Ultrafine nanoparticles comprising a functionalized polyorganosiloxane matrix and including metal complexes; method for obtaining same and uses thereof in medical imaging and/or therapy

Abstract

The invention relates to novel biocompatible hybrid nanoparticles of very small size, useful in particular for diagnostics and/or therapy. The purpose of the invention is to offer novel nanoparticles which are useful in particular as contrast agents in imaging (e.g. MRI) and/or in other diagnostic techniques and/or as therapeutic agents, which give better performance than the known nanoparticles of the same type and which combine both a small size (for example less than 20 nm) and a high loading with metals (e.g. rare earths), in particular so as to have, in imaging (e.g. MRI), strong intensification and a correct response (increased relaxivity) at high frequencies. Thus, the nanoparticles according to the invention, with diameter dbetween 1 and 20 nm, each comprise a polyorganosiloxane (POS) matrix including gadolinium cations optionally associated with doping cations; a chelating graft CDTPABA (diethylenetriaminepentaacetic acid bisanhydride) bound to the POS matrix by an —Si—C— covalent bond, and present in sufficient quantity to be able to complex all the gadolinium cations; and optionally another functionalizing graft Gf* bound to the POS matrix by an —Si—C— covalent bond (where Gf* can be derived from a hydrophilic compound (PEG); from a compound having an active ingredient PA1; from a targeting compound; from a luminescent compound (fluorescein). The method for the production of these nanoparticles and the applications thereof in imaging and in therapy also form part of the invention.