Abstrakt
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 excited states of photosensitizers.
The work provides one of the very scarce systematic studies of SOFDF in biologi- cally relevant samples, spanning from solutions of photosensitizers to time-resolved microscopic detection of SOFDF from individual living cells.