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Modeling of biologically relevant lipid multilayers in the context of drug delivery
Saija, Maria Chiara ; Cwiklik, Lukasz (advisor) ; Szczęsna-Iskander, Dorota (referee) ; Heyda, Jan (referee)
Understanding the topical drug delivery at basic physico-chemical and biophysical levels is still challenging. One of the main reasons is the specificity of the processes involved, depending on the delivery target. The tear film lipid layer plays a vital role in ocular health and serves as a target for topical ophthalmic drug delivery. This doctoral thesis investigates two topics related to topical eye delivery, including a case study of drug delivery systems and their major components in the tear film lipid layer, and the effect of a lipid modification on a lipid-associate peptide as a potential drug. This research is conducted by using molecular dynamics simulations, which are comple- mented by various experimental techniques. The research about the drug delivery systems is threefold: the first objective is to study the impact of commonly used preservatives on the tear film lipid layer; the second one is to explore the influence of the latanoprost drug on the tear lipids; the third one is to investigate different drug delivery systems containing latanoprost drug and their interaction with the lipid layer in the tears. These studies are conducted by combining molecular dynamics simulations and the experiments involving the Langmuir-type lipids film. The key findings of this research have practical...
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Theoretical investigation of microporous materials for adsorption and catalysis
Položij, Miroslav ; Nachtigall, Petr (advisor) ; Bludský, Ota (referee) ; Cwiklik, Lukasz (referee)
Theoretical investigation of microporous materials for adsorption and catalysis Microporous materials are defined by a presence of pores with diameter smaller than 2 nm. They comprise a large variety of materials from amorphous materials to very well defined crystalline materials like zeolites or metal organic frameworks. Microporous materials are industrially very important group of materials used for adsorption, gas capture, molecular sieving, or heterogeneous catalysis. Zeolites are by far the most important group of microporous materials due to their use as catalysts for the petroleum cracking. One of the main limitations of the zeolite use in catalysis is their limited pore size. This obstacle can be solved by use of hierarchical zeolites with a secondary mesopore network which allows overcoming the diffusion problems. The aims of this study can be divided into two parts. In the first part, the structures of two-dimensional and hierarchical zeolites were investigated theoretically to identify the structure of new materials and to obtain reliable models to study the hierarchical zeolites. In the second part, the catalytic properties of several microporous materials were modelled to explain their experimental activity. The results of this thesis were used to identify the structure of a large...
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Theoretical Investigation of Properties of 3D and 2D Zeolites
Ho, Viet Thang ; Nachtigall, Petr (advisor) ; Fišer, Jiří (referee) ; Cwiklik, Lukasz (referee)
Zeolites have been widely used in many different fields including catalysis, adsorption and separation, ion exchange, or gas storage. Conventional zeolites have three- dimensional (3D) structures with microporous channel system; typical pore sizes are well below 1 nanometer, therefore, diffusion limitation plays important role in many process and bulkier reactants (or products) cannot enter (or leave) the zeolite channel system. Two-dimensional (2D) zeolites prepared in last years can lift all diffusion limitation and they thus offer a very attractive alternative to conventional 3D zeolites. 2D zeolites attracted considerable attention on the experimental side; however, understanding of 2D zeolites based on computational investigation or on a combination of experimental and computational investigation is limited. A motivation for the computational work presented here is to improve our understanding of properties of 2D zeolites based on computational investigation. The originality of the research presented herein is in the strategy: we carried out systematic investigation of properties of corresponding 2D and 3D zeolites and we focus on the identification of similarities and differences. The most important zeolite properties, i.e., presence of Brønsted and Lewis acid sites, are investigated. A number of...
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Clustering of aqueous aminoacids and similar molecules in the presence of phospholipid monolayers
Kukharchuk, Alexandra ; Cwiklik, Lukasz (advisor) ; Berka, Karel (referee)
Amino acid phenylalanine plays a key role in numerous biological processes and is also involved in amyloid fibril diseases. The aim of the thesis is to deepen our understanding of its behavior and partitioning at interfaces, and to investigate its clustering. Classical atomistic molecular dynamics simulations were performed for phenylalanine and three other aromatic molecules which chemical structure is derived from it - phenylglycine, phenylacetic acid and tyrosine. Molecules are simulated at both water-air and at water-DPPC-air interfaces. Phenylalanine, phenylglycine and phenylacetic acid demonstrate surface activity at the water-air interface, whereas tyrosine is not surface active. All molecules interact with the lipid monolayer at the water-DPPC-air interface but only phenylalanine penetrates deep into the monolayer. Formation of transient clusters is observed in the interfacial regions, mostly for phenylalanine. Powered by TCPDF (www.tcpdf.org)
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Does oxidation make the organic aerosol coatings more hydrophilic? Insight from molecular dynamics study of oxidized surfactant monolayers
Roeselová, Martina ; Khabiri, Morteza ; Cwiklik, Lukasz
Organic compounds are ubiquitous in atmospheric aerosols. The morphology and structure of the organic phase affect the optical properties of the aerosols, their heterogeneous reactivity as well as their ability to nucleate cloud droplets and ice particles. It is commonly assumed that atmospheric oxidative ageing of the organic material, leading to the formation of polar groups such as carbonyl (=O), hydroxyl (-OH) and carboxylic acid (-COOH), will render the aerosol particle surfaces increasingly more hydrophilic, hence, able to take up more water. Field measurements have shown that a large fraction of the organic material found in aerosols are surface active compounds, such as fatty acids and lipids(Tervahattu, 2002 and 2005). An inverted micelle structure, with an aqueous core surrounded by an organic surfactant layer, has thus been proposed for aqueous aerosols, both marine and continental (Donaldson, 2006). While recent experiments suggest the existence of more complex structures, such as organic inclusions and surfactant lenses (Dennis-Smither, 2012), a monolayer (ML) of surface active organics on an aqueous subphase (the so called Langmuir monolayers) represents the basic model system used in laboratory studies aimed at elucidating the effect of oxidative processes on structural properties of organic coatings on aerosol particles. In our previous work, we used molecular dynamics computer simulations to study the structure and stability of oxidized phospholipid MLs (Khabiri, 2012). In this contribution, we employed the molecular dynamics simulation technique to investigate – with atomistic resolution – structural changes occuring in a fatty acid ML upon moderate degree of oxidation.
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