National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Spectroscopic Study of Singlet Oxygen in Cells and Model Systems
Scholz, Marek ; Dědic, Roman (advisor) ; Heřman, Petr (referee) ; Kubát, Pavel (referee)
Title: Spectroscopic Study of Singlet Oxygen in Cells and Model Systems Author: Marek Scholz Department: Department of Chemical Physics and Optics Supervisor: doc. RNDr. Roman Dědic, Ph.D., KChFO Abstract: Singlet oxygen (1O2), the first excited state of molecular oxygen, plays many important roles in nature and technology. The work is aimed at development of novel methods for monitoring of 1O2 in cells and other biological samples. Two main ap- proaches were employed: direct detection of the very weak near-infrared phospho- rescence of 1O2, and detection of Singlet Oxygen-Feedback Delayed Fluorescence (SOFDF), which is the emission from the photosensitizer induced by energy transfer from 1O2. The first part of the thesis introduces the basic concepts of photophysics and photochemistry of 1O2: its generation, deactivation, applications, and overview of detection methods. The second part presents the experimental results. Wide-field mi- crospectroscopic detection of 1O2 phosphorescence enabled us to acquire 1O2-based images and near-infrared spectra from single cells incubated with photosensitizers. However, the direct detection suffers from the inherently very low phosphorescence quantum yield. It is shown that SOFDF may overcome this problem and become a promising alternative tool for studies of 1O2 and...
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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