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Jeudi 27 septembre 2018 à 14h00,
Bâtiment A, Salle de seminaires,
25 Avenue des Martyrs, BP 166, 38042 Grenoble Cedex 9

Orateur : Shridevi SHENOI-PERDOOR
"Fluorescent organic@silicate core-shell nanoparticles for in vivo vascular imaging"

Abstract

The aim of this work is the synthesis, optimization and functionalization of fluorescent organic@inorganic core-shell nanoparticles (NPs) to be used for two-photon deep tissue imaging of tumor vascularization. They comprise an organic dye nanocrystalline core surrounded by a silicate crust, and are synthesized using an original spray-drying method. This one-step synthesis requires the control of both the sol-gel chemistry and the nanocrystallization process. Alkoxide precursors, tetramethoxysilane and 1.2-bis(trimethoxysilyl)ethane are chosen to form the silicate shell while an azide-containing organosilane is added to enable further functionalization with alkyne-modified moieties using a click reaction. The organic dyes for the nanocrystalline core are designed to exhibit high fluorescence intensity in the crystal state under two-photon excitation in the near infrared and the appropriate physico-chemical properties to enable their nanocrystallization. Defect-free NPs with high brightness under two-photon excitation were obtained for four of these dyes. The synthesized NPs were then derivatized with different forms of alkyne-modified polyethylene glycol (PEG) to improve their colloidal stability by steric stabilization. The effects of the functionalization were studied using different characterization tools such as fluorescence spectroscopy and dynamic light scattering (DLS) under physiological conditions. The interactions of these core-shell NPs with different plasma proteins were thus investigated, with minimal aggregation in the presence of high concentrations of proteins. Preliminary two-photon fluorescence imaging tests in mice exhibit high brightness.

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