Investigation of the Nano-Bio Interface by the Design and Development of Nanostructured Lanthanide Oxysulfide Thin Films using Ellipsometric and Electrochemical Techniques

Overview & Synopsis

Nanomedicine is the medical use of nanoparticles for the diagnosis and treatment of disease. In diagnosis, nanoparticles can be used both for in vivo diagnosis and for in vitro diagnosis. In this context, (Gd,Ce)2O2S nanoparticles have antioxidant properties conferred by cerium and serve as a contrast agent in MRI thanks to the paramagnetic properties of gadolinium. In vitro as in vivo, nanoparticles interact with proteins, membranes, cells, DNA of organelles. It is therefore important to establish a better understanding of the interface between nanoparticles and biological components, known as the nano-bio interface. It is in this context, at the interface between nanomaterials and biological systems, that this thesis work is articulated. A first chapter presents the chosen method allowing access to the surface of the nanoparticles as well as the tools used. Synthesized colloidally, (Gd,Ce)2O2S NPs are deposited in a thin layer on a substrate by dip coating. A comprehensive study describes their electronic, optical and morphological properties. Finally, the last chapter is dedicated to the study of the nano-bio interface using the thin film as a working electrode in a three-electrode electrochemical system. Using cyclovoltammetry, we were able to study the electronic conduction properties of the system and thus probe the nano-bio interface. Finally, as an opening, we were interested in the use of the thin film as a biosensor allowing the determination of species of interest in solution. A better understanding of the nano-bio interface should enable us to enlighten the community on the decisions to be made when designing nano-objects for nanomedicine.