Studentská vědecká konference

The recent advancements in drug delivery systems have provided promising alternatives in administering pharmaceutical compounds. Specifically, niosomes have the capability of improving bioavailability, stability and controlled delivery of the drug. These self-assembled structures consist of hydrophilic and lipophilic regions in which the active pharmaceutical ingredient (API) can be entrapped. The preparation of niosomes was extensively studied and tested by various methods and conditions. Based on their characterization, which was done by microscopic analysis (SEM, TEM, and cryo-TEM) and light scattering techniques (DLS, DDLS, and SLS), we were able to select optimal formulations required for the encapsulation of an API and metallic nanoparticles. Drug-based niosomes were prepared and analyzed by UV-Visible spectrophotometric method to understand the incorporation and encapsulation efficiency of the drug. Gold and iron oxide nanoparticles have proven to be effective in cancer therapy and diagnostic tools due to their unique properties. Their encapsulation in niosomes produces a hybrid nanocarrier system, combining the benefits of both nanoparticles. This work discusses the preparations of such niosomal systems and their applications in drug delivery technology.

Catalytic monolith converters and particulate filter are devices used in automotive exhaust gas aftertreatment. Purpose of catalytic converters is to abate gaseous pollutants such as CO, nitrogen oxides (NO_x) and hydrocarbons. Particulate filter traps soot and ash particles present in the exhaust gas. Recent efforts aim on making the whole system more compact. One way to accomplish this is to coat catalytic material directly into the filter as on-wall layer or inside the porous wall. This arrangement saves space, weight and cost of the device, reduces overall heat losses and simplifies soot combustion in contact with the catalyst. On the other hand, distribution of the catalytic material must be optimized to meet the antagonistic requirements – low pressure drop and at the same time high filtration efficiency and conversion of gas pollutants. In this work, I study the influence of inlet concentration of reactants and distribution of catalytic material on the overall CO conversion. For the purpose of this work, I use micro-scale 3D-CFD model of porous catalytic filter with nonlinear Langmuir-Hinshelwood kinetics developed in OpenFOAM. The results show sensitivity of the light-off temperature to both gas composition and catalyst distribution in the filter.  

Automotive catalyst is nowadays an inherent part of the exhaust gas after-treatment systems for combustion engines. During the internal combustion, there is not only the formation of non-toxic gases, but also traces of toxic and polluting substances like carbon monoxide (CO), unburned hydrocarbons, nitrogen oxides (NO_x) and particulate matter (PM). Aiming on decrease the emissions of these harmful gases, sophisticated devices as the three-way catalyst have been created. One of the most important reactions is the oxidation of carbon monoxide into carbon dioxide (CO₂). The purpose of this work is to understand how the flow distribution of the inlet mixture can affect CO oxidation in catalytic monolith. The experiments were performed using a special computer-controlled apparatus constituted by a reactor containing a flow distributor and samples of the catalytic monolith, accompanied by analysers, mass-flow controllers and multi-way valve for rapid switching of lean and rich reaction mixtures. CO light-off curves measured with and without several different flow distributors are compared and effects of non-uniform flow distribution on CO conversion are discussed.

This work deals with development and validation of in vitro dissolution method for an intramuscular depot suspension. Such pharmaceutical formulation is injected into a muscle in a form of a prodrug, which is a substance similar to an API (active pharmaceutical ingredient) with no pharmacological effect on a human body. A depot of solid prodrug particles is formed at the site of administration, which gradually dissolves into the tissue fluid. In a liquid phase, the prodrug is converted to the API by enzymes, which are naturally present in a human body. The API is subsequently transported via blood circulation to the site of action. This research deals with design of the dissolution method, which is an experimental setup that mimics the described process under in vitro conditions and allows us to measure the API release kinetics. This dissolution method is part of generic drug development and can also be used for the drug quality control. Various types of dissolution methods were developed for particular depot suspension along with an analytical method to determine the concentration of the API and prodrug. Furthermore, computer simulation was created, which describes the dissolution kinetics of the suspension based on particle size distribution and their specific surface area.  

The amorphization of APIs (Active pharmaceutic ingredients) keeps being an important topic for pharmaceutic companies.  The main reason is that the majority of newly discovered APIs are poorly soluble. Preparing them in an amorphous state is a way how to make them dissolve faster. Another reason is that the amorphous form cannot be patented and thus provides a possibility for generic companies to avoid patent collisions. Amorphization in the mesopores of silica particles can be an efficient approach to future drug formulations. The small pores prevent loaded drug from crystallizing, the high specific surface (>1000 m²/g) further promotes dissolution, and the thermal and mechanical stability and biocompatibility make the utilization for oral dosage forms highly desirable. Loading of API into the silica particles can be done by a variety of methods, for example by melt loading, equilibria loading from a solution or by solvent evaporation loading. In this work, the solvent evaporation method is explored in detail in order to obtain general guidelines for the preparation of silica drug formulations in the future. The prepared samples were evaluated by a variety of analytical methods and their dissolution rate was measured and compared with crude API.  

Bone grafting is a widely adopted clinical technique with over 2 million cases every year. It is used for the treatment of wounds that require structural support for the injury to heal properly, followed by a subsequent resorption or a permanent placement of the graft.  However, the clinical limitations have been reached with regards to large defects. The incorporated graft, which acts as a cellular scaffold, has to provide a sufficient means for vascularisation and transport of substances both in and out of the structure to prevent necrosis. This places certain requirements on the scaffold surface and porosity as well as the material rate of resorption.  The utilisation of 3D printing presents a possible solution to this problem. Using bioresorbable poly(ε-caprolactone) (PCL) polymer, patient-specific structures can be created and enhanced by the addition of hydroxyapatite (HA) particles. This study is aimed to describe the properties and processing parameters of PCL/HA scaffolds created using the 3D printing technique and evaluate their dependency on the hydroxyapatite content.  

In recent years, significant progress has been made in the research of liquid marbles. However, currently, liquid marbles are prepared by manually dripping the liquid onto a layer of powder particles. The aim of this work is to make the fabrication of liquid marbles automated in order to allow larger-scale applications. For the production of liquid marbles and especially for pharmaceutical applications, monodisperse droplets of liquid are required in order to ensure that the content of active pharmaceutical ingredient and the dissolution rate are consistent. In this study, the options of dividing flow and thus using a single pump to drive multiple nozzles are investigated. Furthermore, comparison of different pumping principles was made for dripping and jetting. Moreover, a drop-on-demand system was tested. The effects of a thin wire connected to the nozzle was examined as a potential way to decrease droplet size in the dripping regime. The experiments were carried out using viscous glycerol-water mixtures and a polymer melt. The droplet diameter was measured with a high-speed camera and subsequent image analysis.