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Theses

Chimie de surface de nanocristaux fluorescents pour l’imagerie biologique

Abstract : Semiconductor nanocrystals (or Quantum Dots, QDs) have unique optical properties that make them interesting probes for biological imaging. Thanks to their high quantum fluorescence yields, they are particularly promising for short-infrared fluorescence imaging, which is a spectral domain that allows a good deep spatial resolution in biological tissues. In this PhD, our goal is to study specialy the surface chemistry of QDs in order to optimize their behavior in complex biological medium and to develop functional pH or enzymatic activity imaging probes. The use of nanoparticles (NP) in vivo requires to reduce the formation of a protein corona adsorbed on their surface. It is possible to use so-called "stealth" polymers to limit this adsorption, and avoid their recognition by the immune system. In this PhD we compare the stealth properties of QDs coated with block polymer ligands with different zwitterions. We have shown, particularly, that poly(sulfobetaine) coated QDs allows a complete elimination of protein adsorption in serum, unlike those covered with carboxybetaine or phosphorylcholine. These results are correlated with the diffusion of these QDs in the cytoplasm of living cells. Thanks to the surface chemistry of QDs, it is also possible to design functional probes, for example by modulating their fluorescence by an energy transfer under the action of a biochemical factor. Thus, in this PhD, we demonstrate two concepts using QDs for short or visible infrared pH imaging, developing different pH-sensitive surface chemistries in order to modulate their interaction with gold NPs.
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Submitted on : Monday, August 31, 2020 - 3:34:28 PM
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Manon Debayle. Chimie de surface de nanocristaux fluorescents pour l’imagerie biologique. Matériaux. Sorbonne Université, 2019. Français. ⟨NNT : 2019SORUS481⟩. ⟨tel-02926287⟩

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