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Intraparticle Transport and Release of Dextran in Silica Spheres with Cylindrical Mesopores
Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry. (Materials Chemistry Research Group)
Division of Cell Physics, Department of Applied Physics, AlbaNova, KTH.
YKI, Institute of Surface Chemistry.
YKI, Institute of Surface Chemistry.
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2010 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 6, no 1, 466-470 p.Article in journal (Refereed) Published
Abstract [en]

The transport of oligomeric molecules in silica spheres with cylindrical mesopores has been quantified and related to the features of the internal structures in the spherical particles and the interactions at the polymer-pore interface. An emulsion-solvent-evaporation method was used to produce silica spheres having cylindrical mesopores with an average pore diameter of 6.5 nm. The transport of dextran molecules (fluorescently tagged) with molecular weights of 3000 and 10000 g/mol were quantified using confocal laser scanning microscopy (CLSM). The intraparticle concentrations profiles in the dextran-containing spheres were flat at all times, suggesting that the underpinning diffusion is not fully isotropic and the release is controlled by the pores close to the external surface of the spheres. The release of dextran into the solution is characterized by an initial burst, followed by a long-term sustained release. This behaviour cannot be described by a spherical model with a single diffusion constant (or a surface-induced mass transfer resistance). The release follows a logarithmic time-dependency that can be described by a Temkin model.

Place, publisher, year, edition, pages
2010. Vol. 6, no 1, 466-470 p.
Keyword [en]
Mesoporous particles, controlled release, dextran, CLSM, molecular transport
National Category
Inorganic Chemistry
Research subject
Materials Science
Identifiers
URN: urn:nbn:se:su:diva-27800DOI: 10.1021/la902092eOAI: oai:DiVA.org:su-27800DiVA: diva2:218352
Projects
Synthesis, functionalisation and controlled release of mesoporous materials
Available from: 2009-05-19 Created: 2009-05-19 Last updated: 2011-02-16Bibliographically 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.
Keyword
Mesoporous, spheres, particles, CLSM, TEM, controlled-release, molecular transport, lipid membrane, enzyme, intraparticle, lipase, solid support
National Category
Inorganic Chemistry
Research subject
Materials Science
Identifiers
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)
Opponent
Supervisors
Projects
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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