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The radial dependence of the spatial mesostructure of monodisperse mesoporous silica spheres
Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
2008 (English)In: Microporous and Mesoporous Materials, ISSN 1387-1811, Vol. 112, 589-596 p.Article in journal (Refereed) Published
Abstract [en]

The pore structure of monodisperse mesostructured silica spheres has been investigated by a combination of X-ray diffraction, nitrogen sorption isotherms and transmission electron microscopy (TEM). The radial dependence of the mesostructure has been obtained by TEM analysis of thin microtomed slices taken at different distance from the particle core. A structural model is proposed based on the TEM observations where bundles of the hexagonally ordered cylindrical channels bend and twist, without any preferred direction, close to the particle core and attain a radially extended structure closer to the particle surface. Thermal calcination results in a pore shrinkage of about 16% and some loss of the long-range mesostructure while radiative disintegration and partial removal of the organic template by an UV/Ozone treatment had a negligible effect on the inorganic framework in terms of pore size or spatial pore arrangement.

Place, publisher, year, edition, pages
2008. Vol. 112, 589-596 p.
Keyword [en]
Mesoporous particles, Monodisperse, TEM, Stoeber method, Colloid
URN: urn:nbn:se:su:diva-15273DOI: 10.1016/j.micromeso.2007.10.041ISI: 000256713300066OAI: diva2:181793
Available from: 2008-11-26 Created: 2008-11-26 Last updated: 2009-05-20Bibliographically approved
In thesis
1. Harnessing Mesoporous Spheres - transport studies and biotechnological applications
Open this publication in new window or tab >>Harnessing Mesoporous Spheres - transport studies and biotechnological applications
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Applications in controlled release and delivery calls for a good understanding of molecular transport within the carrier material and the dominating release mechanisms. It is clear that a better understanding of hindered transport and diffusion of guest molecules is important when developing new porous materials, e.g., surfactant templated silica spheres, for biotechnological applications. Confocal laser scanning microscopy was used to quantify the bulk release and intraparticle transport of small charged fluorescent dyes, and fluorescently-tagged neutral dextran, from mesoporous silica spheres. The time dependent release and the concentration profiles within the spheres have been used to analyze the release mechanisms using appropriate models. While the small, non-adsorbing anionic dye is released following a simple diffusion driven process, the concentration of the cationic dye varies radially within the spheres after loading. The release of the cationic dye is controlled by diffusion after an initial period of rapid release, which could be due to a significant fraction of the cationic dye that remains permanently attached to the negatively charged walls of the mesoporous silica spheres. The diffusion of dextran and the resulting flat concentration profiles could be related to the complex structural feature of the cylindrical pores close to the surface, and a possible conformational change of the dextran with the concentration. The stability and leaching of a catalytic enzyme, lipase, immobilized in hydrophobilized mesoporous support has also been quantified. Colloidal monodisperse mesoporous silica spheres were synthesized and transmission electron microscopy showed that the inner pore structure display a radially extending pores. The mesoporous spheres were used as solid supports for a lipid membrane incorporated with a multi-subunit redox-driven proton pump, which was shown to remain functional.

Place, publisher, year, edition, pages
Stockholm: Department of Physical, Inorganic and Structural Chemistry, Stockholm University, 2009. 69 p.
Mesoporous, spheres, particles, CLSM, TEM, controlled-release, molecular transport, lipid membrane, enzyme, intraparticle, lipase, solid support
National Category
Inorganic Chemistry
Research subject
Materials Science
urn:nbn:se:su:diva-27797 (URN)978-91-7155-898-5 (ISBN)
Public defence
2009-09-02, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 8 C, Stockholm, 10:00 (English)
Synthesis, functionalisation and controlled release of mesoporous materials
Available from: 2009-05-27 Created: 2009-05-19 Last updated: 2009-05-20Bibliographically approved

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Ng, Jovice Boon SingVasiliev, PetrBergström, Lennart
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