Optimisation de dérivés triphénylamines pour le marquage d'ADN: de l'étude des propriétés de fluorescence à deux photons à l'analyse structurale de brins d'ADN

Abstract : Due to the rather poor properties of two-photon induced fluorescence (TPIF) emission of most endogenous biological substances, the performances of two-photon induced microscopy are strongly correlated to the development of specific fluorescent labels. In the frame of a previous work, vinyl-pyridinium substituted triphenylamines dyes (TP) have been shown to exhibit particularly interesting properties: good water solubility, small size, high photostability, high molecular brightness ( 2p f ), fluorescence intensity enhancement in the presence of DNA, red emission... Altogether such properties happen to be rarely met: the aim of the work presented here was to get a better understanding of the origin of such performances together with investigating potential optimization routes. Towards this objective, we have developed a specific time resolved two-photon fluorescent microscopy set-up. Various derivatives have been studied in order to establish structure-properties relationships. Similarly, different environments have been considered (buffer solution, natural and synthetic DNA). We could demonstrate that TP derivatives specifically interact with DNA, presumably via insertion into the minor groove of double stranded DNA. This insertion causes a very strong restriction of intramolecular motions together with a change in the fluorophore environment (experiencing a change from an aqueous environment leading to quenching, to anorganic environment): there results both a reduction of the non-radiative relaxation rate and an increase ofthe radiative relaxation rate. In order to get complementary nanoscale characterization of TP dyes-DNA interactions, we have performed further scanning tunnelling microscopy studies at the UHV-solid interface. We have moreover tried to take advantage of the specific TP-DNA interactions to immobilize DNA onto atomically at gold substrates.
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Germain Metgé. Optimisation de dérivés triphénylamines pour le marquage d'ADN: de l'étude des propriétés de fluorescence à deux photons à l'analyse structurale de brins d'ADN. Biophysique [physics.bio-ph]. Université Paris Sud - Paris XI, 2010. Français. ⟨tel-00592404⟩

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