Surface Engineering of Magnetite Nanoparticles with Redox Ligands for Near Infrared Theranostic Applications

Axe Coeur de Chimie - Synthèse

Projet de recherche mené du 01/11/17 au 30/10/19

Laboratoires porteurs
  • Phénix
    Porteur de projet :
    Ali Abou-Hassan
  • IPCM
Mots clés

magnetite – non-innocent redox ligands – nanomedecine – photothermal nanotherapies

Abstract

The advent of nanotechnology brings along new approaches to face current challenges in tumor therapy. Currently, gold nanoparticles (plasmonic) and maghemite nanoparticles (magnetic) are prime candidates for the development of photothermal and magnetic therapies respectively. These two thermal nanotherapies are being extensively studied, particularly through the constant development of novel nanostructures for an optimized heating. However, for both magnetic and plasmonic modalities, their incontestable assets are still facing important barriers. Combining both therapies i.e photothermal and magnetic hyperthermia by association of both materials in a single nanostructure to form multifunctional nanohybrids would be one strategy to overcome these issues. However, on top of the heat sensitivity issues previously discussed and the cost of gold, synthesis of such structures is both time and money consuming, difficult to control and the biocompatibility of the final structure is not guaranteed; which may limit the application of the hybrids. Chemically, magnetite (Fe3O4) is a conducting mixed valence iron oxide that has an inverse spinel-structure with Fe(II) and Fe(III) in the octahedral sites of the crystal. This distribution of mixed oxidation states at the surface of magnetite was found to produce an intervalence d-d charge transfer (IVCT) that gives rise to an absorption in the second near infrared (NIR-II) region at 1000–1350 nm. Theoretically such intervalence band can be used for photothermia, however the challenge is to avoid Fe(II) oxidation by air in order to preserve it.

Bioinspired by redox cofactors in metalloenzymes, redox non-innocent ligands (NILs) have so far mostly been included in well-defined molecular architectures and their potential use in colloidal chemistry remains unexplored. In this project we propose to use redox ligands for surface engineering of magnetite nanoparticles in order to prevent their surface from oxidation and preserve their electronic  and optical properties in the near infra-red (NIR) which can be used for combined magnetic and photothermia applications in nanomedicine. Moreover NILs will be used as an anchored chemical platform towards surface functionalization while modulating magnetic properties and its spin state which can affect the relaxation times (T1 and T2) for MRI imaging. Consequently a large panel of new functionalities available for theranostic applications will emerge from the combination of magnetite and redox ligands, which are summarized, in this figure.