PhD Work

Nevertheless, there are strong exploratory incentives because of terahertz spectroscopic sensitivity to molecular states (rotational, vibrational…) and weak bounds in and between molecules. In the case of biological object, terahertz waves are especially sensitive to water: its quantity, physico-chemical state and solutes. We implemented an Attenuated Total internal Reflection (ATR) imaging setup in order to distinguish live cells from their physiological bathing medium. 

Throughout this work, I characterized both theoretically and experimentally the ATR setup. The first demonstration of the contrast origin in the terahertz images obtained was done. It arises from the intracellular content, more specifically the proteins and peptides dissolved in the cytoplasm.

A precise analysis of the underlying mechanism of this proteinaceous terahertz contrast has also been developed. It gives access to original spectroscopic information about water, dissolved proteins and the hydration shell around them.

Taking advantage of our whole setup comprehension, we proposed it as a non-invasive tool for quantitative live-cell permeabilization assessment in physiological conditions. During permeabilization, aka increased molecular transfers through the cell membrane, our tool allows to quantify the transfer of peptides and proteins. Live cell permeabilization has a large application range, from fluorochrome entry in imaging, to drugs or gene therapy. In order to ensure molecules crossing the cell membrane, it’s necessary to alter its properties without compromising cell viability. A study of two permeabilization methods has been proposed: chemical permeabilization and electroporation. In both cases dose effect mechanisms were quantitatively characterized. Our terahertz tool demonstrated great advantages over classical permeabilization quantification methods and permeabilization reversibility assessment methods.

Publications

PhD Thesis (in French)

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