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Synthèse et fonctionnalisation de nanocristaux fluorescents (Quantum Dots) pour l'imagerie et la caractérisation des propriétés hydrophobes/hydrophiles de biofilms bactériens

Abstract : Microorganisms predominantly live in communities, such as biofilms, in which extracellular polymeric substances (EPS) form the matrix and stabilize the three-dimensional structure. Hydrophobic microdomains allow the cohesiveness of these hydrophilic, polyanionic systems. The localization of these hydrophobic sites is very important to understand the variability and the reactivity of the EPS. The objective of our work was to engineer new fluorescent probes with amphiphilic or hydrophilic properties able to label the EPS. For that purpose, we have synthesized a series of fluorescent CdSe-core nanocrystals, also called Quantum Dots (QDs), modified at their periphery with hydrophilic (3-mercaptopropionic acid) or amphiphilic ligands (dihydrolipoic acid coupled to hydrophobic aminoacids like Leucine or Phenylalanine). Using confocal fluorescence microscopy and fluorescence correlation spectroscopy (FCS), we demonstrated that the functionalized QDs strongly associated with the EPS of S. oneidensis biofilms and allow imaging of these microbial communities. The location of these probes within the EPS was dependent on the surface ligand structure and on its density at the periphery of QDs. A homogeneous dispersion of hydrophilic QDs in the whole biofilm was observed, while amphiphilic QDs clusterized in the small hydrophobic domains. These new fluorescent probes will be of great use to understand the development and the reorganization of complex biological matrix like biofilms.
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https://hal.univ-lorraine.fr/tel-01746378
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  • HAL Id : tel-01746378, version 1

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Fadi Aldeek. Synthèse et fonctionnalisation de nanocristaux fluorescents (Quantum Dots) pour l'imagerie et la caractérisation des propriétés hydrophobes/hydrophiles de biofilms bactériens. Médecine humaine et pathologie. Université Henri Poincaré - Nancy 1, 2010. Français. ⟨NNT : 2010NAN10078⟩. ⟨tel-01746378⟩

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