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Sustained Release from Mesosporous Nanoparticles: evaluation of structural properties associated with controlled release rate
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.ORCID iD: 0000-0002-5496-9664
2008 (English)In: Current Drug Delivery, ISSN 1567-2018, E-ISSN 1875-5704, Vol. 5, no 3, 177-185 p.Article in journal (Refereed) Published
Abstract [en]

We present here a detailed study of the controlled release of amino acid derived amphiphilic molecules from the internal pore structure of mesoporous nanoparticle drug delivery systems with different structural properties; namely cubic and hexagonal structures of various degrees of complexity. The internal pore surface of the nanomaterials presented has been functionalised with amine moieties through a one pot method. Release profiles obtained by Alternating Ionic Current measurements are interpreted in terms of specific structural and textural parameters of the porous nanoparticles such as pore geometry and connectivity. Results indicate that diffusion coefficients are lower by as much as four orders of magnitude in 2-dimensional structures in comparison to 3-dimensional mesoporous solids. A fast release in turn is observed from mesocaged materials AMS-9 and AMS-8 where the presence of structural defects is thought to lead to a slightly lower diffusion coefficient in the latter. Amount of pore wall functionalisation and number of binding sites on the model drug are found to have little effect on the drug release rate.

Place, publisher, year, edition, pages
2008. Vol. 5, no 3, 177-185 p.
National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
URN: urn:nbn:se:uu:diva-17498DOI: 10.2174/156720108784911686PubMedID: 18673261OAI: oai:DiVA.org:uu-17498DiVA: diva2:45269
Available from: 2008-08-07 Created: 2008-08-07 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Novel Syntheses, Structures and Functions of Mesoporous Silica Materials
Open this publication in new window or tab >>Novel Syntheses, Structures and Functions of Mesoporous Silica Materials
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The field of mesoporous silica has been studied for about 20 years but it is still an area attracting a lot of attention. The use of novel templating molecules and several issues related to the synthesis and fine structural details are still poorly understood. These aspects are of special relevance to the theme of this thesis, which includes novel work on three fronts; the synthesis, characterization and applications of mesoporous materials.

The work described in this thesis aims to contribute to the mesoporous field by developing novel methods of mesoporous silica synthesis without relying on surfactant micelles as the templating agent but focusing instead on the stacking arrangement of aromatic molecules such as folic acid. The novel route presented here leads to 2D hexagonal structures with p6mm symmetry possessing high mesoporosity and large surface areas. The versatility of this route at various synthesis temperatures and using hydrothermal treatments has also been investigated.

A novel strategy is also proposed for the synthesis of mesocaged materials with Pm3n symmetry structures. The mechanism relies on the penetration of the neutral propylamino moiety of a co-structure directing agent into the hydrophobic core of the surfactant micelles. Beside these novel pathways, the effect of hydrothermal treatment (HT) at 100 oC on the 3D cubic Ia3d structure (AMS-6) over a long period of time was also examined, and the results show a phase transformation from a 3D cubic Ia3d to a 2D hexagonal p6mm structure and a return to the 3D cubic Ia3d structure at a later stage in the synthesis. This unexpected result is discussed.

In this work, the detailed structural characterization of mesoporous materials using electron microscopy techniques is an important task. In particular, to extend previous knowledge, the fine structural details of mesocaged materials possessing Pm3n symmetry prepared with various amphiphilic surfactants under acidic and alkaline conditions has been investigated using electron crystallography and sorption studies. The results show subtle fine structural differences with materials prepared under alkaline conditions exhibiting the largest mesocage sizes. The cage and window sizes are primarily determined by the charge density of the surfactant and the thickness of the hydration layer surrounding the surfactant micelles.

The relationship between the mesoporous structure and its function has been investigated by evaluating the rate of release of amphiphilic molecules, used as model molecules, from the internal pore structures of mesoporous materials with different pore geometries. In a similar study, the rate of proton diffusion from a liquid surrounding the mesoporous nanoparticles into the pore system of AMS-n was also assessed. The results show that the diffusion coefficients for the proton absorption process are higher than those for the release of the surfactant template molecules, with more complex 3D mesocaged particles showing the highest diffusion coefficients in both cases.

Finally, the quantity of CO2 adsorption was measured by modifying the internal surfaces of mesocaged material with n-propylamino groups. Results show that the cage-connecting window sizes limit the surface coverage of n-propylamino groups by pore blocking and affect the volume of CO2 adsorption. In addition, at the molecular level, CO2 adsorption shows physisorption or chemisorption depending on the localized distribution of n-propylamino groups, as studied by in-situ infrared spectroscopy.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. 82 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 733
National Category
Materials Engineering
Research subject
Materials Science
Identifiers
urn:nbn:se:uu:diva-122289 (URN)978-91-554-7786-8 (ISBN)
Public defence
2010-05-21, Siegbahnsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2010-04-28 Created: 2010-04-07 Last updated: 2010-05-18
2. Drug Diffusion and Nano Excipient Formation Studied by Electrodynamic Methods
Open this publication in new window or tab >>Drug Diffusion and Nano Excipient Formation Studied by Electrodynamic Methods
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

New smart drugs demand new smart drug delivery systems and also new smart analysis methods for the drug delivery process and material characterization. This thesis contributes to the field by introducing a new electrodynamic approach for studying the drug diffusion proc-esses as well as the formation of a new type of drug delivery systems, the so called mesoporous nano excipients.

Drug diffusion processes from different pharmaceutical materials were examined. The transport of charged drug substances was investigated by electrodynamic methods; either as a release process governed by diffusion using the alternating ionic current method or by applying a voltage, sinusoidal or dc, to force the drug ions to move in an electric field.

Temperature-dependent drug release from microcrystalline cellulose tablets was examined in order to extract information about the diffu-sion process. Percolation theory was also employed to binary mixtures of an insoluble and electrically insulating matrix material together with a soluble and ionic conducting drug. Further, dielectric spectros-copy was proven to be a powerful method for examining the state of vesicle formation of drug and surfactant molecules in a carbopol gel. Finally, a new potential class of pharmaceutical materials were exam-ined, namely the AMS-n mesoporous materials, showing that the al-ternating ionic current method is powerful both in the study of the synthesis of and in the release process from these.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 73 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 293
Keyword
Functional materials, drug release, electrodynamic methods, diffusion, Funktionella material
Identifiers
urn:nbn:se:uu:diva-7818 (URN)978-91-554-6864-4 (ISBN)
Public defence
2007-05-07, 2001, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:00
Opponent
Supervisors
Available from: 2007-04-13 Created: 2007-04-13 Last updated: 2015-09-11Bibliographically approved

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Brohede, UlrikaAtluri, RambabuGarcia Bennett, AlfonsoStrömme, Maria

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