title: Novel contributions on luminescent apatite-based colloids intended for medical imaging.
abstract: The setup of colloidal hybrid nanosystems based on biomimetic calcium phosphate apatites doped with europium ions has recently raised great interest in the pharmacological community, especially due to their bio-inspired character. This is especially relevant in relation with medical imaging for cancer diagnosis. Questions however remain in relation to a number of applicability aspects, some of which have been examined in this contribution. In a first part of this work, we explored further the luminescence properties of such colloidal nanoparticles. We pointed out, upon excitation of europium, the existence of some non-radiative de-excitation via the vibration of O-H oscillators located at the vicinity of the Eu(3+) luminescent centers. The replacement of Eu(3+) by Tb(3+) ions, less prone to non-radiative de-excitation, was then tested in a preliminary way and can be seen as a promising alternative. In a second part of this work, we inspected the possibility to store these colloids in a dry state while retaining a re-suspension ability preserving the nanometer size of the initial nanoparticles, and we propose a functional protocol involving the addition of glucose prior to freeze-drying. We finally showed for the first time, based on titrations of intracellular Ca(2+) and Eu(3+) ions, that folic acid-functionalized biomimetic apatite nanoparticles were able to target cancer cells that overexpress folate receptors on their membrane, which we point out here in the case of T-47-D breast carcinoma cells, as opposed to ZR-75-1 cells that do not express folate receptors. This contribution thus opens new exciting perspectives in the field of targeted cancer diagnosis, thus confirming the promise of biomimetic apatites-based colloidal formulations.
authors: 1CIRIMAT Carnot Institute, UMR CNRS/INPT/UPS, University of Toulouse, France.
authors: Ahmed
authors: A
authors: Al-Kattan
authors: Veronique
authors: V
authors: Santran
authors: Pascal
authors: P
authors: Dufour
authors: Jeannette
authors: J
authors: Dexpert-Ghys
authors: Christophe
authors: C
authors: Drouet
mesh_terms: D001031:Apatites / Q000737:chemistry*; D045744:Cell Line, Tumor; D003102:Colloids; D003952:Diagnostic Imaging; D005492:Folic Acid / Q000737:chemistry; D006801:Humans; D049449:Luminescence
chemical_list: D001031:Apatites; D003102:Colloids; D005492:Folic Acid
keywords: Bionanotechnology; biomimetic apatites; cancer; colloids; hybrid materials; hydroxyapatite; luminescence; materials-cells interactions