čas: 21.4.2021 19:08:09
Obnovit | RAW
List of available PhD theses
Advanced formulation approaches for topical delivery
Although skin appears to be a macroscopically homogeneous and biologically passive structure, it is exactly the opposite: it is incredibly heterogeneous both chemically and structurally, and it is host to a diversity of active cells such as macrophages and bacteria. Traditional approaches to topical delivery have relied on relatively simple systems such as passive diffusion from water- or oil-based solutions or creams/gels. The aim of this project is to investigate bioactive transport as a mechanism for topical delivery and find a solution to such molecules as therapeutic peptides, which are known to be extremely challenging to formulate and delivery to the body. This project will explore the use of drug delivery systems that are actively phagocytised for targeting macrophages residing in the skin. These drug delivery systems will include naturally sourced polysaccharide shells or lipidic vesicles obtained from single-cell organisms. Their mild immunogenicity, biocompatibility and ability to encapsulate a broad range of molecules will be utilized for the formulation of APIs that have proven to be challenging by traditional means.
Design and application of supra-lipidic structures
The gastro-intestinal transit, emulsification, digestion and absorption of lipidic components from food is crucial not only from the nutritional point of view but also for the dissolution and absorption of many drugs, and therefore their bioavailability. An increasing number of active pharmaceutical ingredients (APIs) that enter the drug development process are highly lipophilic, which makes their bioavailability susceptible to patient-specific dietary habits and often leads to undesired phenomena such as positive food effect. For some APIs, the bioavailability can be up to five times higher when taken on a full stomach compared to bioavailability in the fasted state. The aim of this project is to develop a formulation platform that would make the dissolution, absorption and pharmacokinetics of lipophilic APIs independent of food intake, while not containing a large amount of lipids in the formulation itself. The idea is to create particles that “look like lipids” on the outside but their volume contains predominantly the API or other excipients. Such structures can include e.g. drug suspensions encapsulated in giant liposomes or their aggregates, drug nanocrystals coated by a phospholipid monolayer, or drug-loaded mesoporous silica particles encapsulated within a lipid bi-layer. These elementary structures can also be combined, carrying e.g. several different APIs, functional excipients for absorption enhancement, or pH modifiers that can further reduce patient-to-patient variability.
Development of 3D cell cultures for the evaluation of drug delivery systems
Development of scaling-up methods of industrial mechanically agitated reactors
Fermenters or, in general, mechanically agitated aerated vessels are frequently used in industry for the intensification of gas-liquid mass transfer, especially in the case of a low gas to liquid volume ratio. Industrial processes as aerobic fermentations, hydrogenations and chlorinations can serve as examples of their application. In many processes the gas-liquid interfacial mass transfer becomes the rate determining step, so the volumetric mass transfer coefficient becomes the key parameter in the design. Mass transfer laboratory pays many year effort to gas-liquid mass transfer measurement in mechanically agitated gas-liquid dispersions with the aim to formulate the scaling-up rules for industrial vessels design. In the frame of this research an extensive experimental work has been done using various batch types (coalescent, non-coalescent, viscous) and for various impeller types (from purely axially pumping to purely radially pumping ones) and their combinations. After collecting large data series in laboratory scale vessels, experimental work continues using pilot-plant vessel equipped with a modern computer controlled regulation and data acquisition system in the form used also in industry. The aim of the PhD work is to collect the transport characteristics (impeller power, gas hold-up and volumetric mass transfer coefficient, kLa) measured in the pilot-plant vessel using various types of impellers (e.g., Rushton Turbine, Lightnin, Techmix, Pitched Blade impellers). The experimental research will be now focused to the transport characteristics in viscous batch and in the presence of solid particles. Both high viscosity and solid particles presence are typical features of industrial fermentation broths. Based both on the laboratory data and on the pilot-plant data the scaling-up rules will be formulated, which will be employable for industrial gas-liquid contactors design. A PhD student will get acquainted with the design methods of other gas-liquid and vapour-liquid processes as well, because he/she will work in the team dealing also with the absorption columns, distillation columns and ejector bubble columns design. More info: Tomáš Moucha, UCT building B, ground floor, room No. T02a, phone: 220 443 299, e-mail: firstname.lastname@example.org
Erosion-controlled drug release from super-placebo tablets
The rate of drug release from a pharmaceutical tablet is one of its most important quality attributes. As an ever-increasing number of Active Pharmaceutical Ingredients (APIs) are developed in alternative solid-state forms such as metastable polymorphs, co-crystals or amorphs, it is desirable to control the rate of drug release by the properties of the tablet matrix rather than by the properties of the API itself. The aim of this project is to explore the so-called “super-placebo” concept, i.e. tablets that erode in a defined way which is independent of the API they contain. The project will systematically explore the relationship between the rate of tablet erosion, the proportion of soluble and insoluble excipients (e.g. mannitol, microcrystalline cellulose), and the manufacturing process parameters (e.g. compaction pressure). The ability to control drug release rate will be demonstrated using several real-world APIs. Advanced instrumental methods such as Magnetic Resonance Imaging, x-ray micro CT and high-speed video-imaging will be used in order to gain a deep understanding of the underlying tablet erosion mechanisms.
Formulation and bioavailability of natural poly-actives
Current paradigm in pharmaceutical drug development and its regulatory environment is based on the concept of Active Pharmaceutical Ingredient (API) as a well-defined single molecular entity that is contained in the dosage form at a precise quantity and chemical purity. Although rational in many ways, this approach is rather different from evolution-proof substances found in Nature. The main drawback is single-API medicines is the development of drug resistance over historically extremely short time periods (only a few decades), which is problematic not only in the area of antibiotics but also in cancer treatment, anti-fungal and various anti-parasitic drugs that gradually lose their effectiveness. In contrast, there are examples of natural systems that maintain their efficacy for many millennia. Perhaps the most prominent example of such material is bee propolis. Chemically, propolis is a mixture of several hundred chemical species with location- and season-dependent composition, which would completely disqualify it as a registered medicinal substance. However, it is exactly this variable multi-component character that makes is so robust and durable, not giving pathogens a chance to develop resistance. Propolis contains both water-soluble and water-insoluble components and is typically applied as ethanol dispersion only for surface treatment. The aim of this project is to explore formulation approaches that could enable oral administration of propolis and ensure its safety and bioavailability. The project is multidisciplinary and will include not only formulation and analytical work, but also in vitro and in vivo testing of biological efficacy.
High-throughput development and continuous manufacturing of SMEDD systems
Self micro-emulsifying drug delivery systems (SMEDDS) are formulations that spontaneously form a mini- or micro-emulsion upon contact with water. They typically contain the active pharmaceutical ingredient (API), a mixture of oils or low-melting lipids in which the API is soluble, and one or more surfactants and co-surfactants. SMEDDS are complex ternary or higher-order mixtures whose phase behaviour and properties are notoriously difficult to predict at present. Therefore, the development of SMEDDS is to a large extent an empirical process. Due to a large number of formulation components and their possible ratios, it is rarely possible to completely cover the entire design space, which may lead to sub-optimum formulations or even a false rejection of a particular API as non-formulatable. The aim of this project is to construct a device and develop a methodology for automatic combinatorial screening of SMEDDS formulations and their continuous manufacturing based on the so-called liquid marbles. The project will build on a recently developed patented device called “Marblemat” and extend its capabilities towards combinatorial mixing of formulation components and serial production of liquid marbles with systematically varying composition. Simultaneously, capability for high-throughput testing of the formulation properties such as mechanical strength, temperature stability and dissolution properties will be implemented and demonstrated on several industry-relevant APIs.
Mathematical modeling of microfluidic devices for separation of racemic
Microfluidic devices are characterized by a large ratio of interfacial area to internal volume. This can be used in chemical separations by extraction or membrane processes. Separation of optically active substances, often important pharmaceutical or food products, at membranes or sorbents with anchored chiral selectors represents a great challenge for chemical engineers. Mathematical modeling can lead to a better understanding of complex processes in such devices and consequently to the design of efficient microfluidic separators. The main objectives of the PhD project are: Based on preliminary and available experimental data, a mathematical-physical description of mass and momentum transport in microfluidic devices with anchored chiral selectors will be developed. Mathematical models of processes on different spatial scales will be created. They will include description of transport of the separated chemicals by diffusion, convection and electromigration. Models will be analyzed numerically. Parameter values that ensure high separation efficiency and high productivity of the microfluidic system will be searched in the parameter space. The lab is equipped with modern computers. The participation of the doctoral student in grant projects and active participation in international scientific conferences is expected.
Micro-cybernetics and Micro-robotics in chemistry
The topic of the work is focused on the development and management of the so-called microrobots and their formations. The project is based on cooperation with the Institute of Chemical Engineering, where they have been dealing with the movement of microparticles for a long time. The work assumes (i) the study of advanced methods of electron microscope image analysis, (ii) the design of specific methods and algorithms for guiding, controlling and optimizing the path of motion of microrobots and (iii) the implementation and verification.
Microfluidic systems for the synthesis and separation of optically active
Microfluidic reactors and separators are modern devices that represent an alternative to conventional batch and flow systems used in biotechnology. The small spatial scale ensures reproducible reaction conditions and intensive mass and heat transfer. Microfluidic devices generally lack moving parts and allow easy combination of many unit operations such as mixers, separators, reactors. The main objectives of the PhD project are: Study of kinetics of selected enzymatic reactions, which lead to production of optically active chemicals that are used in pharmacy, food industry or synthesis of chemical specialties. Design and fabrication of microfluidic separators with embedded membrane or sorbents with attached chiral selectors for separation of racemic mixtures. Testing of manufactured microfluidic devices for selective separation of selected optically active compounds. Evaluation of the possibility of accelerated transport of optically active substances through membranes by means of an imposed electric field. The lab is equipped with technologies for the production of microfluidic systems, modern measuring instruments and powerful computers. The participation of the doctoral student in grant projects and active participation in international scientific conferences is expected.
Natural Fibre Reinforced Thermoplactics for Structural Applications
The recent increase in use of woven fibre composites is a direct outcome of technical advances in materials development and manufacturing technologies. This class of composites is of intense interest for applications in operational structures, where durability and damage tolerance are first-rank considerations; thus, understanding damage is of key importance for applications where the ability to maintain structural health during operational life andthusincreasing overall reliability are top priorities. In spite of this, the study of their mechanical properties, in particular the damage resistance of these materials, is still in its infancy, and one of the main sourcesof conservatism in their use is uncertainty regarding damage characterization and failure initiation. Existing work on short (unwoven) vegetal-fibre composites shows that incorporation of vegetal fibres shows great promise. This study will focus on fabrication and failure characterization vianNon-DdestructiveEevaluation (NDE) of an emerging class of laminated composite materials, viz. those based on a thermoplastic matrix reinforced with woven vegetable-based fibre fabric layers. A particular focus will be given to flax fibre fabrics included in a thermoplastic acrylic matrix byvVacuum-aAssistedrResiniInfusion (VARI). Such composites have the following advantages: i) the use of bio-based and biodegradable fibres as replacement for conventional synthetic fibres, ii) the use of a recyclable matrix by crushing/reshaping or depolymerisation, iii) therRoom-tTemperature (RT) manufacturing process that may limit thermal degradation of the flax fibre (including its physicochemical treatment) despite the inherent heat release induced by the matrix polymerization. To reach optimal mechanical properties in terms of stress transfer from matrix to fibre, good fibre-matrix interface compatibilization and adhesion will be required. Once composite manufacturing is optimized, a manufacturability of these materials and their failure during their life cycle will be performed.
Naturally sourced particles for drug encapsulation and delivery
Drug encapsulation into a suitable carrier particle is a common method used in situations where it is possible to either modify the surface properties (e.g. powder flowability or dispersibility in water), to protect the encapsulated component from the environment (e.g. enzymatic digestion in the GI tract) or to control the rate of drug release. Several man-made encapsulation processes are known. However, there are also many natural systems that rely on encapsulation – the cell walls of single cell organisms or their spores, natural particles such as pollen, extra-cellular vesicles, or sub-cellular structures such as vacuoles or other organelles. Some of these structures are highly specific in terms of drug diffusion and its selectivity, or in terms of recognition by cells of the immune system e.g. due to specific shape of the presence of immunomodulatory functional groups on the surface. Yeast glucan particles can serve as a prime example. The aim of this inter-disciplinary project is to investigate the potential of several different types of naturally sourced particles in drug formulation and drug delivery. Both cell-wall derived particles and organelle-based particles will be considered. Special attention will be paid to the process of particle extraction and isolation, as well to the drug encapsulation methodology.
On-line measurement and control of continuous pharmaceutical manufacturing
The manufacturing of pharmaceutical products is typically carried out batch-wise. While this makes sense for products that are manufactured only occasionally in small quantities, batch processes also have several drawbacks. These include excessive dead-times, need for cleaning to avoid cross-contamination, and generally poorer control over the product quality. By switching pharmaceutical manufacturing to a continuous mode, equipment utilisation can be increased theoretically to 100 %, the footprint of the facilities can be substantially reduced, and standard feed-back and feed-forward control schemes applied. A crucial component of continuous manufacturing processes is on-line measurement of key quality attributes such as particle size distribution, composition uniformity of granular blends, or moisture content. Advanced analytical instruments such as Near-Infrared probes can be used for this purpose. The aim of this project is to explore the on-line measurement and control methods for continuous pharmaceutical manufacturing in an industrial setting and combine them with computer simulation tools in order to optimize the overall process robustness and operability.
Polymer-based membranes for highly selective removal of CO2 from biogas
Membrane-based gas separation technology has contributed significantly to the development of energy-efficient systems for natural gas purification. Also CO2 removal from biogas, with CO2 contents exceeding 40% has more recently known rapid growth and development. Major challenge of polymer membranes for gas separation is related to their susceptibility to plasticization at high CO2 partial pressures. CO2 excessively swells the polymer and eases the permeation of CH4, thus reducing the selectivity. Membrane crosslinking is one of the best ways to prevent the plasticization. Mixed matrix membranes (MMMs), consisting of fillers homogeneously dispersed in a polymeric matrix aim at combining the processibility of polymers and the superior separation properties of the porous fillers. Metal-organic frameworks (MOFs) are such materials which have attracted considerable attention due to their tailorable functionality, well-defined pore size, pore tunability and breathing effects. MMMs for biogas upgrading will be prepared with increased permeabilities by choosing proper MOF/polymer combinations and modifying the thermal treatment, employing core-shell MOF materials with high bulk porosity and a selective shell layer.
Preparation of drug delivery carriers for treatment of rheumatoid arthritis
Rheumatoid arthritis (RA) is a chronic autoimmune disorder, mainly affecting joints that are identified by inflammation and swelling of the synovium of the joint. Today, apart from the conventional synthetic disease-modifying antirheumatic drugs (DMARDs), a number of biological DMARDs have been approved. Recently the first targeted synthetic DMARD has also been approved, while other targeted compounds are in the development phase. Particularly interesting is group of drugs which are based on gold complexes. Despite their promising properties, these drugs has low solubility in water and thus low bioavailability. Therefore, within this project we plan to investigate possibility to prepare more soluble compounds of gold complexes using crystal engineering approach as well as formulate these drugs into various nanocarriers. Combination of various preparation and analytical techniques will be used to investigate stability of gold complexes. In the next step we will investigate the impact of encapsulation matrix or complexation partner on the dissolution characteristics of gold complexes.
Process scale-up of pharmaceutical spray drying
Spray drying is versatile method for converting solutions, suspensions or pastes into dry, free-flowing powders in the pharmaceutical, food and nutraceutical industries. During product development, the formulation and process variables are typically optimised using a laboratory-scale spray dryer, and the process is then transferred to a pilot or full manufacturing scale. However, it is notoriously difficult to maintain the same particle properties using spray dryers at different scales, which often necessitated long and expensive trials to be carried out at the large scale. The aim of this project is to develop a robust methodology for spray drying process scale-up in an industrial pharmaceutical setting. The main focus will on the transferability of particle size and particle morphology, as these two parameters are known to be the most sensitive to parameters that vary between the laboratory and the manufacturing scale spray-dryers: the initial droplet size and the drying conditions (temperature, gas flowrate, and residence time in the drying chamber).
Solvent and pH stable membranes with ultra-sharp molecular weight cut-off values
Membrane-based separations currently offer the best strategy to decrease energy requirements and environmental footprint through newly developed solvent resistant nanofiltration (SRNF) or solvent-tolerant nanofiltration (STNF). So-called solvent activation of polymeric membranes involves treatment of an existing membrane by contacting it with solvents or solvent mixtures, which is hypothesized to restructure the membrane polymer through solvatation, increase polymer chain flexibility and organization into suitable structures. This will be verified by systematically treating membranes with different solvents and testing them for the separation of synthetic liquid streams. A high-throughput set-up will be used. Fundamental physico-chemical characterisations of the membranes before and after the treatments will provide insight in the changes at molecular level. The characterization techniques include gas and liquid uptake experiments (diffusivity), PALS (positron annihilation lifetime spectroscopy, to determine free volume element distributions), ERD (elastic recoil scattering, providing elemental analysis in membrane depth profiles), solid state NMR (nuclear magnetic resonance), TGA (thermogravimetric analysis) and DSC (differential scanning calorimetry).
Study of transport characteristics in various types of bioreactors
The production of new biotechnology and pharmaceutical products is based on a bioreactor design. The choice of a suitable type of bioreactor is crucial with respect to maximum yield, but it is also limited by the lifetime of the microorganisms present. The aim of the doctoral study is to compare design parameters (transport characteristics) of three types of the most commonly used bioreactors. The results will be used to characterize the differences and similarities of specific types of bioreactors in terms of gas distribution, mass transfer and mixing depending on the total energy supplied to the system. Transport characteristics will be obtained experimentally for model batches, which will be designed based on physical properties of real broths. Both cooperating departments are well equipped and have all the three types of bioreactors i) mechanically stirred reactor, ii) bubbled column and iii) air-lift reactor. All bioreactors are adapted to measure transport characteristics by the same methods, therefore the results will be comparable. Requirements for applicant: master degree in chemical or mechanical engineering, organic technology, biotechnology etc.; ability for teamwork; systematic and creative approach to scientific problems; interest in experimental work Further information: Assoc. Prof. Tomáš Moucha, building B of UCT Prague, room T02, e-mail: email@example.com
Tailoring of nanostructure in mixed matrix membranes for selective removal of CO2 from biogas
Membrane separation processes belong to modern technologically important separation methods, which are less demanding (economically and ecologically) in comparison with classical separation methods. For the gas separation applications, mainly polymer membranes are used. Their performance (permeability or separation effect) can be additionally adjusted by the targeted embedding of liquid or solid additives into the polymer matrix. The dissertation thesis will focus on the preparation, characterization, and testing of the so-called mixed matrix membranes for the separation of gases based on glassy polymers and functional nano-additives with a purposefully prepared structure. In addition, modeling of the separation process will be part of the work. The result of this work will be prepared and tested membrane material for the effective removal of CO2 from biogas and extension of knowledge in the given membrane field.
The importance of topological indices for determining the similarity of molecules
Using molecular descriptors, it is possible to mathematically describe molecules. This is applied in many fields where it is necessary to look for new substances with specific properties or to predict unknown properties of substances. An important type of molecular descriptors are the so-called topological indices, which characterize a given molecule according to its size, degree of branching and overall shape. The work assumes (i) study of various types of molecular descriptors, especially topological indices (ii) study of correlations of specific topological indices with properties of molecules (iii) comparison of algorithmic complexity for calculation of specific topological indices (iv) implementation of selected algorithms for calculation of specific topological indices.