title: Intraparticle transport and release of dextran in silica spheres with cylindrical mesopores.
abstract: The transport of oligomeric molecules in silica spheres with cylindrical mesopores has been quantified and related to the structural features of the spherical particles and the interactions at the solid-liquid 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 10,000 g/mol was quantified using confocal laser scanning microscopy (CLSM). The intraparticle concentration profiles in the dextran-containing spheres were flat at all times, suggesting that the release is not isotropic and not limited by diffusion. The release of dextran into the solution is characterized by an initial burst, followed by long-term sustained release. The release follows a logarithmic time dependency, which was rationalized by coupling concentration-dependent effective diffusion constants with adsorption/desorption.
authors.affiliation: Materials Chemistry Research Group, Department of Physical, Inorganic and Structural Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Jovice B S
authors.initials: JB
authors.lastname: Ng
authors.forename: Padideh
authors.initials: P
authors.lastname: Kamali-Zare
authors.forename: Malin
authors.initials: M
authors.lastname: Sörensen
authors.forename: Hjalmar
authors.initials: H
authors.lastname: Brismar
authors.forename: Niklas
authors.initials: N
authors.lastname: Hedin
authors.forename: Lennart
authors.initials: L
authors.lastname: Bergström
mesh_terms: D000327:Adsorption; D003911:Dextrans / Q000737:chemistry*; D004058:Diffusion; D005456:Fluorescent Dyes / Q000737:chemistry; D007934:Leuconostoc; D008027:Light; D008970:Molecular Weight; D038761:Photobleaching; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013997:Time Factors; D014835:Volatilization
chemical_list: D003911:Dextrans; D005456:Fluorescent Dyes; D012997:Solvents; D012822:Silicon Dioxide