New approach to analyse spin probe and spin trap ESR

Electron Spin Resonance (ESR) spectroscopy is a powerful tool for the direct study of free radicals, providing information about their surrounding and identity. Objects that normally don’t possess an unpaired electron also can be studied using the spin probe ESR technique. In this way structural and chemical information about the surrounding of the unpaired electron can be obtained as well as dynamic information about the spin probe motion. ESR spectra contain detailed information about the electron distribution in the molecule and the properties of its surroundings, but the analysis and interpretation of ESR data are quite complicated and involve different approaches ranging from simple estimation of signal intensity to sophisticated modeling of the molecule under study in order to predict its magnetic parameters.

The goal of this thesis is to develop new comprehensive methods for the analysis of ESR spectra and interpretation of magnetic parameters. A new approach for the analysis of fast isotropic spectra is proposed. It is based on a combination of an experimental approach (multifrequency ESR) and accurate spectra simulation using an improved model, that will be further introduced below. The determined magnetic parameters of the spin probe are directly interpreted in terms of structural information about the spin probe surroundings (lipid bilayer). The obtained magnetic parameters of various spin traps are interpreted by artificial neural networks (ANN) in order to obtain information about the identities of trapped radicals.

Then, Density Functional Theory (DFT) calculations are applied to study the mechanism of reactions involving free radicals detected by spin trapping ESR and to calculate magnetic parameters of the radical adducts.