[Show abstract][Hide abstract] ABSTRACT: The present thesis examines the effects of incorporating biomolecules into self-assembled
nanostructures. This approach is exemplified by short DNA molecules in
environments close to lipid bilayers and the immobilization of enzymes into
mesoporous silica particles. The biomolecules and attached chromophore probes are
studied in the nanostructures using optical spectroscopy. An important part of the
thesis work is the spectroscopical considerations enforced by the complex samples
formed by the biomolecules and the nanostructures. The small confining spaces rich
in surfaces have effects on the physical properties of the nanostructures.
The movement of the large biomolecules are hindered by the narrow
environments and this is utilized for electrophoretic separation and orientation of
oligonucleotides in lyotropic liquid crystals. The cubic phase of the monoolein-water
system was shown to act as an electrophoresis matrix for both water soluble
oligonucleotides and bilayer anchored molecules. The lamellar phase of the sodium
octanoate-decanol-water system was used to introduce macroscopic ordering of
oligonucleotides and bilayer bound chromophores for studies by linear dichroism. In
addition to the orientational effects of the chromophores interacting with the lipid
bilayers, spectral effects of the bilayer environment were also studied.
In the spectroscopic studies of enzyme immobilized into mesoporous silica
particles the pore pH were found to be slightly different compared to the external
volume. Furthermore, direct spectroscopic determination of the pore loading was
examined in contrast to common indirect approaches. Finally, the concept of pore
filling as an analysis tool and the particle size influence on immobilization are
[Show abstract][Hide abstract] ABSTRACT: Since the discovery of microemulsions by Jack H. Shulman, there have been huge progresses made in applying microemulsion syst ems in a plethora of research and industrial processes. Microemulsions are clear, stable, isotropic mixtures of oil, water and surfactant, frequently in combination with a cosurfactant. Microemulsions are optically isotropic and thermodynamically stable liquid solutions of oil, water and amphiphile. To date microemulsions have been shown to be able to protect labile drug, control drug release, increase drug solubility, increase bioavailability and reduce patient variability. Furthermore, it has proven possible to formulate preparations suitable for most routes of administration. Since the discovery of microemulsions, they have attained increasing significance both in basic research and in industry. Due to their unique proper ties, namely, ultralow interfacial tension, large interfacial area, thermodynamic stability and the ability to solubilise otherwise immiscible liquids, uses and applications of microemulsions have been numerous. Microemulsions are readily distinguished from normal emulsions by their transparency, low viscosity and more fundamentally their thermodynamic stability. Microemulsions are shown to be effective dermal delivery mechanism for several active ingredients for pharmaceutical and cosmetic applications. Topical microemulsions allow rapid penetration of active molecules due to the large surface area of the internal phase, and their components reduce the barrier property of stratum corneum. Microemulsions thereby enhance dermal absorption compared with conventional formulations and are therefore a promising vehicle due to their pot ential for transdermal drug delivery.
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