|
|
Effect of iron oxide nanoparticles with ascorbic acid on neural stem cells
Jiráková, Klára ; Moskvin, Maksym ; Horák, Daniel ; Jendelová, Pavla
Cells labelled with iron oxide nanoparticles (ION) can be tracked by magnetic resonance imaging (MRI) in several applications. However, various studies demonstrated toxicity and oxidative stress induction associated with nanoparticles exposure. We analysed biologic effects after the exposure of two types of iron oxide nanoparticles (with and without an antioxidative agent, an ascorbic acid) on human neural stem cells. The labelled cells in gel phantoms were detected in MRI and they showed decreased relaxation rates in comparison with control. ION slightly decreased cell proliferation in comparison with unlabelled cells, which was dependent on concentration and presence of ascorbic acid. None of the nanoparticle type showed negative effect on cell viability and both demonstrated minor effect on reactive oxygen species (ROS) formation. Unfortunately, ascorbic acid bound to nanoparticles did not show any effect on ROS attenuation. Cells exposed to both types of nanoparticles showed increased positivity for a phosphorylated form of H2AX a marker of double strand breaks. We showed that ION in low concentrations do not affect cell viability, but have negative effect on cells on DNA level. Their potential use for oxidative stress reduction is dependent on the concentration of ascorbic acid bound to the nanoparticles and this should be further increased.
|
|
|
Design and characterization of advanced polymer-coated upconversion nanoparticles
Kostiv, Uliana ; Horák, Daniel (advisor) ; Kaman, Ondřej (referee) ; Brožek, Jiří (referee)
Lanthanide-based upconversion nanoparticles are able to absorb low-energy near-infrared (NIR) photons and emit visible or ultraviolet light. This unique optical property enables luminescent detection without autofluorescence from biological samples that is crucial for bioimaging and diagnostics. Moreover, NIR irradiation allows to deliver light deep into the tissue, which can be used for drug or gene delivery and NIR-induced photodynamic therapy (PDT) of tumors. Despite huge effort during the last 10 years devoted to the upconversion nanoparticle synthesis and their surface engineering, preparation of the particles suitable for biomedical applications still remains a big challenge. The current work is focused on synthesis of the upconversion nanoparticles with controllable morphology, size, distribution, crystallinity, and high upconversion efficiency, as well as on desirable surface modification by biocompatible inorganic or organic polymers. Neat and functionalized homogeneous silica shell was introduced on the NaYF4:Yb3+ /Er3+ and NaGdF4:Yb3+ /Er3+ nanoparticles to enhance their biocompatibility and colloidal stability in water. To render the nanoparticles with targeting moieties, their surface was decorated with cell-adhesive RGD or cell-penetrating TAT peptides. The RGD- and TAT- conjugated...
|
|
|
Preparation of uniform superparamagnetic particles with polymer coating for biomedical applications
Patsula, Vitalii ; Horák, Daniel (advisor) ; Sysel, Petr (referee) ; Matějíček, Pavel (referee)
Aim of this thesis was to design and prepare polymer-coated monodisperse Fe3O4 nanoparticles as a safe and non-toxic contrast agent for magnetic resonance imaging (MRI) and heat mediator for hyperthermia. Uniform superparamagnetic Fe3O4 nanoparticles were synthesized by thermal decomposition of Fe(III) oleate, mandelate, or glucuronate in high- boiling solvents at temperature >285 řC. Size of the particles was controlled in the range of 8- 27 nm by changing reaction parameters, i.e., temperature, type of iron precursor, and concentration of stabilizer (oleic acid and/or oleylamine), while preserving uniformity of the nanoparticles. Because particles contained hydrophobic stabilizer on the surface, they were dispersible only in organic solvents. To ensure water dispersibility, oleic acid on the particle surface was replaced by hydrophilic and biocompatible methoxy-poly(ethylene glycol) (PEG) and poly(3-O-methacryloyl-α-D-glucopyranose) by ligand exchange. Polymers were previously terminated with anchoring-end groups (hydroxamic or phosphonic) to provide firm bonding to iron atoms on the particle surface. Fe3O4 nanoparticles were also hydrophilized by encapsulation into a silica shell by reverse microemulsion method. Tetramethyl orthosilicate was used to prepare Fe3O4@SiO2 nanoparticles, which were...
|
|
| |
|
|
Superparamagnetic nano- and microparticles with hydrophilic surfaces
Babič, Michal ; Horák, Daniel (advisor) ; Šňupárek, Jaromír (referee) ; Šafařík, Ivo (referee)
This work deals with a preparation of superparamagnetic nano- and microparticles with hydrophilic surfaces for bioapplications. The wok is divided into three parts in consonance with experimentally solved problem. First part describes a choice and an optimalization of synthesis of iron oxides nanoparticles with appropriate toxicological, morphological and physico-chemical properties, which surface can be post synthetically modified. Maghemite - γ-Fe2O3 particles were prepared by consequent oxidation of mangnetite - Fe3O4 as an initial substance for a preparation of materials for diagnostics and separations. A conventional alkaline coprecipitation method of magnetite preparation was modified to produce nanoparticles with narrowed size distribution without use of surfactants during their synthesis. Prepared maghemite nanoparticles were cca. 6 nm in diameter and their saturation magnetization was Ms ~ 70 A·m2 ·kg-1 . Such observed value is far higher in comparison with the state of the art and argues thus a proposition the Ms depends not on the preparation method, but only on the nanoparticles size. Maghemite nanoparticles morphology was evaluated by picture analysis of SEM and TEM micrographs, hydrodynamic size and zetapotential was measured with DLS. The structure of the maghemite was confirmed with...
|
|
|
Preparation and characterization of superparamagnetic inorganic/polymer particles for biomedical application
Zasońska, Beata Anna ; Horák, Daniel (advisor) ; Šafařík, Ivo (referee) ; Sysel, Petr (referee)
Superparamagnetic -Fe2O3 nanoparticles were synthesized by coprecipitation of ferric and ferrous salts with a base. Resulting nanoparticles were coated with shells, such as poly(N,N- dimethylacrylamide) (PDMAAm), neat and functionalized silica (SiO2 and SiO2-NH2), and polyaniline (PANI). PDMAAm shell was introduced by modification of iron oxide nanoparticle surface with an initiator and N,N-dimethylacrylamide was polymerized producing -Fe2O3&PDMAAm core-shell particles. In case of SiO2-NH2 shell, tetramethyl orthosilicate was used to yield -Fe2O3&SiO2 nanoparticles, which were subsequently modified by (3-aminopropyl)triethoxysilane to prepare γ-Fe2O3&SiO2-NH2 particles. Oxidation of aniline hydrochloride with ammonium persulfate in an aqueous solution of poly(N-vinylpyrrolidone) in the presence of iron oxides produced -Fe2O3&PANI nanoparticles. Finally, the last type of the particles was based on thionin-modified poly(carboxymethyl methacrylate) (PCMMA&Th). The particles were characterized by techniques, such as scanning and transmission electron microscopy (SEM and TEM) and dynamic light scattering (DLS) to determine the particle morphology and hydrodynamic diameter. The presence of the functional groups, chemical composition, and the iron content were investigated by Fourier-transform...
|
|
|
Plasmid DNAs interactions with lanthanoide compounds
Budko, Kateryna ; Horák, Daniel (referee) ; Rittich, Bohuslav (advisor)
Recently much attention is given to lanthanides and their complexes as excellent catalysts for cleavage of nucleic acids. The thesis has been focused on the cleavage of plasmid and bacterial DNA by ions Nd3+ and Y3+ and by different carriers containing the lanthanide compounds. The creation of single-stranded nicks and double-stranded ones in the plasmid DNA molecules was studied by agarose gel electrophoresis. Verification of the cleavage of bacterial DNA was made by polymerase chain reaction using primers specific for the domain Bacteria and genus and species-specific primers. The results will be used in the development of the method that will allow perfect carriers`s coverage verification with the magnetic perovskit nucleus and other carriers with the lanthanide compounds.
|
|
|
Preparation and Characterization of Magnetic Carriers from Hypercrosslinked Polystyrene Microspheres and their Application in a Biosensor.
Šálek, Petr ; Šňupárek, Jaromír (referee) ; Šafařík,, Ivo (referee) ; Horák, Daniel (advisor)
With the aim to develop and characterize a functionalized highly magnetic polymer carrier of micrometer size and of a narrow particle size distribution that will be suitable for biological application, hypercrosslinked microspheres were prepared. Simultaneously, the relation between structure and properties of product was observed. Condition of dispersion polymerization were optimized to obtain starting monodisperse poly(styrene-co-divinylbenzene) [P(St-DVB)] microspheres. The P(St-DVB) microspheres of different degree of crosslinking were prepared and effect of some polymerization parameters such as type of solvent, initiator, concentration and mode of DVB addition on morphology, size and particle size distribution were investigated. The starting microspheres were hypercrosslinked to obtain microporous inner structure. Hyperosslinked particles had very large specific surface area (> 1000 m2/g) and a high content of micropores (ca. 0.6 ml/g). First, P(St-DVB) microspheres were chloromethylated using three different chloromethylation agents to regulate their porous properties. Hypercrosslinking was achieved by the addition of stannic chloride as a catalyst and by increasing a temperature. The hypercrosslinked microspheres were then functionalized with sulfo- or aminogroups. The functional groups captured precipitated iron oxide inside the porous structure of the microspheres and also served as a reactive site for intended immobilization of the protein. A solution of ferrous and ferric chloride was imbibed under vacuum into the porous structure and the iron oxide was precipitated by an aqueous ammonia solution. Finally, the magnetic functionalized hypercrosslinked micropsheres were integrated into a biosensor for qualitative detection of ovalbumin.
|
|
|
OpenSource SW for data traffic inspection
Horák, Daniel ; Stančík, Peter (referee) ; Hajný, Jan (advisor)
This work deals with a usage of free and open software for filtering of network traffic and its installation in network gateway in small and middle-sized networks. Main focus is on filtering the http protocol on the level of a application layer. At the start a problems of free and open software is analyzed along with its advantages that result from its usage.There are as well given reasons for choosing the Debian GNU/Linux distribution. Further there are discussed possibilities of filtering network traffic on packets level and status filter along with the soft- ware iptables. Main part focuses on a filtering of http traffic on the application layer level using program Squid and DansGuardian. In a practical part the installation and configuration of operating system Debian GNU/Linux is presented including base services (ssh, DNS and DHCP server). Further more there are installations and configurations of softwares Squid and DansGuardian demonstrated. For DansGuardian there is a web configuration interface created.
|
|
|
Automated system for installing and configuring GNU/Linux virtual hosts
Horák, Daniel ; Polívka, Michal (referee) ; Pelka, Tomáš (advisor)
This work deals with possibilities of administration of virtual machines (mainly from the developer's point of view) and available methods for automatic installation of GNU/Linux distributions. First part contains the information about virtualisation technologies and possibilities to configure them with a libvirt library. The definition and specification of each part of virtualisation environment (virtual machines, disks, networks) using XML is described. Further more the possibilities of automatic installation of Linux distributions based on RedHat and Debian considering the virtualisation environment are discussed. The possibility of copying an existing disk with installed system is also mentioned. In a practical part a server application for control and management of virtual machines including automatic installation of operating system is proposed and realised.
|
guest ::
RSS feed.