Abstract
Classical and quantum electrodynamics theories have predicted the existence of dipole-dipole electrodynamic intermolecular forces since the 1970s, but due to the lack of an experimental platform capable of performing the appropriate tests, these have never been experimentally observed before. In this thesis study and using a specially designed THz spectroscopy device from a biosensor developed for these experiments, we demonstrate experimentally for the first time the activation of resonant electrodynamic forces between biomolecules.By focusing my work on a model protein, R-phycoerythrin (R-PE), which can be excited naturally by an external energy input via a light source, I have been able to demonstrate that if a macromolecule is considered as an open system (energy supply and exchange with a thermal bath), the non-linear internal couplings between its normal modes cause it to undergo a phase transition when the energy input rate exceeds a threshold value. This transition takes place between a state where the energy is incoherently distributed between the normal modes and a state where the input energy is channeled in the lower frequency mode resulting in a coherent oscillation of the whole molecule. By working at different concentrations and different optical excitation powers, I was then able to demonstrate that the activation of the collective intramolecular oscillation of proteins allows to measure a change in the frequency of the collective oscillation when long-range electrodynamics forces are activated, as expected by theoretical work.My thesis work, essentially experimental, thus supports a proof of concept allowing to establish, under certain thermodynamic conditions, that collective oscillations are capable of activating dipole-dipole intermolecular electrodynamic forces at long interaction distances, thus paving the way for the exploration of the potential role of these forces in the life sciences.