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Nanofiber membranes with encapsulated photoactive molecules simultaneously generating NO and 1O2 species
Liška, Vojtěch ; Mosinger, Jiří (advisor) ; Kubíček, Vojtěch (referee)
This thesis focuses on the preparation and study of a new type of photoactive polycaprolactone nanofibrous membrane with encapsulated NO photodonor 4-(N- (aminopropyl)-3-(trifluoromethyl)-4-nitrobenzenamine)-7-nitrobenzofurazan and photosensitizer chlorin e6. The electrospun nanofibrous membrane exhibits efficient photogeneration of NO and singlet oxygen molecules, which initiate facial and space photoantibacterial properties. The structure of the prepared NO photodonor was studied by NMR spectroscopy and UV-VIS absorption spectroscopy measurements. The resulting nanofibrous material was studied by scanning electron microscopy, and the successful encapsulation of both photoactive species was studied by absorption and fluorescence spectroscopy. Photogeneration of the NO molecule was studied by direct amperometric detection of NO and by reaction with a chemical substrate. The photogeneration of singlet oxygen O2( Δg 1 ) was studied by time-resolved spectroscopy and by reaction with a chemical substrate. Significant photoantibacterial properties were demonstrated on the bacterial strain Escherichia coli DH5α. Both antibacterial effects were studied by monitoring the number of colony forming units (CFU) using image analysis, and the facial effect by scanning electron microscopy. Keywords: singlet...
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Photoactive chlorophyll nanoparticles
Ludačka, Pavel ; Mosinger, Jiří (advisor) ; Lang, Kamil (referee)
Photoactive sulfonated and non-sulfonated polystyrene nanoparticles (NPs) with encapsulated THF extract from spinach (Spinacia oleracea) were prepared. The preparation of NPs is based on a simple nanoprecipitation method that uses the same solvent (THF) to dissolve the sulfonated or non-sulfonated polystyrene nanofiber membrane and for the extraction itself. Based on spectral and HPLC analysis, it was found that the THF extract and NPs contain chlorophyll a, chlorophyll b, β-carotene and lutein. Time-resolved spectroscopy shows that the extract is a potent source of singlet oxygen O2(1 g) thank to the photosensitizer chlorophyll. The photogeneration of O2(1 g) is partially suppressed by the carotenoids in the extract, which quench O2(1 g). To reduce the quenching effect of carotenoids, it is possible to use dilute extract or pre-irradiated samples with visible light because of carotenoids rapid breakup. A strong photooxidative and antibacterial effect of NPs prepared from an extract generating O2(1 g) was demonstrated on chemical substrates and Escherichia coli. The photoactivity of NPs is initiated by visible light. Key words Chlorophyll, photosensitizer, nanoparticle, singlet oxygen
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Polymer nanoparticles generating singlet oxygen
Berzédiová, Veronika ; Mosinger, Jiří (advisor) ; Tyrpekl, Václav (referee)
This theses focuses on preparation and characterisation and comparison of two types of polymer nanoparticles using photophysical methods. The first type was polystyrene nanoparticles prepared by modified nanoprecipitation method from polymeric sulfonated nanofiber membranes with diffrent content of sulfonated groups. The second type was polymer nanoparticles with diferent lenght of hydrophobic polycaprolactone (PCL) and hydrophilic poly(ethyleneglycol) (PEG) blocks. Both types of nanoparticles conteined encapsulated photosensitizer 5,10,15,20-meso-tetraphenylporphyrin with a high quantum singlet oxygen yield. In the prepared nanoparticles with a photosensitizer, the kinetics of singlet oxygen generation was studied using time resolved spectroscopy. The relative efficiency of photooxidation was studied using external akceptor of singlet oxygen. The effect of temperature, size and matrix (type of polymer) of nanoparticles on photooxidation efficiency was also studied. In the next part of this these was studied the influence of time on the size and stability of nanoparticles and also the effect of solution pH and ionic strength on prepared nanoparticles.
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Delayed fluorescence of Protoporphyrin IX for medical diagnosis
Vinklárek, Ivo ; Scholz, Marek (advisor) ; Alster, Jan (referee)
The aim of this work is to analyse mechanisms of delayed fluorescence in solutions of protoporphyrin IX mainly through measurements of time-resolved spectroscopy. Delayed fluorescence is a type of fluorescence in which luminophore undergoes reversed intersystem crossing from triplet state to singlet state which is subsequently brought to the ground state by emission of photon. One of the applications of delayed fluorescence is a measurement of oxygen partial tension in mitochondria in vivo. For the right interpretation of the data it is necessary to understand the processes of generation of delayed fluorescence. A new experimental setup for simultaneous time-resolved measurements in infra-red and visible spectral regions was developed and tested as a part of the work. Absorption and fluorescence spectra of protoporphyrin IX were measured under different conditions in dimethylformamide and ethylenglycol solutions. The influence of photodegradation was regarded as well. Then we measured kinetics of protoporphyrin IX with the main focus on the influence of singlet oxygen-sensitized delayed fluorescence. Our research indicates that it participates together with thermal delayed fluorescence, which could be helpful in further interpretation and analysis of the experimental data. The research was carried out in...
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