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Magnetic nanoparticles with antibacterial properties: Synthesis, characterization and biological applications
Shatan, Anastasiia-Bohdana ; Horák, Daniel (advisor) ; Kaman, Ondřej (referee) ; Matějíček, Pavel (referee)
In response to the escalating global threat of antibiotic resistance, innovative strategies are imperative. This thesis focuses on surface-engineered magnetic nanoparticles (MNPs) with potent antibacterial properties, aiming to combat antibiotic resistance effectively. Specifically, uniform 16-nm Fe3O4 nanoparticles were synthesized via oleic acid-stabilized thermal decomposition of Fe(III) oleate in a high-boiling organic solvent. Optionally, 8-nm γ-Fe2O3 particles were obtained by coprecipitation of Fe2+ and Fe3+ salts in a basic medium. For the application of antibacterial MNPs in biological media, water-dispersible nanoparticles were required. Hence, original magnetic particles containing hydrophobic oleic acid (OA) coating were modified with silica using a water-in-oil reverse microemulsion. Subsequent modification with (3-mercaptopropyl)trimethoxysilane and decoration with silver nanoclusters yielded Fe3O4@SiO2-Ag nanoparticles. Additionally, neat Fe3O4 particles were coated with Sipomer PAM-200 containing both phosphate and methacrylic groups, facilitating attachment to the iron oxide and enabling (co)polymerization with 2-(dimethylamino)ethyl methacrylate and/or 2- tert-butylaminoethyl methacrylate. Furthermore, γ-Fe2O3 nanoparticles were rendered antimicrobial through modification with...
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Preparation and characterization of nanoparticles with encapsulated antimicrobial component
Dohnalová, Marie ; Strečanská, Paulína (referee) ; Márová, Ivana (advisor)
This bachelor thesis is focused on the preparation and characterization of particles with encapsulated natural substances with antioxidant and antimicrobial properties. Selected antioxidants were anthocyanins, eugenol and vitamin E, as one of the most powerful antioxidants. At the same time, antimicrobial agents were chosen, in this case eugenol. In the theoretical part, individual active substances, materials for the preparation of particles, methods of their preparation were characterized and the principle of determining the safety of used materials. In the experimental part, selected active substances were characterized and the preparation of particles was optimized. Two types of liposomes were prepared, for which the encapsulation efficiency, size and stability were determined. Also prepared aqueous extracts of blueberries and blackberries were prepared, for which total anthocyanin content has been determined. The extracted substances from the plant material were encapsulated into alginate particles. Furthermore, the gradual release of active substances from particles into model environments using a spectrophotometer was determined. During the gradual release of active substances from the particles, the antioxidant effect was also monitored, in which it was possible to observe a decrease with the passage of time. The antimicrobial effect of active substances and liposomes against model microorganisms Escherichia coli and Micrococcus luteus was also tested. Cytotoxicity tests on human keratinocytes were performed on selected active substances, extracts and prepared nanoparticles, where it was proven that the selected materials are non-cytotoxic. Finally, a proposal for a possible application form in the form of an alginate hydrogel was created.
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Optimization of Combined Chitosan Particles and their Characterization for Application Use
Netopilík, Tibor ; Hudečková, Helena (referee) ; Márová, Ivana (advisor)
The thesis deals with the preparation and characterization of nanoparticles for cosmetic and food applications. The thesis explores various methods of preparing nanoparticles, including liposomes and chitosomes, and analyses their properties and stability in different model environments. The experimental part includes the determination of the encapsulation efficiency of different vitamins by HPLC and UV-VIS spectrophotometry. Results show the influence of various factors such as time, type of environment and method of preparation on stability and efficiency of the nanoparticles. Furthermore, the optimization of the preparation is carried out chitosomes using ultrasound and magnetic stirrer. Cosmetic products enriched with these nanoparticles were developed and their sensory analysis was proved. This work contributes to the understanding of nanoparticle preparation processes and provides useful information for the development of new cosmetic and food products with improved properties and stability.
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Preparation of nanoparticles and nanofibers for application in anti-acne products
Tilšarová, Kamila ; Veselá, Mária (referee) ; Skoumalová, Petra (advisor)
The diploma thesis was focused on the preparation and characterization of nanoparticles and nanofibres with active substances from chosen herbs with the aim to apply this materials to the products against acne. Various types of extracts were tested on the content of polyphenols, flavonoids and antioxidation activity. These extracts were encapsulated to the liposomes and fibres of polyhydroxybutyrate. Prepared liposomes and fibres were tested mainly on antioxidation activity and antimicrobial activity against the strain Propionibacterium acnes. Then, liposomes were applied to cosmetic emulsions. These creams reported high antioxidation activity and excellent stability determined by analytical centrifugation. Prepared nanofibres also reported high antioxidation activity and antimicrobial effect as well. Finally, particles and fibres were tested in contact with human cells. In appropriate concentration, there was no cytotoxic effect and tested materials can be used in applications on problems with acne.
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Study of organs of mice in inhalation experiments
Vrlíková, Lucie ; Diviš, Pavel (referee) ; Dočekal, Bohumil (advisor)
The diploma thesis is devoted to study potential risks for living organisms resulting from inhalation of nanoparticles of chosen heavy metals. The main aim of this work is the investigation of organs from experimental white mice after their guided inhalation of lead nanoparticles. The samples of liver and lungs from these animals are taken in time periods during the inhalation experiments and processed by specific methods for their evaluation. After pressurized microwave assisted decomposition of selected samples of mice organs in high purity concentrated nitric acid the content of lead is determined by atomic absorption spectrometry with electrothermal atomization. Furthermore, the changes are monitored using the microscopy of histological slides stained with hematoxylin-eosin. The results of both approaches are evaluated and compared within the frame of this work.
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Liquid aprotic electrolytes with TiO2 a Al2O3 nanoparticles
Tomeš, Petr ; Krejza, Ondřej (referee) ; Sedlaříková, Marie (advisor)
The first part of this diploma thesis is dealing with conductivity of liquid electrolytes. The second part is about third generation gel electrolytes and thein conductivity. The electrolytes were inorganic salts LiClO4, LiBF4 and NaClO4 in an aprotic propylene carbonate (PC) -used as a solvent. Nanosized Al2O3 and TiO2 particles were, proportionally to the sample's volume, added to the both – blend and gel samples in an amount expressed by weight percentage (wt). Both liquid and gel electrolytes contained following amount on nanosorbent: 3,46% wt, 7,17% wt, 10,0% wt and 12,0% wt. The liquid electrolytes were gelled using commercially available precursor Superacryl (Spofa dental s.r.o.).
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Effect of sub-micrometer structural features on rheology of polymer nanocomposites
Lepcio, Petr ; Chodák,, Ivan (referee) ; doc.Ing.Marián Lehocký, Ph.D. (referee) ; Jančář, Josef (advisor)
Polymerní nanokompozity (PNCs) mají slibnou budoucnost jako lehké funkční materiály zpracovatelné aditivními výrobními technologiemi. Jejich rychlému rozšíření však brání silná závislost jejich užitných vlastností na prostorovém uspořádání nanočástic (NP). Schopnost řídit disperzi nanočástic je tak klíčovým předpokladem pro jejich uplatnění ve funkčních kompozitech. Tato práce zkoumá přípravu polymerních nanokompozitů v modelové sklotvorné polymerní matrici roztokovou metodou, technikou schopnou vytvářet prostorové uspořádání nanočástic řízené strukturními a kinetickými parametry přípravného procesu. Prezentované výsledky popisují rozdíly mezi změnami rheologického chování roztoku polystyrenu při oscilačním smyku s vysokou amplitudou (LAOS) vyvolanými nanočásticemi. Výsledky vedou k závěru, že vysoce-afinní OP-POSS nanočástice při nízkých koncentracích dobře interagují s PS a tvoří tuhé agregáty, zatímco nízko-afinní OM-POSS nanočástice za těchto podmínek neovlivňují deformační chování polymerních řetězců. Dále byla pozornost zaměřena na vliv použitého rozpouštědla na uspořádání nanočástic v SiO2/PMMA a SiO2/PS nanokompozitech, který je v literatuře prezentován jako parametr řídící prostorové uspořádání nanočástic v pevném stavu. Důraz byl kladen na kvalitativní rozdíly mezi „špatně dispergovanými“ shluky nanočástic, které byly na základě rheologie a strukturální analýzy (TEM, USAXS) identifikovány jako polymerními řetězci vázané nanočásticové klastry a dva typy agregátů, jeden termodynamického a druhý kinetického původu. Jednotlivé druhy agregátů se vyznačují odlišnými kinetikami vzniku a rozdílnými vlastnostmi jak mezi sebou, tak v porovnání s dispergovanými nanočásticemi. Pozorované typy disperze nanočástic byly kvantitativně posouzeny podle svých rheologických vlastností během roztokové přípravy, podle kterých byla vyhodnocena míra adsorpce polymeru na povrch nanočástic a atrakce ve vypuzeném objemu. Výsledky byly porovnány s teorií PRISM. Důležitost uspořádání nanočástic byla demonstrována na porovnání teplot skelných přechodů různých struktur při stejném chemickém složení.
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Nanoparticles of platinum metals in the environment
Berka, Michal ; Kučerík, Jiří (referee) ; Komendová, Renata (advisor)
Platinum nanoparticles, mainly released from automotive catalysts, pose a potential risk to the environment. The aim of this bachelor thesis is to investigate the effect of platinum nanoparticles on soil properties at different humidities. Specifically, how nanoparticles affect the stability of hydrogen bridges, the stability of aliphatic crystals, and water retention in soil. For the analysis of relations between platinum nanoparticles, water and soil, a method of thermal analysis was used, namely differential scanning calorimetry. The theoretical part is devoted to the general introduction to platinum metals and nanoparticles. And the preparation of nanoparticles, their characterization and their properties. The result of the experiments is that platinum nanoparticles affect the soil properties relatively significantly.
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The development of ultra-high strength (UHPC) and reactive powder (RPC) composites
Rundt, Lukáš ; Hela,, Vlastimil (referee) ; Hela, Rudolf (advisor)
Bachelor’s thesis studies ultra-high strength concrete and reactive powder composites. In theoretical part there are researched and described properties of raw materials used for their production, mainly additions. Design methodology, processing and types of curing are also studied. Psychical mechanic and durability properties of fresh and hardened concrete are described. In practical part 4 mixtures were designed and prepared and their rheological properties, strengths after 7 and 90 days in case of UHPC and strengths after 7, 28 and 60 days in case of RPC were tested.
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