nm) were successfully synthesized without templates from carbon quantum dots. As catalysts, both mesoporous carbons and Cu nanoparticles on mesoporous carbons show superior catalytic activity and stability for the selective oxidation of cyclooctene. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00716f

  4. Gated silica mesoporous supports for controlled release and signaling applications.

    PubMed

    Coll, Carmen; Bernardos, Andrea; Martínez-Máñez, Ramón; Sancenón, Félix

    2013-02-19

    Blending molecular and supramolecular advances with materials science has resulted in recent years in the development of new organic-inorganic hybrid materials displaying innovative functionalities. One appealing concept in this field is the development of gated nanodevices. These materials are prepared by grafting molecular or supramolecular caps onto the external surface of mesoporous inorganic scaffolds loaded with a particular cargo. The caps or "gates" can then be opened and the cargo delivered at will upon the application of a given stimulus. In this Account, we report some of the recent advances we have made in designing such materials for drug delivery and as new chromo-fluorogenic probes. For controlled release applications, we have prepared capped hybrid mesoporous supports capable of being selectively opened by applying certain physical and chemical stimuli. We report examples of gated materials opened by changes in pH (using polyamines as caps), light (employing spiropyran derivatives or gold nanoparticles), and temperature (using selected paraffins). We also report gated materials opened by enzymes that cleave capping molecules based on lactose, hydrolyzed starch, and peptides. The use of enzymes is especially appealing because molecular caps built of enzyme-specific sequences made of peptides or other cleavable molecules could allow on-command delivery of drugs and biomolecules in specialized contexts. In the second part of the manuscript, we revisit the possibility of using hybrid gated nanomaterials as sensory systems. In such systems, when target analytes interact with the cap, their presence triggers the transport of a dye from pores to the solution, resulting in a chromo-fluorogenic signal that allows their detection. Two approaches are possible. In the first one, pores remain open and the dye can diffuse into the solution, until the presence of a target analyte binds to receptors in the caps and closes the gate. In the second approach, the caps

  5. Mesoporous silica nanoparticles for treating spinal cord injury

    NASA Astrophysics Data System (ADS)

    White-Schenk, Désirée.; Shi, Riyi; Leary, James F.

    2013-02-01

    An estimated 12,000 new cases of spinal cord injury (SCI) occur every year in the United States. A small oxidative molecule responsible for secondary injury, acrolein, is an important target in SCI. Acrolein attacks essential proteins and lipids, creating a feed-forward loop of oxidative stress in both the primary injury area and the surrounding areas. A small molecule used and FDA-approved for hypertension, hydralazine, has been found to "scavenge" acrolein after injury, but its delivery and short half-life, as well as its hypertension effects, hinder its application for SCI. Nanomedical systems broaden the range of therapeutic availability and efficacy over conventional medicine. They allow for targeted delivery of therapeutic molecules to tissues of interest, reducing side effects of untargeted therapies in unwanted areas. Nanoparticles made from silica form porous networks that can carry therapeutic molecules throughout the body. To attenuate the acrolein cascade and improve therapeutic availability, we have used a one-step, modified Stober method to synthesize two types of silica nanoparticles. Both particles are "stealth-coated" with poly(ethylene) glycol (PEG) (to minimize interactions with the immune system and to increase circulation time), which is also a therapeutic agent for SCI by facilitating membrane repair. One nanoparticle type contains an amine-terminal PEG (SiNP-mPEG-Am) and the other possesses a terminal hydrazide group (SiNP-mPEG-Hz). The former allows for exploration of hydralazine delivery, loading, and controlled release. The latter group has the ability to react with acrolein, allowing the nanoparticle to scavenge directly. The nanoparticles have been characterized and are being explored using neuronal PC-12 cells in vitro, demonstrating the potential of novel silica nanoparticles for use in attenuating secondary injury after SCI.

  6. Catalytic pyrolysis of waste rice husk over mesoporous materials

    PubMed Central

    2012-01-01

    Catalytic fast pyrolysis of waste rice husk was carried out using pyrolysis-gas chromatography/mass spectrometry [Py-GC/MS]. Meso-MFI zeolite [Meso-MFI] was used as the catalyst. In addition, a 0.5-wt.% platinum [Pt] was ion-exchanged into Meso-MFI to examine the effect of Pt addition. Using a catalytic upgrading method, the activities of the catalysts were evaluated in terms of product composition and deoxygenation. The structure and acid site characteristics of the catalysts were analyzed by Brunauer-Emmett-Teller surface area measurement and NH3 temperature-programmed desorption analysis. Catalytic upgrading reduced the amount of oxygenates in the product vapor due to the cracking reaction of the catalysts. Levoglucosan, a polymeric oxygenate species, was completely decomposed without being detected. While the amount of heavy phenols was reduced by catalytic upgrading, the amount of light phenols was increased because of the catalytic cracking of heavy phenols into light phenols and aromatics. The amount of aromatics increased remarkably as a result of catalytic upgrading, which is attributed to the strong Brönsted acid sites and the shape selectivity of the Meso-MFI catalyst. The addition of Pt made the Meso-MFI catalyst even more active in deoxygenation and in the production of aromatics. PMID:22221540

  7. Enhancing plasma peptide MALDI-TOF-MS profiling by mesoporous silica assisted crystallization.

    PubMed

    Terracciano, Rosa; Casadonte, Francesca; Pasqua, Luigi; Candeloro, Patrizio; Di Fabrizio, Enzo; Urbani, Andrea; Savino, Rocco

    2010-02-15

    Promising profiling techniques based on new material/solid phase extraction for capturing "molecular signatures" from body fluids are being coupled to MALDI-TOF-MS. Sample preparation significantly influences spectrum quality in this ionization method. Mesoporous silica beads (MSB), by the means of nano-sized porous channels with high surface area, enable harvesting of peptides from plasma and serum excluding large size proteins. We have investigated the morphology of a sample slurry, developed as a new tool for plasma peptides enrichment based on mesoporous materials. Our study highlights a correlation between crystals morphology and enhanced performances in MALDI-TOF-MS analysis. This is the first report which correlates the increase in signal intensity with crystal formation in samples preparations which make use of various kinds of slurries for the analysis of samples clinically relevant like human plasma.

  8. Core-shell-type magnetic mesoporous silica nanocomposites for bioimaging and therapeutic agent delivery.

    PubMed

    Wang, Yao; Gu, Hongchen

    2015-01-21

    Advances in nanotechnology and nanomedicine offer great opportunities for the development of nanoscaled theranostic platforms. Among various multifunctional nanocarriers, magnetic mesoporous silica nanocomposites (M-MSNs) attract prominent research interest for their outstanding properties and potential biomedical applications. This Research News article highlights recent progress in the design of core-shell-type M-MSNs for both diagnostic and therapeutic applications. First, an overview of synthetic strategies for three representative core-shell-type M-MSNs with different morphologies and structures is presented. Then, the diagnostic functions of M-MSNs is illustrated for magnetic resonance imaging (MRI) applications. Next, magnetic targeted delivery and stimuli-responsive release of drugs, and effective package of DNA/siRNA inside mesopores using M-MSNs as therapeutic agent carriers are discussed. The article concludes with some important challenges that need to be overcome for further practical applications of M-MSNs in nanomedicine. PMID:25238634

  9. Synthesis and characterization of amorphous mesoporous silica using TEMPO-functionalized amphiphilic templates

    NASA Astrophysics Data System (ADS)

    de Vries, Wilke; Doerenkamp, Carsten; Zeng, Zhaoyang; de Oliveira, Marcos; Niehaus, Oliver; Pöttgen, Rainer; Studer, Armido; Eckert, Hellmut

    2016-05-01

    Inorganic-organic hybrid materials based on amorphous mesoporous silica containing organized nitroxide radicals within its mesopores have been prepared using the micellar self-assembly of TEOS solutions containing the nitroxide functionalized amphiphile (4-(N,N-dimethyl-N-hexadecylammonium)-2,2,6,6-tetramethyl-piperidin-N-oxyl-iodide) (CAT-16). This template has been used both in its pure form and in various mixtures with cetyl trimethylammonium bromide (CTAB). The samples have been characterized by chemical analysis, N2 sorption studies, magnetic susceptibility measurements, and various spectroscopic methods. While electron paramagnetic resonance (EPR) spectra indicate that the strength of the intermolecular spin-spin interactions can be controlled via the CAT-16/CTAB ratio, nuclear magnetic resonance (NMR) data suggest that these interactions are too weak to facilitate cooperative magnetism.

  10. Films Consisting of Innumerable Tapered Nanopillars of Mesoporous Silica for Universal Antireflection Coatings.

    PubMed

    Miyata, Hirokatsu; Kitamura, Shin; Watanabe, Masatoshi; Takahashi, Masahiko

    2016-05-20

    Films with a fine structure consisting of innumerable nanopillars of mesoporous silica (MPS) are formed by a reactive ion etching process with a fluorine-containing gas. Each nanopillar has a tapered shape with a uniform height, which effectively suppresses reflection by the formation of an ideal graded refractive index structure. The nanopillars are spontaneously formed under low-pressure conditions, wherein locally deposited Al-F compounds, originating from an alumina plate in the etching chamber, work as a fine etching mask. The high etching rate of the MPS film allows a very high aspect ratio of the nanopillars. The refractive index of the MPS nanopillars can be universally tuned by a controlled incorporation of TiO2 into the mesopores, which results in effective reduction of reflectance on a given substrate. The outstanding antireflection performance is experimentally demonstrated for glass substrates with a wide refractive index range. PMID:27017295

  11. Biocompatible mesoporous silica nanoparticles with different morphologies for animal cell membrane penetration

    SciTech Connect

    Trewyn, B.; Nieweg, J.; Zhao, Y,; Lin, V.

    2007-11-24

    Two MCM-41 type, fluorescein-labeled mesoporous silica nanomaterials (MSNs) consisting of spherical and tube-shaped particles were synthesized and characterized. Both materials have hexagonally arranged mesopores with high surface area (>950 m{sup 2}/g) and a narrow distribution of pore diameters. The cellular uptake efficiency and kinetics of both MSNs were measured in a cancer cell line (CHO) and a noncancerous cell line (fibroblasts) by flow cytometry and fluorescence confocal microscopy. The correlation between the particle morphology and aggregation of MSNs to the effectiveness of cellular uptake was investigated. We envision that our study on the morphology dependent endocytosis of MSNs would lead to future developments of efficient transmembrane nanodevices for intracellular sensing and gene/drug delivery.

  12. Co(2+)@Mesoporous Silica Monoliths: Tailor-Made Nanoreactors for Confined Soft Chemistry.

    PubMed

    Delahaye, Emilie; Moulin, Robinson; Aouadi, Merwen; Trannoy, Virgile; Beaunier, Patricia; Fornasieri, Giulia; Bleuzen, Anne

    2015-11-16

    Mesoporous silica monoliths with various ordered nanostructures containing transition metal M(2+) cations in variable amounts were elaborated and studied. A phase diagram depicting the different phases as a function of the M(2+) salt/tetramethyl orthosilicate (TMOS) and surfactant P123/TMOS ratios was established. Thermal treatment resulted in mesoporous monoliths containing isolated, accessible M(2+) species or condensed metal oxides, hydroxides, and salts, depending on the strength of the interactions between the metal species and the ethylene oxide units of P123. The ordered mesoporosity of the monoliths containing accessible M(2+) ions was used as a nanoreactor for the elaboration of various transition metal compounds (Prussian blue analogues, Hofmann compounds, metal-organic frameworks), and this opens the way to the elaboration of a large range of nanoparticles of multifunctional materials.

  13. Periodic mesoporous hydridosilica--synthesis of an "impossible" material and its thermal transformation into brightly photoluminescent periodic mesoporous nanocrystal silicon-silica composite.

    PubMed

    Xie, Zhuoying; Henderson, Eric J; Dag, Ömer; Wang, Wendong; Lofgreen, Jennifer E; Kübel, Christian; Scherer, Torsten; Brodersen, Peter M; Gu, Zhong-Ze; Ozin, Geoffrey A

    2011-04-01

    There has always been a fascination with "impossible" compounds, ones that do not break any rules of chemical bonding or valence but whose structures are unstable and do not exist. This instability can usually be rationalized in terms of chemical or physical restrictions associated with valence electron shells, multiple bonding, oxidation states, catenation, and the inert pair effect. In the pursuit of these "impossible" materials, appropriate conditions have sometimes been found to overcome these instabilities and synthesize missing compounds, yet for others these tricks have yet to be uncovered and the materials remain elusive. In the scientifically and technologically important field of periodic mesoporous silicas (PMS), one such "impossible" material is periodic mesoporous hydridosilica (meso-HSiO(1.5)). It is the archetype of a completely interrupted silica open framework material: its pore walls are comprised of a three-connected three-dimensional network that should be so thermodynamically unstable that any mesopores present would immediately collapse upon removal of the mesopore template. In this study we show that meso-HSiO(1.5) can be synthesized by template-directed self-assembly of HSi(OEt)(3) under aqueous acid-catalyzed conditions and after template extraction remains stable to 300 °C. Above this temperature, bond redistribution reactions initiate a metamorphic transformation which eventually yields periodic mesoporous nanocrystalline silicon-silica, meso-ncSi/SiO(2), a nanocomposite material in which brightly photoluminescent silicon nanocrystallites are embedded within a silica matrix throughout the mesostructure. The integration of the properties of silicon nanocrystallinity with silica mesoporosity provides a wealth of new opportunities for emerging nanotechnologies.

  14. Chelating-Template-Assisted in Situ Encapsulation of Zinc Ferrite Inside Silica Mesopores for Enhanced Gas-Sensing Characteristics.

    PubMed

    Niu, Kui; Liang, Liman; Peng, Fei; Zhang, Fan; Gu, Yao; Tian, Hongyan

    2016-09-21

    A facile in situ approach has been designed to synthesize zinc ferrite/mesoporous silica guest-host composites. Chelating surfactant, N-hexadecyl ethylenediamine triacetic acid, was employed as structure-directing agent to fabricate mesoporous silica skeleton and simultaneously as complexing agent to incorporate stoichiometric amounts of zinc and iron ions into silica cavities. On this basis, spinel zinc ferrite nanoparticles with grain sizes less than 3 nm were encapsulated in mesoporous channels after calcination. The silica mesostructure, meanwhile, displayed a successive transformation from hexagonal p6mm through bicontinuous cubic Ia3̅d to lamellar phase with increasing the dopant concentration in the initial template solution. In comparison with zinc ferrite nanopowder prepared without silica host, the composite with bicontinuous architecture exhibited higher sensitivity, lower detection limit, lower optimum working temperature, quicker response, and shorter recovery time in sensing performance toward hydrogen sulfide. The significant improvements are from the high surface-to-volume ratio of the guest oxides and the three-dimensional porous structure of the composite. We believe the encapsulation route presented here may pave the way for directly introducing complex metal oxide into mesoporous silica matrix with tailorable mesophases for applications in sensing or other fields. PMID:27579863

  15. Chelating-Template-Assisted in Situ Encapsulation of Zinc Ferrite Inside Silica Mesopores for Enhanced Gas-Sensing Characteristics.

    PubMed

    Niu, Kui; Liang, Liman; Peng, Fei; Zhang, Fan; Gu, Yao; Tian, Hongyan

    2016-09-21

    A facile in situ approach has been designed to synthesize zinc ferrite/mesoporous silica guest-host composites. Chelating surfactant, N-hexadecyl ethylenediamine triacetic acid, was employed as structure-directing agent to fabricate mesoporous silica skeleton and simultaneously as complexing agent to incorporate stoichiometric amounts of zinc and iron ions into silica cavities. On this basis, spinel zinc ferrite nanoparticles with grain sizes less than 3 nm were encapsulated in mesoporous channels after calcination. The silica mesostructure, meanwhile, displayed a successive transformation from hexagonal p6mm through bicontinuous cubic Ia3̅d to lamellar phase with increasing the dopant concentration in the initial template solution. In comparison with zinc ferrite nanopowder prepared without silica host, the composite with bicontinuous architecture exhibited higher sensitivity, lower detection limit, lower optimum working temperature, quicker response, and shorter recovery time in sensing performance toward hydrogen sulfide. The significant improvements are from the high surface-to-volume ratio of the guest oxides and the three-dimensional porous structure of the composite. We believe the encapsulation route presented here may pave the way for directly introducing complex metal oxide into mesoporous silica matrix with tailorable mesophases for applications in sensing or other fields.

  16. Synthesis of mesoporous Co/Ce-SBA-15 materials and their catalytic performance in the catalytic oxidation of benzene

    SciTech Connect

    Mu Zhen; Li Jinjun; Tian Hua; Hao Zhengping Qiao Shizhang

    2008-10-02

    Cerium-containing SBA-15 mesoporous materials, with different Ce/Si molar ratios, were synthesized by a direct hydrothermal synthesis method and further modified by impregnation with 10, 15 and 20 wt.% Co. Characterizations by powder X-ray diffraction (XRD), N{sub 2} sorption, inductively coupled plasma (ICP) and UV-vis spectroscopy were carried out. The small-angle XRD and N{sub 2} sorption characterizations showed that these Co supported materials have less-ordered mesoporous structures with partial blockage of pores, and their specific surface area, pore volume and pore size were relatively lower than those of unsupported cerium-containing SBA-15. Spinel Co{sub 3}O{sub 4} constituted the predominant cobalt phase in the prepared catalysts, and CeO{sub 2} was also detected. All the Co supported catalysts exhibited high catalytic activity in the oxidation of benzene.

  17. Synthesis, characterization, and biodistribution studies of (99m)Tc-labeled SBA-16 mesoporous silica nanoparticles.

    PubMed

    de Barros, André Luís Branco; de Oliveira Ferraz, Karina Silva; Dantas, Thais Cristina Soares; Andrade, Gracielle Ferreira; Cardoso, Valbert Nascimento; Sousa, Edésia Martins Barros de

    2015-11-01

    Along with anti-cancer drug delivery researches, many efforts have been done to develop new tracers for diagnostic applications. Based on advances in molecular imaging, nanoparticles can be used to visualize, characterize and measure biological process at molecular and cellular level. Therefore, the purpose of this study was to synthesize, characterize and radiolabeled mesoporous silica nanoparticles (MSNs) for in vivo applications. The nanoparticles were synthesized, functionalized with 3-aminopropyltriethoxysilane (APTES) and then, anchored with diethylenetriaminepentaacetic acid (DTPA). Particles were physicochemical characterized by elemental analysis (CHN), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and zeta potential, and were morphologically characterized by scanning electron microscopy (SEM), low-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. Results indicate that functionalization process was successfully achieved. Next, functionalized silica nanoparticles were radiolabeled with technetium-99m showing high radiochemical yields and high radiolabeled stability. These findings allow the use of the particles for in vivo applications. Biodistribution and scintigraphic images were carried out in healthy mice in order to determine the fate of the particles. Results from in vivo experiments showed high uptake by liver, as expected due to phagocytosis. However, particles also showed a significant uptake in the lungs, indicated by high lung-to-non-target tissue ratio. In summary, taking into account the great potential of these silica mesoporous structures to carry molecules this platform could be a good strategy for theranostic purposes.

  18. Synthesis, characterization, and biodistribution studies of (99m)Tc-labeled SBA-16 mesoporous silica nanoparticles.

    PubMed

    de Barros, André Luís Branco; de Oliveira Ferraz, Karina Silva; Dantas, Thais Cristina Soares; Andrade, Gracielle Ferreira; Cardoso, Valbert Nascimento; Sousa, Edésia Martins Barros de

    2015-11-01

    Along with anti-cancer drug delivery researches, many efforts have been done to develop new tracers for diagnostic applications. Based on advances in molecular imaging, nanoparticles can be used to visualize, characterize and measure biological process at molecular and cellular level. Therefore, the purpose of this study was to synthesize, characterize and radiolabeled mesoporous silica nanoparticles (MSNs) for in vivo applications. The nanoparticles were synthesized, functionalized with 3-aminopropyltriethoxysilane (APTES) and then, anchored with diethylenetriaminepentaacetic acid (DTPA). Particles were physicochemical characterized by elemental analysis (CHN), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and zeta potential, and were morphologically characterized by scanning electron microscopy (SEM), low-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. Results indicate that functionalization process was successfully achieved. Next, functionalized silica nanoparticles were radiolabeled with technetium-99m showing high radiochemical yields and high radiolabeled stability. These findings allow the use of the particles for in vivo applications. Biodistribution and scintigraphic images were carried out in healthy mice in order to determine the fate of the particles. Results from in vivo experiments showed high uptake by liver, as expected due to phagocytosis. However, particles also showed a significant uptake in the lungs, indicated by high lung-to-non-target tissue ratio. In summary, taking into account the great potential of these silica mesoporous structures to carry molecules this platform could be a good strategy for theranostic purposes. PMID:26249579

  19. Adsorption of carbon dioxide from gas streams via mesoporous spherical-silica particles.

    PubMed

    Lu, Chungsying; Bai, Hsunling; Su, Fengsheng; Chen, Wenfa; Hwang, Jyh Feng; Lee, Hsiu-Hsia

    2010-04-01

    A relatively new mesoporous silica sorbent for environmental protection applications (i.e., mesoporous spherical-silica particles [MSPs]), was modified by N-[3-(trimethoxysilyl)propyl]ethylenediamine (EDA) solution and was tested for its potential in the separation of carbon dioxide (CO2) from flue gas. The CO2 adsorption capacity of MSP and MSP (EDA) increased with temperature from 20 to 60 degrees C but decreased with temperature from 60 to 100 degrees C. The mechanism of CO2 adsorption on both samples is mainly attributed to physical interaction regardless of temperature change. The MSP (EDA) have good adsorption performance as compared with EDA-modified zeolite or granular activated carbon conducted in this study and many types of silica sorbents reported in the literature. The cyclic CO2 adsorption showed that spent MSP (EDA) could be effectively regenerated at 120 degrees C for 25 min and CO2 adsorption capacity of MSP (EDA) was preserved during 16 cycles of adsorption and thermal regeneration. These results suggests that MSP (EDA) are efficient CO2 sorbents and can be stably used in the prolonged cyclic operation.

  20. Facile, one-pot synthesis, and antibacterial activity of mesoporous silica nanoparticles decorated with well-dispersed silver nanoparticles.

    PubMed

    Tian, Yue; Qi, Juanjuan; Zhang, Wei; Cai, Qiang; Jiang, Xingyu

    2014-08-13

    In this study, we exploit a facile, one-pot method to prepare MCM-41 type mesoporous silica nanoparticles decorated with silver nanoparticles (Ag-MSNs). Silver nanoparticles with diameter of 2-10 nm are highly dispersed in the framework of mesoporous silica nanoparticles. These Ag-MSNs possess an enhanced antibacterial effect against both Gram-positive and Gram-negative bacteria by preventing the aggregation of silver nanoparticles and continuously releasing silver ions for one month. The cytotoxicity assay indicates that the effective antibacterial concentration of Ag-MSNs shows little effect on human cells. This report describes an efficient and economical route to synthesize mesoporous silica nanoparticles with uniform silver nanoparticles, and these nanoparticles show promising applications as antibiotics.

  1. Poly(lactic) acid fibers loaded with mesoporous silica for potential applications in the active food packaging

    NASA Astrophysics Data System (ADS)

    Cacciotti, Ilaria; Nanni, Francesca

    2016-06-01

    Multifunctional fibrous systems based on poly(lactic) acid (PLA), mesoporous silica (SiO2) and ascorbic acid (AA) were produced by means of electrospinning technique, for potential applications in the active food packaging sector, as platform for the controlled release of antioxidant and/or antimicrobial agents with the additional filtering function. The ascorbic acid was physisorbed on the surface of mesoporous silica in order to stabilize it and to extend its antioxidant action. The influence of mesoporous silica and ascorbic acid on the microstructural and mechanical properties was investigated, revealing a revelant mechanical reinforcement in the case of fibers loaded only with SiO2 and a decrement in the case of SiO2 with physisorbed ascorbic acid, due to the worse interface between the fillers and the polymeric matrix.

  2. Catalytic Conversion of Pinus densiflora Over Mesoporous Catalysts Using Pyrolysis Process.

    PubMed

    Joo, Sung Kyun; Lee, In-Gu; Lee, Hyung Won; Chea, Kwang-Seok; Jo, Tae Su; Jung, Sang-Chul; Kim, Sang Chai; Ko, Chang Hyun; Park, Young-Kwon

    2016-02-01

    Catalytic pyrolysis experiments were conducted to investigate the possibility of obtaining valuable chemicals from Pinus densiflora, a native Korean tree species occupying 21.4% of the total area under forests in South Korea. Two representative mesoporous catalysts, Al-MCM-41 and Al-MSU-F, as well as hierarchical mesoporous MFI (Meso-MFI) that has both mesopores and micropores, were used as catalysts. Compared to non-catalytic pyrolysis, catalytic pyrolysis was shown to reduce the fractions of levoglucosan, phenolics, and acids in bio-oil, while increasing the fractions of aromatics, PAHs, and furans. Meso-MFI with strong acid sites showed a high selectivity toward aromatics and PAHs, whereas Al-MCM-41 and Al-MSU-F with weak acid sites exhibited a high selectivity toward furanic compounds. The results of this study indicate that choosing a catalyst with an adequate quantity of acidic sites with the required strength is critical for enhancing the production of desired chemicals from Pinus densiflora. PMID:27433632

  3. Yolk-shell nanoarchitectures with a Ru-containing core and a radially oriented mesoporous silica shell: facile synthesis and application for one-pot biomass conversion by combining with enzyme.

    PubMed

    Wei, Wei; Zhao, Yu; Peng, Shichao; Zhang, Haoyang; Bian, Yipeng; Li, Hexing; Li, Hui

    2014-12-10

    In this paper, we develop a facile strategy for fabricating a yolk-shell structured catalytic system that consists of a core made of Ru supported on mesoporous carbon, which is encaged within a silica shell that has ordered radial mesochannels. A region-selective etching mechanism for the formation of the yolk-shell nanoarchitectures is proposed based on the stronger adsorption ability of the carbon core for etching agent than that of the silica shell for etching agent. By combining such material with amyloglucosidase, one-pot hydrolysis-hydrogenation of dextrin to sorbitol can be conducted, delivering enhanced efficiency and showing great promise for biomass conversion applications. PMID:25405326

  4. Hollow mesoporous silica as a high drug loading carrier for regulation insoluble drug release.

    PubMed

    Geng, Hongjian; Zhao, Yating; Liu, Jia; Cui, Yu; Wang, Ying; Zhao, Qinfu; Wang, Siling

    2016-08-20

    The purpose of this study was to develop a high drug loading hollow mesoporous silica nanoparticles (HMS) and apply for regulation insoluble drug release. HMS was synthesized using hard template phenolic resin nanoparticles with the aid of cetyltrimethyl ammonium bromide (CTAB), which was simple and inexpensive. To compare the difference between normal mesoporous silica (NMS) and hollow mesoporous silica in drug loading efficiency, drug release behavior and solid state, NMS was also prepared by soft template method. Transmission electron microscopy (TEM), specific surface area analysis, FT-IR and zeta potential were employed to characterize the morphology structure and physicochemical property of these carriers. The insoluble drugs, carvedilol and fenofibrate(Car and Fen), were chosen as the model drug to be loaded into HMS and NMS. We also chose methylene blue (MB) as a basic dye to estimate the adsorption ability of these carriers from macroscopic and microscopic view, and the drug-loaded carriers were systematically studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and UV-vis spectrophotometry. What' more, the in vivo process of HMS was also study by confocal microscopy and in vivo fluorescence imaging. In order to confirm the gastrointestinal safety of HMS, the pathological examination of stomach and intestine also be evaluated. HMS allowed a higher drug loading than NMS and exhibited a relative sustained release curve, while NMS was immediate-release. And the effect of preventing drugs crystallization was weaker than NMS. As for in vivo process, HMS was cleared relatively rapidly from the mouse gastrointestinal and barely uptake by intestinal epithelial cell in this study due to its large particle size. And the damage of HMS to gastrointestinal could be ignored. This study provided a simple method to obtain high drug loading and regulation insoluble drug release, expanded the application of inorganic carriers in drug delivery system

  5. Nanowire Ice of Phase VI and Distorted VII in Mesoporous Silica Nanotorus Superlattice

    NASA Astrophysics Data System (ADS)

    Zhu, Jinlong; Zhang, Jianzhong; Zhao, Yusheng

    2014-03-01

    The motivation of nano H2O realization and characterization is the highly polarized nature of H2O molecules and the spatial hydrogen bonded networks both in liquid and solid form. The hydrogen bonding character of water molecules results in a remarkably rich phase diagram in the pressure-temperature space. Water/Ice confined in nanochannels showed novel structures and properties as results of hydrophobic and hydrophilic interactions and hydrogen bonding interaction between water molecule and the surface of nanochannel. Studies on nano H2O can provide potential pathway to understand the complicated structure evolutions of ice in the P- T space, because the interplay between nano-confinement and strong intermolecular hydrogen interactions can lead to even richer ice structures which were not found in the none-confined bulk form. The high pressure experiment indicated that the pressure of nanowire ice VI and VII shifted up to 1.7 GPa and 2.5 GPa, and about ~ 0.65 GPa and 0.4 GPa higher than that of normal ice. The nano size effect and the strength of mesoporous silica nanotorus are responsible for the pressure shifts of ice phase regions. More pronounced, the cubic ice VII changed into a tetragonal distorted ``psuedocubic'' structure of the nanowire ice when confined in the mesoporous tubes. The degree of tetragonality increased with increasing pressure, which is resulted from the uniaxial pressure nanowire ice felt, and the anisotropic hydrogen bonding interactions including the H2O-H2O hydrogen bonds in the bulk of the ice and the H2O-silica -OH hydrogen bonds between the interface of nanowire ice and mesoporous silica. The experimental work has benefited from the use of CHESS at Cornell University, which is supported by the NSF award DMR-0936384.

  6. In vivo delivery of bovine viral diahorrea virus, E2 protein using hollow mesoporous silica nanoparticles.

    PubMed

    Mahony, D; Cavallaro, A S; Mody, K T; Xiong, L; Mahony, T J; Qiao, S Z; Mitter, N

    2014-06-21

    Our work focuses on the application of mesoporous silica nanoparticles as a combined delivery vehicle and adjuvant for vaccine applications. Here we present results using the viral protein, E2, from bovine viral diarrhoea virus (BVDV). BVDV infection occurs in the target species of cattle and sheep herds worldwide and is therefore of economic importance. E2 is a major immunogenic determinant of BVDV and is an ideal candidate for the development of a subunit based nanovaccine using mesoporous silica nanoparticles. Hollow type mesoporous silica nanoparticles with surface amino functionalisation (termed HMSA) were characterised and assessed for adsorption and desorption of E2. A codon-optimised version of the E2 protein (termed Opti-E2) was produced in Escherichia coli. HMSA (120 nm) had an adsorption capacity of 80 μg Opti-E2 per mg HMSA and once bound E2 did not dissociate from the HMSA. Immunisation studies in mice with a 20 μg dose of E2 adsorbed to 250 μg HMSA was compared to immunisation with Opti-E2 (50 μg) together with the traditional adjuvant Quillaja saponaria Molina tree saponins (QuilA, 10 μg). The humoral responses with the Opti-E2/HMSA nanovaccine although slightly lower than those obtained for the Opti-E2 + QuilA group demonstrated that HMSA particles are an effective adjuvant that stimulated E2-specific antibody responses. Importantly the cell-mediated immune responses were consistently high in all mice immunised with Opti-E2/HMSA nanovaccine formulation. Therefore we have shown the Opti-E2/HMSA nanoformulation acts as an excellent adjuvant that gives both T-helper 1 and T-helper 2 mediated responses in a small animal model. This study has provided proof-of-concept towards the development of an E2 subunit nanoparticle based vaccine. PMID:24811899

  7. Modification of acrylic bone cement with mesoporous silica nanoparticles: effects on mechanical, fatigue and absorption properties.

    PubMed

    Slane, Josh; Vivanco, Juan; Meyer, Jill; Ploeg, Heidi-Lynn; Squire, Matthew

    2014-01-01

    Polymethyl methacrylate bone cement is the most common and successful method used to anchor orthopedic implants to bone, as evidenced by data from long-term national joint registries. Despite these successes, mechanical failure of the cement mantle can result in premature failure of an implant which has lead to the development of a variety of techniques aimed at enhancing the mechanical properties of the cement, such as the addition of particulate or fiber reinforcements. This technique however has not transitioned into clinical practice, likely due to problems relating to interfacial particle/matrix adhesion and high cement stiffness. Mesoporous silica nanoparticles (MSNs) are a class of materials that have received little attention as polymer reinforcements despite their potential ability to overcome these challenges. Therefore, the objective of the present study was to investigate the use of mesoporous silica nanoparticles (MSNs) as a reinforcement material within acrylic bone cement. Three different MSN loading ratios (0.5%, 2% and 5% (wt/wt)) were incorporated into a commercially available bone cement and the resulting impact on the cement's static mechanical properties, fatigue life and absorption/elution properties were quantified. The flexural modulus and compressive strength and modulus tended to increase with higher MSN concentration. Conversely, the flexural strength, fracture toughness and work to fracture all significantly decreased with increasing MSN content. The fatigue properties were found to be highly influenced by MSNs, with substantial detrimental effects seen with high MSN loadings. The incorporation of 5% MSNs significantly increased cement's hydration degree and elution percentage. The obtained results suggest that the interfacial adhesion strength between the nanoparticles and the polymer matrix was poor, leading to a decrease in the flexural and fatigue properties, or that adequate dispersion of the MSNs was not achieved. These findings

  8. Preparation and Characterization of Rifampin Loaded Mesoporous Silica Nanoparticles as a Potential System for Pulmonary Drug Delivery

    PubMed Central

    Mohseni, Meysam; Gilani, Kambiz; Mortazavi, Seyed Alireza

    2015-01-01

    The goal of this research is to determine the feasibility of loading rifampin into mesoporous silica nanoparticles. Rifampin was selected as a model lipophilic molecule since it is a well-documented and much used anti tuberculosis drug. The mesoporous silica nanoparticles were prepared by using tetraethyl ortho silicate and cetyltrimethyl ammonium bromide (as surfactant). The prepared nanoparticles were characterized in terms of their particle size measurement and porosimetry. The results showed that the particle size is 218 ± 46 nm (mean ± SD) and surface area is 816 m2g-1. In order to load rifampin within the mesopores, adsorption experiments using three different solvents (methanol, water and dimethyl sulfoxide) were carried out. The loading procedure resulted in a significant improvement in the amount of rifampin loaded into mesoporous silica nanoparticles and methanol was found to be a suitable solvent, providing a drug entrapment efficiency of 52 %. Rifampin loaded nanoparticles underwent different in-vitro tests including, SEM and drug release. The in-vitro drug release was investigated using buffer phosphate (pH=7.4). Regarding the drug release study, a biphasic pattern of release was observed. The drug-loaded mesoporous silica nanoparticles were capable of releasing 95% of their drug content after 24 h, following a faster release in the first four hours. The prepared rifampin loaded nanoparticles seem to have potential for use as a pulmonary drug delivery. PMID:25561909

  9. Biosensing Paraoxon in Simulated Environmental Samples by Immobilized Organophosphorus Hydrolase in Functionalized Mesoporous Silica

    SciTech Connect

    Lei, Chenghong; Valenta, Michelle M.; Saripalli, Prasad; Ackerman, Eric J.

    2007-01-01

    There is a critical need for highly sensitive, cost-effective sensors to conduct ecological analyses for environmental and homeland security related applications. We report here on a method which significantly overcomes this difficulty, and demonstrate its application in a biosensor for aquatic environmental applications. A fast-responding and stable biosensor was developed via immobilization of organophosphorus hydrolase (OPH) in functionalized mesoporous silica (FMS) with pore sizes in tens of nanometers. The sensor was tested for detection of paraoxon in simulated environmental samples, under wide ranging physico-chemical conditions.

  10. Neoglycoenzyme-Gated Mesoporous Silica Nanoparticles: Toward the Design of Nanodevices for Pulsatile Programmed Sequential Delivery.

    PubMed

    Díez, Paula; Sánchez, Alfredo; de la Torre, Cristina; Gamella, María; Martínez-Ruíz, Paloma; Aznar, Elena; Martínez-Máñez, Ramón; Pingarrón, José M; Villalonga, Reynaldo

    2016-03-01

    We report herein the design of a stimulus-programmed pulsatile delivery system for sequential cargo release based on the use of a lactose-modified esterase as a capping agent in phenylboronic acid functionalized mesoporous silica nanoparticles. The dual-release mechanism was based on the distinct stability of the cyclic boronic acid esters formed with lactose residues and the long naturally occurring glycosylation chains in the modified neoglycoenzyme. Cargo delivery in succession was achieved using glucose and ethyl butyrate as triggers. PMID:26966914

  11. Self-Assembled Mercaptan on Mesoporous Silica (SAMMS) technology of mercury removal and stabilization

    SciTech Connect

    Feng, Xiangdong; Liu, Jun; Fryxell, G.E.

    1997-09-01

    This paper explains the technology developed to produce Self-Assembled Mercaptan on Mesoporous Silica (SAMMS) for mercury removal from aqueous wastewater and from organic wastes. The characteristics of SAMMS materials, including physical characteristics and mercury loading, and its application for mercury removal and stabilization are discussed. Binding kinetics and binding speciations are reported. Preliminary cost estimates are provided for producing SAMMS materials and for mercury removal from wastewater. The characteristics of SAMMS in mercury separation were studied at PNNL using simulated aqueous tank wastes and actual tritiated pump oil wastes from Savannah River Site; preliminary results are outlined. 47 refs., 16 figs., 16 tabs.

  12. Aerosol Droplet Delivery of Mesoporous Silica Nanoparticles: A Strategy for Respiratory-Based Therapeutics

    PubMed Central

    Li, Xueting; Xue, Min; Raabe, Otto G.; Aaron, Holly L.; Eisen, Ellen A.; Evans, James E.; Hayes, Fred A.; Inaga, Sumire; Tagmout, Abderrahmane; Takeuchi, Minoru; Vulpe, Chris; Zink, Jeffrey I.; Risbud, Subhash H.; Pinkerton, Kent E.

    2015-01-01

    A highly versatile nanoplatform that couples mesoporous silica nanoparticles (MSN) with an aerosol technology to achieve direct nanoscale delivery to the respiratory tract is described. This novel method can deposit MSN nanoparticles throughout the entire respiratory tract, including nasal, tracheobronchial and pulmonary regions using a water-based aerosol. This delivery method was successfully tested in mice by inhalation. The MSN nanoparticles used have the potential for carrying and delivering therapeutic agents to highly specific target sites of the respiratory tract. The approach provides a critical foundation for developing therapeutic treatment protocols for a wide range of diseases where aerosol delivery to the respiratory system would be desirable. PMID:25819886

  13. Mesoporous silica nanoparticles with controlled loading of cationic dendrimer for gene delivery

    NASA Astrophysics Data System (ADS)

    Lin, Jian-Tao; Wang, Chao; Zhao, Yi; Wang, Guan-Hai

    2014-09-01

    In this work, a series of polyamidoamine (PAMAM) dendrimer-functionalized mesoporous silica nanoparticles (MSNs) with predictable and adjustable cationic charge densities for gene delivery were designed, synthesized and characterized. The ‘clickable’ MSNs with controlled and randomly distributed azide groups were synthesized by co-condensation method, and PAMAM dendrimer was conjugated to MSNs via quantitative click modification. The structures of PAMAM-functionalized MSNs were characterized by FTIR, XRD and TEM analyses. Dendrimer-functionalized MSNs formed complexes with plasmid DNA (pDNA), and the complexes were successfully transfected into human kidney cell 293 T. The in vitro cytotoxicity and gene transfection efficacy were also investigated.

  14. Synthesis, characterization, and catalytic application of ordered mesoporous carbon–niobium oxide composites

    SciTech Connect

    Gao, Juan-Li; Gao, Shuang; Liu, Chun-Ling; Liu, Zhao-Tie; Dong, Wen-Sheng

    2014-11-15

    Graphical abstract: The ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process. - Highlights: • Ordered mesoporous carbon–niobium oxide composites were synthesized. • The content of Nb{sub 2}O{sub 5} in the composites could be tuned from 38 to 75%. • Niobium species were highly dispersed in amorphous carbon framework walls. • The composites exhibited good catalytic performance in the dehydration of fructose. - Abstract: Ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process using phenolic resol as carbon source, niobium chloride as precursor and amphiphilic triblock copolymer Pluronic F127 as template. The resulting materials were characterized using a combination of techniques including differential scanning calorimetry–thermogravimetric analysis, N{sub 2} physical adsorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results show that with increasing the content of Nb{sub 2}O{sub 5} from 38 to 75% the specific surface area decreases from 306.4 to 124.5 m{sup 2} g{sup −1}, while the ordered mesoporous structure is remained. Niobium species is well dispersed in the amorphous carbon framework. The mesoporous carbon–niobium oxide composites exhibit high catalytic activity in the dehydration of fructose to 5-hydroxymethylfurfural. A 100% conversion of fructose and a 76.5% selectivity of 5-hydroxymethylfurfural were obtained over the carbon–niobium oxide composite containing 75% Nb{sub 2}O{sub 5} under the investigated reaction conditions.

  15. Expanding the Versatility of Mesoporous Silica Nanoparticles towards Drug Delivery for In-vitro, In-vivo and Clinical Applications

    NASA Astrophysics Data System (ADS)

    Ferris, Daniel Patrick

    The work covered in this thesis focuses on research developments in the mesoporous silica nanoparticle platform as a drug delivery vehicle for containment and controlled release of therapeutic agents to inhibit disease. Mesoporous silica is a very versatile material with a very robust structure that is easily modified both internally and externally to change its physical properties. Once modified, the silica nanoparticies can be loaded with therapeutic agents that can be isolated from interacting with their surroundings until an on command delivery signal is received. In this dissertation, first, application of a noninvasive externally controlled means of activation such as light activation and magnetically based heating have been investigated and achieved. Next, by altering the structure of rotaxanes based on azobenzene, steps towards a self-sealing light activated full rotaxane system have been developed. Then, through the manipulation of the particle structure as well as the internal pore environment of silica particle, the interaction between guest drug molecules and the particles has been better understood towards optimizing drug loading and release efficiency. Finally, surface modification of silica nanoparticles with biomolcules has been achieved and observed to increase the efficacy of the silica nanoparticle system in the cellular environment. A combination of all these areas of research results in the advancement of the mesoporous silica nanoparticle drug delivery system towards utilization within living organisms.

  16. Fluorescent monodisperse spherical particles based on mesoporous silica containing rhodamine 6G

    NASA Astrophysics Data System (ADS)

    Trofimova, E. Yu.; Grudinkin, S. A.; Kukushkina, Yu. A.; Kurdyukov, D. A.; Medvedev, A. V.; Yagovkina, M. A.; Golubev, V. G.

    2012-06-01

    Fluorescent monodisperse spherical silica (SiO2) particles with a regular mesoporous structure containing encapsulated Rhodamine 6G (R6G) dye have been synthesized. The as-synthesized particles have been coated with SiO2 and SiO2-CTAB (cetyltrimethylammonium bromide, C16H33N(CH3)3Br) shells in order to prevent uncontrolled release of the dye from pores. The kinetics of R6G release from the pores of silica particles has been studied. It has been found that the particles synthesized by adding CTAB and R6G to the reaction mixture, as well as the particles coated with the SiO2-CTAB shell, are characterized by the maximum duration of dye release from the pores, which is probably associated with the formation of chemical bonds between R6G and CTAB molecules.

  17. Observations on size confinement effect in B-C-N nanoparticles embedded in mesoporous silica channels

    SciTech Connect

    Tripathi, Neeti; Yamashita, Masaru; Akai, Tomoko; Uchida, Takeyuki

    2014-07-07

    Fluorescent B-C-N/silica nanoparticles were synthesized by solution impregnation method. Effect of B-C-N particle size on the optical properties was investigated by varying the silica pore sizes. Formation of B-C-N nanoparticles within the mesoporous matrix is confirmed by x-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. Furthermore, a remarkable blue-shift in emission peak centres with decreasing pore size in conjugation with band gap modification, ascribed to the size confinement effect. A detailed analysis of experimental results by theoretically defined confinement models demonstrates that the B-C-N nanoparticles in the size range of 3–13 nm falls within the confinement regime. This work demonstrated the experimental evidence of the size confinement effect in smaller size B-C-N nanoparticles.

  18. Modulating in vitro release and solubility of griseofulvin using functionalized mesoporous silica nanoparticles.

    PubMed

    Jambhrunkar, Siddharth; Qu, Zhi; Popat, Amirali; Karmakar, Surajit; Xu, Chun; Yu, Chengzhong

    2014-11-15

    Mesoporous silica nanoparticles (MCM-41) were used as a carrier system to study the influence of surface charge and hydrophobicity on solubility and in-vitro drug release behavior of Griseofulvin, a potent antifungal drug with low water solubility. Bare MCM-41 with a pure silica composition, MCM-41 after amino functionalization (MCM-41-NH2) and methyl functionalization (MCM-41-CH3) were used in this study followed by encapsulation of griseofulvin. Various characterization techniques have been employed to confirm the successful drug loading inside the nanopores. The surface functionalization on MCM-41 is found to have significant effect on griseofulvin's in vitro release and solubility. Both negatively and positively charged surface showed enhancement in solubility and drug release of griseofulvin. However, the hydrophobic modification led to a retarded drug release, which is caused by the poor wetting effect in the case of MCM-41-CH3 nanoparticles.

  19. Hexagonal mesoporous silica modified with 2-mercaptothiazoline for removing mercury from water solution

    NASA Astrophysics Data System (ADS)

    Evangelista, Sheila M.; DeOliveira, Edimar; Castro, Gustavo R.; Zara, Luiz F.; Prado, Alexandre G. S.

    2007-05-01

    A method for the attachment of 2-mercaptothiazoline (MTZ) to modified silica gel has been developed. In the first step, a new silylant agent was synthesized, named SiMTZ, by the reaction between MTZ molecule and chloropropyltrimethoxysilane (SiCl). SiMTZ and tetraethylortosilicate were co-condensed in the presence of n-dodecylamine, a neutral surfactant template, to produce a modified ordered hexagonal mesoporous silica named HMTZ. The modified material contained 0.89 ± 0.03 mmol of 2-mercaptothiazoline per gram of silica. FT-IR, FT-Raman, 29Si- and 13C-NMR spectra were in agreement with the proposed structure of the modified mesoporous silica in the solid state. HMTZ material has been used for divalent mercury adsorption from aqueous solution at 298 ± 1 K. The series of adsorption isotherms were adjusted to a modified Langmuir equation. The maximum number of moles of mercury adsorbed gave 2.34 ± 0.09 mmol/g of material. The same interaction was followed by calorimetric titration on an isoperibol calorimeter. The HMTZ presented a high capacity for the removal of the contaminant mercury from water. The ΔH and Δ G values for the interaction were determined to be -56.34 ± 1.07 and -2.14 ± 0.11 kJ mol -1. This interaction process was accompanied by a decrease of entropy value (-182 J mol -1 K -1). Thus, the interaction between mercury and HMTZ resulted in a spontaneous thermodynamic system with a high favorable exothermic enthalpic effect.

  20. Triblock siloxane copolymer surfactant: template for spherical mesoporous silica with a hexagonal pore ordering.

    PubMed

    Stébé, M J; Emo, M; Forny-Le Follotec, A; Metlas-Komunjer, L; Pezron, I; Blin, J L

    2013-02-01

    Ordered mesoporous silica materials with a spherical morphology have been prepared for the first time through the cooperative templating mechanism (CTM) by using a silicone triblock copolymer as template. The behavior of the pure siloxane copolymer amphiphile in water was first investigated. A direct micellar phase (L(1)) and a hexagonal (H(1)) liquid crystal were found. The determination of the structural parameters by SAXS measurements leads us to conclude that in the hexagonal liquid crystal phase a part of the ethylene oxide group is not hydrated as observed for the micelles. Mesoporous materials were then synthesized from the cooperative templating mechanism. The recovered materials were characterized by SAXS measurements, nitrogen adsorption-desorption analysis, and transmission and scanning electron microscopy. The results clearly evidence that one can control the morphology and the nanostructuring of the resulting material by modifying the synthesis parameters. Actually, highly ordered mesoporous materials with a spherical morphology have been obtained with a siloxane copolymer/tetramethoxysilane molar ratio of 0.10 after hydrothermal treatment at 100 °C. Our study also supports the fact that the interactions between micelles and the hydrolyzed precursor are one of the key parameters governing the formation of ordered mesostructures through the cooperative templating mechanism. Indeed, we have demonstrated that when the interactions between micelles are important, only wormhole-like structures are recovered.

  1. One-pot pseudomorphic crystallization of mesoporous porous silica to hierarchical porous zeolites

    SciTech Connect

    Xing, Jun-Ling; Jiang, Shu-Hua; Pang, Jun-Ling; Yuan, En-Hui; Ma, Xiao-Jing; Lam, Koon-Fung; Xue, Qing-Song; Zhang, Kun

    2015-09-15

    Hierarchically porous silica with mesopore and zeolitic micropore was synthesized via pseudomorphic crystallization under high-temperature hydrothermal treatment in the presence of cetyltrimethylammonium tosylate and tetrapropylammonium ions. A combined characterization using small-angle X-ray diffraction (XRD), nitrogen adsorption, high-resolution transmission electron microscopy (TEM), thermogravimetric analysis (TG), and elemental analysis showed that dual templates, CTA{sup +} and TPA{sup +} molecules, can work in a cooperative manner to synthesize mesoporous zeolite in a one-pot system by precisely tuning the reaction conditions, such as reaction time and temperature, and type and amount of heterometal atoms. It is found that the presence of Ti precursor is critical to the successful synthesis of such nanostructure. It not only retards the nucleation and growth of crystalline MFI domains, but also acts as nano-binder or nano-glue to favor the assembly of zeolite nanoblocks. - Graphical abstract: Display Omitted - Highlights: • A facile method to synthesize mesoporous zeolites with hierarchical porosity was presented. • It gives a new insight into keeping the balance between mesoscopic and molecular ordering in hierarchical porous materials. • A new understanding on the solid–solid transformation mechanism for the synthesis of titanosilicate zeolites was proposed.

  2. Mesoporous Nano-Silica Serves as the Degradation Inhibitor in Polymer Dielectrics

    PubMed Central

    Yang, Yang; Hu, Jun; He, Jinliang

    2016-01-01

    A new generation of nano-additives for robust high performance nanodielectrics is proposed. It is demonstrated for the first time that mesoporous material could act as “degradation inhibitor” for polymer dielectrics to sequestrate the electrical degradation products then restrain the electrical aging process especially under high temperature conditions, which is superior to the existing additives of nanodielectrics except further increasing the dielectric strength. Polyethylenimine (PEI) loaded nano-scaled mesoporous silica MCM-41 (nano-MS) is doped into the dielectric matrix to prepare the PP/MCM-41-PEI nanocomposites. PEI provides the amines to capture the electrical degradation products while the MCM-41 brackets afford large adsorption surface, bring down the activating temperature of the absorbent then enhance the absorptive capacity. The electrical aging tests confirm the contribution of the mesoporous structure to electrical aging resistance and FT-IR analysis of the electrical degraded regions demonstrates the chemical absorption especially under high temperature conditions. Take the experimental data as examples, extending the aging durability and dielectric strength of polymer dielectrics by 5 times and 16%, respectively, can have substantial commercial significance in energy storage, power electronics and power transmission areas. PMID:27338622

  3. Mesoporous Nano-Silica Serves as the Degradation Inhibitor in Polymer Dielectrics.

    PubMed

    Yang, Yang; Hu, Jun; He, Jinliang

    2016-06-24

    A new generation of nano-additives for robust high performance nanodielectrics is proposed. It is demonstrated for the first time that mesoporous material could act as "degradation inhibitor" for polymer dielectrics to sequestrate the electrical degradation products then restrain the electrical aging process especially under high temperature conditions, which is superior to the existing additives of nanodielectrics except further increasing the dielectric strength. Polyethylenimine (PEI) loaded nano-scaled mesoporous silica MCM-41 (nano-MS) is doped into the dielectric matrix to prepare the PP/MCM-41-PEI nanocomposites. PEI provides the amines to capture the electrical degradation products while the MCM-41 brackets afford large adsorption surface, bring down the activating temperature of the absorbent then enhance the absorptive capacity. The electrical aging tests confirm the contribution of the mesoporous structure to electrical aging resistance and FT-IR analysis of the electrical degraded regions demonstrates the chemical absorption especially under high temperature conditions. Take the experimental data as examples, extending the aging durability and dielectric strength of polymer dielectrics by 5 times and 16%, respectively, can have substantial commercial significance in energy storage, power electronics and power transmission areas.

  4. Mesoporous Nano-Silica Serves as the Degradation Inhibitor in Polymer Dielectrics

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Hu, Jun; He, Jinliang

    2016-06-01

    A new generation of nano-additives for robust high performance nanodielectrics is proposed. It is demonstrated for the first time that mesoporous material could act as “degradation inhibitor” for polymer dielectrics to sequestrate the electrical degradation products then restrain the electrical aging process especially under high temperature conditions, which is superior to the existing additives of nanodielectrics except further increasing the dielectric strength. Polyethylenimine (PEI) loaded nano-scaled mesoporous silica MCM-41 (nano-MS) is doped into the dielectric matrix to prepare the PP/MCM-41-PEI nanocomposites. PEI provides the amines to capture the electrical degradation products while the MCM-41 brackets afford large adsorption surface, bring down the activating temperature of the absorbent then enhance the absorptive capacity. The electrical aging tests confirm the contribution of the mesoporous structure to electrical aging resistance and FT-IR analysis of the electrical degraded regions demonstrates the chemical absorption especially under high temperature conditions. Take the experimental data as examples, extending the aging durability and dielectric strength of polymer dielectrics by 5 times and 16%, respectively, can have substantial commercial significance in energy storage, power electronics and power transmission areas.

  5. Nanotherapeutics of PTEN Inhibitor with Mesoporous Silica Nanocarrier Effective for Axonal Outgrowth of Adult Neurons.

    PubMed

    Kim, Min Soo; El-Fiqi, Ahmed; Kim, Jong-Wan; Ahn, Hong-Sun; Kim, Hyukmin; Son, Young-Jin; Kim, Hae-Won; Hyun, Jung Keun

    2016-07-27

    Development of therapeutic strategies such as effective drug delivery is an urgent and yet unmet need for repair of damaged nervous systems. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) regulates axonal regrowth of central and peripheral nervous systems; its inhibition, meanwhile, facilitates axonal outgrowth of injured neurons. Here we show that nanotherapeutics based on mesoporous silica nanoparticles loading PTEN-inhibitor bisperoxovanadium (BpV) are effective for delivery of drug molecules and consequent improvement of axonal outgrowth. Mesoporous nanocarriers loaded BpV drug at large amount (27 μg per 1 mg of carrier), and released sustainably over 10 d. Nanocarrier-BpV treatment of primary neurons from the dorsal root ganglions (DRGs) of rats and mice at various concentrations induced them to actively take up the nanocomplexes with an uptake efficiency as high as 85%. The nanocomplex-administered neurons exhibited significantly enhanced axonal outgrowth compared with those treated with free-BpV drug. The expression of a series of proteins involved in PTEN inhibition and downstream signaling was substantially up-/down-regulated by the nanocarrier-BpV system. Injection of the nanocarriers into neural tissues (DRG, brain cortex, and spinal cord), moreover, demonstrated successful integration into neurons, glial cells, oligodendrocytes, and macrophages, suggesting the possible nanotherapeutics applications in vivo. Together, PTEN-inhibitor delivery via mesoporous nanocarriers can be considered a promising strategy for stimulating axonal regeneration in central and peripheral nervous systems. PMID:27386893

  6. Progammed synthesis of magnetic mesoporous silica coated carbon nanotubes for organic pollutant adsorption

    NASA Astrophysics Data System (ADS)

    Tong, Yue; Zhang, Min; Xia, Peixiong; Wang, Linlin; Zheng, Jing; Li, Weizhen; Xu, Jingli

    2016-05-01

    Magnetic mesoporous silica coated carbon nanotubes were produced from hydrophilic monodisperse magnetic nanoparticles decorated carbon nanotubes using well controlled programmed synthesis method and were characterized by TEM, XRD, FTIR, TGA, N2 adsorption-desorption and VSM. The well-designed mesoporous magnetic nanotubes had a large specific area, a highly open mesoporous structure and high magnetization. Firstly, SiO2-coated maghemite/CNTs nanoparticles (CNTs/Fe3O4@SiO2 composites) were synthesized by the combination of high temperature decomposition process and an sol-gel method, in which the iron acetylacetonate as well as TEOS acted as the precursor for maghemite and SiO2, respectively. The CNTs/Fe3O4@SiO2 composites revealed a core-shell structure, Then, CNTs/Fe3O4@mSiO2 was obtained by extracting cetyltrimethylammonium bromide (CTAB) via an ion-exchange procedure. The resulting composites show not only a magnetic response to an externally applied magnetic field, but also can be a good adsorbent for the organic pollutant in the ambient temperature.

  7. Mesoporous Nano-Silica Serves as the Degradation Inhibitor in Polymer Dielectrics.

    PubMed

    Yang, Yang; Hu, Jun; He, Jinliang

    2016-01-01

    A new generation of nano-additives for robust high performance nanodielectrics is proposed. It is demonstrated for the first time that mesoporous material could act as "degradation inhibitor" for polymer dielectrics to sequestrate the electrical degradation products then restrain the electrical aging process especially under high temperature conditions, which is superior to the existing additives of nanodielectrics except further increasing the dielectric strength. Polyethylenimine (PEI) loaded nano-scaled mesoporous silica MCM-41 (nano-MS) is doped into the dielectric matrix to prepare the PP/MCM-41-PEI nanocomposites. PEI provides the amines to capture the electrical degradation products while the MCM-41 brackets afford large adsorption surface, bring down the activating temperature of the absorbent then enhance the absorptive capacity. The electrical aging tests confirm the contribution of the mesoporous structure to electrical aging resistance and FT-IR analysis of the electrical degraded regions demonstrates the chemical absorption especially under high temperature conditions. Take the experimental data as examples, extending the aging durability and dielectric strength of polymer dielectrics by 5 times and 16%, respectively, can have substantial commercial significance in energy storage, power electronics and power transmission areas. PMID:27338622

  8. Slow-release formulation of a new biological pesticide, pyoluteorin, with mesoporous silica.

    PubMed

    Chen, Jie; Wang, Wei; Xu, Yuquan; Zhang, Xuehong

    2011-01-12

    A slow-release formula of potential biological pesticide Pyoluteorin (Plt) was prepared by using nanophase material of silicon dioxide loading drugs. The final experimental formula was m(Plt:Brij56:TMOS:HCl(aq)) = 0.04:1.4:2:1, synthesized by a highly ordered monolith (HOM) method. This formula can continuously release 85.13 ± 2.03 % of Plt within 28 days. A characterization study showed the formula formed a well-ordered mesoporous structure, with a surface area of 822 m(2) g(-1), with a measured mesoporous volume of 0.41 cm(3) g(-1) and a narrow distribution for the pore size centered at 2.4 nm. A bioactivity experiment showed it authentically prolonged the antifungal effects. This study is the first to report mesoporous formulations for biological pesticides and indicates a potentially interesting drug carrier. The association of a nanostructured silica to the molecular state of the drug holds great interests for field applications as it overcomes the rapid loss of biological function during drug utilities.

  9. Organically functionalized mesoporous silica as a support for synthesis and catalysis

    NASA Astrophysics Data System (ADS)

    McEleney, Kevin Andrew

    Mesoporous silicates are excellent materials for supported catalysis due to their ease of functionalization, tunable pore size and high surface areas. Mesoporous silicates have been utilized in a variety of applications such as drug delivery scaffolds and catalyst supports. Functionalization of the surface can be achieved by either grafting of alkoxy silanes or co-condensation of the organosilane with the inorganic silica source. My research in this area can be divided into two components. In the first, we address the significant issue of metal contamination after reactions that are catalyzed by transition metals. In the second, we examine the design of new catalysts based on organic/inorganic composites. Ruthenium catalyzed processes such as olefin metathesis or asymmetric hydrogenation, are often underutilized due to the difficulty of removing the ruthenium by-products. Attempts to remove ruthenium involve treating the solution with a scavenging reagent followed by silica chromatography. Often these scavenging agents are expensive phosphines or toxic agents like lead tetra-acetate. SBA-15 functionalized with aminopropyl triethoxysilane displays a high affinity for ruthenium. Furthermore, it can be utilized to remove ruthenium by-products from olefin metathesis or hydrogenation reactions without the need for silica chromatography. We have also prepared sulfur-functionalized mesoporous silicates that have a high affinity for palladium. The materials after loading prove to be active catalysts for a variety of palladium catalyzed processes such as Suzuki-Miyaura and Sonogashira couplings. The catalysts are recyclable with moderate loss of activity and structure, depending on the method of incorporation of the thiol. We have characterized the as-synthesized and used catalysts by nitrogen sorption, TEM, X-ray photoelectron spectroscopy (XPS) and a variety of homogeneity tests were performed on the catalysts. Periodic mesoporous organosilicates (PMOs) are a well known

  10. Cholera toxin subunit B-mediated intracellular trafficking of mesoporous silica nanoparticles toward the endoplasmic reticulum

    NASA Astrophysics Data System (ADS)

    Walker, William Andrew

    In recent decades, pharmaceutical research has led to the development of numerous treatments for human disease. Nanoscale delivery systems have the potential to maximize therapeutic outcomes by enabling target specific delivery of these therapeutics. The intracellular localization of many of these materials however, is poorly controlled, leading to sequestration in degradative cellular pathways and limiting the efficacy of their payloads. Numerous proteins, particularly bacterial toxins, have evolved mechanisms to subvert the degradative mechanisms of the cell. Here, we have investigated a possible strategy for shunting intracellular delivery of encapsulated cargoes from these pathways by modifying mesoporous silica nanoparticles (MSNs) with the well-characterized bacterial toxin Cholera toxin subunit B (CTxB). Using established optical imaging methods we investigated the internalization, trafficking, and subcellular localization of our modified MSNs in an in vitro animal cell model. We then attempted to demonstrate the practical utility of this approach by using CTxB-modified mesoporous silica nanoparticles to deliver propidium iodide, a membrane-impermeant fluorophore.

  11. Synthesis and improved SERS performance of silver nanoparticles-decorated surface mesoporous silica microspheres

    NASA Astrophysics Data System (ADS)

    Jiang, Tao; Wang, Xiaolong; Zhang, Li; Zhou, Jun; Zhao, Ziqi

    2016-08-01

    This study reported the improved Raman enhancement ability of silver nanoparticles (Ag NPs) decorated on surface mesoporous silica microspheres (MSiO2@Ag) than that of Ag NPs on solid silica microspheres (SSiO2@Ag). These two kinds of hybrid structures were prepared by a facile single-step hydrothermal reaction with polyvinylpyrrolidone (PVP) serves as both a reductant and stabilizer. The as-synthesized MSiO2@Ag microspheres show more significant surface-enhanced Raman scattering (SERS) activity for 4-mercaptobenzoic acid (4MBA) than SSiO2@Ag microspheres with enhancement factors as 9.20 × 106 and 4.39 × 106, respectively. The proposed reason for the higher SERS activity is estimated to be the contribution of more Raman probe molecules at the mesoporous channels where an enhanced electromagnetic field exists. Such a field was identified by theoretical calculation result. The MSiO2@Ag microspheres were eventually demonstrated for the SERS detection of a typical chemical toxin namely methyl parathion with a detection limit as low as 1 × 10-3 ppm, showing its promising potential in biosensor application.

  12. Adsorption, kinetic and thermodynamic studies for manganese extraction from aqueous medium using mesoporous silica.

    PubMed

    Idris, Salah Ali Mahgoub

    2015-02-15

    This paper describes studies of functionalized mesoporous silica employed as adsorbent for Mn(II) from aqueous solutions. The surface area of MCM-41 and diethylenetriamine functionalized-MCM-41 used in this study were 760 and 318 m(2) g(-1) (N2 adsorption). A strong dependence on pH in the Mn(II) adsorption capacity and best results were obtained at pH 6.5-7. The adsorption onto the diethylenetriamine functionalized-MCM-41 followed the pseudo-second-order kinetic model and the highest reaction rate 0.324 min(-1) was observed at low initial concentration 10 ppm. The equilibrium data showed excellent correlation with the Langmuir isotherm model and the maximum adsorption capacity of Mn(II) reached 88.9 mg/g for DETA-MCM-41 indicating that the adsorption occurs on a homogeneous surface by monolayer sorption without interaction between the adsorbed ions. These data contribute to the understanding of mechanisms involved in mesoporous silica and provide some practical clues to improve the adsorption efficiency (uptake capacity and kinetics) of Mn(II) ions.

  13. Mesoporous-silica nanofluidic channels for quick enrichment/extraction of trace pesticide molecules

    NASA Astrophysics Data System (ADS)

    Xu, Pengcheng; Chen, Chuanzhao; Li, Xinxin

    2015-11-01

    As nanofluidic channels, uniaxially oriented mesoporous-silica is, for the first time, in-situ self-assembled in a microfluidic chip for quick enrichment/extraction of ng L-1(ppt)-level organo-phosphorous (OP) pesticide residue from aqueous solution to ethanol. This micro/nano combined pre-treatment chip is essential for following gas chromatography-mass spectrometry (GC-MS) quantitative analysis. Featuring huge surface area and dense silanol groups at the inwall surface, the mesoporous-silica is uniaxially self-assembled in a micro-reservoir to form a pile of nanofluidic channels (diameter = 2.1 nm). The captured/enriched pesticide molecules in the nanochannels can be efficiently extracted by much smaller volume of ethanol due to its much higher solubility to OP. In our affirming experiment, three mixed OP pesticides of dichlorvos, paraoxon and chlorpyrifos (in water) are captured/enriched by the nano-channels and eluted/extracted by only 0.6 mL ethanol. The whole process only takes 16 min. The GC-MS quantitative results for the extracted three pesticides indicate that the extraction recovery achieves 80%. The achieved limit of quantification (LOQ) and the limit of detection (LOD) are 100 ng L-1 and 30 ng L-1, respectively. The nanofluidic-channel pre-treatment technique is promising in various application fields like agriculture and food safety security.

  14. Mesoporous-silica nanofluidic channels for quick enrichment/extraction of trace pesticide molecules.

    PubMed

    Xu, Pengcheng; Chen, Chuanzhao; Li, Xinxin

    2015-01-01

    As nanofluidic channels, uniaxially oriented mesoporous-silica is, for the first time, in-situ self-assembled in a microfluidic chip for quick enrichment/extraction of ng L(-1)(ppt)-level organo-phosphorous (OP) pesticide residue from aqueous solution to ethanol. This micro/nano combined pre-treatment chip is essential for following gas chromatography-mass spectrometry (GC-MS) quantitative analysis. Featuring huge surface area and dense silanol groups at the inwall surface, the mesoporous-silica is uniaxially self-assembled in a micro-reservoir to form a pile of nanofluidic channels (diameter = 2.1 nm). The captured/enriched pesticide molecules in the nanochannels can be efficiently extracted by much smaller volume of ethanol due to its much higher solubility to OP. In our affirming experiment, three mixed OP pesticides of dichlorvos, paraoxon and chlorpyrifos (in water) are captured/enriched by the nano-channels and eluted/extracted by only 0.6 mL ethanol. The whole process only takes 16 min. The GC-MS quantitative results for the extracted three pesticides indicate that the extraction recovery achieves 80%. The achieved limit of quantification (LOQ) and the limit of detection (LOD) are 100 ng L(-1) and 30 ng L(-1), respectively. The nanofluidic-channel pre-treatment technique is promising in various application fields like agriculture and food safety security. PMID:26596908

  15. Mesoporous Silica Nanoparticles in Cancer Therapy: Relevance of the Targeting Function.

    PubMed

    Pasqua, Luigi; Leggio, Antonella; Sisci, Diego; Andò, Sebastiano; Morelli, Catia

    2016-01-01

    In the last years, the oncologic research is focusing on the optimization of the clinical approach to the tumor disease, through the development of new therapeutic strategies combining currently used antineoplastic drugs to targeted delivery systems. In fact, due to the drugs poor selectivity for cancer cells, an highly aggressive style of dosing is necessary to eradicate tumors, causing severe toxicity to normal cells. Therefore, localized drug delivery would, ideally, improve the therapeutic efficacy, minimizing side effects. Mesoporous silica nanoparticles (MSNs) have been proposed as a promising class of versatile drug/DNA delivery vehicles, as well as efficient tools for fluorescent cell tracking. To date, the major limitation is that MSNs enter the cells regardless of a target-specific functionalization. Therefore, this review is aimed to give a brief up to date overview on mesoporous silica based-drug delivery vehicles, specifically applied to tumor therapy, giving particular emphasis to the importance of a targeting function grafted on the carrier surface, so to avoid an indiscriminate uptake by cells.

  16. Mesoporous-silica nanofluidic channels for quick enrichment/extraction of trace pesticide molecules

    PubMed Central

    Xu, Pengcheng; Chen, Chuanzhao; Li, Xinxin

    2015-01-01

    As nanofluidic channels, uniaxially oriented mesoporous-silica is, for the first time, in-situ self-assembled in a microfluidic chip for quick enrichment/extraction of ng L−1(ppt)-level organo-phosphorous (OP) pesticide residue from aqueous solution to ethanol. This micro/nano combined pre-treatment chip is essential for following gas chromatography-mass spectrometry (GC-MS) quantitative analysis. Featuring huge surface area and dense silanol groups at the inwall surface, the mesoporous-silica is uniaxially self-assembled in a micro-reservoir to form a pile of nanofluidic channels (diameter = 2.1 nm). The captured/enriched pesticide molecules in the nanochannels can be efficiently extracted by much smaller volume of ethanol due to its much higher solubility to OP. In our affirming experiment, three mixed OP pesticides of dichlorvos, paraoxon and chlorpyrifos (in water) are captured/enriched by the nano-channels and eluted/extracted by only 0.6 mL ethanol. The whole process only takes 16 min. The GC-MS quantitative results for the extracted three pesticides indicate that the extraction recovery achieves 80%. The achieved limit of quantification (LOQ) and the limit of detection (LOD) are 100 ng L−1 and 30 ng L−1, respectively. The nanofluidic-channel pre-treatment technique is promising in various application fields like agriculture and food safety security. PMID:26596908

  17. Molecular ordering of mixed surfactants in mesoporous silicas: A solid-state NMR study

    SciTech Connect

    Kobayashi, Takeshi; Mao, Kanmi; Wang, Shy-Guey; Lin, Victor S.-Y.; Pruski, Marek

    2011-02-17

    The use of mixed surfactants in the synthesis of mesoporous silica nanoparticles (MSNs) is of importance in the context of adjusting pore structures, sizes and morphologies. In the present study, the arrangement of molecules in micelles produced from a mixture of two surfactants, cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPB) was detailed by solid-state NMR spectroscopy. Proximities of methyl protons in the trimethylammonium headgroup of CTAB and protons in the pyridinium headgroup of CPB were observed under fast magic angle spinning (MAS) by {sup 1}H-{sup 1}H double quantum (DQ) MAS NMR and NOESY. This result suggested that CTAB and CPB co-exist in the pores without forming significant monocomponent domain structures. {sup 1}H-{sup 29}Si heteronuclear correlation (HETCOR) NMR showed that protons in the headgroups of CTAB are in closer proximity to the silica surface than those in the CPB headgroups. The structural information obtained in this investigation leads to better understanding of the mechanisms of self-assembly and their role in determining the structure and morphology of mesoporous materials.

  18. Reversing Cancer Multidrug Resistance in Xenograft Models via Orchestrating Multiple Actions of Functional Mesoporous Silica Nanoparticles.

    PubMed

    Yang, Debin; Wang, Tingfang; Su, Zhigui; Xue, Lingjing; Mo, Ran; Zhang, Can

    2016-08-31

    A multistimuli responsive drug delivery system (DDS) based on sulfhydryl and amino-cofunctionalized mesoporous silica nanoparticles (SH/NH2-MSNs) has been developed, in which the multifunctional hyaluronic acid (HA) derivatives were grafted onto the SH/NH2-MSNs by disulfide bonds for targeting delivery, controlling drug release and reversing multidrug resistance (MDR). The doxorubicin (Dox) loaded multifunctional HA derivatives modified mesoporous silica nanoparticles (Dox/HHS-MSNs) were enzyme and redox sensitive, which could respond to the intracellular stimuli of hyaluronidase (HAase) and glutathione (GSH) successively and prevent drug leakage before reaching the tumor tissues. The cellular uptake experiments showed that Dox/HHS-MSNs were vulnerable to be endocytosed into the Dox-resistant human breast adenocarcinoma (MCF-7/ADR) cells, efficiently realized the endolysosomal escape and remained in the cytoplasm. Because of orchestrating multiple actions above including active targeting, endolysosomal escape and efficient multilevel drug release, Dox/HHS-MSNs could induce the strongest apoptosis and cytotoxicity of MCF-7/ADR cells. Furthermore, a series of in vivo studies on MCF-7/ADR tumor-bearing xenograft mouse models demonstrated that Dox/HHS-MSNs possessed the enhanced tumor-targeting capacity and the best therapeutic efficacy to reverse cancer MDR. PMID:27420116

  19. Thermoresponsive mesoporous silica nanoparticles as a carrier for skin delivery of quercetin.

    PubMed

    Ugazio, Elena; Gastaldi, Lucia; Brunella, Valentina; Scalarone, Dominique; Jadhav, Sushilkumar A; Oliaro-Bosso, Simonetta; Zonari, Daniele; Berlier, Gloria; Miletto, Ivana; Sapino, Simona

    2016-09-10

    Recently, mesoporous silica nanoparticles (MSNs) have emerged as promising drug delivery systems able to preserve the integrity of the carried substance and/or to selectively reach a target site; however, they have rarely been explored for skin application. In this study, thermoresponsive MSNs, designed to work at physiologic cutaneous temperature, are proposed as innovative topical carriers for quercetin (Q), a well-known antioxidant. The thermosensitive nanoparticles were prepared by functionalizing two different types of matrices, with pore size of 3.5nm (MSNsmall) and 5.0nm (MSNbig), carrying out a free radical copolymerization of N-isopropylacrylamide (NIPAM) and 3-(methacryloxypropyl)trimethoxysilane (MPS) inside the mesopores. The obtained copolymer-grafted MSNs (copoly-MSNs) were physico-chemically characterized and their biocompatibility was attested on a human keratinocyte cell line (HaCaT). The release profiles were assessed and the functional activity of Q, free or loaded, was evaluated in terms of antiradical and metal chelating activities. Ex vivo accumulation and permeation through porcine skin were also investigated. The characterization confirmed the copolymer functionalization of the MSNs. In addition, both the bare and functionalized silica matrices were found to be biocompatible. Among the copolymer-grafted complexes, Q/copoly-MSNbig exhibited more evident thermoresponsive behavior proving the potential of these thermosensitive systems for advanced dermal delivery. PMID:27421910

  20. Effective antifouling using quorum-quenching acylase stabilized in magnetically-separable mesoporous silica.

    PubMed

    Lee, Byoungsoo; Yeon, Kyung-Min; Shim, Jongmin; Kim, Sang-Ryoung; Lee, Chung-Hak; Lee, Jinwoo; Kim, Jungbae

    2014-04-14

    Highly effective antifouling was achieved by immobilizing and stabilizing an acylase, disrupting bacterial cell-to-cell communication, in the form of cross-linked enzymes in magnetically separable mesoporous silica. This so-called "quorum-quenching" acylase (AC) was adsorbed into spherical mesoporous silica (S-MPS) with magnetic nanoparticles (Mag-S-MPS), and further cross-linked for the preparation of nanoscale enzyme reactors of AC in Mag-S-MPS (NER-AC/Mag-S-MPS). NER-AC effectively stabilized the AC activity under rigorous shaking at 200 rpm for 1 month, while free and adsorbed AC lost more than 90% of their initial activities in the same condition within 1 and 10 days, respectively. When applied to the membrane filtration for advanced water treatment, NER-AC efficiently alleviated the biofilm maturation of Pseudomonas aeruginosa PAO1 on the membrane surface, thereby enhancing the filtration performance by preventing membrane fouling. Highly stable and magnetically separable NER-AC, as an effective and sustainable antifouling material, has a great potential to be used in the membrane filtration for water reclamation.

  1. Further Insight into the Definite Morphology and Formation Mechanism of Mesoporous Silica KCC-1.

    PubMed

    Febriyanti, E; Suendo, V; Mukti, R R; Prasetyo, A; Arifin, A F; Akbar, M A; Triwahyono, S; Marsih, I N; Ismunandar

    2016-06-14

    The unique three-dimensional pore structure of KCC-1 has attracted significant attention and has proven to be different compared to other conventional mesoporous silica such as the MCM-41 family, SBA-15, or even MSN nanoparticles. In this research, we carefully examine the morphology of KCC-1 to define more appropriate nomenclature. We also propose a formation mechanism of KCC-1 based on our experimental evidence. Herein, the KCC-1 morphology was interpreted mainly on the basis of compiling all observation and information taken from SEM and TEM images. Further analysis on TEM images was carried out. The gray value intensity profile was derived from TEM images in order to determine the specific pattern of this unique morphology that is found to be clearly different from that of other types of porous spherical-like morphologies. On the basis of these results, the KCC-1 morphology would be more appropriately reclassified as bicontinuous concentric lamellar morphology. Some physical characteristics such as the origin of emulsion, electrical conductivity, and the local structure of water molecules in the KCC-1 emulsion were disclosed to reveal the formation mechanism of KCC-1. The origin of the KCC-1 emulsion was characterized by the observation of the Tyndall effect, conductometry to determine the critical micelle concentration, and Raman spectroscopy. In addition, the morphological evolution study during KCC-1 synthesis completes the portrait of the formation of mesoporous silica KCC-1. PMID:27120557

  2. Selenate adsorption on pre-coordinated Fe3+-silane complexes grafted on mesoporous silicas.

    PubMed

    Otsuka, Ryo; Yoshitake, Hideaki

    2014-08-01

    Fe3+ was coordinated N-[2-(aminoethyl)-3-aminopropyltriethoxysilane], AEAPTES, followed by being grafted on MCM-41, SBA-15 and Cab-O-sil M7D. The mixing ratio, n = [AEAPTES]/[Fe], in the above coordination reaction was varied from 1 to 3. These nine functionalized silicas, denoted as Fe(en)n-silica (n = 1, 2, 3 and silica = MCM-41, SBA-15 and M7D), were used for the adsorption of aqueous selenate. The saturation of adsorption isotherm occurred at Se/Fe = 2 on Fe(en)2- MCM-41 and Fe(en)2-SBA-15, while Fe(en)- and Fe(en)3-MCM-41 and Fe(en)- and Fe(en)3-SBA-15 adsorbed selenate until Se/Fe = 1. The saturation at Se/Fe = 1 was obtained for all absorbents prepared with M7D substrate, suggesting a transformation of the adsorption sites realized on Fe(en)2-MCM-41 and Fe(en)2-SBA-15. The concave curvature of the surface of mesoporous silicas is possibly critical to retain the coordination structure of adsorption sites. The largest capacity obtained among these adsorbents was 1.1 mmol/g, found on Fe(en)2-SBA-15. The structure of adsorption sites was analysed by X-ray absorption spectroscopies in order to obtain the evidences for the distortion of coordination structure induced by grafting and the bond formation between Se and Fe after adsorption. PMID:25936127

  3. Cobalt- and iron-based nanoparticles hosted in SBA-15 mesoporous silica and activated carbon from biomass: Effect of modification procedure

    NASA Astrophysics Data System (ADS)

    Tsoncheva, Tanya; Genova, Izabela; Paneva, Daniela; Dimitrov, Momtchil; Tsyntsarski, Boyko; Velinov, Nicolay; Ivanova, Radostina; Issa, Gloria; Kovacheva, Daniela; Budinova, Temenujka; Mitov, Ivan; Petrov, Narzislav

    2015-10-01

    Ordered mesoporous silica of SBA-15 type and activated carbon, prepared from waste biomass (peach stones), are used as host matrix of nanosized iron and cobalt particles. The effect of preparation procedure on the state of loaded nanoparticles is in the focus of investigation. The obtained materials are characterized by Boehm method, low temperature physisorption of nitrogen, XRD, UV-Vis, FTIR, Mossbauer spectroscopy and temperature programmed reduction with hydrogen. The catalytic behaviour of the samples is tested in methanol decomposition. The dispersion, oxidative state and catalytic behaviour of loaded cobalt and iron nanoparticles are successfully tuned both by the nature of porous support and the metal precursor used during the samples preparation. Facile effect of active phase deposition from aqueous solution of nitrate precursors is assumed for activated carbon support. For the silica based materials the catalytic activity could be significantly improved when cobalt acetylacetonate is used during the modification. The complex effect of pore topology and surface functionality of different supports on the active phase formation is discussed.

  4. Characterization and acidic properties of Al-SBA-15 materials prepared by post-synthesis alumination of a low-cost ordered mesoporous silica

    NASA Astrophysics Data System (ADS)

    Gómez-Cazalilla, M.; Mérida-Robles, J. M.; Gurbani, A.; Rodríguez-Castellón, E.; Jiménez-López, A.

    2007-03-01

    A series of Al-containing SBA-15 type materials with different Si/Al ratio, were prepared by post-synthesis modification of a pure highly ordered mesoporous silica SBA-15 obtained by using sodium silicate as silica source, and amphiphilic block copolymer as structure-directing agent. A high level of aluminum incorporation was achieved, reaching an Si/Al ratio of up to 5.5, without any significant loss in the textural properties of SBA-15. These materials were fully characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), 27Al NMR spectroscopy, and N 2 adsorption at 77 K. The acid properties of these materials have been evaluated by NH 3-TPD, adsorption of pyridine and deuterated acetonitrile coupled to FTIR spectroscopy. The effective acidity of these materials was evaluated using two catalytic reactions: 2-propanol dehydrogenation and 1-butene isomerization. The adsorption of basic probe molecules and the catalytic behavior revealed an evolution of the acid properties with the Al content. These studies have shown that the Al-SBA-15 materials contain Brønsted and Lewis acid sites with medium acidity which makes them appropriate to be used as acid catalysts in heterogeneous catalysis, catalytic supports, and adsorbents.

  5. Stimulus-response mesoporous silica nanoparticle-based chemiluminescence biosensor for cocaine determination.

    PubMed

    Chen, Zhonghui; Tan, Yue; Xu, Kefeng; Zhang, Lan; Qiu, Bin; Guo, Longhua; Lin, Zhenyu; Chen, Guonan

    2016-01-15

    Mesoporous silica nanoparticles (MSN) based controlled release system had been coupled with diverse detection technologies to establish biosensors for different targets. Chemiluminescence (CL) system of luminol/H2O2 owns the characters of simplicity, low cost and high sensitivity, but the targets of which are mostly focused on some oxidants or which can participate in a chemical reaction that yields a product with a role in the CL reaction. In this study, chemiluminescent detection technique had been coupled with mesoporous silica-based controlled released system for the first time to develop a sensitive biosensor for the target which does not cause effect to the CL system itself. Cocaine had been chosen a model target, the MSN support was firstly loaded with glucose, then the positively charged MSN interacted with negatively charged oligonucleotides (the aptamer cocaine) to close the mesopores of MSN. At the present of target, cocaine binds with its aptamer with high affinity; the flexible linear aptamer structured will become stems structured through currently well-defined non-Waston-Crick interactions and causes the releasing of entrapped glucose into the solution. With the assistant of glucose oxidase (GOx), the released glucose can react with the dissolved oxgen to produce gluconic acid and H2O2, the latter can enhance the CL of luminol in the NaOH solution. The enhanced CL intensity has a relationship with the cocaine concentration in the range of 5.0-60μM with the detection limit of 1.43μM. The proposed method had been successfully applied to detect cocaine in serum samples with high selectivity. The same strategy can be applied to develop biosensors for different targets.

  6. Study of Mesoporous Silica Nanoparticles' (MSNs) intracellular trafficking and their application as drug delivery vehicles

    NASA Astrophysics Data System (ADS)

    Yanes, Rolando Eduardo

    Mesoporous silica nanoparticles (MSNs) are attractive drug delivery vehicle candidates due to their biocompatibility, stability, high surface area and efficient cellular uptake. In this dissertation, I discuss three aspects of MSNs' cellular behavior. First, MSNs are targeted to primary and metastatic cancer cell lines, then their exocytosis from cancer cells is studied, and finally they are used to recover intracellular proteins. Targeting of MSNs to primary cancer cells is achieved by conjugating transferrin on the surface of the mesoporous framework, which resulted in enhancement of nanoparticle uptake and drug delivery efficacy in cells that overexpress the transferrin receptor. Similarly, RGD peptides are used to target metastatic cancer cell lines that over-express integrin alphanubeta3. A circular RGD peptide is bound to the surface of MSNs and the endocytosis and cell killing efficacy of camptothecin loaded nanoparticles is significantly improved in cells that express the target receptor. Besides targeting, I studied the ultimate fate of phosphonate coated mesoporous silica nanoparticles inside cells. I discovered that the nanoparticles are exocytosed from cells through lysosomal exocytosis. The nanoparticles are exocytosed in intact form and the time that they remain inside the cells is affected by the surface properties of the nanoparticles and the type of cells. Cells that have a high rate of lysosomal exocytosis excrete the nanoparticles rapidly, which makes them more resistant to drug loaded nanoparticles because the amount of drug that is released inside the cell is limited. When the exocytosis of MSNs is inhibited, the cell killing efficacy of nanoparticles loaded with camptothecin is enhanced. The discovery that MSNs are exocytosed by cells led to a study to determine if proteins could be recovered from the exocytosed nanoparticles. The procedure to isolate exocytosed zinc-doped iron core MSNs and identify the proteins bound to them was developed

  7. Multifunctional upconversion mesoporous silica nanostructures for dual modal imaging and in vivo drug delivery.

    PubMed

    Li, Chunxia; Yang, Dongmei; Ma, Ping'an; Chen, Yinyin; Wu, Yuan; Hou, Zhiyou; Dai, Yunlu; Zhao, Jihong; Sui, Changping; Lin, Jun

    2013-12-20

    Incorporating the agents for magnetic resonance imaging (MRI), optical imaging, and therapy in one nanostructured matrix to construct multifunctional nanomedical platform has attracted great attention for simultaneous diagnostic and therapeutic applications. In this work, a facile methodology is developed to construct a multifunctional anticancer drug nanocarrier by combining the special advantages of upconversion nanoparticles and mesoporous silica. β-NaYF4 :Yb(3+) , Er(3+) @β-NaGdF4 :Yb(3+) is chosen as it can provide the dual modality of upconversion luminescence and MRI. Then mesoporous silica is directly coated onto the upconversion nanoparticles to form discrete, monodisperse, highly uniform, and core-shell structured nanospheres (labeled as UCNPs@mSiO2 ), which are subsequently functionalized with hydrophilic polymer poly(ethylene glycol) (PEG) to improve the colloidal stability and biocompatibility. The obtained multifunctional nanocomposites can be used as an anticancer drug delivery carrier and applied for imaging. The anticancer drug doxorubicin (DOX) is absorbed into UCNPs@mSiO2 -PEG nanospheres and released in a pH-sensitive pattern. In vitro cell cytotoxicity tests on cancer cells verify that the DOX-loaded UCNPs@mSiO2 -PEG has comparable cytotoxicity with free DOX at the same concentration of DOX. In addition, the T1 -weighted MRI that measures in aqueous solutions reveals that the contrast brightening increases with the concentration of Gd(3+) component. Upconversion luminescence images of UCNPs@mSiO2 -PEG uptaken by cells show green emission under 980 nm infrared laser excitation. Finally, the nanocomposites show low systematic toxicity and high in vivo antitumor therapy efficacy. These findings highlight the fascinating features of upconversion-mesoporous nanocomposites as multimodality imaging contrast agents and nanocarrier for drug molecules.

  8. Peptide-laden mesoporous silica nanoparticles with promoted bioactivity and osteo-differentiation ability for bone tissue engineering.

    PubMed

    Luo, Zuyuan; Deng, Yi; Zhang, Ranran; Wang, Mengke; Bai, Yanjie; Zhao, Qiang; Lyu, Yalin; Wei, Jie; Wei, Shicheng

    2015-07-01

    Combination of mesoporous silica materials and bioactive factors is a promising niche-mimetic solution as a hybrid bone substitution for bone tissue engineering. In this work, we have synthesized biocompatible silica-based nanoparticles with abundant mesoporous structure, and incorporated bone-forming peptide (BFP) derived from bone morphogenetic protein-7 (BMP-7) into the mesoporous silica nanoparticles (MSNs) to obtain a slow-release system for osteogenic factor delivery. The chemical characterization demonstrates that the small osteogenic peptide is encapsulated in the mesoporous successfully, and the nitrogen adsorption-desorption isotherms suggest that the peptide encapsulation has no influence on mesoporous structure of MSNs. In the cell experiment, the peptide-laden MSNs (p-MSNs) show higher MG-63 cell proliferation, spreading and alkaline phosphatase (ALP) activity than the bare MSNs, indicating good in vitro cytocompatibility. Simultaneously, the osteogenesis-related proteins expression and calcium mineral deposition disclose enhanced osteo-differentiation of human mesenchymal stem cells (hMSCs) under the stimulation of the p-MSNs, confirming that BFP released from MSNs could significantly promote the osteogenic differentiation of hMSCs, especially at 500μg/mL of p-MSNs concentration. The peptide-modified MSNs with better bioactivity and osteogenic differentiation make it a potential candidate as bioactive material for bone repairing, bone regeneration, and bio-implant coating applications. PMID:25969416

  9. Peptide-laden mesoporous silica nanoparticles with promoted bioactivity and osteo-differentiation ability for bone tissue engineering.

    PubMed

    Luo, Zuyuan; Deng, Yi; Zhang, Ranran; Wang, Mengke; Bai, Yanjie; Zhao, Qiang; Lyu, Yalin; Wei, Jie; Wei, Shicheng

    2015-07-01

    Combination of mesoporous silica materials and bioactive factors is a promising niche-mimetic solution as a hybrid bone substitution for bone tissue engineering. In this work, we have synthesized biocompatible silica-based nanoparticles with abundant mesoporous structure, and incorporated bone-forming peptide (BFP) derived from bone morphogenetic protein-7 (BMP-7) into the mesoporous silica nanoparticles (MSNs) to obtain a slow-release system for osteogenic factor delivery. The chemical characterization demonstrates that the small osteogenic peptide is encapsulated in the mesoporous successfully, and the nitrogen adsorption-desorption isotherms suggest that the peptide encapsulation has no influence on mesoporous structure of MSNs. In the cell experiment, the peptide-laden MSNs (p-MSNs) show higher MG-63 cell proliferation, spreading and alkaline phosphatase (ALP) activity than the bare MSNs, indicating good in vitro cytocompatibility. Simultaneously, the osteogenesis-related proteins expression and calcium mineral deposition disclose enhanced osteo-differentiation of human mesenchymal stem cells (hMSCs) under the stimulation of the p-MSNs, confirming that BFP released from MSNs could significantly promote the osteogenic differentiation of hMSCs, especially at 500μg/mL of p-MSNs concentration. The peptide-modified MSNs with better bioactivity and osteogenic differentiation make it a potential candidate as bioactive material for bone repairing, bone regeneration, and bio-implant coating applications.

  10. Silanol-assisted carbinolamine formation in an amine-functionalized mesoporous silica surface: Theoretical investigation by fragmentation methods

    DOE PAGES

    de Lima Batista, Ana P.; Zahariev, Federico; Slowing, Igor I.; Braga, Ataualpa A. C.; Ornellas, Fernando R.; Gordon, Mark S.

    2015-12-15

    The aldol reaction catalyzed by an amine-substituted mesoporous silica nanoparticle (amine-MSN) surface was investigated using a large molecular cluster model (Si392O958C6NH361) combined with the surface integrated molecular orbital/molecular mechanics (SIMOMM) and fragment molecular orbital (FMO) methods. Three distinct pathways for the carbinolamine formation, the first step of the amine-catalyzed aldol reaction, are proposed and investigated in order to elucidate the role of the silanol environment on the catalytic capability of the amine-MSN material. The computational study reveals that the most likely mechanism involves the silanol groups actively participating in the reaction, forming and breaking covalent bonds in the carbinolamine step.more » Furthermore, the active participation of MSN silanol groups in the reaction mechanism leads to a significant reduction in the overall energy barrier for the carbinolamine formation. In addition, a comparison between the findings using a minimal cluster model and the Si392O958C6NH361 cluster suggests that the use of larger models is important when heterogeneous catalysis problems are the target.« less

  11. Immobilization of tetramethylguanidine on mesoporous SBA-15 silica: a heterogeneous basic catalyst for transesterification of soybean oil.

    PubMed

    Xie, Wenlei; Fan, Mingliang

    2013-07-01

    An active heterogeneous catalyst, namely 1,1,3,3-tetramethylguanidine (TMG) immobilized on mesoporous SBA-15 silica (SBA-15-pr-TMG), was prepared and the catalytic activity was investigated for transesterification of soybean oil with methanol. The heterogeneous catalysts were characterized using Hammett titration method, Fourier transform infrared spectra, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption, and X-ray photoelectron spectroscopy techniques. It is shown that the activity of the catalysts for the transesterification reaction is closely related to their basic properties. By using this catalyst, an environmentally benign process for biodiesel production in a heterogeneous manner was developed. When the reaction was carried out at reflux of methanol, with a molar ratio of methanol to soybean oil of 15:1, a reaction time 12h and a catalyst amount 5 wt%, the oil conversion of 91.7% was achieved. The catalyst could be recovered easily and reused without significant degradation in activity.

  12. Silanol-assisted carbinolamine formation in an amine-functionalized mesoporous silica surface: Theoretical investigation by fragmentation methods

    SciTech Connect

    de Lima Batista, Ana P.; Zahariev, Federico; Slowing, Igor I.; Braga, Ataualpa A. C.; Ornellas, Fernando R.; Gordon, Mark S.

    2015-12-15

    The aldol reaction catalyzed by an amine-substituted mesoporous silica nanoparticle (amine-MSN) surface was investigated using a large molecular cluster model (Si392O958C6NH361) combined with the surface integrated molecular orbital/molecular mechanics (SIMOMM) and fragment molecular orbital (FMO) methods. Three distinct pathways for the carbinolamine formation, the first step of the amine-catalyzed aldol reaction, are proposed and investigated in order to elucidate the role of the silanol environment on the catalytic capability of the amine-MSN material. The computational study reveals that the most likely mechanism involves the silanol groups actively participating in the reaction, forming and breaking covalent bonds in the carbinolamine step. Furthermore, the active participation of MSN silanol groups in the reaction mechanism leads to a significant reduction in the overall energy barrier for the carbinolamine formation. In addition, a comparison between the findings using a minimal cluster model and the Si392O958C6NH361 cluster suggests that the use of larger models is important when heterogeneous catalysis problems are the target.

  13. Synthesis and characterization of Pt nanoparticles with different morphologies in mesoporous silica SBA-15 for methanol oxidation reaction.

    PubMed

    Chen, C S; Lai, Y T; Chen, T C; Chen, C H; Lee, J F; Hsu, C W; Kao, H M

    2014-11-01

    Mesoporous SBA-15 silica materials functionalized with and without carboxylic acid groups were used to effectively control the morphology of Pt crystals, and the materials thus obtained were applied to methanol oxidation reactions. The Pt particles aggregated to form long spheroids inside the channels in pure SBA-15. When carboxylic acid groups were utilized, the SBA-15(-COOH) material facilitated the formation of higher Pt surface area, smaller Pt nanoparticles and nearly spherical shape due to the strong interaction between Pt(4+) ions and carboxylic acid on SBA-15. The Pt(4+) ions on the SBA-15(-COOH) material can be directly transformed to reduced Pt particles during calcination. The methanol oxidation activity on a Pt surface is strongly dependent on the shape of Pt particles. The near-spherical Pt nanoparticles on the SBA-15(-COOH) exhibited higher catalytic activity during methanol oxidation than Pt catalysts on unmodified SBA-15. The near-spherical Pt particles on the SBA-15(-COOH) contained large numbers of terrace sites on their surfaces, which led to high efficiency during methanol oxidation.

  14. Ni Nanoparticles Supported on Cage-Type Mesoporous Silica for CO2 Hydrogenation with High CH4 Selectivity.

    PubMed

    Budi, Canggih Setya; Wu, Hung-Chi; Chen, Ching-Shiun; Saikia, Diganta; Kao, Hsien-Ming

    2016-09-01

    Ni nanoparticles (around 4 nm diameter) were successfully supported on cage-type mesoporous silica SBA-16 (denoted as Ni@SBA-16) via wet impregnation at pH 9, followed by the calcination-reduction process. The Ni@SBA-16 catalyst with a very high Ni loading amount (22.9 wt %) exhibited exceptionally high CH4 selectivity for CO2 hydrogenation. At a nearly identical loading amount, the Ni@SBA-16 catalysts with smaller particle size of Ni NPs surprisingly exhibited a higher catalytic activity of CO2 hydrogenation and also led to a higher selectivity on CH4 formation than the Ni@SiO2 catalysts. This enhanced activity of the Ni@SBA-16 catalyst is suggested to be an accumulative result of the advantageous structural properties of the support SBA-16 and the well confined Ni NPs within the support; both induced a favorable reaction pathway for high selectivity of CH4 in CO2 hydrogenation. PMID:27531065

  15. Distribution of 1-Butyl-3-methylimidazolium Bistrifluoromethylsulfonimide in Mesoporous Silica as a Function of Pore Filling

    SciTech Connect

    Han, Kee Sung; Wang, Xiqing; Hagaman, Edward {Ed} W; Dai, Sheng

    2013-01-01

    Rotational dynamics of the ionic liquid (IL) 1-butyl-3-methlyimidazolium bistrifluoromethylsulfonimide, [C4mim][Tf2N], 1, as a neat liquid and confined in mesoporous silica were investigated by 1H spin-spin (T2) and spin-lattice (T1) relaxation measurements and 13C NMR spectroscopy. Translational dynamics (self-diffusion) were monitored via the diffusion coefficient, D, obtained with 1H pulsed field gradient NMR measurements. These data were used to determine the distribution of 1 in the pores of KIT-6, a mesoporous silica with a bicontinuous gyroid pore structure, as a function of filling fraction. Relaxation studies performed as a function of filling factor and temperature, reveal a dynamic heterogeneity in both translational and rotational motions for 1 at filling factors, f, = 0.2-1.0 (f = 1 corresponds to fully filled pores). Spin-lattice and spin-spin relaxation times reveal the motion of 1 in silica mesopores conform to that expected for a two-dimensional relaxation model. The relaxation dynamics are interpreted using a two-state, fast exchange model for all motions; a slow rotation (and translation) of molecules in contact with the surface and a faster motion approximated by the values for bulk relaxation and diffusion. 1 retains liquid like behavior at all filling factors and temperatures that extend to ca. 50 degrees below the bulk melting point. Translational motion in these systems, interpreted with MD-simulated diffusivity limits, confirms the high propensity of 1 to form a monolayer film on the silica surface at low filling factors.. The attractive interaction of 1 with the surface is greater than that for self-association of 1. The trends in diffusion data at short and long diffusion time suggest that the population of surface-bound 1 is in intimate contact with 1 in the pores. This condition is most easily met at higher filling fractions with successive additions of 1 increasing the layer thickness built up on the surface layer.

  16. One-step synthesis of amine-functionalized hollow mesoporous silica nanoparticles as efficient antibacterial and anticancer materials

    PubMed Central

    Hao, Nanjing; Jayawardana, Kalana W.; Chen, Xuan; De Zoysa, Thareendra

    2015-01-01

    In this study, amine-functionalized hollow mesoporous silica nanoparticles with an average diameter of ~100 nm and shell thickness of ~20 nm were prepared by an one-step process. This new nanoparticulate system exhibited excellent killing efficiency against mycobacterial (M. smegmatis strain mc2 651) and cancer cells (A549). PMID:25562524

  17. Highly monodisperse rattle-structured nanomaterials with gold nanorod core-mesoporous silica shell as drug delivery vehicles and nanoreactors.

    PubMed

    Choi, Eunjin; Kwak, Minjeong; Jang, Byungchul; Piao, Yuanzhe

    2013-01-01

    Rattle-structured nanomaterials composed of a gold nanorod in a mesoporous silica nanocapsule (AuNR@mSiO(2)) were prepared by a novel solution-based consecutive process. The drug-loading properties of the nanomaterial and regrowth control of the core nanoparticles were also studied.

  18. Removal of malachite green dye from aqueous solution using mesoporous silica synthesized from 1-octyl-3-methylimidazolium chloride ionic liquid

    NASA Astrophysics Data System (ADS)

    Ekka, Basanti; Nayak, Soumitra Ranjan; Dash, Priyabrat; Patel, Raj Kishore

    2016-04-01

    In this research, mesoporous silica was synthesized via a modified sol-gel route using 1-octyl-3-methylimidazolium chloride and was employed to remove malachite green (MG) dye from aqueous solution. Subsequently, this material was characterized and identified by different techniques such as Fourier transform infrared spectroscopy (FT-IR), N2 adsorption-desorption method, scanning electron microscopy (SEM), and thermosgravimetric analysis (TGA). Unique properties such as high surface area and pore diameter, in addition to highly reactive atoms and presence of various functional groups make the mesoporous silica possible for efficient removal of malachite green (MG). In batch experimental set-up, optimum conditions for quantitative removal of MG by mesoporous silica was attained by varying different variables such as adsorbent dosage, initial dye concentration, contact time, and pH. Optimum values were set as pH of 8.0, 0.5 g of adsorbent at contact time of 120 min. The adsorption of MG follows the pseudo-second-order rate equation. Equilibrium data fitted well with the Freundlich model at all amount of adsorbent, while maximum adsorption capacity was 5.981 mg g-1 for 0.5 g mesoporous silica synthesized in IL.

  19. Highly sensitive determination of capsaicin using a carbon paste electrode modified with amino-functionalized mesoporous silica.

    PubMed

    Ya, Yu; Mo, Leixing; Wang, Tianshun; Fan, Yegeng; Liao, Jie; Chen, Zhongliang; Manoj, Kumar Srivastava; Fang, Fengxue; Li, Chunya; Liang, Jun

    2012-06-15

    Mesoporous silica (MS) and amino-functionalized mesoporous silica (NH(2)-FMS) were prepared and characterized using the techniques of transmission electron microscopy (TEM) and nitrogen adsorption-desorption. Voltammetry was used to investigate the electrochemical behavior of capsaicin at the amino-functionalized mesoporous silica, which was modified through carbon paste electrode (NH(2)-FMS/CPE). NH(2)-FMS/CPE showed better performance for the electrochemical oxidation of capsaicin, when compared with bare carbon paste electrode (CPE) and mesoporous silica modified carbon paste electrode (MS/CPE). We optimized the experimental conditions influencing the determination of capsaicin. Under optimal conditions, the oxidation peak current was proportional to capsaicin concentration in the range of 0.040-0.40 μmol L(-1)and 0.40-4.0 μmol L(-1), when the detection limit was 0.020 μmol L(-1) (S/N=3). The above method was successfully applied to determine capsaicin in hot pepper samples, yielding satisfactory results. The spiked recoveries were in the range of 93.1-100.7%.

  20. Near-field radiative heat transfer across a pore and its effects on thermal conductivity of mesoporous silica

    NASA Astrophysics Data System (ADS)

    Li, Jing; Feng, Yanhui; Zhang, Xinxin; Huang, Congliang; Wang, Ge

    2015-01-01

    Mesoporous silica substrate consists of uniformly distributed, unconnected cylindrical or spherical pores. Since the diameters of the pores are less than the wavelength, near-field radiative heat transfer across a cylindrical or spherical pore was simulated by employing the fluctuation dissipation theorem and Green function. Such factors as the diameter of the pore, and the temperature of the material were analyzed. It turned out that when the diameter is greater than 1 nm and less than 50 nm, the radiative heat flux at the mesoscale is 2-6 orders higher than the value at the macroscale, and decreases exponentially with the pore radius increasing for both cylindrical and spherical pore. The thermal conductivity of the mesoporous silica was modified with consideration of near-field radiation. It was concluded that the combined thermal conductivities of mesoporous silica which considering near-field radiation can agree with the experimental results more properly than non-considering near-field radiation. The smaller the pore diameter, the more significant the near-field radiation effect. The combined thermal conductivities of mesoporous silica decrease gradually with the pore diameter increasing, while increase smoothly with the temperature increasing.

  1. One-pot synthesis of magnetically recyclable mesoporous silica supported acid-base catalysts for tandem reactions.

    PubMed

    Jun, Samuel Woojoo; Shokouhimehr, Mohammadreza; Lee, Dong Jun; Jang, Youngjin; Park, Jinkyung; Hyeon, Taeghwan

    2013-09-14

    We report one-pot synthesis of magnetically recyclable mesoporous silica catalysts for tandem acid-base reactions. The catalysts could be easily recovered from the reaction mixture using a magnet, and the pore size of the catalysts could be controlled by introducing a swelling agent, resulting in the significant enhancement of the reaction rate.

  2. Efficiency enhancement in dye sensitized solar cells using dual function mesoporous silica as scatterer and back recombination inhibitor

    NASA Astrophysics Data System (ADS)

    Tanvi; Mahajan, Aman; Bedi, R. K.; Kumar, Subodh; Saxena, Vibha; Aswal, D. K.

    2016-08-01

    In the present work, we report the usage of mesoporous silica for improving light harvesting as well as for suppression of back recombination without affecting the extent of dye loading on TiO2 films. Synthesized mesoporous SiO2 was characterized by X-ray photoelectron spectroscopy, X-ray diffraction, Brunauer Emmett and Teller measurement, Scanning electron microscopy and Transmission electron microscopy. DSSCs were fabricated by incorporating different wt% of mesoporous SiO2 in TiO2 paste. An improvement of 50% was observed for devices fabricated using 0.75 wt% of mesoporous SiO2. The mechanism behind the improvement was investigated using electrochemical impedance spectroscopy and UV-Vis spectroscopy.

  3. Dummy molecularly imprinted mesoporous silica prepared by hybrid imprinting method for solid-phase extraction of bisphenol A.

    PubMed

    Yu, Dan; Hu, Xiaolei; Wei, Shoutai; Wang, Qiang; He, Chiyang; Liu, Shaorong

    2015-05-29

    A novel hybrid dummy imprinting strategy was developed to prepare a mesoporous silica for the solid-phase extraction (SPE) of bisphenol A (BPA). A new covalent template-monomer complex (BPAF-Si) was first synthesized with 2,2-bis(4-hydroxyphenyl)hexafluoropropane (BPAF) as the template. The imprinted silica was obtained through the gelation of BPAF-Si with tetraethoxysilane and the subsequent removal of template by thermal cleavage, and then it was characterized by FT-IR spectroscopy, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption-desorption isotherms. Results showed that the new silica had micron-level particle size and ordered mesoporous structure. The static binding test verified that the imprinted silica had much higher recognition ability for BPA than the non-imprinted silica. The imprinted silica also showed high extraction efficiencies and high enrichment factor for SPE of BPA. Using the imprinted silica, a SPE-HPLC-UV method was developed and successfully applied for detecting BPA in BPA-spiked tap water and lake water samples with a recovery of 99-105%, a RSD of 2.7-5.0% and a limit of detection (S/N=3) of 0.3ng/mL. The new imprinted silica avoided the interference of the residual template molecules and reduced the non-specific binding sites, and therefore it can be utilized as a good sorbent for SPE of BPA in environmental water samples. PMID:25892637

  4. Ordered hexagonal mesoporous aluminosilicates with low Si/Al ratio: synthesis, characterization, and catalytic application.

    PubMed

    Liu, Aifeng; Che, Hongwei; Liu, Chuanzhi; Fu, Quanrong; Jiang, Ruijiao; Wang, Cheng; Wang, Liang

    2014-06-01

    Ordered hexagonal mesoporous aluminosilicates with lower Si/Al ratio below 5 have been successfully synthesized via the co-assembly of preformed aluminosilicate precursors with Gemini surfactant [C12H25N+(CH3)2(CH2)6N+(CH3)2C12H25] x 2Br(-) as the template. Powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, N2 adsorption-desorption isotherm measurements, Fourier transform infrared spectroscopy, 27Al nuclear magnetic resonance, thermogravimetric analysis, and temperature-programmed desorption of cyclohexylamine are employed to characterize the resulting samples. The phenol alkylation reaction is carried out to evaluate their catalytic performances. These studies indicate that the sample with a low Si/Al ratio of 3 still retains a highly ordered hexagonal mesoporous structure. And it also possesses the highest acidity of 0.96 mmol among the samples with lower Si/Al ratios below 5 due to its higher specific surface area together with more content of tetrahedrally coordinated Al in the framework. The catalytic tests confirm that the acidity of the samples plays a key role in determining their catalytic performances.

  5. Enhancement of Alkaline Protease Activity and Stability via Covalent Immobilization onto Hollow Core-Mesoporous Shell Silica Nanospheres

    PubMed Central

    Ibrahim, Abdelnasser Salah Shebl; Al-Salamah, Ali A.; El-Toni, Ahmed M.; Almaary, Khalid S.; El-Tayeb, Mohamed A.; Elbadawi, Yahya B.; Antranikian, Garabed

    2016-01-01

    The stability and reusability of soluble enzymes are of major concerns, which limit their industrial applications. Herein, alkaline protease from Bacillus sp. NPST-AK15 was immobilized onto hollow core-mesoporous shell silica (HCMSS) nanospheres. Subsequently, the properties of immobilized proteases were evaluated. Non-, ethane- and amino-functionalized HCMSS nanospheres were synthesized and characterized. NPST-AK15 was immobilized onto the synthesized nano-supports by physical and covalent immobilization approaches. However, protease immobilization by covalent attachment onto the activated HCMSS–NH2 nanospheres showed highest immobilization yield (75.6%) and loading capacity (88.1 μg protein/mg carrier) and was applied in the further studies. In comparison to free enzyme, the covalently immobilized protease exhibited a slight shift in the optimal pH from 10.5 to 11.0, respectively. The optimum temperature for catalytic activity of both free and immobilized enzyme was seen at 60 °C. However, while the free enzyme was completely inactivated when treated at 60 °C for 1 h the immobilized enzyme still retained 63.6% of its initial activity. The immobilized protease showed higher Vmax, kcat and kcat/Km, than soluble enzyme by 1.6-, 1.6- and 2.4-fold, respectively. In addition, the immobilized protease affinity to the substrate increased by about 1.5-fold. Furthermore, the enzyme stability in various organic solvents was significantly enhanced upon immobilization. Interestingly, the immobilized enzyme exhibited much higher stability in several commercial detergents including OMO, Tide, Ariel, Bonux and Xra by up to 5.2-fold. Finally, the immobilized protease maintained significant catalytic efficiency for twelve consecutive reaction cycles. These results suggest the effectiveness of the developed nanobiocatalyst as a candidate for detergent formulation and peptide synthesis in non-aqueous media. PMID:26840303

  6. Enhancement of Alkaline Protease Activity and Stability via Covalent Immobilization onto Hollow Core-Mesoporous Shell Silica Nanospheres.

    PubMed

    Ibrahim, Abdelnasser Salah Shebl; Al-Salamah, Ali A; El-Toni, Ahmed M; Almaary, Khalid S; El-Tayeb, Mohamed A; Elbadawi, Yahya B; Antranikian, Garabed

    2016-01-29

    The stability and reusability of soluble enzymes are of major concerns, which limit their industrial applications. Herein, alkaline protease from Bacillus sp. NPST-AK15 was immobilized onto hollow core-mesoporous shell silica (HCMSS) nanospheres. Subsequently, the properties of immobilized proteases were evaluated. Non-, ethane- and amino-functionalized HCMSS nanospheres were synthesized and characterized. NPST-AK15 was immobilized onto the synthesized nano-supports by physical and covalent immobilization approaches. However, protease immobilization by covalent attachment onto the activated HCMSS-NH₂ nanospheres showed highest immobilization yield (75.6%) and loading capacity (88.1 μg protein/mg carrier) and was applied in the further studies. In comparison to free enzyme, the covalently immobilized protease exhibited a slight shift in the optimal pH from 10.5 to 11.0, respectively. The optimum temperature for catalytic activity of both free and immobilized enzyme was seen at 60 °C. However, while the free enzyme was completely inactivated when treated at 60 °C for 1 h the immobilized enzyme still retained 63.6% of its initial activity. The immobilized protease showed higher V(max), k(cat) and k(cat)/K(m), than soluble enzyme by 1.6-, 1.6- and 2.4-fold, respectively. In addition, the immobilized protease affinity to the substrate increased by about 1.5-fold. Furthermore, the enzyme stability in various organic solvents was significantly enhanced upon immobilization. Interestingly, the immobilized enzyme exhibited much higher stability in several commercial detergents including OMO, Tide, Ariel, Bonux and Xra by up to 5.2-fold. Finally, the immobilized protease maintained significant catalytic efficiency for twelve consecutive reaction cycles. These results suggest the effectiveness of the developed nanobiocatalyst as a candidate for detergent formulation and peptide synthesis in non-aqueous media.

  7. Sandwich-like mesoporous silica flakes for anticancer drug transport-Synthesis, characterization and kinetics release study.

    PubMed

    Mijowska, E; Cendrowski, K; Barylak, M; Konicki, W

    2015-12-01

    In this paper, we present the technology of synthesis, characterization and release kinetics of anticancer drug molecules from sandwich-like mesoporous silica nanoflakes. Mesoporous silica nanoflakes are a very attractive material due to their versatility, low cytotoxicity, large surface area, high pore volume and unique feature of containing parallel pores openon both sides. Nanosilica flakes were prepared through the formation of a mesoporous silica layer on a graphene oxide surface. After graphene oxide removal, the silica nanostructures were filled by an anticancer drug-methotrexate. Release kinetics studies were performed in different temperatures, imitating the conditions in living organisms. Release data was analyzed using the zero-order model, first-order model, Higuchi model and Korsmeyer-Peppas model. The optical properties of samples, and the kinetics of drug release from the nanostructure, were examined by UV-vis spectrophotometer. Data obtained from long term studies showed that the system can serve as an anticancer drug carrier system, since a significant amount of methotrexate was loaded to the material and released. The mechanism of MTX release from mesoporous silica nanoflakes appeared to be a parallel processes of diffusion through water-filled mesopores and degradation of the mSiO2 matrix. Physical and chemical characterization was undertaken by transmission electron microscopy (TEM) and X-ray dispersion spectroscopy (EDX). The specific surface area of the samples was measured through the adsorption of N2 isotherm, interpreted with the Brunauer-Emmett-Teller model (BET). TGA and UV-vis analyses were conducted in order to estimate the amount of the released drug.

  8. Development and application of multi-functionalized mesoporous silica nanomaterials in intracellular drug delivery and heterogeneous catalysis

    NASA Astrophysics Data System (ADS)

    Tsai, Chih-Hsiang

    This dissertation presents research on the development of mesoporous silica nanomaterials and their applications on the fields of drug delivery system and heterogeneous catalysis. Mesoporous silica nanoparticles (MSNs) featuring several particular physicochemical properties are of great interest in material science and applied chemistry. With high biocompatibility and large pore size, MSNs have been regarded as a highly promising platform for intracellular controlled release of drugs and biomolecules. On the other hand, the robust silica framework and easy surface functionalization make MSNs decent solid supports for various types of heterogeneous catalysis. A newly developed surfactant-assistant drug delivery system is investigated. A series of biocompatible phosphate monoester surfactant (PMES) containing PMES-MSN were synthesized and well characterized. The formation mechanism of these special radially-aligned mesostructure was systematic studied by TEM technique and carbon nanocasting. We found that the particle size and shape as well as the structural integrity can be tuned by the ratio of aminopropyltrimethoxysilane (APTMS) and PMES. For biological application, the controlled release of the hydrophobic drug, resveratrol, was tested both in solution and in vitro. It showed that the surfactant-containing PMES-MSNs has a loading capacity around 4 times higher than its surfactant-free counterpart. In addition, a sustained release pattern was observed in the PMES-MSNs release system, indicating the feature of surfactant-assistance. The in vitro study in HeLa cells demonstrated that PMES-MSNs can be efficiently endocytosed. We also observed an endosomal escape of PMES-MSNs within the HeLa cells probably due to proton sponge effect and the assistance of PMES. A series of bifunctionalized MSN catalysts with diarylammonium triflate groups (DAT) as active acid sites and pentafluorophenyl groups (PFP) as secondary functional groups for the catalysis of esterification

  9. Multifunctional polymer-capped mesoporous silica nanoparticles for pH-responsive targeted drug delivery

    NASA Astrophysics Data System (ADS)

    Niedermayer, Stefan; Weiss, Veronika; Herrmann, Annika; Schmidt, Alexandra; Datz, Stefan; Müller, Katharina; Wagner, Ernst; Bein, Thomas; Bräuchle, Christoph

    2015-04-01

    A highly stable modular platform, based on the sequential covalent attachment of different functionalities to the surface of core-shell mesoporous silica nanoparticles (MSNs) for targeted drug delivery is presented. A reversible pH-responsive cap system based on covalently attached poly(2-vinylpyridine) (PVP) was developed as drug release mechanism. Our platform offers (i) tuneable interactions and release kinetics with the cargo drug in the mesopores based on chemically orthogonal core-shell design, (ii) an extremely robust and reversible closure and release mechanism based on endosomal acidification of the covalently attached PVP polymer block, (iii) high colloidal stability due to a covalently coupled PEG shell, and (iv) the ability to covalently attach a wide variety of dyes, targeting ligands and other functionalities at the outer periphery of the PEG shell. The functionality of the system was demonstrated in several cell studies, showing pH-triggered release in the endosome, light-triggered endosomal escape with an on-board photosensitizer, and efficient folic acid-based cell targeting.A highly stable modular platform, based on the sequential covalent attachment of different functionalities to the surface of core-shell mesoporous silica nanoparticles (MSNs) for targeted drug delivery is presented. A reversible pH-responsive cap system based on covalently attached poly(2-vinylpyridine) (PVP) was developed as drug release mechanism. Our platform offers (i) tuneable interactions and release kinetics with the cargo drug in the mesopores based on chemically orthogonal core-shell design, (ii) an extremely robust and reversible closure and release mechanism based on endosomal acidification of the covalently attached PVP polymer block, (iii) high colloidal stability due to a covalently coupled PEG shell, and (iv) the ability to covalently attach a wide variety of dyes, targeting ligands and other functionalities at the outer periphery of the PEG shell. The

  10. Preparation, characterization and catalytic properties of MCM-48 supported tungstophosphoric acid mesoporous materials for green synthesis of benzoic acid

    SciTech Connect

    Wu, Hai-Yan; Zhang, Xiao-Li; Chen, Xi; Chen, Ya; Zheng, Xiu-Cheng

    2014-03-15

    MCM-48 and tungstophosphoric acid (HPW) were prepared and applied for the synthesis of HPW/MCM-48 mesoporous materials. The characterization results showed that HPW/MCM-48 obtained retained the typical mesopore structure of MCM-48, and the textural parameters decreased with the increase loading of HPW. The catalytic oxidation results of benzyl alcohol and benzaldehyde with 30% H{sub 2}O{sub 2} indicated that HPW/MCM-48 was an efficient catalyst for the green synthesis of benzoic acid. Furthermore, 35 wt% HPW/MCM-48 sample showed the highest activity under the reaction conditions. Highlights: • 5–45 wt% HPW/MCM-48 mesoporous catalysts were prepared and characterized. • Their catalytic activities for the green synthesis of benzoic acid were investigated. • HPW/MCM-48 was approved to be an efficient catalyst. • 5 wt% HPW/MCM-48 exhibited the highest catalytic activity.

  11. Molecular Simulation Study of the Early Stages of Formation of Bioinspired Mesoporous Silica Materials.

    PubMed

    Centi, Alessia; Jorge, Miguel

    2016-07-19

    The use of bioinspired templates, such as polyamines and polypeptides, could lead to significant improvements in the synthesis conditions under which mesoporous materials are traditionally produced, removing the need for strong pH as well as high temperature or pressure. In this work, we perform atomistic molecular dynamics simulations of 1,12-diaminododecane surfactants, in water and in the presence of silica monomers, to investigate the early stages of synthesis of one of the first examples of bioinspired silica materials. Different surfactant concentrations and pH were considered, clarifying the influence of the charge state of the molecules on the self-assembly process. We show that the amphiphilic amines form stable lamellar structures at equilibrium in the range from intermediate to high pH values. In a later stage, when silica species are added to the system, our results reveal that, in the same range of pH, silicates strongly adsorb around these aggregates at the interface with water. This causes a considerable modification of the curvature of the layer, which suggests a tendency for the system to evolve from a lamellar phase to the formation of vesicle structures. Furthermore, we show that silica monomers are able to penetrate the layer spontaneously when defects are created as a result of surfactants' head-to-head repulsion. These findings are in agreement with experimental observations and support the pillaring mechanism postulated for this class of materials. However, our simulations indicate that the aggregation process is driven by charge matching between surfactant heads and silica monomers rather than by hydrogen bond interactions between neutral species, as had been previously hypothesized. PMID:27340948

  12. NMR provides checklist of generic properties for atomic-scale models of periodic mesoporous silicas.

    PubMed

    Shenderovich, Ilja G; Mauder, Daniel; Akcakayiran, Dilek; Buntkowsky, Gerd; Limbach, Hans-Heinrich; Findenegg, Gerhard H

    2007-10-25

    MCM-41 and SBA-15 silicas were studied by (29)Si solid-state NMR and (15)N NMR in the presence of (15)N-pyridine with the aim to formulate generic structural parameters that may be used as a checklist for atomic-scale structural models of this class of ordered mesoporous materials. High-quality MCM-41 silica constitutes quasi-ideal arrays of uniform-size pores with thin pore walls, while SBA-15 silica has thicker pore walls with framework and surface defects. The numbers of silanol (Q(3)) and silicate (Q(4)) groups were found to be in the ratio of about 1:3 for MCM-41 and about 1:4 for our SBA-15 materials. Combined with the earlier finding that the density of surface silanol groups is about three per nm(2) in MCM-41 (Shenderovich, et al. J. Phys. Chem. B 2003, 107, 11924) this allows us to discriminate between different atomic-scale models of these materials. Neither tridymite nor edingtonite meet both of these requirements. On the basis of the hexagonal pore shape model, the experimental Q(3):Q(4) ratio yields a wall thickness of about 0.95 nm for MCM-41 silica, corresponding to the width of ca. four silica tetrahedra. The arrangement of Q(3) groups at the silica surfaces was analyzed using postsynthesis surface functionalization. It was found that the number of covalent bonds to the surface formed by the functional reagents is affected by the surface morphology. It is concluded that for high-quality MCM-41 silicas the distance between neighboring surface silanol groups is greater than 0.5 nm. As a result, di- and tripodical reagents like (CH(3))(2)Si(OH)(2) and CH(3)Si(OH)(3) can form only one covalent bond to the surface. The residual hydroxyl groups of surface-bonded functional reagents either remain free or interact with other reagent molecules. Accordingly, the number of surface silanol groups at a given MCM-41 or SBA-15 silica may not decrease but increase after treatment with CH(3)Si(OH)(3) reagent. On the other hand, nearly all surface silanol groups

  13. Synthesis and Characterization of Ordered Mesoporous Silica with Controlled Macroscopic Morphology for Membrane Applications

    NASA Astrophysics Data System (ADS)

    Stohlman, Olive R.

    2011-12-01

    Ordered mesoporous materials have tunable pore sizes between 2 and 50 nm and are characterized by ordered pore structures and high surface areas (~1000 m2/g). This makes them particularly favorable for a number of membrane applications such as protein separation, polymer extrusion, nanowire fabrication and membrane reactors. These membranes can be fabricated as top-layers on macroporous supports or as embedded membranes in a dense matrix. The first part of the work deals with the hydrothermal synthesis and water-vapor/oxygen separation properties of supported MCM-48 and a new Al-MCM-48 type membrane for potential use in air conditioning systems. Knudsen-type permeation is observed in these membranes. The combined effect of capillary condensation and the aluminosilicate matrix resulted in the highest separation factor (142) in Al-MCM-48 membranes, with a water vapor permeance of 6x10 -8mol/m2·Pa·s. The second part focuses on synthesis of embedded mesoporous silica membranes with helically ordered pores by a novel Counter Diffusion Self-Assembly (CDSA) method. This method is an extension of the interfacial synthesis method for fiber synthesis using tetrabutylorthosilicate (TBOS) and cetyltrimethylammonium bromide (CTAB) as the silica source and surfactant respectively. The initial part of this study determined the effect of TBOS height and humidity on fiber formation. From this study, the range of TBOS heights for best microscopic and macroscopic ordering were established. Next, the CDSA method was used to successfully synthesize membranes, which were characterized to have good support plugging and an ordered pore structure. Factors that influence membrane synthesis and plug microstructure were determined. SEM studies revealed the presence of gaps between the plugs and support pores, which occur due to shrinking of the plug on drying. Development of a novel liquid deposition method to seal these defects constituted the last part of this work. Post sealing, excess

  14. Low molecular weight protein enrichment on mesoporous silica thin films for biomarker discovery.

    PubMed

    Fan, Jia; Gallagher, James W; Wu, Hung-Jen; Landry, Matthew G; Sakamoto, Jason; Ferrari, Mauro; Hu, Ye

    2012-04-17

    The identification of circulating biomarkers holds great potential for non invasive approaches in early diagnosis and prognosis, as well as for the monitoring of therapeutic efficiency.(1-3) The circulating low molecular weight proteome (LMWP) composed of small proteins shed from tissues and cells or peptide fragments derived from the proteolytic degradation of larger proteins, has been associated with the pathological condition in patients and likely reflects the state of disease.(4,5) Despite these potential clinical applications, the use of Mass Spectrometry (MS) to profile the LMWP from biological fluids has proven to be very challenging due to the large dynamic range of protein and peptide concentrations in serum.(6) Without sample pre-treatment, some of the more highly abundant proteins obscure the detection of low-abundance species in serum/plasma. Current proteomic-based approaches, such as two-dimensional polyacrylamide gel-electrophoresis (2D-PAGE) and shotgun proteomics methods are labor-intensive, low throughput and offer limited suitability for clinical applications.(7-9) Therefore, a more effective strategy is needed to isolate LMWP from blood and allow the high throughput screening of clinical samples. Here, we present a fast, efficient and reliable multi-fractionation system based on mesoporous silica chips to specifically target and enrich LMWP.(10,11) Mesoporous silica (MPS) thin films with tunable features at the nanoscale were fabricated using the triblock copolymer template pathway. Using different polymer templates and polymer concentrations in the precursor solution, various pore size distributions, pore structures, connectivity and surface properties were determined and applied for selective recovery of low mass proteins. The selective parsing of the enriched peptides into different subclasses according to their physicochemical properties will enhance the efficiency of recovery and detection of low abundance species. In combination with mass

  15. Theoretical and experimental study of isothiazolinone adsorption onto ordered mesoporous silica

    NASA Astrophysics Data System (ADS)

    Mardones, Lucas E.; Legnoverde, María Soledad; Simonetti, Sandra; Basaldella, Elena I.

    2016-12-01

    Mesoporous silica SBA-15 particles were synthesized in order to evaluate their effectiveness as encapsulating agents for a commercial biocide composed of a mixture of methylisothiazolinone and chloromethylisothiazolinone (MIT/CMIT). Three powdered samples of silica particles having different textural properties, sizes and morphologies were hydrothermally obtained and then characterized by SEM, TEM, SAXS, and nitrogen adsorption-desorption measurements. Adsorption of the biocide on the prepared materials was investigated, and the results showed that adsorption capacities increase as the particle size becomes smaller. Higher biocide amounts were also retained on particles having increased pore size and pore volume. Additionally, a most probable interaction mechanism between MIT/CMIT and SBA-15 is proposed on the basis of molecular modeling calculations. The theoretical approach indicates that two adsorption geometries with comparable minimum levels of strength can be adopted by the biocide: planar adsorption when the biocide molecule rings are adsorbed on the silica surface and vertical adsorption when the O atom of the MIT/CMIT interacts with the H atom of silanols.

  16. Synthesis and Nanofiltration Membrane Performance of Oriented Mesoporous Silica Thin Films on Macroporous Supports.

    PubMed

    Clark Wooten, M Kaitlyn; Koganti, Venkat R; Zhou, Shanshan; Rankin, Stephen E; Knutson, Barbara L

    2016-08-24

    Silica thin films with accessible hexagonal close-packed (HCP) pores have been deposited on macroporous supports to achieve composite nanofiltration membranes. The properties of these pore channels have been characterized through solvent flux and solute diffusion experiments. A chemically neutral surface (provided by a cross-linked layer of P123 copolymer) for silica thin film synthesis on the alumina macroporous support promotes the alignment of HCP channels vertical to the substrate, where the mesopore templating agent is block copolymer P123 (poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)). Vertical pore alignment is achieved for thin films (less than ∼100 nm) on a neutral surface and by sandwiching thicker films (∼240 nm) between two chemically neutral surfaces. Solvent flux through the composite membranes is consistent with accessible 10 nm diameter pores. Size selectivity of the membranes is characterized from the permeability of fluorescently tagged solutes (ranging from 4000 to 70 000 Da), where a size cut off occurs at 69 000 Da for the model protein bovine serum albumin. These permeability studies of the nanofiltration membranes serve to demonstrate solute transport in oriented silica thin film membranes and also highlight their versatility for membrane-based separations. PMID:27479791

  17. Immune response to functionalized mesoporous silica nanoparticles for targeted drug delivery.

    PubMed

    Heidegger, Simon; Gössl, Dorothée; Schmidt, Alexandra; Niedermayer, Stefan; Argyo, Christian; Endres, Stefan; Bein, Thomas; Bourquin, Carole

    2016-01-14

    Multifunctional mesoporous silica nanoparticles (MSN) have attracted substantial attention with regard to their high potential for targeted drug delivery. For future clinical applications it is crucial to address safety concerns and understand the potential immunotoxicity of these nanoparticles. In this study, we assess the biocompatibility and functionality of multifunctional MSN in freshly isolated, primary murine immune cells. We show that the functionalized silica nanoparticles are rapidly and efficiently taken up into the endosomal compartment by specialized antigen-presenting cells such as dendritic cells. The silica nanoparticles showed a favorable toxicity profile and did not affect the viability of primary immune cells from the spleen in relevant concentrations. Cargo-free MSN induced only very low immune responses in primary cells as determined by surface expression of activation markers and release of pro-inflammatory cytokines such as Interleukin-6, -12 and -1β. In contrast, when surface-functionalized MSN with a pH-responsive polymer capping were loaded with an immune-activating drug, the synthetic Toll-like receptor 7 agonist R848, a strong immune response was provoked. We thus demonstrate that MSN represent an efficient drug delivery vehicle to primary immune cells that is both non-toxic and non-inflammagenic, which is a prerequisite for the use of these particles in biomedical applications. PMID:26659601

  18. A molecular dynamics simulations study on ethylene glycol-water mixtures in mesoporous silica.

    PubMed

    Schmitz, Rebecca; Müller, Niels; Ullmann, Svenja; Vogel, Michael

    2016-09-14

    We perform molecular dynamics simulations to investigate structural and dynamical properties of ethylene glycol-water (EG-WA) mixtures in mesoporous silica. To obtain comprehensive insights into the dependence of liquid behaviors on the confinement features, we exploit that straightforward modification of the force field parameters allows us to vary the properties of the hydrogen-bond network of the confined liquid, we alter the polarity of the silica surface, and we consider amorphous as well as crystalline matrices. It is observed that the confinement induces a micro-phase separation in the liquid, which qualitatively depends on the properties of both liquid and matrix so that EG or WA molecules may be preferentially adsorbed at the silica surface. Furthermore, it is found that the confinement strongly affects the liquid dynamics. Largely independent of the polarity and structure of the matrix, structural relaxation is about a factor of 10(4) slower at the pore wall than in the pore center. Moreover, the non-Arrhenius temperature dependence of the bulk mixture turns into an Arrhenius behavior of the confined mixture so that the spatial restriction can slow down or speed up the structural relaxation, depending on temperature. PMID:27634271

  19. A molecular dynamics simulations study on ethylene glycol-water mixtures in mesoporous silica

    NASA Astrophysics Data System (ADS)

    Schmitz, Rebecca; Müller, Niels; Ullmann, Svenja; Vogel, Michael

    2016-09-01

    We perform molecular dynamics simulations to investigate structural and dynamical properties of ethylene glycol-water (EG-WA) mixtures in mesoporous silica. To obtain comprehensive insights into the dependence of liquid behaviors on the confinement features, we exploit that straightforward modification of the force field parameters allows us to vary the properties of the hydrogen-bond network of the confined liquid, we alter the polarity of the silica surface, and we consider amorphous as well as crystalline matrices. It is observed that the confinement induces a micro-phase separation in the liquid, which qualitatively depends on the properties of both liquid and matrix so that EG or WA molecules may be preferentially adsorbed at the silica surface. Furthermore, it is found that the confinement strongly affects the liquid dynamics. Largely independent of the polarity and structure of the matrix, structural relaxation is about a factor of 104 slower at the pore wall than in the pore center. Moreover, the non-Arrhenius temperature dependence of the bulk mixture turns into an Arrhenius behavior of the confined mixture so that the spatial restriction can slow down or speed up the structural relaxation, depending on temperature.

  20. pH and ion strength modulated ionic species loading in mesoporous silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Liu, Jianbo; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Yang, Meng; Li, Li; Xu, Jianguo

    2013-10-01

    Mesoporous silica nanoparticles (MSN) have emerged as appealing host materials to accommodate guest molecules for biomedical applications, and recently various methods have been developed to modulate the loading of guest molecules in the silica matrix. Herein, it was demonstrated that pH and ion strength showed great influence on the loading of charged species into the nanoparticles, taking MCM-41 as a host MSN model and methylviologen (MV2+) and 1,5-naphthalene disulfonate (NDS2-) as typical charged ionic guest molecules. As the pH increased from 3.0 to 8.0, the loading amount of MV2+ increased gradually, while on the contrary, it decreased gradually for NDS2-, for the solution pH changed the electrostatic interaction between the silica matrix and the ionic guest molecules. Additionally, the adding of NaCl reduced the electrostatic interaction, which resulted in a decreasing of the electrostatic rejection and electrostatic accumulation for the molecules carrying the same and the opposite charge to the particle respectively. Thus, pH and ion strength can be employed as simple approaches to modulate the loading of charged molecules and permselectivity in MSN. This work has a definite guidance function for molecule loading, transport modulation, controlled release as well as sensors based on MSN.

  1. Immune response to functionalized mesoporous silica nanoparticles for targeted drug delivery.

    PubMed

    Heidegger, Simon; Gössl, Dorothée; Schmidt, Alexandra; Niedermayer, Stefan; Argyo, Christian; Endres, Stefan; Bein, Thomas; Bourquin, Carole

    2016-01-14

    Multifunctional mesoporous silica nanoparticles (MSN) have attracted substantial attention with regard to their high potential for targeted drug delivery. For future clinical applications it is crucial to address safety concerns and understand the potential immunotoxicity of these nanoparticles. In this study, we assess the biocompatibility and functionality of multifunctional MSN in freshly isolated, primary murine immune cells. We show that the functionalized silica nanoparticles are rapidly and efficiently taken up into the endosomal compartment by specialized antigen-presenting cells such as dendritic cells. The silica nanoparticles showed a favorable toxicity profile and did not affect the viability of primary immune cells from the spleen in relevant concentrations. Cargo-free MSN induced only very low immune responses in primary cells as determined by surface expression of activation markers and release of pro-inflammatory cytokines such as Interleukin-6, -12 and -1β. In contrast, when surface-functionalized MSN with a pH-responsive polymer capping were loaded with an immune-activating drug, the synthetic Toll-like receptor 7 agonist R848, a strong immune response was provoked. We thus demonstrate that MSN represent an efficient drug delivery vehicle to primary immune cells that is both non-toxic and non-inflammagenic, which is a prerequisite for the use of these particles in biomedical applications.

  2. Preparation of the narrow size distribution USPIO in mesoporous silica for magnetic field guided drug delivery and release

    NASA Astrophysics Data System (ADS)

    Zapotoczny, B.; Guskos, N.; Kozioł, J. J.; Dudek, M. R.

    2015-01-01

    Ultra-small superparamagnetic iron oxides (USPIO) with an average diameter of 2 nm were synthesized in mesoporous silica using the method of co-precipitation of Fe2+ and Fe3+ ions in aqueous solution directly in the silica nanopores. Two types of the silica material, hexagonal phase MCM-41 and mesoporous silica spheres (MSS), were used. The resulting magnetically modified silica samples show high-quality superparamagnetic properties which persist also at low temperatures near 2 K. Their magnetization saturation in an applied external magnetic field exceeds 15 emu/g. The magnetically modified silica samples were studied with the help of the ferromagnetic resonance (FMR), SQUID-magnetometry, X-ray diffraction (XRD), dynamic light scattering (DLS) and TEM/EDX microscopy. The studies were complemented by confirming the possibility of drug release by the modified silica samples where the standard fluorescent dye was used as an example. The prepared material is suggested to be considered for magnetic field guided drug delivery and release.

  3. Biocompatible zwitterionic sulfobetaine copolymer-coated mesoporous silica nanoparticles for temperature-responsive drug release.

    PubMed

    Sun, Jiao-Tong; Yu, Zhi-Qiang; Hong, Chun-Yan; Pan, Cai-Yuan

    2012-05-14

    A novel nanocontainer, which could regulate the release of payloads, has been successfully fabricated by attaching zwitterionic sulfobetaine copolymer onto the mesoporous silica nanoparticles (MSNs). RAFT polymerization is employed to prepare the hybrid poly(2-(dimethylamino)ethyl methacrylate)-coated MSNs (MSN-PDMAEMA). Subsequently, the tertiary amine groups in PDMAEMA are quaternized with 1,3-propanesultone to get poly(DMAEMA-co-3-dimethyl(methacryloyloxyethyl)ammonium propanesulfonate)-coated MSNs [MSN-Poly(DMAEMA-co-DMAPS)]. The zwitterionic PDMAPS component endows the nanocarrier with biocompatibility, and the PDMAEMA component makes the copolymer shell temperature-responsive. Controlled release of loaded rhodamine B has been achieved in the saline solutions. PMID:22488562

  4. Bioresponsive hyaluronic acid-capped mesoporous silica nanoparticles for targeted drug delivery.

    PubMed

    Chen, Zhaowei; Li, Zhenhua; Lin, Youhui; Yin, Meili; Ren, Jinsong; Qu, Xiaogang

    2013-01-28

    In this paper, we present a facile strategy to synthesize hyaluronic acid (HA) conjugated mesoporous silica nanoparticles (MSP) for targeted enzyme responsive drug delivery, in which the anchored HA polysaccharides not only act as capping agents but also as targeting ligands without the need of additional modification. The nanoconjugates possess many attractive features including chemical simplicity, high colloidal stability, good biocompatibility, cell-targeting ability, and precise cargo release, making them promising agents for biomedical applications. As a proof-of-concept demonstration, the nanoconjugates are shown to release cargoes from the interior pores of MSPs upon HA degradation in response to hyaluronidase-1 (Hyal-1). Moreover, after receptor-mediated endocytosis into cancer cells, the anchored HA was degraded into small fragments, facilitating the release of drugs to kill the cancer cells. Overall, we envision that this system might open the door to a new generation of carrier system for site-selective, controlled-release delivery of anticancer drugs.

  5. Probing the Microenvironment in the Confined Pores of Mesoporous Silica Nanoparticles

    PubMed Central

    2015-01-01

    The microenvironment inside of the pores of mesoporous silica nanoparticles is probed using spectroscopic techniques. The probe molecules are sealed inside of the pores by a nanovalve system that is capable of controlling the access to the pore and ensuring the exclusive probing of the pore environment without any interference from the probe molecules on the outer surface of the particles or from the surrounding solution. Rigidochromism studies are used to evaluate the rigidity of the solvent matrix inside of the pore, and dynamic fluorescence anisotropy experiments are employed to determine the rotational diffusion freedom of the probe molecule. The data show that those probe molecules are neither completely free to move nor tightly attached to the pore wall, and their mobility is changed by altering the charge of the pore wall. PMID:24803992

  6. Functionalized Hollow Mesoporous Silica Nanoparticles for Tumor Vasculature Targeting and PET Image-Guided Drug Delivery

    PubMed Central

    Chakravarty, Rubel; Goel, Shreya; Hong, Hao; Chen, Feng; Valdovinos, Hector F.; Hernandez, Reinier; Barnhart, Todd E.; Cai, Weibo

    2014-01-01

    Aim Development of multifunctional and well-dispersed hollow mesoporous silica nanoparticles (HMSNs) for tumor vasculature targeted drug delivery and positron emission tomography (PET) imaging. Materials and Methods Amine functionalized HMSNs (150–250 nm) were conjugated with a macrocyclic chelator, NOTA, PEGylated and loaded with anti-angiogenesis drug, Sunitinib. Cyclo(Arg-Gly-Asp-D-Tyr-Lys) (cRGDyK) peptide was attached to the nanoconjugate and radiolabeled with 64Cu for PET imaging. Results 64Cu-NOTA-HMSN-PEG-cRGDyK exhibited integrin specific uptake both in vitro and in vivo. PET results indicated ~ 8 %ID/g uptake of targeted nanoconjugates in U87MG tumors, which correlated well with ex vivo and histological analyses. Enhanced tumor targeted delivery of sunitinib was also observed. Conclusions We successfully developed tumor vasculature targeted HMSNs for PET imaging and image guided drug delivery. PMID:25955122

  7. pH-responsive composite microspheres based on magnetic mesoporous silica nanoparticle for drug delivery.

    PubMed

    Wen, Hao; Guo, Jia; Chang, Baisong; Yang, Wuli

    2013-05-01

    pH-responsive composite microspheres, consisting of a core of Fe₃O₄ nanoparticle, a sandwiched layer of mesoporous silica and a shell of crosslinked poly (methacrylic acid) (PMAA), were successfully synthesized via distillation precipitation polymerization. The pKa of the composite microsphere increased with the increase in the crosslinking density. Doxorubicin hydrochloride (DOX) was applied as a model drug, and the behavior of drug storage/release was investigated. The cumulative release of DOX-loaded composite microsphere in vitro showed that the drug release rate was much faster below its pKa than that of above its pKa. Because pH of most tumor tissues was lower than that of normal tissues, the pH-responsive composite microspheres are promising drug delivery system especially for cancer therapy.

  8. Visible Light and pH Responsive Polymer-Coated Mesoporous Silica Nanohybrids for Controlled Release.

    PubMed

    Wang, Guojie; Dong, Jie; Yuan, Tingting; Zhang, Juchen; Wang, Lei; Wang, Hao

    2016-07-01

    A visible light and pH responsive anticancer drug delivery system based on polymer-coated mesoporous silica nanoparticles (MSNs) has been developed. Perylene-functionalized poly(dimethylaminoethyl methacrylates) sensitive to visible light and pH are electrostatically attached on the surface of MSNs to seal the nanopores. Stimulation of visible light and acid can unseal the nanopores to induce controlled drug release from the MSNs. More interestingly, the release can be enhanced under the combined stimulation of the dual-stimuli. The synergistic effect of visible light and acid stimulation on the efficient release of anticancer drugs from the nanohybrids endows the system with great potential for cancer therapy. PMID:26938147

  9. Pore shape and sorption behaviour in mesoporous ordered silica films1

    PubMed Central

    Fritz-Popovski, Gerhard; Morak, Roland; Sharifi, Parvin; Amenitsch, Heinz; Paris, Oskar

    2016-01-01

    Mesoporous silica films templated by pluronic P123 were prepared using spin and dip coating. The ordered cylindrical structure within the films deforms due to shrinkage during calcination. Grazing-incidence small-angle X-ray scattering (GISAXS) measurements reveal that both the unit cell and the cross section of the pores decrease in size, mainly normal to the surface of the substrate, leading to elliptical cross sections of the pores with axis ratios of about 1:2. Water take-up by the pores upon changing the relative humidity can be monitored quantitatively by the shift in the critical angle of X-ray reflection as seen by the Yoneda peak. PMID:27738418

  10. Mesoporous Silica Nanoparticles as Controlled Release Drug Delivery and Gene Transfection Carriers

    SciTech Connect

    Igor I. Slowing; Juan L. Viveo-Escoto; Chia-Wen Wu; Victor S. Y. Lin

    2008-04-10

    In this review, we highlight the recent research developments of a series of surface-functionalized mesoporous silica nanoparticle (MSN) materials as efficient drug delivery carriers. The synthesis of this type of MSN materials is described along with the current methods for controlling the structural properties and chemical functionalization for biotechnological and biomedical applications. We summarized the advantages of using MSN for several drug delivery applications. The recent investigations of the biocompatibility of MSN in vitro are discussed. We also describe the exciting progress on using MSN to penetrate various cell membranes in animal and plant cells. The novel concept of gatekeeping is introduced and applied to the design of a variety of stimuli-responsive nanodevices. We envision that these MSN-based systems have a great potential for a variety of drug delivery applications, such as the site-specific delivery and intracellular controlled release of drugs, genes, and other therapeutic agents.

  11. Enhanced Sensitivity of Cancer Stem Cells to Chemotherapy Using Functionalized Mesoporous Silica Nanoparticles.

    PubMed

    Chen, Zhenzhen; Zhu, Pingping; Zhang, Yushun; Liu, Yating; He, Yuling; Zhang, Lifen; Gao, Yanfeng

    2016-08-01

    Cancer stem cells (CSCs) are responsible for cancer drug resistance with high expression of ABCG2, which pumps the internalized chemotherapeutic out to escape drug-induced cytotoxicity. Here, we established a functionalized mesoporous silica nanoparticle (MSN) system to deliver shABCG2 and doxorubicin (Dox) synergistically. With excellent cell uptake and endosomal escape capacities, the dual-delivery carriers internalized shABCG2 and Dox into CSCs efficiently. ABCG2 depletion increased intracellular and intranuclear Dox enrichment, drove vigorous Dox-induced cell death, and impaired the self-renewal of CSCs. Additionally, the nanoparticles eliminated tumors efficiently and reduced tumor initiation by CSCs in vivo, with negligible side effects. Our findings suggest that well-designed delivery systems for conventional chemotherapeutic agents are promising for CSC therapy. PMID:27348602

  12. Development of mesoporous silica nanomaterials as a vehicle for anticancer drug delivery

    PubMed Central

    Yanes, Rolando E; Tamanoi, Fuyuhiko

    2012-01-01

    The development of delivery vehicles that would carry therapeutic agents selectively to cancer cells has become an important focus in biomedical research. Nanoparticles have received much attention because the advances made in this field have resulted in multiple biocompatible materials. In particular, mesoporous silica nanoparticles (MSNs) offer a solid framework with porous structure and high surface area that allows for the attachment of different functional groups. In this article we discuss the different surface modifications made to MSNs that have allowed for the construction of targeted nanoparticles to enhance accumulation and uptake in target sites, the incorporation of nanomachines for controlled cargo release and the combination with superparamagnetic metals for MRI cell labeling. We also discuss biocompatibility, biodistribution and drug-delivery efficacy of MSNs. Finally, we mention the construction of multifunctional nanoparticles that combine all of the previously examined nanoparticle modifications. PMID:22506096

  13. [Preparation and stability of β-carotene loaded using mesoporous silica nanoparticles as carriers system].

    PubMed

    Liu, Jing; Ren, Zhi-hui; Wang, Hai-yuan; Jin, Xing-hua

    2015-09-01

    1,3,5-Trimethylbenzene (1,3,5-TMB) was used as the pore-enlarging modifier to expand the pore size of MCM-41 (mobil company of matter) mesoporous silica nanoparticles. The solvent impregnation method was adopted to assemble non-water-soluble β-carotene into the pore channel of MCM-41. The MCM-41 and drug assemblies were characterized by TEM, FT-IR, elemental analysis and N2 adsorption-desorption. The results showed that MCM-41 has good sphericity and regular pore structure. The research also investigated the optimal loading time, the drug loading and the vitro stability of the β-carotene. As a drug carrier, the modified MCM-41 showing a shorter drug loading time, the drug loading as high as 85.58% and the stability of β-carotene in drug assemblies has improved. The study of this new formulation provides a new way for β-carotene application. PMID:26983203

  14. Mesoporous Silica Nanoparticles with Co-Condensed Gadolinium Chelates for Multimodal Imaging

    PubMed Central

    Taylor-Pashow, Kathryn M. L.; Della Rocca, Joseph; Lin, Wenbin

    2013-01-01

    Several mesoporous silica nanoparticle (MSN) contrast agents have been synthesized using a co-condensation method to incorporate two different Gd3+ complexes at very high loadings (15.5–28.8 wt %). These MSN contrast agents, with an MCM-41 type pore structure, were characterized using a variety of methods including SEM and TEM, nitrogen adsorption measurements, thermogravimetric analysis (TGA), direct current plasma (DCP) spectroscopy, and powder X-ray diffraction (PXRD). The magnetic resonance (MR) relaxivities of these contrast agents were determined using a 3 T MR scanner. The r1 relaxivities of these nanoparticles range from 4.1 to 8.4 mM−1s−1 on a per Gd basis. Additionally, the MSN particles were functionalized with an organic fluorophore and cancer cell targeting peptide to allow for demonstration of both the optical and MR contrast enhancing capabilities in vitro. PMID:24527205

  15. MRI-visualized, dual-targeting, combined tumor therapy using magnetic graphene-based mesoporous silica.

    PubMed

    Wang, Yi; Huang, Rongqin; Liang, Guohai; Zhang, Zhengyong; Zhang, Peng; Yu, Shaoning; Kong, Jilie

    2014-01-15

    Targeting peptide-modified magnetic graphene-based mesoporous silica (MGMSPI) are synthesized, characterized, and developed as a multifunctional theranostic platform. This system exhibits many merits, such as biocompatibility, high near-infrared photothermal heating, facile magnetic separation, large T2 relaxation rates (r2), and a high doxorubicin (DOX) loading capacity. In vitro and in vivo results demonstrate that DOX-loaded MGMSPI (MGMSPID) can integrate magnetic resonance imaging, dual-targeting recognition (magnetic targeting and receptor-mediated active targeting), and chemo-photothermal therapy into a single system for a visualized-synergistic therapy of glioma. In addition, it is observed that the MGMSPID system has heat-stimulated, pH-responsive, sustained release properties. All of these characteristics would provide a robust multifunctional theranostic platform for visualized glioma therapy.

  16. Magnetic field enhanced cell uptake efficiency of magnetic silica mesoporous nanoparticles.

    PubMed

    Liu, Qian; Zhang, Jixi; Xia, Weiliang; Gu, Hongchen

    2012-06-01

    The advantages of using magnetic mesoporous silica nanoparticles (M-MSNs) in biomedical applications have been widely recognized. However, poor uptake efficiency may hinder the potential of M-MSNs in many applications, such as cell tracking, drug delivery, fluorescence and magnetic resonance imaging. An external magnetic field may improve the cellular uptake efficiency. In this paper, we evaluated the effect of a magnetic field on the uptake of M-MSNs. We found that the internalization of M-MSNs by A549 cancer cells could be accelerated and enhanced by a magnetic field. An endocytosis study indicated that M-MSNs were internalized by A549 cells mainly through an energy-dependent pathway, namely clathrin-induced endocytosis. Transmission electron microscopy showed that M-MSNs were trafficked into lysosomes. With the help of a magnetic field, anticancer drug-loaded M-MSNs induced elevated cancer cell growth inhibition.

  17. The synthesis and application involving regulation of the insoluble drug release from mesoporous silica nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Jia; Wang, Yan; Zheng, Xin; Zhang, Ying; Sun, Changshan; Gao, Yikun; Jiang, Tongying; Wang, Siling

    2015-03-01

    Mesoporous silica nanotubes (SNT) were synthesized using hard template carbon nanotubes (CNT) with the aid of cetyltrimethyl ammonium bromide (CTAB) in a method, which was simple and inexpensive. Scanning electron microscopy, transmission electron microscopy and specific surface area analysis were employed to characterize the morphology and structure of SNT, and the formation mechanism of SNT was also examined by Fourier transform infrared spectroscopy. There are few published reports of the mesoporous SNT with large specific surface area applied in the drug delivery systems to improve the amount of drug loading. In addition, the structure of SNT allows investigators to control the drug particle size in the pore channels and significantly increase the drug dissolution rate. The insoluble drug, cilostazol, was chosen as a model drug to be loaded into SNT and we developed a simple and efficient method for regulating the drug release by using a gelatin coating with different thicknesses around the SNT. The release rate was adjusted by the amount of gelatin surrounding the SNT, with an increased barrier leading to a reduction in the release rate. A model developed on the basis of the Weibull modulus was established to fit the release results.

  18. Use of ordered mesoporous silica to enhance the oral bioavailability of ezetimibe in dogs.

    PubMed

    Kiekens, Filip; Eelen, Siemon; Verheyden, Loes; Daems, Tinne; Martens, Johan; Van Den Mooter, Guy

    2012-03-01

    The aim of this study was to investigate the bioavailability enhancement of the biopharmaceutics classification system class II compound ezetimibe loaded in ordered mesoporous silica (OMS) in dogs. The OMS was characterized as highly ordered mesoporous material with a narrow pore size distribution. Ezetimibe was loaded in OMS via incipient wetness impregnation to obtain a 20% (w/w) drug load, characterized by nitrogen adsorption and differential scanning calorimetry, and formulated in one capsule and two tablet formulations. Physicochemical characterization of loaded OMS indicated that ezetimibe molecules were molecularly deposited on the hydrophilic surface of the OMS. Two in vitro dissolution experiments were performed at 37°C in simulated gastric fluid with 0.1% sodium lauryl sulfate or Tween 80 to determine the drug release. All concepts were compared in vitro and in vivo with the commercially available tablet Ezetrol®. A dog study was designed to determine the oral bioavailability of ezetimibe capsules and tablets. The tablet preparations showed similar results to that of Ezetrol®. The capsule formulation demonstrated a faster absorption into the blood circulation, including a superior metabolization of ezetimibe into the active glucuronide conjugate. In vivo evaluation in dogs confirmed the improvement of ezetimibe absorption with the use of OMS as drug delivery technology. PMID:22190350

  19. Enzyme responsive drug delivery system based on mesoporous silica nanoparticles for tumor therapy in vivo

    NASA Astrophysics Data System (ADS)

    Liu, Yun; Ding, Xingwei; Li, Jinghua; Luo, Zhong; Hu, Yan; Liu, Junjie; Dai, Liangliang; Zhou, Jun; Hou, Changjun; Cai, Kaiyong

    2015-04-01

    To reduce the toxic side effects of traditional chemotherapeutics in vivo, we designed and constructed a biocompatible, matrix metalloproteinases (MMPs) responsive drug delivery system based on mesoporous silica nanoparticles (MSNs). MMPs substrate peptide containing PLGLAR (sensitive to MMPs) was immobilized onto the surfaces of amino-functionalized MSNs via an amidation reaction, serving as MMPs sensitive intermediate linker. Bovine serum albumin was then covalently coupled to linker as end-cap for sealing the mesopores of MSNs. Lactobionic acid was further conjugated to the system as targeting motif. Doxorubicin hydrochloride was used as the model anticancer drug in this study. A series of characterizations revealed that the system was successfully constructed. The peptide-functionalized MSNs system demonstrated relatively high sensitivity to MMPs for triggering drug delivery, which was potentially important for tumor therapy since the tumor’s microenvironment overexpressed MMPs in nature. The in vivo experiments proved that the system could efficiently inhibit the tumor growth with minimal side effects. This study provides an approach for the development of the next generation of nanotherapeutics toward efficient cancer treatment.

  20. Multifunctional polymer-capped mesoporous silica nanoparticles for pH-responsive targeted drug delivery.

    PubMed

    Niedermayer, Stefan; Weiss, Veronika; Herrmann, Annika; Schmidt, Alexandra; Datz, Stefan; Müller, Katharina; Wagner, Ernst; Bein, Thomas; Bräuchle, Christoph

    2015-05-01

    A highly stable modular platform, based on the sequential covalent attachment of different functionalities to the surface of core-shell mesoporous silica nanoparticles (MSNs) for targeted drug delivery is presented. A reversible pH-responsive cap system based on covalently attached poly(2-vinylpyridine) (PVP) was developed as drug release mechanism. Our platform offers (i) tuneable interactions and release kinetics with the cargo drug in the mesopores based on chemically orthogonal core-shell design, (ii) an extremely robust and reversible closure and release mechanism based on endosomal acidification of the covalently attached PVP polymer block, (iii) high colloidal stability due to a covalently coupled PEG shell, and (iv) the ability to covalently attach a wide variety of dyes, targeting ligands and other functionalities at the outer periphery of the PEG shell. The functionality of the system was demonstrated in several cell studies, showing pH-triggered release in the endosome, light-triggered endosomal escape with an on-board photosensitizer, and efficient folic acid-based cell targeting.

  1. Folic acid-functionalized mesoporous silica nanospheres hybridized with AIE luminogens for targeted cancer cell imaging

    NASA Astrophysics Data System (ADS)

    Wang, Zilong; Xu, Bin; Zhang, Lei; Zhang, Jibo; Ma, Tenghe; Zhang, Jiabao; Fu, Xueqi; Tian, Wenjing

    2013-02-01

    Fluorescent nanoparticles (FNPs) have been found to be useful as visualization tools for biological sensing, probing, imaging, and monitoring. Applied to targeted cancer cell imaging, FNPs are highly desirable for early stage cancer diagnosis and treatment. However, the light emission from most of the FNPs reported is severely limited because of the aggregation-caused quenching (ACQ) effect. Herein, we present highly emissive inorganic-organic nanoparticles with core-shell structures for targeted cancer cell imaging. Coated with a folate-functionalized silica shell, 9,10-distyrylanthracene (DSA) fluorogens with aggregation-induced emission (AIE) properties served as the fluorescent core, affording folate-functionalized fluorescent silica nanoparticles (FFSNPs) with a high fluorescence quantum yield (up to 20%). The FFSNPs are of small size (diameter ~60 nm), monodispersed, stable in aqueous suspension, and pose little toxicity to living cells and thus can be utilized for targeted HeLa cell imaging. In addition, the FFSNPs are mesoporous and therefore can potentially be used as vehicles for controlled, externally activated release of anticancer drugs.Fluorescent nanoparticles (FNPs) have been found to be useful as visualization tools for biological sensing, probing, imaging, and monitoring. Applied to targeted cancer cell imaging, FNPs are highly desirable for early stage cancer diagnosis and treatment. However, the light emission from most of the FNPs reported is severely limited because of the aggregation-caused quenching (ACQ) effect. Herein, we present highly emissive inorganic-organic nanoparticles with core-shell structures for targeted cancer cell imaging. Coated with a folate-functionalized silica shell, 9,10-distyrylanthracene (DSA) fluorogens with aggregation-induced emission (AIE) properties served as the fluorescent core, affording folate-functionalized fluorescent silica nanoparticles (FFSNPs) with a high fluorescence quantum yield (up to 20%). The

  2. Steam stable mesoporous silica MCM-41 stabilized by trace amounts of Al.

    PubMed

    Tompkins, Jordan T; Mokaya, Robert

    2014-02-12

    Evaluation of low and ultralow Al content (Si/Al between 50 and 412) aluminosilicate Al-MCM-41 materials synthesized via three contrasting alumination routes, namely, direct mixed-gel synthesis, post-synthesis wet grafting, and post-synthesis dry grafting, indicates that trace amounts of Al introduced via dry grafting can stabilize mesoporous silica MCM-41 to steaming at 900 °C for 4 h. It was found that trace amounts of Al (Si/Al > 400) introduced via so-called dry grafting of Al stabilize the virtually purely siliceous MCM-41 to steaming, whereas Al incorporated via other methods that involve aqueous media such as direct mixed gel synthesis or wet grafting of Al offer only limited protection at low Al content. It is particularly remarkable that a post-synthesis dry grafted Al-MCM-41 material possessing trace amounts of Al (i.e., Si/Al ratio of 412) and surface area and pore volume of 1112 m(2)/g and 1.20 cm(3)/g, respectively, retains 90% (998 m(2)/g) of the surface area and 85% (1.03 cm(3)/g) of the pore volume after exposure to steaming at 900 °C for 4 h. Under similar steam treatment conditions, the mesostructure of pure silica Si-MCM-41 is virtually destroyed and undergoes a 93% reduction in surface area (958 m(2)/g to 69 m(2)/g) and 88% decrease in pore volume (0.97 cm(3)/g to 0.12 cm(3)/g). The steam stable ultralow (i.e., trace) Al containing MCM-41 materials is found to be virtually similar to mesoporous pure silica Si-MCM-41 with hardly any detectable acidity. The improvement in steam stability arises from not only the presence of trace amounts of Al, but also from an apparent increase in the level of silica condensation that is specific to dry grafted alluminosilicate MCM-41 materials. The more highly condensed framework has fewer silanol groups and therefore is more resistant to hydrolysis under steaming conditions.

  3. Sugar and pH dual-responsive mesoporous silica nanocontainers based on competitive binding mechanisms

    NASA Astrophysics Data System (ADS)

    Yilmaz, M. Deniz; Xue, Min; Ambrogio, Michael W.; Buyukcakir, Onur; Wu, Yilei; Frasconi, Marco; Chen, Xinqi; Nassar, Majed S.; Stoddart, J. Fraser; Zink, Jeffrey I.

    2014-12-01

    A sugar and pH dual-responsive controlled release system, which is highly specific towards molecular stimuli, has been developed based on the binding between catechol and boronic acid on a platform of mesoporous silica nanoparticles (MSNs). By grafting phenylboronic acid stalks onto the silica surface, catechol-containing β-cyclodextrins can be attached to the orifices of the MSNs' nanopores through formation of boronate esters which block access to the nanopores. These esters are stable enough to prevent cargo molecules from escaping. The boronate esters disassociate in the presence of sugars, enabling the molecule-specific controlled-release feature of this hybrid system. The rate of release has been found to be tunable by varying both the structures and the concentrations of sugars, as a result of the competitive binding nature associated with the mechanism of its operation. Acidification also induces the release of cargo molecules. Further investigations show that the presence of both a low pH and sugar molecules provides cooperative effects which together control the rate of release.A sugar and pH dual-responsive controlled release system, which is highly specific towards molecular stimuli, has been developed based on the binding between catechol and boronic acid on a platform of mesoporous silica nanoparticles (MSNs). By grafting phenylboronic acid stalks onto the silica surface, catechol-containing β-cyclodextrins can be attached to the orifices of the MSNs' nanopores through formation of boronate esters which block access to the nanopores. These esters are stable enough to prevent cargo molecules from escaping. The boronate esters disassociate in the presence of sugars, enabling the molecule-specific controlled-release feature of this hybrid system. The rate of release has been found to be tunable by varying both the structures and the concentrations of sugars, as a result of the competitive binding nature associated with the mechanism of its operation

  4. Development of TRPN dendrimer-modified disordered mesoporous silica for CO{sub 2} capture

    SciTech Connect

    Zhang, Xiaoyun; Zhang, Sisi; Qin, Hongyan; Wu, Wei

    2014-08-15

    Highlights: • A novel series of TRPN dendrimers are synthesized. • Structurally disordered mesoporous silica was used to develop the CO{sub 2} adsorbent. • The CO{sub 2} adsorption capacity is relatively high. • The sorbent exhibits a high stability after 12 cycling runs. • The sorbent achieves complete desorption at low temperature (60 °C). - Abstract: A novel series of tri(3-aminopropyl) amine (TRPN) dendrimers were synthesized and impregnated on structurally disordered mesoporous silica (DMS) to generate CO{sub 2} adsorbents (TS). The physicochemical and adsorption properties of the adsorbents before and after dendrimer modification were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and N{sub 2} adsorption–desorption (N{sub 2}-BET) techniques. CO{sub 2} adsorption–desorption tests indicated that the sorbent demonstrates high CO{sub 2} adsorption capacity (138.1 mg g{sup −1} for G1 sample TS-G1-3CN-50 and 91.7 mg g{sup −1} for G2 sample TS-G2-6CN-50), and can completely desorb CO{sub 2} under vacuum at 60 °C. Its CO{sub 2} adsorption capacity at 25 °C increases with the amine loading, achieving the highest adsorption capacity (140.6 mg g{sup −1} for TS-G1-3CN) at 60%. The developed TS materials exhibited excellent cycling stability. After 12 consecutive adsorption–desorption runs, TS-G1-3CN-50 shows an adsorption capacity of 136.0 mg g{sup −1}, retaining 98.5% of its original value.

  5. Development and Testing of Diglycolamide Functionalized Mesoporous Silica for Sorption of Trivalent Actinides and Lanthanides.

    PubMed

    Shusterman, Jennifer A; Mason, Harris E; Bowers, Jon; Bruchet, Anthony; Uribe, Eva C; Kersting, Annie B; Nitsche, Heino

    2015-09-23

    Sequestration of trivalent actinides and lanthanides present in used nuclear fuel and legacy wastes is necessary for appropriate long-term stewardship of these metals, particularly to prevent their release into the environment. Organically modified mesoporous silica is an efficient material for recovery and potential subsequent separation of actinides and lanthanides because of its high surface area, tunable ligand selection, and chemically robust substrate. We have synthesized the first novel hybrid material composed of SBA-15 type mesoporous silica functionalized with diglycolamide ligands (DGA-SBA). Because of the high surface area substrate, the DGA-SBA was found to have the highest Eu capacity reported so far in the literature of all DGA solid-phase extractants. The sorption behavior of europium and americium on DGA-SBA in nitric and hydrochloric acid media was tested in batch contact experiments. DGA-SBA was found to have high sorption of Am and Eu in pH 1, 1 M, and 3 M nitric and hydrochloric acid concentrations, which makes it promising for sequestration of these metals from used nuclear fuel or legacy waste. The kinetics of Eu sorption were found to be two times slower than that for Am in 1 M HNO3. Additionally, the short-term susceptibility of DGA-SBA to degradation in the presence of acid was probed using (29)Si and (13)C solid-state NMR spectroscopy. The material was found to be relatively stable under these conditions, with the ligand remaining intact after 24 h of contact with 1 M HNO3, an important consideration in use of the DGA-SBA as an extractant from acidic media. PMID:26334933

  6. Enzyme responsive mesoporous silica nanoparticles for targeted tumor therapy in vitro and in vivo

    NASA Astrophysics Data System (ADS)

    Liu, Junjie; Zhang, Beilu; Luo, Zhong; Ding, Xingwei; Li, Jinghua; Dai, Liangliang; Zhou, Jun; Zhao, Xiaojing; Ye, Jingya; Cai, Kaiyong

    2015-02-01

    This study reports a biocompatible controlled drug release system based on mesoporous silica nanoparticles (MSNs) for tumor microenvironment responsive drug delivery. It was fabricated by grafting phenylboronic acid conjugated human serum albumin (PBA-HSA) onto the surfaces of MSNs as a sealing agent, via an intermediate linker of a functional polypeptide, which was composed of two functional units: the polycation cell penetrating peptide (CPP) polyarginine, and matrix metalloproteinase 2 (MMP-2) substrate peptide. A series of characterizations confirmed that the system had been successfully constructed. In vitro tests proved that the anticancer drug loading system could efficiently induce cell apoptosis in vitro. More importantly, the in vivo tumor experiments confirmed that the anticancer loading system could efficiently inhibit tumor growth with minimal side effects.This study reports a biocompatible controlled drug release system based on mesoporous silica nanoparticles (MSNs) for tumor microenvironment responsive drug delivery. It was fabricated by grafting phenylboronic acid conjugated human serum albumin (PBA-HSA) onto the surfaces of MSNs as a sealing agent, via an intermediate linker of a functional polypeptide, which was composed of two functional units: the polycation cell penetrating peptide (CPP) polyarginine, and matrix metalloproteinase 2 (MMP-2) substrate peptide. A series of characterizations confirmed that the system had been successfully constructed. In vitro tests proved that the anticancer drug loading system could efficiently induce cell apoptosis in vitro. More importantly, the in vivo tumor experiments confirmed that the anticancer loading system could efficiently inhibit tumor growth with minimal side effects. Electronic supplementary information (ESI) available: FTIR spectra, TGA curves, BET and BJH parameters, zeta potentials of nanoparticles; cleavage assay of the peptide detected by HPLC and MS; dose-dependent cytotoxicity of MSNs

  7. Development of efficient amine-modified mesoporous silica SBA-15 for CO{sub 2} capture

    SciTech Connect

    Zhang, Xiaoyun; Qin, Hongyan; Zheng, Xiuxin; Wu, Wei

    2013-10-15

    Graphical abstract: - Highlights: • A secondary amine AN-TEPA is used to modify the SBA-15. • CO{sub 2} adsorption capacity (180.1 mg g{sup −1}-adsorbent for 70% amine loading) is high. • The sorbent exhibits a high stability after 12 cycling runs. • The modified SBA-15 achieves complete desorption at low temperature (100 °C). - Abstract: A novel CO{sub 2} sorbent was prepared by impregnating mesoporous silica, SBA-15, with acrylonitrile (AN)-modified tetraethylenepentamine (TEPA) in order to increase CO{sub 2} adsorption capacity and improve cycling stability. The mesoporous silica with pre- and post-surface modification was investigated by X-ray diffraction characterization (XRD), N{sub 2} adsorption–desorption test (N{sub 2}-BET), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The adsorption/desorption performance of S-TN (TN: AN modified TEPA) and S-TEPA was studied by dynamic adsorption. Test results showed that the solid base-impregnated SBA-15 demonstrated high CO{sub 2} adsorption capacity (180.1 mg g{sup −1}-adsorbent for 70% amine loading level). Compared to S-TEPA (24.1% decrease of initial capacity), S-TN with 50% amine loading exhibited improved cycling stability, 99.9% activity reserved (from initial 153.0 mg g{sup −1} to 151.3 mg g{sup −1}) after 12 cycles of adsorption/desorption at 100 °C. A mechanism of molecular structure of the loaded amine was attributed to the improved performance.

  8. A mesoporous silica nanoparticle with charge-convertible pore walls for efficient intracellular protein delivery

    NASA Astrophysics Data System (ADS)

    Park, Hee Sung; Kim, Chan Woo; Lee, Hong Jae; Hye Choi, Ji; Lee, Se Geun; Yun, Young-Pil; Kwon, Ick Chan; Lee, Seung Jin; Jeong, Seo Young; Lee, Sang Cheon

    2010-06-01

    We report a smart mesoporous silica nanoparticle (MSN) with a pore surface designed to undergo charge conversion in intracellular endosomal condition. The surface of mesopores in the silica nanoparticles was engineered to have pH-hydrolyzable citraconic amide. Solid-state nuclear magnetic resonance (NMR), Fourier-transform infrared (FT-IR) spectroscopy, and Brunauer-Emmett-Teller (BET) analyses confirmed the successful modification of the pore surfaces. MSNs (MSN-Cit) with citraconic amide functionality on the pore surfaces exhibited a negative zeta potential (-10 mV) at pH 7.4 because of the presence of carboxylate end groups. At cellular endosomal pH (~5.0), MSN-Cit have a positive zeta potential (16 mV) indicating the dramatic charge conversion from negative to positive by hydrolysis of surface citraconic amide. Cytochrome c (Cyt c) of positive charges could be incorporated into the pores of MSN-Cit by electrostatic interactions. The release of Cyt c can be controlled by adjusting the pH of the release media. At pH 7.4, the Cyt c release was retarded, whereas, at pH 5.0, MSN-Cit facilitated the release of Cyt c. The released Cyt c maintained the enzymatic activity of native Cyt c. Hemolytic activity of MSN-Cit over red blood cells (RBCs) was more pronounced at pH 5.0 than at pH 7.0, indicating the capability of intracellular endosomal escape of MSN carriers. Confocal laser scanning microscopy (CLSM) studies showed that MSN-Cit effectively released Cyt c in endosomal compartments after uptake by cancer cells. The MSN developed in this work may serve as efficient intracellular carriers of many cell-impermeable therapeutic proteins.

  9. Targeting Innate Immunity with dsRNA-Conjugated Mesoporous Silica Nanoparticles Promotes Antitumor Effects on Breast Cancer Cells.

    PubMed

    Ultimo, Amelia; Giménez, Cristina; Bartovsky, Pavel; Aznar, Elena; Sancenón, Félix; Marcos, M Dolores; Amorós, Pedro; Bernardo, Ana R; Martínez-Máñez, Ramón; Jiménez-Lara, Ana M; Murguía, José R

    2016-01-26

    We describe herein a Toll-like receptor 3 (TLR3) targeting delivery system based on mesoporous silica nanoparticles capped with the synthetic double stranded RNA polyinosinic-polycytidylic acid (poly(I:C)) for controlled cargo delivery in SK-BR-3 breast carcinoma cells. Our results show that poly(I:C)-conjugated nanoparticles efficiently targeted breast cancer cells due to dsRNA-TLR3 interaction. Such interaction also triggered apoptotic pathways in SK-BR-3, significantly decreasing cells viability. Poly(I:C) cytotoxic effect in breast carcinoma cells was enhanced by loading nanoparticles' mesopores with the anthracyclinic antibiotic doxorubicin, a commonly used chemotherapeutic agent. PMID:26641630

  10. Coating with mesoporous silica remarkably enhances the stability of the highly active yet fragile flower-like MgO catalyst for dimethyl carbonate synthesis.

    PubMed

    Cui, Zhi-Min; Chen, Zhe; Cao, Chang-Yan; Song, Wei-Guo; Jiang, Lei

    2013-07-11

    Flower-like MgO is a highly effective catalyst for the synthesis of dimethyl carbonate through the transesterification method, and coating the catalyst with mesoporous silica significantly enhances the stability of the MgO catalyst.

  11. In vivo delivery of bovine viral diahorrea virus, E2 protein using hollow mesoporous silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Mahony, D.; Cavallaro, A. S.; Mody, K. T.; Xiong, L.; Mahony, T. J.; Qiao, S. Z.; Mitter, N.

    2014-05-01

    Our work focuses on the application of mesoporous silica nanoparticles as a combined delivery vehicle and adjuvant for vaccine applications. Here we present results using the viral protein, E2, from bovine viral diarrhoea virus (BVDV). BVDV infection occurs in the target species of cattle and sheep herds worldwide and is therefore of economic importance. E2 is a major immunogenic determinant of BVDV and is an ideal candidate for the development of a subunit based nanovaccine using mesoporous silica nanoparticles. Hollow type mesoporous silica nanoparticles with surface amino functionalisation (termed HMSA) were characterised and assessed for adsorption and desorption of E2. A codon-optimised version of the E2 protein (termed Opti-E2) was produced in Escherichia coli. HMSA (120 nm) had an adsorption capacity of 80 μg Opti-E2 per mg HMSA and once bound E2 did not dissociate from the HMSA. Immunisation studies in mice with a 20 μg dose of E2 adsorbed to 250 μg HMSA was compared to immunisation with Opti-E2 (50 μg) together with the traditional adjuvant Quillaja saponaria Molina tree saponins (QuilA, 10 μg). The humoral responses with the Opti-E2/HMSA nanovaccine although slightly lower than those obtained for the Opti-E2 + QuilA group demonstrated that HMSA particles are an effective adjuvant that stimulated E2-specific antibody responses. Importantly the cell-mediated immune responses were consistently high in all mice immunised with Opti-E2/HMSA nanovaccine formulation. Therefore we have shown the Opti-E2/HMSA nanoformulation acts as an excellent adjuvant that gives both T-helper 1 and T-helper 2 mediated responses in a small animal model. This study has provided proof-of-concept towards the development of an E2 subunit nanoparticle based vaccine.Our work focuses on the application of mesoporous silica nanoparticles as a combined delivery vehicle and adjuvant for vaccine applications. Here we present results using the viral protein, E2, from bovine viral

  12. Effect of core-shell structure and chitosan addition on catalytic activities of copper-containing silica-aluminosilicate composites in deNO(x) reaction by H2.

    PubMed

    Chamnankid, Busaya; Samanpratan, Rattanaporn; Kongkachuichay, Paisan

    2012-12-01

    Mesoporous silica-aluminosilicate composites were used as supports for selective catalytic reduction of NO by H2 using copper catalyst. Effect of loading techniques and structures of the supports on the catalytic performance were investigated. The nature, the oxidation state of copper, the structural properties and the morphology of the catalysts were characterized by means of UV-vis spectra, Fourier Transform Infrared Spectroscopy (FTIR), nitrogen sorption, and transmission electron microscopy, respectively. By using substitution technique, the copper(II) species were introduced into the silica-aluminosilicate framework by replacing aluminum atoms that located in the tetrahedral coordination. On the other hand, by using incipient wetness impregnation method, the copper species were deposited on the surface of composite materials. Upon testing their performances in deNO(x) reaction, the catalysts prepared by incipient wetness impregnation method showed higher catalytic activity than those prepared by substitution technique in any copper content. The core-shell structure was able to enhance the catalytic performance. It was found that, among the tested catalysts, the 1.5% Cu loaded core-shell mesoporous silica aluminosilicate composites prepared by an incipient wetness impregnation yielded the highest NO conversion of approximately 59%. However, the addition of chitosan creating macroporosity and controlling the uniform small clusters did not improve the catalytic performance. PMID:23447996

  13. Activators generated by electron transfer for atom transfer radical polymerization of styrene in the presence of mesoporous silica nanoparticles

    SciTech Connect

    Khezri, Khezrollah; Roghani-Mamaqani, Hossein

    2014-11-15

    Graphical abstract: Effect of mesoporous silica nanoparticles (MCM-41) on the activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP) is investigated. Decrement of conversion and number average molecular weight and also increment of polydispersity index (PDI) values are three main results of addition of MCM-41 nanoparticles. Incorporation of MCM-41 nanoparticles in the polystyrene matrix can clearly increase thermal stability and decrease glass transition temperature of the nanocomposites. - Highlights: • Spherical morphology, hexagonal structure, and high surface area with regular pore diameters of the synthesized MCM-41 nanoparticles are examined. • AGET ATRP of styrene in the presence of MCM-41 nanoparticles is performed. • Effect of MCM-41 nanoparticles addition on the polymerization rate, conversion and molecular weights of the products are discussed. • Improvement in thermal stability of the nanocomposites and decreasing T{sub g} values was also observed by incorporation of MCM-41 nanoparticles. - Abstract: Activator generated by electron transfer for atom transfer radical polymerization was employed to synthesize well-defined mesoporous silica nanoparticles/polystyrene composites. Inherent features of spherical mesoporous silica nanoparticles were evaluated by nitrogen adsorption/desorption isotherm, X-ray diffraction and scanning electron microscopy analysis techniques. Conversion and molecular weight evaluations were carried out using gas and size exclusion chromatography respectively. By the addition of only 3 wt% mesoporous silica nanoparticles, conversion decreases from 81 to 58%. Similarly, number average molecular weight decreases from 17,116 to 12,798 g mol{sup −1}. However, polydispersity index (PDI) values increases from 1.24 to 1.58. A peak around 4.1–4.2 ppm at proton nuclear magnetic resonance spectroscopy results clearly confirms the living nature of the polymerization. Thermogravimetric

  14. Graphene-supported ultrafine metal nanoparticles encapsulated by mesoporous silica: robust catalysts for oxidation and reduction reactions.

    PubMed

    Shang, Lu; Bian, Tong; Zhang, Baihui; Zhang, Donghui; Wu, Li-Zhu; Tung, Chen-Ho; Yin, Yadong; Zhang, Tierui

    2014-01-01

    Graphene nanosheet-supported ultrafine metal nanoparticles encapsulated by thin mesoporous SiO2 layers were prepared and used as robust catalysts with high catalytic activity and excellent high-temperature stability. The catalysts can be recycled and reused in many gas- and solution-phase reactions, and their high catalytic activity can be fully recovered by high-temperature regeneration, should they be deactivated by feedstock poisoning. In addition to the large surface area provided by the graphene support, the enhanced catalytic performance is also attributed to the mesoporous SiO2 layers, which not only stabilize the ultrafine metal nanoparticles, but also prevent the aggregation of the graphene nanosheets. The synthetic strategy can be extended to other metals, such as Pd and Ru, for preparing robust catalysts for various reactions.

  15. In Vivo Integrity and Biological Fate of Chelator-Free Zirconium-89-Labeled Mesoporous Silica Nanoparticles

    PubMed Central

    2015-01-01

    Traditional chelator-based radio-labeled nanoparticles and positron emission tomography (PET) imaging are playing vital roles in the field of nano-oncology. However, their long-term in vivo integrity and potential mismatch of the biodistribution patterns between nanoparticles and radio-isotopes are two major concerns for this approach. Here, we present a chelator-free zirconium-89 (89Zr, t1/2 = 78.4 h) labeling of mesoporous silica nanoparticle (MSN) with significantly enhanced in vivo long-term (>20 days) stability. Successful radio-labeling and in vivo stability are demonstrated to be highly dependent on both the concentration and location of deprotonated silanol groups (−Si–O–) from two types of silica nanoparticles investigated. This work reports 89Zr-labeled MSN with a detailed labeling mechanism investigation and long-term stability study. With its attractive radio-stability and the simplicity of chelator-free radio-labeling, 89Zr-MSN offers a novel, simple, and accurate way for studying the in vivo long-term fate and PET image-guided drug delivery of MSN in the near future. PMID:26213260

  16. Investigation of Hexagonal Mesoporous Silica-Supported Composites for Trace Moisture Adsorption

    NASA Astrophysics Data System (ADS)

    Li, Li; Tang, Nian; Wang, Yaxue; Cen, Wanglai; Liu, Jie; Zhou, Yongyan

    2015-11-01

    Moisture control is an important part of effective maintenance program for gas-insulated switchgear (GIS). Herein, hexagonal mesoporous silica (HMS) materials were synthesized by adopting dodecylamine as a structure directing agent, which was then employed as a host for supporting polyethylenimine (PEI) without further calcinations or extraction treatment. The physicochemical properties of the silica support and composites were characterized, and the moisture adsorption capacity of these composites was determined. The reserved template agents resulted in a dramatic improvement in moisture adsorption amount. Among them, 50PEI/DHMS showed the highest adsorption value. The enhanced adsorption could be attributed to the generated hydrogen bonding between amino groups and H2O molecules and the improved diffusion of moisture into the bulk networks of PEI polymers due to its better spatial dispersion imposed by the long alkyl chains of template agents, which was confirmed by thermogravimetry results and hydrogen efficiency analysis. Moreover, the maintained terminal amino groups of templates could also function as active sites for moisture adsorption. The results herein imply that the PEI/DHMS composites could be appealing materials for capturing moisture in GIS.

  17. Surface charge-mediated rapid hepatobiliary excretion of mesoporous silica nanoparticles.

    PubMed

    Souris, Jeffrey S; Lee, Chia-Hung; Cheng, Shih-Hsun; Chen, Chin-Tu; Yang, Chung-Shi; Ho, Ja-an A; Mou, Chung-Yuan; Lo, Leu-Wei

    2010-07-01

    Nanoparticle-assisted drug delivery has been emerging as an active research area in recent years. The in vivo biodistribution of nanoparticle and its following mechanisms of biodegradation and/or excretion determine the feasibility and applicability of such a nano-delivery platform in the practical clinical translation. In this work we report the synthesis of the highly positive charge, near-infrared fluorescent mesoporous silica nanoparticles (MSNs) that demonstrate rapid hepatobiliary excretion, for use as traceable drug delivery platforms of high capacity. MSNs were incorporated with near-infrared fluorescent dye indocyanine green (ICG) via covalent or ionic bonding, to derive comparable constructs of significantly different net surface charge. In vivo fluorescence imaging and subsequent inductively coupled plasma-mass spectroscopy of harvested tissues, urine, and feces revealed markedly different uptake and elimination behaviors between the two conjugations; with more highly charged moieties (+34.4 mV at pH 7.4) being quickly excreted from the liver into the gastrointestinal tract, while less charged moieties (-17.6 mV at pH 7.4) remained sequestered within the liver. Taken together, these findings suggest that charge-dependent adsorption of serum proteins greatly facilitates the hepatobiliary excretion of silica nanoparticles, and that nanoparticle residence time in vivo can be regulated by manipulation of surface charge.

  18. Physical properties of ordered mesoporous SBA-15 silica as immunological adjuvant

    NASA Astrophysics Data System (ADS)

    Mariano-Neto, F.; Matos, J. R.; Cides da Silva, L. C.; Carvalho, L. V.; Scaramuzzi, K.; Sant'Anna, O. A.; Oliveira, C. P.; Fantini, M. C. A.

    2014-10-01

    This work reports a detailed analysis of the ordered mesoporous SBA-15 silica synthesis procedure that provides a matrix with mean pore diameter around 10 nm. The encapsulation of bovine serum albumin (BSA) by four different methods allowed the determination of the best imbibition condition, which is keeping the mixture under rest and solvent evaporation. Simulation of the in situ SAXS scattered intensity of the BSA release in potassium buffer solution, gastrointestinal fluids revealed a slow evolution of BSA content, independent of the media. Proton induced x-ray emission results obtained in calcined mouse organs revealed that silica is only present in the spleen after 35 days and is completely eliminated from all mouse organs after 10 weeks. Biological studies showed that Santa Barbara Amorphous-15 is an effective adjuvant when compared to the traditional Al(OH)3, and is non-toxic to mice, rats, dogs and even cells, such as macrophages and dendritic cells. Recent studies showed that the immunological response is improved by enhancing the inflammatory response and the recruitment of immune competent cells to the site of injection as by the oral route and, most importantly, by increasing the number of phagocytes of a particulate antigen by antigen presenting cells. This research is under the scope of the International Patent WO 07030901, IN248654,ZA2008/02277, KR 1089400, MX297263, JP5091863, CN101287491B.

  19. Multifunctional mesoporous silica nanoparticles mediated co-delivery of paclitaxel and tetrandrine for overcoming multidrug resistance.

    PubMed

    Jia, Lejiao; Li, Zhenyu; Shen, Jingyi; Zheng, Dandan; Tian, Xiaona; Guo, Hejian; Chang, Ping

    2015-07-15

    The objective of the study is to fabricate multifunctional mesoporous silica nanoparticles for achieving co-delivery of conventional antitumor drug paclitaxel (PTX) and the multidrug resistance reversal agent tetrandrine (TET) expecting to overcome multidrug resistance of MCF-7/ADR cells. The nanoparticles were facile to prepare by self-assemble in situ drug loading approach. Namely, PTX and TET were solubilized in the cetyltrimethylammonium bromide (CTAB) micelles and simultaneously silica resources hydrolyze and condense to form nanoparticles. The obtained nanoparticles, denoted as PTX/TET-CTAB@MSN, exhibited pH-responsive release property with more easily released in the weak acidic environment. Studies on cellular uptake of nanoparticles demonstrated TET could markedly increase intracellular accumulation of nanoparticles. Furthermore, the PTX/TET-CTAB@MSN suppressed tumor cells growth more efficiently than only delivery of PTX (PTX-CTAB@MSN) or the free PTX. Moreover, the nanoparticle loading drugs with a PTX/TET molar ratio of 4.4:1 completely reversed the resistance of MCF-7/ADR cells to PTX and the resistance reversion index was 72.3. Mechanism research showed that both TET and CTAB could arrest MCF-7/ADR cells at G1 phase; and besides PTX arrested cells at G2 phase. This nanocarrier might have important potential in clinical implications for co-delivery of multiple drugs to overcome MDR. PMID:25956050

  20. Synthesis of multi-functional large pore mesoporous silica nanoparticles as gene carriers

    NASA Astrophysics Data System (ADS)

    Hartono, Sandy B.; Yu, Meihua; Gu, Wenyi; Yang, Jie; Strounina, Ekaterina; Wang, Xiaolin; Qiao, Shizhang; Yu, Chengzhong

    2014-02-01

    The development of functional nanocarriers that can enhance the cellular delivery of a variety of nucleic acid agents is important in many biomedical applications such as siRNA therapy. We report the synthesis of large pore mesoporous silica nanoparticles (LPMSN) loaded with iron oxide and covalently modified by polyethyleneimine (denoted PEI-Fe-LPMSN) as carriers for gene delivery. The LPMSN have a particle size of ˜200 nm and a large pore size of 11 nm. The large pore size is essential for the formation of large iron oxide nanoparticles to increase the magnetic properties and the adsorption capacity of siRNA molecules. The magnetic property facilitates the cellular uptake of nanocarriers under an external magnetic field. PEI is covalently grafted on the silica surface to enhance the nanocarriers’ affinity against siRNA molecules and to improve gene silencing performance. The PEI-Fe-LPMSN delivered siRNA-PLK1 effectively into osteosarcoma cancer cells, leading to cell viability inhibition of 80%, higher compared to the 50% reduction when the same dose of siRNA was delivered by a commercial product, oligofectamine.

  1. Enzymatic conversion of CO2 to bicarbonate in functionalized mesoporous silica

    PubMed Central

    Yu, Yuehua; Chen, Baowei; Qi, Wen; Li, Xiaolin; Shin, Yongsoon; Lei, Chenghong; Liu, Jun

    2011-01-01

    We report here a concept converting carbon dioxide to biocarbonate in a biomimetic nanoconfiguration. Carbonic anhydrase (CA), the fastest enzyme that can covert carbon dioxide to bicarbonate, can be spontaneously entrapped in carboxylic acid group-functionalized mesoporous silica (HOOC-FMS) with super-high loading density (up to 0.5 mg of protein/mg of FMS) in sharp contrast to normal porous silica. The binding of CA to HOOC-FMS resulted in a partial conformational change comparing to the enzyme free in solution, but it can be overcome with increased protein loading density. The higher the protein loading density, the less conformational change, hence the higher enzymatic activity and the higher enzyme immobilization efficiency (up to >60%). The released enzyme still displayed the native conformational structure and the same high enzymatic activity as that prior to the enzyme entrapment, indicating that the conformational change resulted from the electrostatic interaction of CA with HOOC-FMS was not permanent. This work may provide a new approach converting carbon dioxide to biocarbonate that can be integrated with the other part of biosynthesis process for the assimilation of carbon dioxide. PMID:22287934

  2. Multifunctional mesoporous silica nanoparticles mediated co-delivery of paclitaxel and tetrandrine for overcoming multidrug resistance.

    PubMed

    Jia, Lejiao; Li, Zhenyu; Shen, Jingyi; Zheng, Dandan; Tian, Xiaona; Guo, Hejian; Chang, Ping

    2015-07-15

    The objective of the study is to fabricate multifunctional mesoporous silica nanoparticles for achieving co-delivery of conventional antitumor drug paclitaxel (PTX) and the multidrug resistance reversal agent tetrandrine (TET) expecting to overcome multidrug resistance of MCF-7/ADR cells. The nanoparticles were facile to prepare by self-assemble in situ drug loading approach. Namely, PTX and TET were solubilized in the cetyltrimethylammonium bromide (CTAB) micelles and simultaneously silica resources hydrolyze and condense to form nanoparticles. The obtained nanoparticles, denoted as PTX/TET-CTAB@MSN, exhibited pH-responsive release property with more easily released in the weak acidic environment. Studies on cellular uptake of nanoparticles demonstrated TET could markedly increase intracellular accumulation of nanoparticles. Furthermore, the PTX/TET-CTAB@MSN suppressed tumor cells growth more efficiently than only delivery of PTX (PTX-CTAB@MSN) or the free PTX. Moreover, the nanoparticle loading drugs with a PTX/TET molar ratio of 4.4:1 completely reversed the resistance of MCF-7/ADR cells to PTX and the resistance reversion index was 72.3. Mechanism research showed that both TET and CTAB could arrest MCF-7/ADR cells at G1 phase; and besides PTX arrested cells at G2 phase. This nanocarrier might have important potential in clinical implications for co-delivery of multiple drugs to overcome MDR.

  3. In Vivo Integrity and Biological Fate of Chelator-Free Zirconium-89-Labeled Mesoporous Silica Nanoparticles.

    PubMed

    Chen, Feng; Goel, Shreya; Valdovinos, Hector F; Luo, Haiming; Hernandez, Reinier; Barnhart, Todd E; Cai, Weibo

    2015-08-25

    Traditional chelator-based radio-labeled nanoparticles and positron emission tomography (PET) imaging are playing vital roles in the field of nano-oncology. However, their long-term in vivo integrity and potential mismatch of the biodistribution patterns between nanoparticles and radio-isotopes are two major concerns for this approach. Here, we present a chelator-free zirconium-89 ((89)Zr, t1/2 = 78.4 h) labeling of mesoporous silica nanoparticle (MSN) with significantly enhanced in vivo long-term (>20 days) stability. Successful radio-labeling and in vivo stability are demonstrated to be highly dependent on both the concentration and location of deprotonated silanol groups (-Si-O(-)) from two types of silica nanoparticles investigated. This work reports (89)Zr-labeled MSN with a detailed labeling mechanism investigation and long-term stability study. With its attractive radio-stability and the simplicity of chelator-free radio-labeling, (89)Zr-MSN offers a novel, simple, and accurate way for studying the in vivo long-term fate and PET image-guided drug delivery of MSN in the near future.

  4. Immune response to functionalized mesoporous silica nanoparticles for targeted drug delivery

    NASA Astrophysics Data System (ADS)

    Heidegger, Simon; Gößl, Dorothée; Schmidt, Alexandra; Niedermayer, Stefan; Argyo, Christian; Endres, Stefan; Bein, Thomas; Bourquin, Carole

    2015-12-01

    Multifunctional mesoporous silica nanoparticles (MSN) have attracted substantial attention with regard to their high potential for targeted drug delivery. For future clinical applications it is crucial to address safety concerns and understand the potential immunotoxicity of these nanoparticles. In this study, we assess the biocompatibility and functionality of multifunctional MSN in freshly isolated, primary murine immune cells. We show that the functionalized silica nanoparticles are rapidly and efficiently taken up into the endosomal compartment by specialized antigen-presenting cells such as dendritic cells. The silica nanoparticles showed a favorable toxicity profile and did not affect the viability of primary immune cells from the spleen in relevant concentrations. Cargo-free MSN induced only very low immune responses in primary cells as determined by surface expression of activation markers and release of pro-inflammatory cytokines such as Interleukin-6, -12 and -1β. In contrast, when surface-functionalized MSN with a pH-responsive polymer capping were loaded with an immune-activating drug, the synthetic Toll-like receptor 7 agonist R848, a strong immune response was provoked. We thus demonstrate that MSN represent an efficient drug delivery vehicle to primary immune cells that is both non-toxic and non-inflammagenic, which is a prerequisite for the use of these particles in biomedical applications.Multifunctional mesoporous silica nanoparticles (MSN) have attracted substantial attention with regard to their high potential for targeted drug delivery. For future clinical applications it is crucial to address safety concerns and understand the potential immunotoxicity of these nanoparticles. In this study, we assess the biocompatibility and functionality of multifunctional MSN in freshly isolated, primary murine immune cells. We show that the functionalized silica nanoparticles are rapidly and efficiently taken up into the endosomal compartment by specialized

  5. An Interface Coassembly in Biliquid Phase: Toward Core-Shell Magnetic Mesoporous Silica Microspheres with Tunable Pore Size.

    PubMed

    Yue, Qin; Li, Jialuo; Luo, Wei; Zhang, Yu; Elzatahry, Ahmed A; Wang, Xiqing; Wang, Chun; Li, Wei; Cheng, Xiaowei; Alghamdi, Abdulaziz; Abdullah, Aboubakr M; Deng, Yonghui; Zhao, Dongyuan

    2015-10-21

    Core-shell magnetic mesoporous silica microspheres (Magn-MSMs) with tunable large mesopores in the shell are highly desired in biocatalysis, magnetic bioseparation, and enrichment. In this study, a shearing assisted interface coassembly in n-hexane/water biliquid systems is developed to synthesize uniform Magn-MSMs with magnetic core and mesoporous silica shell for an efficient size-selective biocatalysis. The synthesis features the rational control over the electrostatic interaction among cationic surfactant molecules, silicate oligomers, and Fe3O4@RF microspheres (RF: resorcinol formaldehyde) in the presence of shearing-regulated solubilization of n-hexane in surfactant micelles. Through this multicomponent interface coassembly, surfactant-silica mesostructured composite has been uniformly deposited on the Fe3O4@RF microspheres, and core-shell Magn-MSMs are obtained after removing the surfactant and n-hexane. The obtained Magn-MSMs possess excellent water dispersibility, uniform diameter (600 nm), large and tunable perpendicular mesopores (5.0-9.0 nm), high surface area (498-623 m(2)/g), large pore volume (0.91-0.98 cm(3)/g), and high magnetization (34.5-37.1 emu/g). By utilization of their large and open mesopores, Magn-MSMs with a pore size of about 9.0 nm have been demonstrated to be able to immobilize a large bioenzyme (trypsin with size of 4.0 nm) with a high loading capacity of ∼97 μg/mg via chemically binding. Magn-MSMs with immobilized trypsin exhibit an excellent convenient and size selective enzymolysis of low molecular proteins in the mixture of proteins of different sizes and a good recycling performance by using the magnetic separability of the microspheres.

  6. An Interface Coassembly in Biliquid Phase: Toward Core-Shell Magnetic Mesoporous Silica Microspheres with Tunable Pore Size.

    PubMed

    Yue, Qin; Li, Jialuo; Luo, Wei; Zhang, Yu; Elzatahry, Ahmed A; Wang, Xiqing; Wang, Chun; Li, Wei; Cheng, Xiaowei; Alghamdi, Abdulaziz; Abdullah, Aboubakr M; Deng, Yonghui; Zhao, Dongyuan

    2015-10-21

    Core-shell magnetic mesoporous silica microspheres (Magn-MSMs) with tunable large mesopores in the shell are highly desired in biocatalysis, magnetic bioseparation, and enrichment. In this study, a shearing assisted interface coassembly in n-hexane/water biliquid systems is developed to synthesize uniform Magn-MSMs with magnetic core and mesoporous silica shell for an efficient size-selective biocatalysis. The synthesis features the rational control over the electrostatic interaction among cationic surfactant molecules, silicate oligomers, and Fe3O4@RF microspheres (RF: resorcinol formaldehyde) in the presence of shearing-regulated solubilization of n-hexane in surfactant micelles. Through this multicomponent interface coassembly, surfactant-silica mesostructured composite has been uniformly deposited on the Fe3O4@RF microspheres, and core-shell Magn-MSMs are obtained after removing the surfactant and n-hexane. The obtained Magn-MSMs possess excellent water dispersibility, uniform diameter (600 nm), large and tunable perpendicular mesopores (5.0-9.0 nm), high surface area (498-623 m(2)/g), large pore volume (0.91-0.98 cm(3)/g), and high magnetization (34.5-37.1 emu/g). By utilization of their large and open mesopores, Magn-MSMs with a pore size of about 9.0 nm have been demonstrated to be able to immobilize a large bioenzyme (trypsin with size of 4.0 nm) with a high loading capacity of ∼97 μg/mg via chemically binding. Magn-MSMs with immobilized trypsin exhibit an excellent convenient and size selective enzymolysis of low molecular proteins in the mixture of proteins of different sizes and a good recycling performance by using the magnetic separability of the microspheres. PMID:26186087

  7. Cancer cell detection and therapeutics using peroxidase-active nanohybrid of gold nanoparticle-loaded mesoporous silica-coated graphene.

    PubMed

    Maji, Swarup Kumar; Mandal, Amal Kumar; Nguyen, Kim Truc; Borah, Parijat; Zhao, Yanli

    2015-05-13

    Development of efficient artificial enzymes is an emerging field in nanobiotechnology, since these artificial enzymes could overcome serious disadvantages of natural enzymes. In this work, a new nanostructured hybrid was developed as a mimetic enzyme for in vitro detection and therapeutic treatment of cancer cells. The hybrid (GSF@AuNPs) was prepared by the immobilization of gold nanoparticles (AuNPs) on mesoporous silica-coated nanosized reduced graphene oxide conjugated with folic acid, a cancer cell-targeting ligand. The GSF@AuNPs hybrid showed unprecedented peroxidase-like activity, monitored by catalytic oxidation of a typical peroxidase substrate, 3,3',5,5'-tetramethylbenzidine (TMB), in the presence of H2O2. On basis of this peroxidase activity, the hybrid was utilized as a selective, quantitative, and fast colorimetric detection probe for cancer cells. Finally, the hybrid as a mimetic enzyme was employed for H2O2- and ascorbic acid (AA)-mediated therapeutics of cancer cells. In vitro experiments using human cervical cancer cells (HeLa cells) exhibited the formation of reactive oxygen species (OH(•) radical) in the presence of peroxidase-mimic GSF@AuNPs with either exogenous H2O2 or endogenous H2O2 generated from AA, leading to an enhanced cytotoxicity to HeLa cells. In the case of normal cells (human embryonic kidney HEK 293 cells), the treatment with the hybrid and H2O2 or AA showed no obvious damage, proving selective killing effect of the hybrid to cancer cells.

  8. TiO{sub 2} supported on rod-like mesoporous silica SBA-15: Preparation, characterization and photocatalytic behaviour

    SciTech Connect

    Li, Yanjuan; Li, Nan; Tu, Jinchun; Li, Xiaotian; Wang, Beibei; Chi, Yue; Liu, Darui; Yang, Dianfan

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Rod-like SBA-15 and normal SBA-15 were used to prepare TiO{sub 2}/SBA-15 composites. Black-Right-Pointing-Pointer TiO{sub 2}/SBA-15 composites were studied as catalysts for methyl orange photodegradation. Black-Right-Pointing-Pointer TiO{sub 2}/Rod-SBA-15 exhibited higher photocatalytic activity than TiO{sub 2}/Nor-SBA-15. Black-Right-Pointing-Pointer The higher catalytic activity was a result of the controlled morphology of SBA-15. -- Abstract: TiO{sub 2} nanoparticles have been successfully incorporated in the pores of mesoporous silica SBA-15 with different morphologies by a wet impregnation method. The composites were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma (ICP) emission spectroscopy, transmission electron microscopy (TEM), N{sub 2}-sorption and UV-Vis diffuse reflectance spectroscopy. The photodegradation of methyl orange (MO) was used to study their photocatalytic property. It is indicated that the morphology of SBA-15 had a great influence on the photocatalytic activity of the composites. When TiO{sub 2}/SBA-15 composite was prepared by loading TiO{sub 2} nanoparticles on uniform rod-like SBA-15 of 1 {mu}m length, it showed higher photocatalytic degradation rate than that on less regular but much larger SBA-15 support. This difference was rationalized in terms of the homogeneously distributed and shorter channels of rod-like SBA-15, which favored mass transport and improved the efficient utilization of the pore surface.

  9. Sub-1-micron mesoporous silica particles functionalized with cyclodextrin derivative for rapid enantioseparations on ultra-high pressure liquid chromatography.

    PubMed

    Ai, Feng; Li, Laisheng; Ng, Siu-Choon; Tan, Timothy Thatt Yang

    2010-11-26

    Mesoporous silica particles of relatively uniform sub-1-micron size (0.6-0.9 μm) were successfully prepared by a modified synthesis strategy and applied in chiral separation in an ultra-high pressure liquid chromatography system. These particles were prepared via a ternary surfactant system (Pluronic P123, F127 and hexadecyltrimethyl-ammonium bromide) and subsequently derivatized with perphenylcarbamoylated-β-cyclodextrin moieties. The mesoporous silica particles, despite their submicron size, enabled low back-pressure operation on an ultra-high pressure liquid chromatography system at a maximum flow rate of 2 ml/min. In addition, the particles possessed high surface area (480 m(2)/g) and thus afforded high cyclodextrin derivative loading (32 μmol/g), demonstrating rapid enantioseparation and good resolution of 6 basic and neutral racemates.

  10. Highly monodisperse rattle-structured nanomaterials with gold nanorod core-mesoporous silica shell as drug delivery vehicles and nanoreactors

    NASA Astrophysics Data System (ADS)

    Choi, Eunjin; Kwak, Minjeong; Jang, Byungchul; Piao, Yuanzhe

    2012-12-01

    Rattle-structured nanomaterials composed of a gold nanorod in a mesoporous silica nanocapsule (AuNR@mSiO2) were prepared by a novel solution-based consecutive process. The drug-loading properties of the nanomaterial and regrowth control of the core nanoparticles were also studied.Rattle-structured nanomaterials composed of a gold nanorod in a mesoporous silica nanocapsule (AuNR@mSiO2) were prepared by a novel solution-based consecutive process. The drug-loading properties of the nanomaterial and regrowth control of the core nanoparticles were also studied. Electronic supplementary information (ESI) available: Experimental section and additional SEM and TEM images. See DOI: 10.1039/c2nr32885b

  11. Layer-by-layer engineering fluorescent polyelectrolyte coated mesoporous silica nanoparticles as pH-sensitive nanocarriers for controlled release

    NASA Astrophysics Data System (ADS)

    Du, Pengcheng; Zhao, Xubo; Zeng, Jin; Guo, Jinshan; Liu, Peng

    2015-08-01

    Fluorescent core/shell composite has been fabricated by the layer-by-layer (LbL) assembly of the fluorescein isothiocyanate modified chitosan (CS-FITC) and sodium alginate (AL) onto the carboxyl modified mesoporous silica nanoparticles (MSN-COOH), followed by PEGylation. It exhibits stability in high salt-concentration media and the pH responsive fluorescent feature can be used for cell imaging. Furthermore, the modified MSN cores can enhance the DOX loading capacity and the multifunctional polyelectrolyte shell can adjust the drug release upon the media pH, showing a low leakage quantity at the neutral environment but significantly enhanced release at lower pH media mimicking the tumor environments. Therefore, the biocompatible fluorescent polyelectrolyte coated mesoporous silica nanoparticles (MSN-LBL-PEG) offer promise for tumor therapy.

  12. Structural and dynamical properties of guest molecules confined in mesoporous silica materials revealed by NMR.

    PubMed

    Buntkowsky, Gerd; Breitzke, Hergen; Adamczyk, Anna; Roelofs, Frank; Emmler, Thomas; Gedat, Egbert; Grünberg, Bob; Xu, Yeping; Limbach, Hans-Heinrich; Shenderovich, Ilja; Vyalikh, Anastasia; Findenegg, Gerhard

    2007-09-21

    In the last fifteen years several novel porous silica materials, which are periodically structured on the mesoscopic length scale, have been synthesized. They are of broad interest for fundamental studies of surface-substrate interactions, for studies of the dynamics of guest molecules in confinement and for studies of the effect of confinement on the structural and thermophysical properties of fluids. Examples of such confinement effects include the change of the freezing and melting points or glass transitions of the confined liquids. These effects are studied by combinations of several NMR techniques, such as (15)N- and (2)H-solid-state NMR line shape analysis, MAS NMR and NMR diffusometry with physico-chemical characterization techniques such as nitrogen adsorption and small angle diffraction of neutrons or X-rays. This combination does not require crystalline samples or special clean and well defined surfaces such as conventional surface science techniques, but can work with typical ill-defined real world systems. The review discusses, after a short introduction, the salient features of these materials and the applied NMR experiments to give the reader a basic knowledge of the systems and the experiments. The rest of the review then focuses on the structural and dynamical properties of guest molecules confined in the mesoporous silica. It is shown that the confinement into the pores leads to fascinating new features of the guests, which are often not known for their bulk phases. These features depend strongly on the interplay of the their interactions with the silica surface and their mutual interactions. PMID:17912415

  13. Templated synthesis of monodisperse mesoporous maghemite/silica microspheres for magnetic separation of genomic DNA

    NASA Astrophysics Data System (ADS)

    Chen, Feng; Shi, Ruobing; Xue, Yun; Chen, Lei; Wan, Qian-Hong

    2010-08-01

    A novel method is described for the preparation of superparamagnetic mesoporous maghemite (γ-Fe 2O 3)/silica (SiO 2) composite microspheres to allow rapid magnetic separation of DNA from biological samples. With magnetite (Fe 3O 4) and silica nanoparticles as starting materials, such microspheres were synthesized by the following two consecutive steps: (1) formation of monodispersed organic/inorganic hybrid microspheres through urea-formaldedyde (UF) polymerization and (2) removal of the organic template and phase transformation of Fe 3O 4 to γ-Fe 2O 3 by calcination at elevated temperatures. The as-synthesized particles obtained by heating at temperature 300 °C feature spherical shape and uniform particle size ( dparticle=1.72 μm), high saturation magnetization ( Ms=17.22 emu/g), superparamagnetism ( Mr/ Ms=0.023), high surface area ( SBET=240 m 2/g), and mesoporosity ( dpore=6.62 nm). The composite microsphere consists of interlocked amorphous SiO 2 nanoparticles, in which cubic γ-Fe 2O 3 nanocrystals are homogeneously dispersed and thermally stable against γ- to α-phase transformation at temperatures up to 600 °C. With the exposed iron oxide nanoparticles coated with a thin layer of silica shell, the magnetic microspheres were used as a solid-phase adsorbent for rapid extraction of genomic DNA from plant samples. The results show that the DNA templates isolated from pea and green pepper displayed single bands with molecular weights greater than 8 kb and A260/ A280 values of 1.60-1.72. The PCR amplification of a fragment encoding the endogenous chloroplast ndhB gene confirmed that the DNA templates obtained were inhibitor-free and amenable to sensitive amplification-based DNA technologies.

  14. Synthesis and characterization of pharmaceutical surfactant templated mesoporous silica: Its application to controlled delivery of duloxetine

    SciTech Connect

    Mani, Ganesh; Pushparaj, Hemalatha; Peng, Mei Mei; Muthiahpillai, Palanichamy; Udhumansha, Ubaidulla; Jang, Hyun Tae

    2014-03-01

    Graphical abstract: - Highlights: • Usefulness of dual pharmaceutical surfactants in silica synthesis was evaluated. • Effects of concentration of secondary template (Tween-40) were studied. • Effects of fixed solvothermal condition on mesostructure formation were studied. • Duloxetine drug loading capability was studied. • Sustained release of duloxetine was evaluated. - Abstract: A new group of mesoporous silica nanoparticles (MSNs) were synthesized using combination pharmaceutical surfactants, Triton X-100 and Tween-40 as template and loaded with duloxetine hydrochloride (DX), for improving the sustained release of DX and patterns with high drug loading. Agglomerated spherical silica MSNs were synthesized by sol–gel and solvothermal methods. The calcined and drug loaded MSNs were characterized using X-ray diffraction (XRD), Braunner–Emmett–Teller (BET), thermogravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), diffuse reflectance ultraviolet–visible (DRS-UV–vis) spectroscopy. MSNs with high surface area and pore volume were selected and studied for their DX loading and release. The selected MSNs can accommodate a maximum of 34% DX within it. About 90% was released at 200 h and hence, the synthesized MSNs were capable of engulfing DX and sustain its release. Further form the Ritger and Peppas, Higuchi model for mechanism drug release from all the MSN matrices follows anomalous transport or Non-Fickian diffusion with the ‘r’ and ‘n’ value 0.9 and 0.45 < n < 1, respectively. So, from this study it could be concluded that the MSNs synthesized using pharmaceutical templates were better choice of reservoir for the controlled delivery of drug which requires sustained release.

  15. Hydrophobic polydimethylsiloxane (PDMS) coating of mesoporous silica and its use as a preconcentrating agent of gas analytes.

    PubMed

    Park, Eun Ji; Cho, Youn Kyoung; Kim, Dae Han; Jeong, Myung-Geun; Kim, Yong Ho; Kim, Young Dok

    2014-09-01

    Mesoporous silica with mean pore size of ∼14 nm was coated by polydimethylsiloxane (PDMS) using a thermal deposition method. We showed that the inner walls of pores larger than ∼8 nm can be coated by thin layers of PDMS, and the surfaces consisting of PDMS-coated silica were superhydrophobic, with water contact angles close to 170°. We used the PDMS-coated silica as adsorbents of various gas-phase chemical warfare agent (CWA) simulants. PDMS-coated silica allowed molecular desorption of various CWA simulants even after exposure under highly humid conditions and, therefore, is applicable as an agent for the preconcentration of gas-phase analytes to enhance the sensitivities of various sensors. PMID:25102134

  16. Mesoporous silica/ionic liquid quasi-solid-state electrolytes and their application in lithium metal batteries

    NASA Astrophysics Data System (ADS)

    Li, Xiaowei; Zhang, Zhengxi; Yin, Kun; Yang, Li; Tachibana, Kazuhiro; Hirano, Shin-ichi

    2015-03-01

    In this work, the ordered mesoporous silica, SBA-15, is chosen as the matrix for the first time to prepare quasi-solid-state electrolytes (QSSEs) with an ionic liquid, LiTFSI salt and PVdF-HFP. The as-obtained QSSEs are evaluated by electrochemical methods. Lithium metal batteries containing these QSSEs exhibit high discharge capacity and good cycle performance at room temperature, indicating successful battery operation.

  17. One-pot two-step synthesis of core-shell mesoporous silica-coated gold nanoparticles.

    PubMed

    Song, Ji-Tao; Zhang, Xiao-Shuai; Qin, Meng-Yao; Zhao, Yuan-Di

    2015-05-01

    Gold nanoparticles coated with mesoporous silica (Au@mSiO2) have been prepared by a facile one-pot two-step method. The resultant Au@mSiO2 exhibit an ideal core-shell structure with uniform mSiO2 coverage and without any interfacial adhesive layer on the Au surface. Some new explanations on the role that CTAB plays in the synthesis of Au@mSiO2 are discussed.

  18. Effects of Mesoporous Silica Coating and Post-Synthetic Treatment on the Transverse Relaxivity of Iron Oxide Nanoparticles

    PubMed Central

    Hurley, Katie R.; Lin, Yu-Shen; Zhang, Jinjin; Egger, Sam M.; Haynes, Christy L.

    2013-01-01

    Mesoporous silica nanoparticles have the capacity to load and deliver therapeutic cargo and incorporate imaging modalities, making them prominent candidates for theranostic devices. One of the most widespread imaging agents utilized in this and other theranostic platforms is nanoscale superparamagnetic iron oxide. Although several core-shell magnetic mesoporous silica nanoparticles presented in the literature have provided high T2 contrast in vitro and in vivo, there is ambiguity surrounding which parameters lead to enhanced contrast. Additionally, there is a need to understand the behavior of these imaging agents over time in biologically relevant environments. Herein, we present a systematic analysis of how the transverse relaxivity (r2) of magnetic mesoporous silica nanoparticles is influenced by nanoparticle diameter, iron oxide nanoparticle core synthesis, and the use of a hydrothermal treatment. This work demonstrates that samples which did not undergo a hydrothermal treatment experienced a drop in r2 (75% of original r2 within 8 days of water storage), while samples with hydrothermal treatment maintained roughly the same r2 for over 30 days in water. Our results suggest that iron oxide oxidation is the cause of the r2 loss, and this oxidation can be prevented both during synthesis and storage by the use of deoxygenated conditions during nanoparticle synthesis. The hydrothermal treatment also provides colloidal stability, even in acidic and highly salted solutions, and a resistance against acid degradation of the iron oxide nanoparticle core. The results of this study show the promise of multifunctional mesoporous silica nanoparticles but will also likely inspire further investigation into multiples types of theranostic devices, taking into consideration their behavior over time and in relevant biological environments. PMID:23814377

  19. Facile large-scale synthesis of brain-like mesoporous silica nanocomposites via a selective etching process.

    PubMed

    Chen, Yu; Wang, Qihua; Wang, Tingmei

    2015-10-21

    The core-shell structured mesoporous silica nanomaterials (MSNs) are experiencing rapid development in many applications such as heterogeneous catalysis, bio-imaging and drug delivery wherein a large pore volume is desirable. We develop a one-pot method for large-scale synthesis of brain-like mesoporous silica nanocomposites based on the reasonable change of the intrinsic nature of the -Si-O-Si- framework of silica nanoparticles together with a selective etching strategy. The as-synthesized products show good monodispersion and a large pore volume of 1.0 cm(3) g(-1). The novelty of this approach lies in the use of an inorganic-organic hybrid layer to assist the creation of large-pore morphology on the outermost shell thereby promoting efficient mass transfer or storage. Importantly, the method is reliable and grams of products can be easily prepared. The morphology on the outermost silica shell can be controlled by simply adjusting the VTES-to-TEOS molar ratio (VTES: triethoxyvinylsilane, TEOS: tetraethyl orthosilicate) as well as the etching time. The as-synthesized products exhibit fluorescence performance by incorporating rhodamine B isothiocyanate (RITC) covalently into the inner silica walls, which provide potential application in bioimaging. We also demonstrate the applications of as-synthesized large-pore structured nanocomposites in drug delivery systems and stimuli-responsive nanoreactors for heterogeneous catalysis. PMID:26394819

  20. Multifunctional Gold-Mesoporous Silica Nanocomposites for Enhanced Two-Photon Imaging and Therapy of Cancer Cells

    PubMed Central

    Croissant, Jonas G.; Qi, Christian; Maynadier, Marie; Cattoën, Xavier; Wong Chi Man, Michel; Raehm, Laurence; Mongin, Olivier; Blanchard-Desce, Mireille; Garcia, Marcel; Gary-Bobo, Magali; Durand, Jean-Olivier

    2016-01-01

    Three dimensional sub-micron resolution has made two-photon nanomedicine a very promising medical tool for cancer treatment since current techniques cause significant side effects for lack of spatial selectivity. Two-photon-excited (TPE) photodynamic therapy (PDT) has been achieved via mesoporous nanoscaffolds, but the efficiency of the treatment could still be improved. Herein, we demonstrate the enhancement of the treatment efficiency via gold-mesoporous organosilica nanocomposites for TPE-PDT in cancer cells when compared to mesoporous organosilica particles. We performed the first comparative study of the influence of the shape and spatial position of gold nanoparticles (AuNPs) with mesoporous silica nanoparticles (MSN) functionalized with thiol groups and doped with a two-photon electron donor (2PS). The resulting multifunctional nanocarriers displayed TPE-fluorescence and were imaged inside cells. Furthermore, mesoporous organosilica NPs decorated gold nanospheres (AuNSs) induced 63 percent of selective killing on MCF-7 breast cancer cells. This study thus provides insights for the design of more effective multifunctional two-photon-sensitive nanocomposites via AuNPs for biomedical applications. PMID:26870736

  1. Formation of a long-lived electron-transfer state in mesoporous silica-alumina composites enhances photocatalytic oxygenation reactivity

    PubMed Central

    Fukuzumi, Shunichi; Doi, Kaoru; Itoh, Akinori; Suenobu, Tomoyoshi; Ohkubo, Kei; Yamada, Yusuke; Karlin, Kenneth D.

    2012-01-01

    A simple donor-acceptor linked dyad, 9-mesityl-10-methylacridinium ion (Acr+-Mes) was incorporated into nanosized mesoporous silica-alumina to form a composite, which in acetonitrile is highly dispersed. In this medium, upon visible light irradiation, the formation of an extremely long-lived electron-transfer state (Acr•-Mes•+) was confirmed by EPR and laser flash photolysis spectroscopic methods. The composite of Acr+-Mes-incorporated mesoporous silica-alumina with an added copper complex [(tmpa)CuII] (tmpa = tris(2-pyridylmethyl)amine) acts as an efficient and robust photocatalyst for the selective oxygenation of p-xylene by molecular oxygen to produce p-tolualdehyde and hydrogen peroxide. Thus, incorporation of Acr+-Mes into nanosized mesoporous silica-alumina combined with an O2-reduction catalyst ([(tmpa)CuII]2+) provides a promising method in the development of efficient and robust organic photocatalysts for substrate oxygenation by dioxygen, the ultimate environmentally benign oxidant. PMID:22543164

  2. Core-shell microcapsules of solid lipid nanoparticles and mesoporous silica for enhanced oral delivery of curcumin.

    PubMed

    Kim, Sanghoon; Diab, Roudayna; Joubert, Olivier; Canilho, Nadia; Pasc, Andreea

    2016-04-01

    Newly designed microcapsules (MC) combining a core of solid lipid nanoparticle (SLN) and a mesoporous silica shell have been developed and explored as oral delivery system of curcumin (CU). CU-loaded MC (MC-CU) are 2 μm sized and have a mesoporous silica shell of 0.3 μm thickness with a wormlike structure as characterized by small angle X-ray scattering (SAXS), nitrogen adsorption/desorption and transmission electron microscopy (TEM) measurements. It was found that SLN acts as reservoir of curcumin while the mesoporous shell insures the protection and the controlled release of the drug. MC-CU displayed a pH-dependent in vitro release profile with marked drug retention at pH 2.8. Neutral red uptake assay together with confocal laser scanning microscopy (CLSM) showed a good cell tolerance to MC-CU at relatively high concentration of inert materials. Besides, the cell-uptake test revealed that fluorescent-MC were well internalized into Caco-2 cells, confirming the possibility to use MC for gut cells targeting. These findings suggest that organic core-silica shell microcapsules are promising drug delivery systems with enhanced bioavailability for poorly soluble drugs. PMID:26752213

  3. Mesoporous silica sub-micron spheres as drug dissolution enhancers: Influence of drug and matrix chemistry on functionality and stability.

    PubMed

    Brigo, Laura; Scomparin, Elisa; Galuppo, Marco; Capurso, Giovanni; Ferlin, Maria Grazia; Bello, Valentina; Realdon, Nicola; Brusatin, Giovanna; Morpurgo, Margherita

    2016-02-01

    Mesoporous silica particles prepared through a simplified Stöber method and low temperature solvent promoted surfactant removal are evaluated as dissolution enhancers for poorly soluble compounds, using a powerful anticancer agent belonging to pyrroloquinolinones as a model for anticancer oral therapy, and anti-inflammatory ibuprofen as a reference compound. Mesoporous powders composed of either pure silica or silica modified with aminopropyl residues are produced. The influence of material composition and drug chemical properties on drug loading capability and dissolution enhancement are studied. The two types of particles display similar size, surface area, porosity, erodibility, drug loading capability and stability. An up to 50% w/w drug loading is reached, showing correlation between drug concentration in adsorption medium and content in the final powder. Upon immersion in simulating body fluids, immediate drug dissolution occurred, allowing acceptor solutions to reach concentrations equal to or greater than drug saturation limits. The matrix composition influenced drug solution maximal concentration, complementing the dissolution enhancement generated by a mesoporous structure. This effect was found to depend on both matrix and drug chemical properties allowing us to hypothesise general prediction behaviour rules. PMID:26652411

  4. o-Vanillin functionalized mesoporous silica - coated magnetite nanoparticles for efficient removal of Pb(II) from water

    NASA Astrophysics Data System (ADS)

    Culita, Daniela C.; Simonescu, Claudia Maria; Patescu, Rodica-Elena; Dragne, Mioara; Stanica, Nicolae; Oprea, Ovidiu

    2016-06-01

    o-Vanillin functionalized mesoporous silica - coated magnetite (Fe3O4@MCM-41-N-oVan) was synthesized and fully characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N2 adsorption-desorption technique and magnetic measurements. The capacity of Fe3O4@MCM-41-N-oVan to adsorb Pb(II) from aqueous solutions was evaluated in comparison with raw mesoporous silica - coated magnetite (Fe3O4@MCM-41) and amino - modified mesoporous silica coated magnetite (Fe3O4@MCM-41-NH2). The effect of adsorption process parameters such us pH, contact time, initial Pb(II) concentration was also investigated. The adsorption data were successfully fitted with the Langmuir model, exhibiting a maximum adsorption capacity of 155.71 mg/g at pH=4.4 and T=298 K. The results revealed that the adsorption rate was very high at the beginning of the adsorption process, 80-90% of the total amount of Pb(II) being removed within the first 60 min, depending on the initial concentration. The results of the present work suggest that Fe3O4@MCM-41-N-oVan is a suitable candidate for the separation of Pb(II) from contaminated water.

  5. Mesoporous silica sub-micron spheres as drug dissolution enhancers: Influence of drug and matrix chemistry on functionality and stability.

    PubMed

    Brigo, Laura; Scomparin, Elisa; Galuppo, Marco; Capurso, Giovanni; Ferlin, Maria Grazia; Bello, Valentina; Realdon, Nicola; Brusatin, Giovanna; Morpurgo, Margherita

    2016-02-01

    Mesoporous silica particles prepared through a simplified Stöber method and low temperature solvent promoted surfactant removal are evaluated as dissolution enhancers for poorly soluble compounds, using a powerful anticancer agent belonging to pyrroloquinolinones as a model for anticancer oral therapy, and anti-inflammatory ibuprofen as a reference compound. Mesoporous powders composed of either pure silica or silica modified with aminopropyl residues are produced. The influence of material composition and drug chemical properties on drug loading capability and dissolution enhancement are studied. The two types of particles display similar size, surface area, porosity, erodibility, drug loading capability and stability. An up to 50% w/w drug loading is reached, showing correlation between drug concentration in adsorption medium and content in the final powder. Upon immersion in simulating body fluids, immediate drug dissolution occurred, allowing acceptor solutions to reach concentrations equal to or greater than drug saturation limits. The matrix composition influenced drug solution maximal concentration, complementing the dissolution enhancement generated by a mesoporous structure. This effect was found to depend on both matrix and drug chemical properties allowing us to hypothesise general prediction behaviour rules.

  6. One-Pot Approach to Prepare Organo-silica Hybrid Capillary Monolithic Column with Intact Mesoporous Silica Nanoparticle as Building Block

    PubMed Central

    Liu, Shengju; Peng, Jiaxi; Liu, Zheyi; Liu, Zhongshan; Zhang, Hongyan; Wu, Ren’an

    2016-01-01

    A facile “one-pot” approach to prepare organo-silica hybrid capillary monolithic column with intact mesoporous silica nanoparticle (IMSN) as crosslinker and building block was described. An IMSN crosslinked octadecyl-silica hybrid capillary monolithic column (IMSN-C18 monolithic column) was successfully prepared, and the effects of fabrication conditions (e.g. concentration of intact mesoporous silica nanoparticle, polycondensation temperature, content of vinyltrimethoxysilane and stearyl methacrylate) on the structures of the IMSN-C18 monolithic column were studied in detail. The IMSN-C18 hybrid monolithic column possessed uniform morphology, good mechanical and pH stability (pH 1.1–11), which was applied to the separations of alkyl benzenes, polycyclic aromatic hydrocarbons (PAHs), as well as proteins. The minimum plate height of 10.5 μm (corresponding to 95000 N m−1) for butylbenzene and high reproducibility were achieved. The analysis of tryptic digest of bovine serum albumin (BSA) was carried out on the IMSN-C18 monolithic column by cLC coupled mass spectrometry (cLC-MS/MS), with the protein sequence coverage of 87.5% for BSA, demonstrating its potential application in proteomics. PMID:27698475

  7. Understanding the synthesis of mesoporous silica particles by evaporation induced self assembly

    NASA Astrophysics Data System (ADS)

    Rathod, Shailendra B.

    2007-12-01

    Evaporation-induced self-assembly (EISA) of amphiphilic molecules within aerosol droplets is an attractive method for synthesis of mesoporous silica particles. The aim of this research was to demonstrate synthetic methodologies to develop novel particle architectures using this technique, and to understand the influence of the competing dynamics within an evaporating droplet undergoing EISA on the particle morphology and mesostructure. Experiments were conducted to control particle characteristics. Particle size and distribution was varied by varying the size and distribution of starting droplets. The compressed gas atomizer, TSI 3076, gave a roughly micron-sized droplets with a polydisperse population, whereas the vibrating orifice aerosol generator (VOAG), TSI 3450, gave a highly monodisperse droplet population when orifices of diameters 10 mum and 20 mum were used. The mesopore size and mesostructure ordering were varied by employing amphiphiles of different geometry and by the use of 1,2,3-trimethylbenzene, a pore-swelling agent. The extent of ordering was influenced by factors that govern the rates of reactions of the silica precursors relative to the rates of amphiphile self-assembly. These factors included acid concentration, the alkyl group in the tetraalkoxysilane precursor, the time for which the sol was aged before droplet generation, and CTAB/Si ratio in the starting sol. Experiments and simulation studies were carried out for particles made using CTAB as the templating agent and TMB as a pore-swelling agent. Analysis of these experiments was used to get insight into the three main dynamic processes occurring inside these droplets: evaporation of the volatile species, amphiphile self-assembly and phase transformation, and hydrolysis and condensation reactions of the silica precursor species. Pore swelling was observed for particles made using the VOAG. Particles made using the 10 mum orifice retained their hexagonal mesostructure upon addition of TMB in

  8. Microwave-induced synthesis of highly dispersed gold nanoparticles within the pore channels of mesoporous silica

    SciTech Connect

    Gu Jinlou; Fan Wei; Shimojima, Atsushi; Okubo, Tatsuya

    2008-04-15

    Highly dispersed gold nanoparticles have been incorporated into the pore channels of SBA-15 mesoporous silica through a newly developed strategy assisted by microwave radiation (MR). The sizes of gold are effectively controlled attributed to the rapid and homogeneous nucleation, simultaneous propagation and termination of gold precursor by MR. Diol moieties with high dielectric and dielectric loss constants, and hence a high microwave activation, were firstly introduced to the pore channels of SBA-15 by a simple addition reaction between amino group and glycidiol and subsequently served as the reduction centers for gold nanoparticles. Extraction of the entrapped gold from the nanocomposite resulted in milligram quantities of gold nanoparticles with low dispersity. The successful assembly process of diol groups and formation of gold nanoparticles were monitored and tracked by solid-state NMR and UV-vis measurements. Characterization by small angle X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the incorporation of gold nanoparticles would not breakup the structural integrity and long-range periodicity of SBA-15. The gold nanoparticles had a narrow size distribution with diameters in the size range of 5-10 nm through TEM observation. The average particles size is 7.9 nm via calculation by the Scherrer formula and TEM measurements. Nitrogen adsorption and desorption isotherms gave further evidence that the employed method was efficient and gold nanoparticles were successfully incorporated into the pore channels of SBA-15. - Graphical abstract: A facile and novel strategy has been developed to incorporate gold nanoparticles into the pore channels of mesoporous SBA-15 assisted by microwave radiation (MR) with mild reaction condition and rapid reaction speed. Due to the rapid and homogeneous nucleation, simultaneous propagation and termination by MR, the size of gold nanoparticles are effectively controlled.

  9. Templated assembly of BiFeO₃ nanocrystals into 3D mesoporous networks for catalytic applications.

    PubMed

    Papadas, I T; Subrahmanyam, K S; Kanatzidis, M G; Armatas, G S

    2015-03-19

    The self-assembly of uniform nanocrystals into large porous architectures is currently of immense interest for nanochemistry and nanotechnology. These materials combine the respective advantages of discrete nanoparticles and mesoporous structures. In this article, we demonstrate a facile nanoparticle templating process to synthesize a three-dimensional mesoporous BiFeO₃ material. This approach involves the polymer-assisted aggregating assembly of 3-aminopropanoic acid-stabilized bismuth ferrite (BiFeO₃) nanocrystals followed by thermal decomposition of the surfactant. The resulting material consists of a network of tightly connected BiFeO₃ nanoparticles (∼6-7 nm in diameter) and has a moderately high surface area (62 m(2) g(-1)) and uniform pores (ca. 6.3 nm). As a result of the unique mesostructure, the porous assemblies of BiFeO₃ nanoparticles show an excellent catalytic activity and chemical stability for the reduction of p-nitrophenol to p-aminophenol with NaBH4.

  10. Catalytic ozonation of sulfosalicylic acid over manganese oxide supported on mesoporous ceria.

    PubMed

    Xing, Shengtao; Lu, Xiaoyang; Liu, Jia; Zhu, Lin; Ma, Zichuan; Wu, Yinsu

    2016-02-01

    Manganese oxide supported on mesoporous ceria was prepared and used as catalyst for catalytic ozonation of sulfosalicylic acid (SA). Characterization results indicated that the manganese oxide was mostly incorporated into the pores of ceria. The synthesized catalyst exhibited high activity and stability for the mineralization of SA in aqueous solution by ozone, and more than 95% of total organic carbon was removed in 30 min under various conditions. Mechanism studies indicated that SA was mainly degraded by ozone molecules, and hydroxyl radical reaction played an important role for the degradation of its ozonation products (small molecular organic acids). The manganese oxide in the pores of CeO2 improved the adsorption of small molecular organic acids and the generation of hydroxyl radicals from ozone decomposition, resulting in high TOC removal efficiency.

  11. Steam Treated Ordered Mesoporous Carbon Nanomaterials for Catalytic Conversion of Silicon Tetrachloride to Trichlorosilane.

    PubMed

    Kwak, Do-Hwan; Akhtar, M Shaheer; Kim, Ji Man; Yang, O-Bong

    2015-09-01

    The steam-pretreatment on ordered-mesoporous carbon (OMC) catalysts was conducted to improve the catalytic properties for silicon tetrachloride (STC) to trichlorosilane (TCS) conversion. The surface area, pore size and pore volume of OMC were significantly changed as a function of pretreatment temperature. The steam-pretreated OMC at 500 degrees C exhibited the high surface area (-1476.4 m2/g) and pore volume (1.89 cm3/g), which leads the highest conversion rate of 10.8% as compared to bare-OMC (4.3%) and the steam-pretreated OMC. The steam-pretreatment on OMC might increase active oxygenated species, which promoted the generation of active sites of C-O-Si-for high conversion of STC to TCS.

  12. Preparation, characterization and catalytic properties of MCM-48 supported tungstophosphoric acid mesoporous materials for green synthesis of benzoic acid

    NASA Astrophysics Data System (ADS)

    Wu, Hai-Yan; Zhang, Xiao-Li; Chen, Xi; Chen, Ya; Zheng, Xiu-Cheng

    2014-03-01

    MCM-48 and tungstophosphoric acid (HPW) were prepared and applied for the synthesis of HPW/MCM-48 mesoporous materials. The characterization results showed that HPW/MCM-48 obtained retained the typical mesopore structure of MCM-48, and the textural parameters decreased with the increase loading of HPW. The catalytic oxidation results of benzyl alcohol and benzaldehyde with 30% H2O2 indicated that HPW/MCM-48 was an efficient catalyst for the green synthesis of benzoic acid. Furthermore, 35 wt% HPW/MCM-48 sample showed the highest activity under the reaction conditions.

  13. Cytotoxicity of various types of gold-mesoporous silica nanoparticles in human breast cancer cells

    PubMed Central

    Liu, Guomu; Li, Qiongshu; Ni, Weihua; Zhang, Nannan; Zheng, Xiao; Wang, Yingshuai; Shao, Dan; Tai, Guixiang

    2015-01-01

    Recently, gold nanoparticles (AuNPs) have shown promising biological applications due to their unique electronic and optical properties. However, the potential toxicity of AuNPs remains a major hurdle that impedes their use in clinical settings. Mesoporous silica is very suitable for the use as a coating material for AuNPs and might not only reduce the cytotoxicity of cetyltrimethylammonium bromide-coated AuNPs but might also facilitate the loading and delivery of drugs. Herein, three types of rod-like gold-mesoporous silica nanoparticles (termed bare AuNPs, core–shell Au@mSiO2NPs, and Janus Au@mSiO2NPs) were specially designed, and the effects of these AuNPs on cellular uptake, toxic behavior, and mechanism were then systematically studied. Our results indicate that bare AuNPs exerted higher toxicity than the Au@mSiO2NPs and that Janus Au@mSiO2NPs exhibited the lowest toxicity in human breast cancer MCF-7 cells, consistent with the endocytosis capacity of the nanoparticles, which followed the order, bare AuNPs > core–shell Au@mSiO2NPs > Janus Au@mSiO2NPs. More importantly, the AuNPs-induced apoptosis of MCF-7 cells exhibited features that were characteristic of intracellular reactive oxygen species (ROS) generation, activation of c-Jun-N-terminal kinase (JNK) phosphorylation, an enhanced Bax-to-Bcl-2 ratio, and loss of the mitochondrial membrane potential. Simultaneously, cytochrome c was released from mitochondria, and the caspase-3/9 cascade was activated. Moreover, both ROS scavenger (N-acetylcysteine) and JNK inhibitor (SP600125) partly blocked the induction of apoptosis in all AuNPs-treated cells. Taken together, these findings suggest that all AuNPs induce apoptosis through the ROS-/JNK-mediated mitochondrial pathway. Thus, Janus Au@mSiO2NPs exhibit the potential for applications in biomedicine, thus aiding the clinical translation of AuNPs. PMID:26491285

  14. Cytotoxicity of various types of gold-mesoporous silica nanoparticles in human breast cancer cells.

    PubMed

    Liu, Guomu; Li, Qiongshu; Ni, Weihua; Zhang, Nannan; Zheng, Xiao; Wang, Yingshuai; Shao, Dan; Tai, Guixiang

    2015-01-01

    Recently, gold nanoparticles (AuNPs) have shown promising biological applications due to their unique electronic and optical properties. However, the potential toxicity of AuNPs remains a major hurdle that impedes their use in clinical settings. Mesoporous silica is very suitable for the use as a coating material for AuNPs and might not only reduce the cytotoxicity of cetyltrimethylammonium bromide-coated AuNPs but might also facilitate the loading and delivery of drugs. Herein, three types of rod-like gold-mesoporous silica nanoparticles (termed bare AuNPs, core-shell Au@mSiO2NPs, and Janus Au@mSiO2NPs) were specially designed, and the effects of these AuNPs on cellular uptake, toxic behavior, and mechanism were then systematically studied. Our results indicate that bare AuNPs exerted higher toxicity than the Au@mSiO2NPs and that Janus Au@mSiO2NPs exhibited the lowest toxicity in human breast cancer MCF-7 cells, consistent with the endocytosis capacity of the nanoparticles, which followed the order, bare AuNPs > core-shell Au@mSiO2NPs > Janus Au@mSiO2NPs. More importantly, the AuNPs-induced apoptosis of MCF-7 cells exhibited features that were characteristic of intracellular reactive oxygen species (ROS) generation, activation of c-Jun-N-terminal kinase (JNK) phosphorylation, an enhanced Bax-to-Bcl-2 ratio, and loss of the mitochondrial membrane potential. Simultaneously, cytochrome c was released from mitochondria, and the caspase-3/9 cascade was activated. Moreover, both ROS scavenger (N-acetylcysteine) and JNK inhibitor (SP600125) partly blocked the induction of apoptosis in all AuNPs-treated cells. Taken together, these findings suggest that all AuNPs induce apoptosis through the ROS-/JNK-mediated mitochondrial pathway. Thus, Janus Au@mSiO2NPs exhibit the potential for applications in biomedicine, thus aiding the clinical translation of AuNPs.

  15. Targeted delivery of doxorubicin to mitochondria using mesoporous silica nanoparticle nanocarriers

    NASA Astrophysics Data System (ADS)

    Qu, Qiuyu; Ma, Xing; Zhao, Yanli

    2015-10-01

    A lot of investigations have been conducted using mesoporous silica nanoparticles (MSNPs) functionalized with different targeting ligands in order to deliver various hydrophobic and hydrophilic drugs to targeted cancer cells. However, the utilization of MSNPs to deliver drug molecules to targeted subcellular organelles has been rarely reported. In this work, we applied targeting ligand-conjugated MSNPs with an average diameter of 80 nm to deliver the anticancer drug doxorubicin (DOX) to mitochondria. Triphenoylphosphonium (TPP) was functionalized on MSNPs as a mitochondria targeting ligand. Mitochondria targeting efficiency was demonstrated in HeLa cells by a co-localization study of mitochondria and functionalized MSNPs as well as by fluorescence analysis in isolated mitochondria. In addition, enhanced cancer cell killing efficacy was achieved when using DOX-loaded and TPP-functionalized MSNPs for mitochondria-targeted delivery. Lowered adenosine triphosphate (ATP) production and decreased mitochondrial membrane potential were observed, demonstrating the mitochondria dysfunction caused by delivered DOX. The positive results indicate promising application potential of MSNPs in targeted subcellular drug delivery.A lot of investigations have been conducted using mesoporous silica nanoparticles (MSNPs) functionalized with different targeting ligands in order to deliver various hydrophobic and hydrophilic drugs to targeted cancer cells. However, the utilization of MSNPs to deliver drug molecules to targeted subcellular organelles has been rarely reported. In this work, we applied targeting ligand-conjugated MSNPs with an average diameter of 80 nm to deliver the anticancer drug doxorubicin (DOX) to mitochondria. Triphenoylphosphonium (TPP) was functionalized on MSNPs as a mitochondria targeting ligand. Mitochondria targeting efficiency was demonstrated in HeLa cells by a co-localization study of mitochondria and functionalized MSNPs as well as by fluorescence analysis

  16. Cytotoxicity of various types of gold-mesoporous silica nanoparticles in human breast cancer cells.

    PubMed

    Liu, Guomu; Li, Qiongshu; Ni, Weihua; Zhang, Nannan; Zheng, Xiao; Wang, Yingshuai; Shao, Dan; Tai, Guixiang

    2015-01-01

    Recently, gold nanoparticles (AuNPs) have shown promising biological applications due to their unique electronic and optical properties. However, the potential toxicity of AuNPs remains a major hurdle that impedes their use in clinical settings. Mesoporous silica is very suitable for the use as a coating material for AuNPs and might not only reduce the cytotoxicity of cetyltrimethylammonium bromide-coated AuNPs but might also facilitate the loading and delivery of drugs. Herein, three types of rod-like gold-mesoporous silica nanoparticles (termed bare AuNPs, core-shell Au@mSiO2NPs, and Janus Au@mSiO2NPs) were specially designed, and the effects of these AuNPs on cellular uptake, toxic behavior, and mechanism were then systematically studied. Our results indicate that bare AuNPs exerted higher toxicity than the Au@mSiO2NPs and that Janus Au@mSiO2NPs exhibited the lowest toxicity in human breast cancer MCF-7 cells, consistent with the endocytosis capacity of the nanoparticles, which followed the order, bare AuNPs > core-shell Au@mSiO2NPs > Janus Au@mSiO2NPs. More importantly, the AuNPs-induced apoptosis of MCF-7 cells exhibited features that were characteristic of intracellular reactive oxygen species (ROS) generation, activation of c-Jun-N-terminal kinase (JNK) phosphorylation, an enhanced Bax-to-Bcl-2 ratio, and loss of the mitochondrial membrane potential. Simultaneously, cytochrome c was released from mitochondria, and the caspase-3/9 cascade was activated. Moreover, both ROS scavenger (N-acetylcysteine) and JNK inhibitor (SP600125) partly blocked the induction of apoptosis in all AuNPs-treated cells. Taken together, these findings suggest that all AuNPs induce apoptosis through the ROS-/JNK-mediated mitochondrial pathway. Thus, Janus Au@mSiO2NPs exhibit the potential for applications in biomedicine, thus aiding the clinical translation of AuNPs. PMID:26491285

  17. Biosafety evaluations of well-dispersed mesoporous silica nanoparticles: towards in vivo-relevant conditions

    NASA Astrophysics Data System (ADS)

    Liu, Tsang-Pai; Wu, Si-Han; Chen, Yi-Ping; Chou, Chih-Ming; Chen, Chien-Tsu

    2015-04-01

    This study aimed to investigate how mesoporous silica nanoparticles (MSNs), especially focussing on their surface functional groups, interacted with Raw 264.7 macrophages, as well as with zebrafish embryos. Upon introducing nanoparticles into a biological milieu, adsorption of proteins and biomolecules onto the nanoparticle surface usually progresses rapidly. Nanoparticles bound with proteins can result in physiological and pathological changes, but the mechanisms remain to be elucidated. In order to evaluate how protein corona affected MSNs and the subsequent cellular immune responses, we experimented in both serum and serum-deprived conditions. Our findings indicated that the level of p-p38 was significantly elevated by the positively charged MSNs, whereas negatively charged MSNs resulted in marked ROS production. Most significantly, our experiments demonstrated that the presence of protein efficiently mitigated the potential nano-hazard. On the other hand, strongly positively charged MSNs caused 94% of the zebrafish embryos to die. In that case, the toxicity caused by the quaternary ammonium ligands on the surface of those nanoparticles was exerted in a dose-dependent manner. In summary, these fundamental studies here provide valuable insights into the design of better biocompatible nanomaterials in the future.This study aimed to investigate how mesoporous silica nanoparticles (MSNs), especially focussing on their surface functional groups, interacted with Raw 264.7 macrophages, as well as with zebrafish embryos. Upon introducing nanoparticles into a biological milieu, adsorption of proteins and biomolecules onto the nanoparticle surface usually progresses rapidly. Nanoparticles bound with proteins can result in physiological and pathological changes, but the mechanisms remain to be elucidated. In order to evaluate how protein corona affected MSNs and the subsequent cellular immune responses, we experimented in both serum and serum-deprived conditions. Our

  18. Multifunctional Mesoporous and Nanostructured Catalysts: Exploring Novel Synthetic Methods, Properties and Applications

    NASA Astrophysics Data System (ADS)

    Das, Sayantani

    Novel multifunctional mesoporous and nanostructured catalysts containing two or more different types of judiciously chosen functional / catalytic groups were developed and their unique and cooperative catalytic activities in various useful organic reactions were explored. First, mesoporous silica material containing tertiary amine/silanol groups was synthesized by simple postgrafting synthetic method. The material was found to exhibit efficient cooperative acid/base bifunctional catalytic activity towards Michael addition reactions between trans-β-nitrostyrene and various active methylene compounds such as malononitrile, acetylacetone and dimethylmalonate. Besides serving as a solid base catalyst, such organoamine-functionalized mesoporous silica materials can be utilized as effective support materials for catalytically active organometallic complexes. This was demonstrated by immobilizing ethylenediamine onto mesoporous silica via postgrafting synthetic method and then complexing Fe(III) onto the supported ethylenediamine groups. This yielded a bifunctional Fe(III)/silanol-based heterogeneous catalyst that showed efficient catalytic activity towards epoxide ring opening reactions. Next, the potential of these types of organic-functionalized mesoporous silicas for immobilization of metallic nanoparticle catalysts was investigated. Specifically, mercaptopropyl-functionalized mesoporous silica was synthesized and the material was then supported with ultrasmall Aun nanoclusters. The catalytic properties of the resulting materials in styrene oxidation were studied. Furthermore, the effect of the removal of the thiol groups from around the surfaces of the gold nanoclusters on catalytic activities of the mesoporous silica-supported nanoparticles was investigated. As mesoporous silica have some limitations of crowding in their pores and poor mass transport for reactants when they are functionalized with larger groups such as nanoparticles, a new strategy was developed

  19. Mesoporous silica nanoparticles as a breast cancer targeting contrast agent for ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Milgroom, Andrew Carson

    Current clinical use of ultrasound for breast cancer diagnostics is strictly limited to a role as a supplementary detection method to other modalities, such as mammography or MRI. A major reason for ultrasound’s role as a secondary method is its inability to discern between cancerous and non-cancerous bodies of similar density, like dense calcifications or benign fibroadenomas. Its detection capabilities are further diminished by the variable density of the surrounding breast tissue with the progression of age. Preliminary studies suggest that mesoporous silica nanoparticles (MSNs) are a good candidate as an in situ contrast agent for ultrasound. By tagging the silica particle surface with the cancer-targeting antibody trastuzumab (Herceptin), suspect regions of interest can be better identified in real time with standard ultrasound equipment. Once the silica-antibody conjugate is injected into the bloodstream and enters the cancerous growth’s vasculature, the antibody arm will bind to HER2, a cell surface receptor known to be dysfunctional or overexpressed in certain types of breast cancer. As more particles aggregate at the cell surface, backscatter of the ultrasonic waves increases as a result of the higher porous silica concentration. This translates to an increased contrast around the lesion boundary. Tumor detection through ultrasound contrast enhancement provides a tremendous advantage over current cancer diagnostics because is it significantly cheaper and can be monitored in real time. Characterization of MCM-41 type MSNs suggests that these particles have sufficient stability and particle size distribution to penetrate through fenestrated tumor vasculature and accumulate in HER2+ breast cancer cells through the enhanced permeation and retention (EPR) effect. A study of acoustic properties showed that particle concentration is linearly correlated to image contrast in clinical frequency-range ultrasound, although less pronounced than typical microbubble

  20. Biomimetic Mn-Catalases Based on Dimeric Manganese Complexes in Mesoporous Silica for Potential Antioxidant Agent.

    PubMed

    Escriche-Tur, Luis; Corbella, Montserrat; Font-Bardia, Mercè; Castro, Isabel; Bonneviot, Laurent; Albela, Belén

    2015-11-01

    Two new structural and functional models of the Mn-catalase with formula [{Mn(III)(bpy)(H2O)}(μ-2-MeOC6H4CO2)2(μ-O){Mn(III)(bpy)(X)}]X, where X = NO3 (1) and ClO4 (2) and bpy = 2,2'-bipyridine, were synthesized and characterized by X-ray diffraction. In both cases, a water molecule and an X ion occupy the monodentate positions. The magnetic properties of these compounds reveal a weak antiferromagnetic behavior (2J = -2.2 cm(-1) for 1 and -0.7 cm(-1) for 2, using the spin Hamiltonian H = -2J S1·S2) and negative zero-field splitting parameter DMn (-4.6 cm(-1) and -3.0 cm(-1) for 1 and 2, respectively). This fact, together with the nearly orthogonal orientation of the Jahn-Teller axes of the Mn(III) ions explain the unusual shape of χMT versus T plot at low temperature. Compound 1 presents a better catalase activity than 2 in CH3CN-H2O media, probably due to a beneficial interaction of the NO3(-) ion with the Mn complex in solution. These compounds were successfully inserted inside two-dimensional hexagonal mesoporous silica (MCM-41 type) leading to the same hybrid material ([Mn2O]@SiO2), without the X group. The manganese complex occupies approximately half of the available pore volume, keeping the silica's hexagonal array intact. Magnetic measurements of [Mn2O]@SiO2 suggest that most of the dinuclear unit is preserved, as a non-negligible interaction between Mn ions is still observed. The X-ray photoelectron spectroscopy analysis of the Mn 3s peak confirms that Mn remains as Mn(III) inside the silica. The catalase activity study of material [Mn2O]@SiO2 reveals that the complex is more active inside the porous silica, probably due to the surface silanolate groups of the pore wall. Moreover, the new material shows catalase activity in water media, while the coordination compounds are not active.

  1. Mesoporous Hybrid Polypyrrole-Silica Nanocomposite Films with a Strata-Like Structure.

    PubMed

    Farghaly, Ahmed A; Collinson, Maryanne M

    2016-06-14

    Using a single-potential-step coelectrodeposition route, Ppy-SiO2 nanocomposite films characterized by a multimodal porous structure were cathodically deposited from ethanolic solutions on oxidizable and nonoxidizable substrates for the first time. The materials produced have an interesting and unique strata-like pore structure along their depth. With the exception of a silica-rich inner region, the nanocomposite films are homogeneous in composition. Because the region closest to the electrode surface is silica-rich, the fabrication of Ppy-SiO2 and Ppy free-standing films become possible using a multistep etching strategy. Such films can be captured on a variety of different supports depending on the application, and they maintain their conductivity when interfaced with an electrode surface. These mesoporous composite films form through a unique mechanism that involves the production of two catalysts, OH(-) and NO(+). Through the process of understanding the reaction mechanism, we highlighted the effect of two simultaneous competing redox reactions occurring at the electrode interface on the morphology of the electrodeposited Ppy nanocomposite films and how solvent can influence the Ppy electropolymerization reaction mechanism and hence control the morphology of the final material. In an ethanolic solvent system, the pyrrole monomers undergo a step-growth polymerization, and particulate-like nanostructured films were obtained even upon changing the monomer or acid concentration. In an aqueous-based system, nanowire-like structures were produced, which is consistent with a chain-growth mechanism. Such materials are promising candidates for a wide range of applications including electrochemical sensing, energy storage, and catalysis. PMID:27245273

  2. Mesoporous silica nanoparticles act as a self-adjuvant for ovalbumin model antigen in mice.

    PubMed

    Mahony, Donna; Cavallaro, Antonino S; Stahr, Frances; Mahony, Timothy J; Qiao, Shi Zhang; Mitter, Neena

    2013-09-23

    Immunization to the model protein antigen ovalbumin (OVA) is investigated using MCM-41 mesoporous silica nanoparticles as a novel vaccine delivery vehicle and adjuvant system in mice. The effects of amino surface functionalization and adsorption time on OVA adsorption to nanoparticles are assessed. Amino-functionalized MCM-41 (AM-41) shows an effect on the amount of OVA binding, with 2.5-fold increase in binding capacity (72 mg OVA/g AM-41) compared to nonfunctionalized MCM-41 (29 mg OVA/g MCM-41). Immunization studies in mice with a 10 μg dose of OVA adsorbed to AM-41 elicits both antibody and cell-mediated immune responses following three subcutaneous injections. Immunizations at a lower 2 μg dose of OVA adsorbed to AM-41 particles results in an antibody response but not cell-mediated immunity. The level of antibody responses following immunization with nanoformulations containing either 2 μg or 10 μg of OVA are only slightly lower than that in mice which receive 50 μg OVA adjuvanted with QuilA, a crude mixture of saponins extracted from the bark of the Quillaja saponaria Molina tree. This is a significant result, since it demonstrates that AM-41 nanoparticles are self-adjuvanting and elicit immune responses at reduced antigen doses in vivo compared to a conventional delivery system. Importantly, there are no local or systemic negative effects in animals injected with AM-41. Histopathological studies of a range of tissue organs show no changes in histopathology of the animals receiving nanoparticles over a six week period. These results establish the biocompatible MCM-41 silica nanoparticles as a new method for vaccine delivery which incorporates a self-adjuvant effect. PMID:23625779

  3. Mesoporous Hybrid Polypyrrole-Silica Nanocomposite Films with a Strata-Like Structure.

    PubMed

    Farghaly, Ahmed A; Collinson, Maryanne M

    2016-06-14

    Using a single-potential-step coelectrodeposition route, Ppy-SiO2 nanocomposite films characterized by a multimodal porous structure were cathodically deposited from ethanolic solutions on oxidizable and nonoxidizable substrates for the first time. The materials produced have an interesting and unique strata-like pore structure along their depth. With the exception of a silica-rich inner region, the nanocomposite films are homogeneous in composition. Because the region closest to the electrode surface is silica-rich, the fabrication of Ppy-SiO2 and Ppy free-standing films become possible using a multistep etching strategy. Such films can be captured on a variety of different supports depending on the application, and they maintain their conductivity when interfaced with an electrode surface. These mesoporous composite films form through a unique mechanism that involves the production of two catalysts, OH(-) and NO(+). Through the process of understanding the reaction mechanism, we highlighted the effect of two simultaneous competing redox reactions occurring at the electrode interface on the morphology of the electrodeposited Ppy nanocomposite films and how solvent can influence the Ppy electropolymerization reaction mechanism and hence control the morphology of the final material. In an ethanolic solvent system, the pyrrole monomers undergo a step-growth polymerization, and particulate-like nanostructured films were obtained even upon changing the monomer or acid concentration. In an aqueous-based system, nanowire-like structures were produced, which is consistent with a chain-growth mechanism. Such materials are promising candidates for a wide range of applications including electrochemical sensing, energy storage, and catalysis.

  4. Investigation of heterogeneous asymmetric dihydroxylation over OsO{sub 4}-(QN){sub 2}PHAL catalysts of functionalized bimodal mesoporous silica with ionic liquid

    SciTech Connect

    Qiu, Shenjie; Sun, Jihong; Li, Yuzhen; Gao, Lin

    2011-08-15

    Highlights: {yields} Functionalized bimodal mesoporous silica with MTMSPIm{sup +}Cl{sup -}. {yields} Mesoporous catalyst immobilized with OsO{sub 4}-(QN){sub 2}PHAL. {yields} Catalysts for asymmetric dihydroxylation reaction with high yield and enatioselectivity. {yields} Recyclable catalysts. -- Abstract: A novel synthesis of the functionalized bimodal mesoporous silica with ionic liquid (FBMMs) was performed. After grafting 1-methyl-3-(trimethoxysilyl)propylimidazolium chloride onto the surface of bimodal mesoporous silicas, 1,4-bis(9-O-quininyl)phthalazine ((QN){sub 2}-PHAL) and K{sub 2}Os(OH){sub 4}.2H{sub 2}O were immobilized onto the modified FBMMs by adsorption or ionic exchange methods, and then, the asymmetric dihydroxylation reaction was carried out by using solid catalysts. Techniques such as X-ray diffraction, Fourier Transform Infrared spectroscopy, N{sub 2} adsorption and desorption were employed to characterize their structure and properties. The results showed that the mesoporous ordering degree of bimodal mesoporous silica decreased after functionalization and immobilization of OsO{sub 4}-(QN){sub 2}PHAL. Being very effective in asymmetric dihydroxylation with high yield and enantioselectivity, the prepared heterogeneous solid catalyst could be recycled for five times with little loss of enantioselectivity, with comparison of those results obtained in homophase system. Moreover, the effect of Osmium catalyst on asymmetric dihydroxylation was investigated.

  5. Self-propelled micromotors based on Au-mesoporous silica nanorods.

    PubMed

    Wang, Ying-Shuai; Xia, Hong; Lv, Chao; Wang, Lei; Dong, Wen-Fei; Feng, Jing; Sun, Hong-Bo

    2015-07-28

    Here, a chemical powered micromotor from the assembly of Au-SiO2 nanorods is presented. This new micromotor can be propelled efficiently by hydrogen bubbles generated from a hydrolysis reaction of aqueous NaBH4 and KBH4 and by oxygen bubbles produced by decomposition of H2O2. The monodisperse Au nanoparticles in mesoporous silica particles could catalyze the decomposition of two different kinds of fuels and produce bubbles. High speeds of 80 μm s(-1) and recycles of more than 30 times are achieved in both NaBH4 and H2O2 media. Locomotion and rolling forms of movement were found. The locomotion forms can be obtained in a larger proportion by patterning the Au-SiO2 nanorods and a PDMS membrane. These micromotors that use multiple fuel sources to power them offer a broader scope of preparation and show considerable promise for diverse applications of nanomotors in different chemical environments.

  6. Mesoporous silica as topical nanocarriers for quercetin: characterization and in vitro studies.

    PubMed

    Sapino, Simona; Ugazio, Elena; Gastaldi, Lucia; Miletto, Ivana; Berlier, Gloria; Zonari, Daniele; Oliaro-Bosso, Simonetta

    2015-01-01

    The flavonoid quercetin is extensively studied for its antioxidant and chemopreventive properties. However the poor water-solubility, low stability and short half-life could restrict its use in skin care products and therapy. The present study was aimed to evaluate the potential of aminopropyl functionalized mesoporous silica nanoparticles (NH2-MSN) as topical carrier system for quercetin delivery. Thermo gravimetric analysis, X-ray diffraction, high resolution transmission electron microscopy, nitrogen adsorption isotherms, FT-IR spectroscopy, zeta potential measurements and differential scanning calorimetry allowed analyzing with great detail the organic-inorganic molecular interaction. The protective effect of this vehicle on UV-induced degradation of the flavonoid was investigated revealing a certain positive influence of the inclusion on the photostability over time. Epidermal accumulation and transdermal permeation of this molecule were ex vivo evaluated using porcine skin mounted on Franz diffusion cells. The inclusion complexation with the inorganic nanoparticles increased the penetration of quercetin into the skin after 24h post-application without transdermal delivery. The effect of quercetin alone or given as complex with NH2-MSN on proliferation of JR8 human melanoma cells was evaluated by sulforhodamine B colorimetric proliferation assay. At a concentration 60 μM the complex with NH2-MSN was more effective than quercetin alone, causing about 50% inhibition of cell proliferation. PMID:25478737

  7. Fluorescent carbon dot modified mesoporous silica nanocarriers for redox-responsive controlled drug delivery and bioimaging.

    PubMed

    Jiao, Jian; Liu, Chang; Li, Xian; Liu, Jie; Di, Donghua; Zhang, Ying; Zhao, Qinfu; Wang, Siling

    2016-12-01

    In this paper, a smart nanocarrier (MSNs-SS-CDPAA) is developed for redox-responsive controlled drug delivery and in vivo bioimaging by grafting fluorescent carbon dots to the surface of mesoporous silica nanoparticles (MSNs) via disulfide bonds. The polyanion polymer poly(acrylic acid) (PAA) was used to prepare the carboxyl-abundant carbon dots (CDPAA) by hydrothermal polymerization. The negatively charged CDPAA were anchored to the openings of MSNs containing the disulfide bonds through amidation and were used as gatekeepers for trapping the drugs within the pores. The in vitro release results indicated that the prepared MSNs-SS-CDPAA/DOX showed highly redox-responsive drug release in pH 7.4 and pH 5.0 PBS. In addition, the redox-responsive release mechanism was studied by measurement of the Zeta potential and fluorescence spectrophotometry. The prepared MSNs-SS-CDPAA exhibited excellent biocompatibility and fluorescence properties. Confocal laser scanning microscopy (CLSM) showed that MSNs-SS-CDPAA could emit blue, green and red fluorescence at an excitation wavelength of 408, 488 and 561nm, respectively. In addition, MSNs-SS-CDPAA/DOX exhibited a high cellular uptake as shown by CDPAA imaging and a therapeutic effect on cancer cells by MTT assay. This study describes a novel strategy for simultaneously controlled drug delivery and real-time imaging to track the behavior of nanoparticles during tumor therapy. PMID:27569517

  8. Amine-Impregnated Mesoporous Silica Nanotube as an Emerging Nanocomposite for CO2 Capture.

    PubMed

    Niu, Mengya; Yang, Huaming; Zhang, Xiangchao; Wang, Yutang; Tang, Aidong

    2016-07-13

    Pristine halloysite nanotubes (HNTs) were pretreated to produce mesoporous silica nanotubes (MSiNTs), which was further impregnated with polyethenimine (PEI) to prepare an emerging nanocomposite MSiNTs/PEI (MP) for CO2 capture. Thermogravimetric analysis (TGA) was employed to analyze the influences of PEI loading amount and adsorption temperature on CO2 adsorption capacity of the nanocomposite. The Brunauer-Emmett-Teller (BET) surface area (SBET) of MSiNTs was six times higher than that of HNTs, and the corresponding pore volume was more than two times higher than that of HNTs. The well dispersion of PEI within the nanotubes of MSiNTs benefits more CO2 gas adsorption, and the adsorption capacity of the nanocomposite could reach 2.75 mmol/g at 85 °C for 2 h. The CO2 adsorption on the nanocomposite was demonstrated to occur via a two-stage process: initially, a sharp linear weight increase at the beginning, and then a relatively slow adsorption step. The adsorption capacity could reach as high as 70% within 2 min. Also, the nanocomposite exhibited good stability on CO2 adsorption/desorption performance, indicating that the as-prepared emerging nanocomposite show an interesting application potential in the field of CO2 capture. PMID:27315143

  9. A mesoporous silica nanosphere-based drug delivery system using an electrically conducting polymer

    NASA Astrophysics Data System (ADS)

    Cho, Youngnam; Shi, Riyi; Ivanisevic, Albena; Ben Borgens, Richard

    2009-07-01

    In this study, a mesoporous silica nanoparticle (MSN)-based nerve growth factor (NGF) delivery system has been successfully embedded within an electroactive polypyrrol (Ppy). The spherical particles with ~100 nm diameter possess a large surface-to-volume ratio for the entrapment of NGF into the pores of MSNs while retaining their bioactivity. Direct incorporation of MSN-NGF within Ppy was achieved during electrochemical polymerization. The loading amount and release profile of NGF from the composite was investigated by sandwich ELISA. The NGF incorporation can be controllable by varying particle concentration or by extending electrodeposition time. The morphology and chemical composition of the Ppy/MSN-NGF composite was evaluated by atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS). Optical and electron microscopy revealed a characteristic attachment of PC 12 cells and the outgrowth of their neurites when grown on the Ppy/MSN-NGF composite as a result of a sustained and controlled release of NGF. In order to observe the effectiveness of electrical stimulation, neurite extension of cells cultured on unstimulated and stimulated Ppy/MSN-NGF was compared. The NGF release in the presence of electrical stimulation promoted significantly greater neurite extension.

  10. Gated mesoporous silica nanoparticles for the controlled delivery of drugs in cancer cells.

    PubMed

    Giménez, Cristina; de la Torre, Cristina; Gorbe, Mónica; Aznar, Elena; Sancenón, Félix; Murguía, Jose R; Martínez-Máñez, Ramón; Marcos, M Dolores; Amorós, Pedro

    2015-03-31

    In recent years, mesoporous silica nanoparticles (MSNs) have been used as effective supports for the development of controlled-release nanodevices that are able to act as multifunctional delivery platforms for the encapsulation of therapeutic agents, enhancing their bioavailability and overcoming common issues such as poor water solubility and poor stability of some drugs. In particular, redox-responsive delivery systems have attracted the attention of scientists because of the intracellular reductive environment related to a high concentration of glutathione (GSH). In this context, we describe herein the development of a GSH-responsive delivery system based on poly(ethylene glycol)- (PEG-) capped MSNs that are able to deliver safranin O and doxorubicin in a controlled manner. The results showed that the PEG-capped systems designed in this work can be maintained closed at low GSH concentrations, yet the cargo can be delivered when the concentration of GSH is increased. Moreover, the efficacy of the PEG-capped system in delivering the cytotoxic agent doxorubicin in cells was also demonstrated.

  11. Development of an oral push–pull osmotic pump of fenofibrate-loaded mesoporous silica nanoparticles

    PubMed Central

    Zhao, Zongzhe; Wu, Chao; Zhao, Ying; Hao, Yanna; Liu, Ying; Zhao, Wenming

    2015-01-01

    In this study, mesoporous silica nanoparticles (MSNs) were used to prepare an oral push–pull osmotic pump. Fenofibrate, the selected model drug, was firstly loaded into the MSNs, followed by a suspending agent consisting of a drug layer of push–pull osmotic pump. Fenofibrate-loaded MSNs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption/desorption analysis, differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD) analysis, and Fourier-transform infrared (FT-IR) spectroscopy. Polyethylene oxide of molecular weight (MW) 100,000 and polyethylene oxide of MW 6,000,000 were selected as the suspending agent and the expanding agent, respectively. Cellulose acetate was used as the semipermeable membrane, along with polyethylene glycol 6,000 to increase the flexibility and control the membrane permeability. The in vitro dissolution studies indicated that the osmotic pump tablet combined with MSNs was able to deliver fenofibrate in an approximately zero-order manner in 24 hours. A pharmacokinetic study showed that, although the maximum plasma concentration of the osmotic pump was lower than that of the reference formulation, the relative bioavailability was increased, indicating that the osmotic pump was more efficient than the reference tablets. Therefore, using MSNs as a carrier for poorly water-soluble drugs is an effective method for preparing osmotic pump tablets. PMID:25784799

  12. Polyglutamic Acid-Gated Mesoporous Silica Nanoparticles for Enzyme-Controlled Drug Delivery.

    PubMed

    Tukappa, Asha; Ultimo, Amelia; de la Torre, Cristina; Pardo, Teresa; Sancenón, Félix; Martínez-Máñez, Ramón

    2016-08-23

    Mesoporous silica nanoparticles (MSNs) are highly attractive as supports in the design of controlled delivery systems that can act as containers for the encapsulation of therapeutic agents, overcoming common issues such as poor water solubility and poor stability of some drugs and also enhancing their bioavailability. In this context, we describe herein the development of polyglutamic acid (PGA)-capped MSNs that can selectively deliver rhodamine B and doxorubicin. PGA-capped MSNs remain closed in an aqueous environment, yet they are able to deliver the cargo in the presence of pronase because of the hydrolysis of the peptide bonds in PGA. The prepared solids released less than 20% of the cargo in 1 day in water, whereas they were able to reach 90% of the maximum release of the entrapped guest in ca. 5 h in the presence of pronase. Studies of the PGA-capped nanoparticles with SK-BR-3 breast cancer cells were also undertaken. Rhodamine-loaded nanoparticles were not toxic, whereas doxorubicin-loaded nanoparticles were able to efficiently kill more than 90% of the cancer cells at a concentration of 100 μg/mL. PMID:27468799

  13. Gated magnetic mesoporous silica nanoparticles for intracellular enzyme-triggered drug delivery.

    PubMed

    An, Na; Lin, Huiming; Yang, Chunyu; Zhang, Ting; Tong, Ruihan; Chen, Yuhua; Qu, Fengyu

    2016-12-01

    The targeting drug release is significant to the anticancer treatment. In this context, the redox-responsive drug delivery has attracted most attention owing to the intracellular reductive environment, such as the high concentration of glutathione reductase in many cancer cells. Herein, a glutathione sensitive drug delivery nanoplatform was constructed by using core-shell mesoporous silica nanocomposite (Fe3O4@mSiO2) as carrier. By a simple silane coupling reaction, the glutathione cleavable diselenide linker has been prepared and grafted on to Fe3O4@mSiO2 to insure the encapsulation of anticancer drug doxorubicin. The detail release kinetics studies reveal the glutathione triggered drug release, which could be further adjusted by varying the amount of diselenide linker. To improve the tumor-targeting, folic acid was grafted. The cellular uptake and drug release investigation was carried out using HeLa (cervical cancer cell line) as the model cancer cell and L02 and HUVEC (human hepatic cell line and human umbilical vein endothelial cells, non-cancerous cell lines) as control, indicating the enhanced cytotoxicity toward HeLa cells that benefits from the fast endocytosis and enhanced cellular drug release owing to their overexpressing folic acid receptors and high concentration of glutathione. Associating with the magnetic targeting, these novel nanomaterials are expected to be promising in the potential application of tumor-targeting therapy.

  14. VEGF₁₂₁-conjugated mesoporous silica nanoparticle: a tumor targeted drug delivery system.

    PubMed

    Goel, Shreya; Chen, Feng; Hong, Hao; Valdovinos, Hector F; Hernandez, Reinier; Shi, Sixiang; Barnhart, Todd E; Cai, Weibo

    2014-12-10

    The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) signaling cascade plays a critical role in tumor angiogenesis and metastasis and has been correlated with several poorly prognostic cancers such as malignant gliomas. Although a number of anti-VEGFR therapies have been conceived, inefficient drug administration still limits their therapeutic efficacy and raises concerns of potential side effects. In the present work, we propose the use of uniform mesoporous silica nanoparticles (MSNs) for VEGFR targeted positron emission tomography imaging and delivery of the anti-VEGFR drug (i.e., sunitinib) in human glioblastoma (U87MG) bearing murine models. MSNs were synthesized, characterized and modified with polyethylene glycol, anti-VEGFR ligand VEGF121 and radioisotope (64)Cu, followed by extensive in vitro, in vivo and ex vivo studies. Our results demonstrated that a significantly higher amount of sunitinib could be delivered to the U87MG tumor by targeting VEGFR when compared with the non-targeted counterparts. The as-developed VEGF121-conjugated MSN could become another attractive nanoplatform for the design of future theranostic nanomedicine.

  15. Chaperonin-Inspired pH Protection by Mesoporous Silica SBA-15 on Myoglobin and Lysozyme.

    PubMed

    Lynch, Michele M; Liu, Jichuan; Nigra, Michael; Coppens, Marc-Olivier

    2016-09-20

    While enzymes are valuable tools in many fields of biotechnology, they are fragile and must be protected against denaturing conditions such as unfavorable solution pH. Within living organisms, chaperonins help enzymes fold into their native shape and protect them from damage. Inspired by this natural solution, mesoporous silica SBA-15 with different pore diameters is synthesized as a support material for immobilizing and protecting enzymes. In separate experiments, the model enzymes myoglobin and lysozyme are physically adsorbed to SBA-15 and exposed to a range of buffered pH conditions. The immobilized enzymes' biocatalytic activities are quantified and compared to the activities of nonimmobilized enzymes in the same solution conditions. It has been observed that myoglobin immobilized on SBA-15 is protected from acidic denaturation from pH 3.6 to 5.1, exhibiting relative activity of up to 350%. Immobilized lysozyme is protected from unfavorable conditions from pH 6.6 to 7.6, with relative activity of up to 200%. These results indicate that the protective effects conferred to enzymes immobilized by physical adsorption to SBA-15 are driven by the enzymes' electrostatic attraction to the material's surface. The pore diameter of SBA-15 affects the quality of protection given to immobilized enzymes, but the contribution of this effect at different pH values remains unclear.

  16. Polymer-Grafted Mesoporous Silica Nanoparticles as Ultrasound-Responsive Drug Carriers.

    PubMed

    Paris, Juan L; Cabañas, M Victoria; Manzano, Miguel; Vallet-Regí, María

    2015-11-24

    A new ultrasound-responsive system based on mesoporous silica nanoparticles was developed for biomedical applications, grafting a copolymer on their surface that acts as gatekeeper of the pores. The nanoparticles can be loaded with a cargo at low temperature (4 °C), taking advantage of the open conformation that the polymer presents under these conditions. Then, at 37 °C the copolymer collapses closing the pore entrances and allowing the nanoparticles to carry the drugs at physiological temperature without premature release, which is of great importance when dealing with cytotoxic drugs in cancer treatments. Upon ultrasound irradiation, the sensitive polymer changes its hydrophobicity and, therefore, its conformation toward coil-like opening the gates and releasing the cargo. These hybrid nanoparticles have been shown to be noncytotoxic and can be internalized into LNCaP cells retaining their ultrasound-responsive capability in the cytoplasm of the cells. Moreover, doxorubicin-loaded hybrid MSNs were incubated with LNCaP cells to show their capacity to induce cell death only when the nanoparticles had been exposed to ultrasound. This work demonstrates that our hybrid-MSNs can be triggered by remote stimuli, which is of capital importance for future applications in drug delivery and cancer therapy. PMID:26456489

  17. Targeted delivery of doxorubicin to mitochondria using mesoporous silica nanoparticle nanocarriers.

    PubMed

    Qu, Qiuyu; Ma, Xing; Zhao, Yanli

    2015-10-28

    A lot of investigations have been conducted using mesoporous silica nanoparticles (MSNPs) functionalized with different targeting ligands in order to deliver various hydrophobic and hydrophilic drugs to targeted cancer cells. However, the utilization of MSNPs to deliver drug molecules to targeted subcellular organelles has been rarely reported. In this work, we applied targeting ligand-conjugated MSNPs with an average diameter of 80 nm to deliver the anticancer drug doxorubicin (DOX) to mitochondria. Triphenoylphosphonium (TPP) was functionalized on MSNPs as a mitochondria targeting ligand. Mitochondria targeting efficiency was demonstrated in HeLa cells by a co-localization study of mitochondria and functionalized MSNPs as well as by fluorescence analysis in isolated mitochondria. In addition, enhanced cancer cell killing efficacy was achieved when using DOX-loaded and TPP-functionalized MSNPs for mitochondria-targeted delivery. Lowered adenosine triphosphate (ATP) production and decreased mitochondrial membrane potential were observed, demonstrating the mitochondria dysfunction caused by delivered DOX. The positive results indicate promising application potential of MSNPs in targeted subcellular drug delivery.

  18. Intracellular chromobody delivery by mesoporous silica nanoparticles for antigen targeting and visualization in real time.

    PubMed

    Chiu, Hsin-Yi; Deng, Wen; Engelke, Hanna; Helma, Jonas; Leonhardt, Heinrich; Bein, Thomas

    2016-05-13

    Chromobodies have recently drawn great attention as bioimaging nanotools. They offer high antigen binding specificity and affinity comparable to conventional antibodies, but much smaller size and higher stability. Chromobodies can be used in live cell imaging for specific spatio-temporal visualization of cellular processes. To date, functional application of chromobodies requires lengthy genetic manipulation of the target cell. Here, we develop multifunctional large-pore mesoporous silica nanoparticles (MSNs) as nanocarriers to directly transport chromobodies into living cells for antigen-visualization in real time. The multifunctional large-pore MSNs feature high loading capacity for chromobodies, and are efficiently taken up by cells. By functionalizing the internal MSN surface with nitrilotriacetic acid-metal ion complexes, we can control the release of His6-tagged chromobodies from MSNs in acidified endosomes and observe successful chromobody-antigen binding in the cytosol. Hence, by combining the two nanotools, chromobodies and MSNs, we establish a new powerful approach for chromobody applications in living cells.

  19. 5-Azacytidine delivered by mesoporous silica nanoparticles regulates the differentiation of P19 cells into cardiomyocytes

    NASA Astrophysics Data System (ADS)

    Cheng, Jin; Ding, Qian; Wang, Jia; Deng, Lin; Yang, Lu; Tao, Lei; Lei, Haihong; Lu, Shaoping

    2016-01-01

    Heart disease is one of the deadliest diseases causing mortality due to the limited regenerative capability of highly differentiated cardiomyocytes. Stem cell-based therapy in tissue engineering is one of the most exciting and rapidly growing areas and raises promising prospects for cardiac repair. In this study, we have synthesized FITC-mesoporous silica nanoparticles (FMSNs) based on a sol-gel method (known as Stöber's method) as a drug delivery platform to transport 5-azacytidine in P19 embryonic carcinoma stem cells. The surfactant CTAB is utilized as a liquid crystal template to self-aggregate into micelles, resulting in the synthesis of MSNs. Based on the cell viability assay, treatment with FMSNs + 5-azacytidine resulted in much more significant inhibition of the proliferation than 5-azacytidine alone. To study the mechanism, we have tested the differentiation genes and cardiac marker genes in P19 cells and found that these genes have been up-regulated in P19 embryonic carcinoma stem cells treated with FMSNs + 5-azacytidine + poly(allylamine hydrochloride) (PAH), with the changes of histone modifications on the regulatory region. In conclusion, with FMSNs as drug delivery platforms, 5-azacytidine can be more efficiently delivered into stem cells and can be used to monitor and track the transfection process in situ to clarify their effects on stem cell functions and the differentiation process, which can serve as a promising tool in tissue engineering and other biomedical fields.

  20. Towards multifunctional, targeted drug delivery systems using mesoporous silica nanoparticles - opportunities & challenges

    NASA Astrophysics Data System (ADS)

    Rosenholm, Jessica M.; Sahlgren, Cecilia; Lindén, Mika

    2010-10-01

    One of the big challenges of medicine today is to deliver drugs specifically to defected cells. Nanoparticulate drug carriers have the potential to answer to this call, as nanoparticles can cross physiological barriers and access different tissues, and also be provided in a targetable form aimed at enhancing cell specificity of the carrier. Recent developments within material science and strong collaborative efforts crossing disciplinary borders have highlighted the potential of mesoporous silica nanoparticles (MSNs) for such targeted drug delivery. Here we outline recent advances which in this sense push MSNs to the forefront of drug delivery development. Relatively straightforward inside-out tuning of the vehicles, high flexibility, and potential for sophisticated release mechanisms make these nanostructures promising candidates for targeted drug delivery such as `smart' cancer therapies. Moreover, due to the large surface area and the controllable surface functionality of MSNs, they can be controllably loaded with large amounts of drugs and coupled to homing molecules to facilitate active targeting, simultaneously carrying traceable (fluorescent or magnetically active) modalities, also making them highly interesting as theragnostic agents. However, the increased relative surface area and small size, and flexible surface functionalization which is beneficially exploited in nanomedicine, consequently also includes potential risks in their interactions with biological systems. Therefore, we also discuss some safety issues regarding MSNs and highlight how different features of the drug delivery platform influence their behaviour in a biological setting. Addressing these burning questions will facilitate the application of MSNs in nanomedicine.

  1. Enzyme-coated mesoporous silica nanoparticles as efficient antibacterial agents in vivo.

    PubMed

    Li, Li-Li; Wang, Hao

    2013-10-01

    Despite the fact that pathogenic infections are widely treated by antibiotics in the clinic nowadays, the increasing risk of multidrug-resistance associated with abuse of antibiotics is becoming a major concern in global public health. The increased death toll caused by pathogenic bacterial infection calls for effective antibiotic alternatives. Lysozyme-coated mesoporous silica nanoparticles (MSNs⊂Lys) are reported as antibacterial agents that exhibit efficient antibacterial activity both in vitro and in vivo with low cytotoxicity and negligible hemolytic side effect. The Lys corona provides multivalent interaction between MSNs⊂Lys and bacterial walls and consequently raises the local concentration of Lys on the surface of cell walls, which promotes hydrolysis of peptidoglycans and increases membrane-perturbation abilities. The minimal inhibition concentration (MIC) of MSNs⊂Lys is fivefold lower than that of free Lys in vitro. The antibacterial efficacy of MSNs⊂Lys is evaluated in vivo by using an intestine-infected mouse model. Experimental results indicate that the number of bacteria surviving in the colon is three orders of magnitude lower than in the untreated group. These natural antibacterial enzyme-modified nanoparticles open up a new avenue for design and synthesis of next-generation antibacterial agents as alternatives to antibiotics.

  2. Synthesis of High Valence Silver-Loaded Mesoporous Silica with Strong Antibacterial Properties

    PubMed Central

    Chen, Chun-Chi; Wu, Hsin-Hsien; Huang, Hsin-Yi; Liu, Chen-Wei; Chen, Yi-Ning

    2016-01-01

    A simple chemical method was developed for preparing high valence silver (Ag)-loaded mesoporous silica (Ag-ethylenediaminetetraacetic acid (EDTA)-SBA-15), which showed strong antibacterial activity. Ag-EDTA-SBA-15 exhibited stronger and more effective antibacterial activity than commercial Ag nanoparticles did, and it offered high stability of high valence silver in the porous matrix and long-lasting antibacterial activity. The synthesized materials were characterized using Fourier transform infrared spectroscopy, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) analysis, and transmission electron microscopy (TEM). Ag existed in both surface complexation and Ag particles. EDTA anchored within a porous structure chelated Ag ions in higher oxidation states and prevented their agglomeration and oxidation reduction. The XRD results showed that most Ag in the Ag-EDTA-SBA-15 existed in higher oxidation states such as Ag(II) and Ag(III). However, the XPS and TEM results showed that Ag easily reduced in lower oxidation states and agglomerated as Ag particles on the exterior layer of the SBA-15. PMID:26742050

  3. Ordered mesoporous silica and alumina thin films studied by X-ray scattering

    NASA Astrophysics Data System (ADS)

    Klotz, M.; Idrissi-Kandri, N.; Ayral, A.; van der Lee, A.; Guizard, C.

    2002-07-01

    The use of X-ray techniques for the characterisation of ordered mesoporous films is demonstrated. Both silica and alumina thin layers with an ordered mesoporosity are studied using low-angle diffraction and grazing incidence reflectometry. It is shown how the internal structure evolves upon drying and how texture can be easily detected using a two-circle diffractometer. The reflectometry data are correlated with results from nitrogen adsorption/desorption experiments. Nous montrons comment les techniques de rayons-X peuvent être utilisées pour la caractérisation des couches à mésoporosité ordonnée. Des couches minces de silice et d'alumine à mésoporosité ordonnée ont été étudiées par diffraction aux petits angles et réflectométrie en incidence rasante. Il est montré comment la structure interne évolue au cours du séchage et comment la texture peut être analysée en utilisant un diffractomètre deux-cercles. Les données de réflectométrie sont corrélées avec les résultats obtenus par des mesures d'adsorption-désorption d'azote.

  4. Mesoporous silica nanoparticles as a delivery system of gadolinium for effective human stem cell tracking.

    PubMed

    Hsiao, Jong-Kai; Tsai, Chih-Pin; Chung, Tsai-Hua; Hung, Yann; Yao, Ming; Liu, Hon-Man; Mou, Chung-Yuan; Yang, Chung-Shi; Chen, Yao-Chang; Huang, Dong-Ming

    2008-09-01

    The progress of using gadolinium (Gd)-based nanoparticles in cellular tracking lags behind that of superparamagnetic iron oxide (SPIO) nanoparticles in magnetic resonance imaging (MRI). Here, dual functional Gd-fluorescein isothiocyanate mesoporous silica nanoparticles (Gd-Dye@MSN) that possess green fluorescence and paramagnetism are developed in order to evaluate their potential as effective T1-enhancing trackers for human mesenchymal stem cells (hMSCs). hMSCs are labeled efficiently with Gd-Dye@MSN via endocytosis. Labeled hMSCs are unaffected in their viability, proliferation, and differentiation capacities into adipocytes, osteocytes, and chondrocytes, which can still be readily MRI detected. Imaging, with a clinical 1.5-T MRI system and a low incubation dosage of Gd, low detection cell numbers, and short incubation times is demonstrated on both loaded cells and hMSC-injected mouse brains. This study shows that the advantages of biocompatibility, durability, high internalizing efficiency, and pore architecture make MSNs an ideal vector of T1-agent for stem-cell tracking with MRI.

  5. A mesoporous silica nanosphere-based drug delivery system using an electrically conducting polymer.

    PubMed

    Cho, Youngnam; Shi, Riyi; Ivanisevic, Albena; Ben Borgens, Richard

    2009-07-01

    In this study, a mesoporous silica nanoparticle (MSN)-based nerve growth factor (NGF) delivery system has been successfully embedded within an electroactive polypyrrol (Ppy). The spherical particles with approximately 100 nm diameter possess a large surface-to-volume ratio for the entrapment of NGF into the pores of MSNs while retaining their bioactivity. Direct incorporation of MSN-NGF within Ppy was achieved during electrochemical polymerization. The loading amount and release profile of NGF from the composite was investigated by sandwich ELISA. The NGF incorporation can be controllable by varying particle concentration or by extending electrodeposition time. The morphology and chemical composition of the Ppy/MSN-NGF composite was evaluated by atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS). Optical and electron microscopy revealed a characteristic attachment of PC 12 cells and the outgrowth of their neurites when grown on the Ppy/MSN-NGF composite as a result of a sustained and controlled release of NGF. In order to observe the effectiveness of electrical stimulation, neurite extension of cells cultured on unstimulated and stimulated Ppy/MSN-NGF was compared. The NGF release in the presence of electrical stimulation promoted significantly greater neurite extension.

  6. Mesoporous silica-supported lipid bilayers (protocells) for DNA cargo delivery to the spinal cord.

    PubMed

    Dengler, Ellen C; Liu, Juewen; Kerwin, Audra; Torres, Sergio; Olcott, Clara M; Bowman, Brandi N; Armijo, Leisha; Gentry, Katherine; Wilkerson, Jenny; Wallace, James; Jiang, Xingmao; Carnes, Eric C; Brinker, C Jeffrey; Milligan, Erin D

    2013-06-10

    Amorphous mesoporous silica nanoparticles ('protocells') that support surface lipid bilayers recently characterized in vitro as carrier constructs for small drug and DNA delivery are reported here as highly biocompatible both in vitro and in vivo, involving the brain and spinal cord following spinal delivery into the lumbosacral subarachnoid space (intrathecal; i.t.). Specifically, positively charged, 1, 2-Dioleoyl-3-Trimethylammonium-Propane (DOTAP)-cholesterol (DOTAP:Chol) liposome-formulated protocells revealed stable in vitro cargo release kinetics and cellular interleukin-10 (IL-10) transgene transfection. Recent approaches using synthetic non-viral vector platforms to deliver the pain-suppressive therapeutic transgene, IL-10, to the spinal subarachnoid space have yielded promising results in animal models of peripheral neuropathy, a condition involving aberrant neuronal communication within sensory pathways in the nervous system. Non-viral drug and gene delivery protocell platforms offer potential flexibility because cargo release-rates can be pH-dependent. We report here that i.t. delivery of protocells, with modified chemistry supporting a surface coating of DOTAP:Chol liposomes and containing the IL-10 transgene, results in functional suppression of pain-related behavior in rats for extended periods. This study is the first demonstration that protocell vectors offer amenable and enduring in vivo biological characteristics that can be applied to spinal gene delivery. PMID:23517784

  7. Intracellular chromobody delivery by mesoporous silica nanoparticles for antigen targeting and visualization in real time

    PubMed Central

    Chiu, Hsin-Yi; Deng, Wen; Engelke, Hanna; Helma, Jonas; Leonhardt, Heinrich; Bein, Thomas

    2016-01-01

    Chromobodies have recently drawn great attention as bioimaging nanotools. They offer high antigen binding specificity and affinity comparable to conventional antibodies, but much smaller size and higher stability. Chromobodies can be used in live cell imaging for specific spatio-temporal visualization of cellular processes. To date, functional application of chromobodies requires lengthy genetic manipulation of the target cell. Here, we develop multifunctional large-pore mesoporous silica nanoparticles (MSNs) as nanocarriers to directly transport chromobodies into living cells for antigen-visualization in real time. The multifunctional large-pore MSNs feature high loading capacity for chromobodies, and are efficiently taken up by cells. By functionalizing the internal MSN surface with nitrilotriacetic acid-metal ion complexes, we can control the release of His6-tagged chromobodies from MSNs in acidified endosomes and observe successful chromobody-antigen binding in the cytosol. Hence, by combining the two nanotools, chromobodies and MSNs, we establish a new powerful approach for chromobody applications in living cells. PMID:27173765

  8. Mesoporous silica coated gold nanorods loaded doxorubicin for combined chemo-photothermal therapy.

    PubMed

    Monem, A Soltan; Elbialy, Nihal; Mohamed, Noha

    2014-08-15

    The efficacy of the combined chemo-photothermal therapy, using a mesoporous silica-coated gold nanorods loaded DOX (pGNRs@mSiO2-DOX), was consistently tested both in vitro and in vivo. The prepared nanoparticles that were characterized using transmission electron microscopy (TEM), UV-vis absorption spectroscopy and zeta potential showed high doxorubicin loading capacity in addition to its pH-responsive release. The pGNRs@mSiO2-DOX photo-heat conversion characteristic found to be stable for several repeated NIR irradiated doses was tested in simulated body fluid. In vitro results showed that pGNRs@mSiO2-DOX causes a significant damage in breast cance